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					                                                               Telecom / IS Glossary                                                          Page 1 of 150

                 Term                                         Description                                              Definition
100BaseT                                                                                       An Ethernet transmission standard operating at 100
                                                                                               megabits per second.
10BaseF                                                                                        10-Mbps baseband Ethernet specification that refers to the
                                                                                               10BaseFB, 10BaseFL, and 10BaseFP standards for
                                                                                               Ethernet over fiber-optic cabling.
10BaseFB                                                                                       10-Mbps baseband Ethernet specification using fiber-optic
                                                                                               cabling. 10BaseFB is part of the IEEE 10BaseF
                                                                                               specification. It is not used to connect user stations, but
                                                                                               instead provides a synchronous signaling backbone that
                                                                                               allows additional segments and repeaters to be connected
                                                                                               to the network. 10BaseFB segments can be up to 1.24
                                                                                               miles (2000 meters) long.
10BaseFL                                                                                       10-Mbps baseband Ethernet specification using fiber-optic
                                                                                               cabling. 10BaseFL is part of the IEEE 10BaseF specification
                                                                                               and, while able to interoperate with FOIRL, is designed to
                                                                                               replace the FOIRL specification. 10BaseFL segments can
                                                                                               be up to 3280 feet (1000 meters) long if used with FOIRL,
                                                                                               and up to 1.24 miles (2000 meters) if 10BaseFL is used
                                                                                               exclusively.
10BaseFP                                                                                       10-Mbps fiber-passive baseband Ethernet specification
                                                                                               using fiber-optic cabling. 10BaseFP is part of the IEEE
                                                                                               10BaseF specification. It organizes a number of computers
                                                                                               into a star topology without the use of repeaters. 10BaseFP
                                                                                               segments can be up to 1640 feet (500 meters) long.
10BaseT                                                                                        An implementation of the Ethernet IEEE standard on 24-
                                                                                               gauge, unshielded twisted-pair wiring, a baseband medium,
                                                                                               at 10 megabits per second.
2.5G                                                                                           Second and half generation (GPRS, EDGE)
2B1Q                                        Two Binary, One Quaternary                         The line code is the ISDN and ADSL standard for
                                                                                               transmission of two voice and data channels at 64 kbps and
                                                                                               one data and signaling channel at 16 kbps. Provides a 2 bits
                                                                                               per baud, 80-kbaud per second, 160-kbps transfer rate. The
                                                                                               most common signaling method on ISDN U interfaces.
2G                                                                                             Second generation (GSM, TDMA, CDMA, PCS)



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 2 of 150

                     Term                                      Description                                              Definition
3G                                                                                             Third generation (UMTS, TD -CDMA, W-CDMA)
3GPP                                                                                           3rd Generation Partnership Project, defining UMTS
                                                                                               standards
4B/5B local fiber                           4-byte/5-byte local fiber                          Fiber channel physical media used for FDDI and ATM.
                                                                                               Supports speeds of up to 100Mbps over multimode fiber.
6BONE                                                                                          The Internet's experimental IPv6 network.
802.x                                                                                          Set of IEEE standards for the definition of LAN protocols.
8B/10B local fiber                          8-byte/10-byte local fiber                         Fiber channel physical media that supports speeds up to
                                                                                               149.76 Mbps over multimode fiber.
A                                           Angstrom                                           A measure of optical wavelength equal to one hundred-
                                                                                               millionth of a centimeter. This unit of measure is being
                                                                                               replaced by nanometers.
A&B Bit Signaling                                                                              Procedure used in T1 transmission facilities in which each
                                                                                               of the 24 T1 subchannels devotes 1 bit of every sixth frame
                                                                                               to the carrying of supervisory signaling information. Also
                                                                                               called 24th channel signaling.
AAA                                         Authentication, Authorization, Accounting          Pronounced "triple a."
AAL                                         ATM Adaptation Layer                               The AAL enables engineers to adapt the ATM layer to
                                                                                               particular services. It lies between the ATM layer and the
                                                                                               higher layers and maps or adapts the functions or services
                                                                                               of the higher layers onto a common ATM bearer service.
AAR                                         Automatic Alternative Routing                      A system for providing continued telecommunications
                                                                                               service in the event that a primary transmission route fails
                                                                                               catastrophically.
AARP                                        AppleTalk Address Resolution Protocol              Protocol in the AppleTalk protocol stack that maps a data-
                                                                                               link address to a network address.
ABCD Signaling                                                                                 4-bit telephony signaling coding in which each letter
                                                                                               represents 1 of the 4 bits. This is often associated with CAS
                                                                                               or robbed-bit signaling on a T1 or E1 telephony trunk.
ABGA                                        Advanced Ball Grid Array                           Chip package




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                         Page 3 of 150

                  Term                                           Description                                            Definition
ABM                                         Asynchronous Balanced Mode                         HDLC (and derivative protocol) communication mode
                                                                                               supporting peer-oriented, point-to-point communications
                                                                                               between two stations, where either station can initiate
                                                                                               transmission.
ABR                                         Available Bit Rate                                 QoS class defined by the ATM Forum for ATM networks.
                                                                                               ABR is used for connections that do not require timing
                                                                                               relationships between source and destination. ABR provides
                                                                                               no guarantees in terms of cell loss or delay, providing only
                                                                                               best-effort service. Traffic sources adjust their transmission
                                                                                               rate in response to information they receive describing the
                                                                                               status of the network and its capability to successfully
                                                                                               deliver data.
ABR                                         Area Border Router                                 Router located on the border of one or more OSPF areas
                                                                                               that connects those areas to the backbone network. ABRs
                                                                                               are considered members of both the OSPF backbone and
                                                                                               the attached areas. They therefore maintain routing tables
                                                                                               describing both the backbone topology and the topology of
                                                                                               the other areas.
ABS                                         Alternative Billing Services                       These are IN services that allow subscribers to charge a call
                                                                                               to a number or telephone other than the one they are using-
                                                                                               for example, by using a charge card, credit card or personal
                                                                                               identification number.
AC                                          Access Charge                                      Monies collected by local telephone companies for use of
                                                                                               their circuits to originate and terminate long-distance calls.
                                                                                               Access charges can be per minute fees levied on long-
                                                                                               distance companies; subscriber line charges (SLCs) levied
                                                                                               directly on regular local lines; fixed monthly fees for special
                                                                                               telephone company circuits such as WAL, DAL, and T-1; or
                                                                                               special access surcharges levied on special access circuits.
Acceptance Mask                                                                                A collection of thresholds assigned to circuit performance
                                                                                               parameters. When used during circuit testing, it
                                                                                               automatically reports whether a particular performance
                                                                                               parameter has failed.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 4 of 150

                   Term                                       Description                                              Definition
Access                                                                                         The method, time, circuit, or facility used to enter the
                                                                                               network. (2) The service provided by local exchange
                                                                                               carriers or alternate access providers, that connects an
                                                                                               interexchange carrier with its customers. Switched access
                                                                                               provides such service over the public switched network;
                                                                                               special access provides dedicated access for private line
                                                                                               services and sometimes at the closed end of switched
                                                                                               services. (3) To retrieve information from a storage
                                                                                               medium. such as videodisc, CD-ROM, computer disc or
                                                                                               videotape.
Access Bandwidth                                                                               The ability of a communications network to provide
                                                                                               bandwidth dynamically so users will receive service
                                                                                               regardless of the bandwidth their service request requires.
Access Code                                                                                    A digit or digits presented to telecommunications equipment
                                                                                               that permits the user to connect to a given service. In
                                                                                               private branch exchange (PBX) operation, access code is
                                                                                               the digits that are dialed connecting a telephone user to a
                                                                                               specific trunk group or to a special service such as paging
                                                                                               or dictation. The term is also frequently applied to the "1"
                                                                                               dialed in many local telephone company areas for the
                                                                                               completion of an interexchange toll call.
Access List                                                                                    List kept by routers to control access to or from the router
                                                                                               for a number of services (for example, to prevent packets
                                                                                               with a certain IP address from leaving a particular interface
                                                                                               on the router).
Access Method                                                                                  In local area networks, the technique and/or program code
                                                                                               used to arbitrate the use of the communications medium by
                                                                                               granting access selectively to individual stations. Examples
                                                                                               are carrier sense multiple access/collision detection
                                                                                               (CSMA/CD) and Token Passing.
Access Router                                                                                  An access device with built-in basic routing protocol
                                                                                               support, specifically designed to allow remote LAN access
                                                                                               to corporate backbone networks. Not designed to replace
                                                                                               backbone routers or to build backbone networks.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 5 of 150

                 Term                                           Description                                            Definition
Access Time                                                                                    The total time required to find, retrieve, and display data
                                                                                               after initiation of a retrieval command. Access time is
                                                                                               usually measured at its worst, or the longest possible time it
                                                                                               takes to get from one section of the medium to another. This
                                                                                               is generally a matter of minutes on videotape two or fewer
                                                                                               seconds on videodisc or CD, and milliseconds or
                                                                                               microseconds on a computer.
ACD                                         Automatic Call Distribution                        Large scale telephone switch with software that has a high
                                                                                               degree of intelligence geared toward routing calls; allows
                                                                                               you to determine how you want calls routed within the
                                                                                               support unit and provides management reports
AC-DC Ringing                                                                                  A system in which telephone ringing uses alternating current
                                                                                               to operate a ringer and direct current to stop the ringing
                                                                                               when the called party answers.
ACDS                                        Automatic Call Distribution Systems                Used by telephone companies and private businesses for
                                                                                               managing high volumes of incoming calls.
ACF                                         Advanced Communications Function                   IBM software products that incorporate IBM's system
                                                                                               network architecture (SNA) and administer
                                                                                               intercommunications between computers.
ACH                                         Automatic Cash Handling                            Mechanized processes for accepting payment from a
                                                                                               customer (such as credit card, debit card, wire transfer,
                                                                                               etc.).
ACK                                         Acknowledgment Code                                A method in which one or more characters are generated at
                                                                                               a receiving device to indicate the information has been
                                                                                               received correctly.
ACR                                         Allowed Cell Rate                                  Parameter defined by the ATM Forum for ATM traffic
                                                                                               management. ACR varies betweent the MCR and the PCR,
                                                                                               and is dynamically controlled using congestion control
                                                                                               mechanisms.
ACS                                         Asynchronous Comunications Server                  A LAN server that enables a network user to dial out of the
                                                                                               network and into the public switched telephone network
                                                                                               (PSTN), or to access nailed-up lines for asynchronous
                                                                                               communications. An asynchronous communications server
                                                                                               is also called a dial-in/dial-out server or a modem server.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 6 of 150

                   Term                                       Description                                              Definition
ACSE                                        Association Control Service Element                OSI convention used to establish, maintain, or terminate a
                                                                                               connection between two applications.
Active Hub                                                                                     Multiported device that amplifies LAN transmission signals.
AD                                          Administrative Domain                              Group of hosts, routers, and networks operated and
                                                                                               managed by a single organization.
Adaptive Equalization                                                                          A technique that allows a modem to continuously analyze
                                                                                               and compensate for variations in the quality of a telephone
                                                                                               line.
Adaptive Routing                                                                               A form of routing in which messages are forwarded through
                                                                                               the network along the most cost-effective path available.
                                                                                               Messages are automatically rerouted as required by
                                                                                               changes in the network topology if, for example, a circuit
                                                                                               becomes disabled.
ADC                                         Access Deficit Charge
ADCCP                                       Advanced Data Communications Control Protocol      ANSI standard bit-oriented data link control protocol.
Address                                                                                        A set of numbers that uniquely identifies something: a
                                                                                               workstation on a LAN, a location in computer memory, or a
                                                                                               packet of data traveling through a network.
Address Mask                                                                                   A 32-bit-long mask used to select an Internet protocol (IP)
                                                                                               address for subnet addressing. The mask selects the
                                                                                               network portion of the IP address and one or more bits of
                                                                                               the local area network (LAN) address.
Address Translation                                                                            Facilities interconnection of multiple networks that each
                                                                                               have their own address plan.
Address Translation                                                                            The process of converting external addresses into
                                                                                               standardized network addresses and vice versa.
Ad-Hoc Mode                                                                                    A client setting that provides independent peer-to-peer
                                                                                               connectivity in a wireless LAN. An alternative set-up is
                                                                                               where PCs communicate with each other through an AP.
                                                                                               See AP and Infrastructure Mode.
ADM                                         Add Drop Multiplexer                               In OSS, a multiplexer that allows a signal to be added into
                                                                                               or dropped out of a SONET span.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                        Page 7 of 150

                 Term                                         Description                                              Definition
ADMD                                        Administrative Management Domain                   X.400 Message Handling System public carrier. The
                                                                                               ADMDs in all countries worldwide together provide the
                                                                                               X.400 backbone.
ADONIS                                                                                         The submarine cable between France and Greece.
ADPCM                                       Adaptive Differential Pulse Code Modulation        Process by which analog voice samples are encoded into
                                                                                               high-quality digital signals.
ADS                                         Asynchrous Data Switching                          A private branch exchange (PBX) system that supports
                                                                                               asynchronous data.
ADSL                                        Asymmetric Digital Subscriber Line                 A digital local loop typically using copper facilities and
                                                                                               providing greater bandwidth in one direction than the other.
                                                                                               ADSL is expected to provide a voice channel for calls over
                                                                                               the public switched network, a bi-directional low-speed data
                                                                                               channel, and a unidirectional 1.5 Mbps channel between the
                                                                                               central office (CO) and the customer premise.
ADU                                         Automatic Dialing Unit                             A device that is programmed with frequently called
                                                                                               numbers. The caller presses one to three digits and the
                                                                                               preprogrammed number is automatically dialed into the
                                                                                               telephone circuit.
AEGUS                                                                                          The submarine cable between Greece and Crete.
AFE                                         Analogue Front End
AFIPS                                       American Federation of Information Processing      An organization of computer-related societies. Members
                                            Societies                                          include the Association for Computer Machinery, the
                                                                                               Institute of Electrical and Electronic Engineers Computer
                                                                                               Group, Simulation Councils, Inc., and American Society for
                                                                                               Information Science.
AGC                                         Automatic Gain Control                             A process that levels out high and low levels of sound to
                                                                                               improve the consistency of the recording.
Agent                                                                                          In NMSs, process that resides in all managed devices and
                                                                                               reports the values of specified variables to management
                                                                                               stations.
Agent                                                                                          Software that processes queries and returns replies on
                                                                                               behalf of an application.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                      Telecom / IS Glossary                                                      Page 8 of 150

                 Term                                            Description                                            Definition
Aggregate Bandwidth                                                                            The total bandwidth of channel carrying a multiplexed bit
                                                                                               stream.
Aggregator                                                                                     An independent entity that brings several subscribers
                                                                                               together to form a group that can obtain long-distance
                                                                                               service at a reduced rate. Subscribers are billed by the
                                                                                               original interchange carrier (IXC). The aggregator only
                                                                                               provides the initial set-up of the plan, and usually provides
                                                                                               no service after that. An aggregator is not a reseller.
AH                                                                                             Authentication Header. A field that follows the IP header in
                                                                                               an IP datagram and provides authentication and integrity
                                                                                               checking for the datagram.
AI                                          Artificial Intelligence                            The capacity of a device to perform human intelligence
                                                                                               functions, such as reasoning, learning, and self-
                                                                                               improvement.
AIM                                         Ascend Inverse Multiplexing Protocol               An in-band protocol used to manage the interconnection of
                                                                                               two remotely located inverse multiplexers.
AIN                                         Advanced Intelligent Network                       A switched voice and data network consisting of a variety of
                                                                                               network elements. It refers to open interfaced, multi-vendor,
                                                                                               telecommunications capabilities that let phone companies
                                                                                               create and customize their service offerings. Also, often
                                                                                               used as shorthand for the next-generation INs.
AIO                                         Asynchronous Input/Output
AIOD                                        Automatic Identification of Outward Dialing        A hardware system or private branch exchange (PBX)
                                                                                               feature that automatically obtains the identity of a calling
                                                                                               station over a separate data link for automatic message
                                                                                               accounting.
AIS                                         Alarm Indication Signal                            In a T1 transmission, an all-ones signal transmitted in lieu of
                                                                                               the normal signal to maintain transmission continuity and to
                                                                                               indicate to the receiving terminal that there is a transmission
                                                                                               fault that is located either at, or upstream from, the
                                                                                               transmitting terminal.
Alarm                                                                                          Notification of an event with a defined severity level. SNMP
                                                                                               message notifying an operator or administrator of a network
                                                                                               problem.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                           Page 9 of 150

                   Term                                       Description                                               Definition
ALBO                                        Automatic Line Build Out                           A method to ease data service unit (DSU) and channel
                                                                                               service unit (CSU) installation by enabling the DSU/CSU to
                                                                                               adjust signal output automatically according to line distance.
Algorithm                                                                                      A set of instructions or mathematical formulas used to solve
                                                                                               a given communications problem. In audio, video and data
                                                                                               coding, the step-by-step procedure (often including
                                                                                               repetition) which provides suitable compression and/or
                                                                                               encryption for the specific application. When used for
                                                                                               compression, this mathematical process results in a
                                                                                               significant reduction in the number of bits required for
                                                                                               transmission and may be either lossless or lossy.
Alias                                                                                          A false signal produced by the analog-to-digital sampling
                                                                                               process. Often caused by failure to observe the Nyquist
                                                                                               criterion and can create artifacts which are subjectively
                                                                                               disturbing. A name that users can use on a bulletin board
                                                                                               that is not their own. Also called handle.
Aliasing                                                                                       A form of image distortion associated with signal sampling.
                                                                                               A common form of aliasing is a stair-stepped appearance
                                                                                               along diagonal and curved lines.
ALM                                         ATM Layer Multiplexer
ALPAL                                                                                          The submarine cable that links Algeria, Palma, and Spain.
Alternate Access                                                                               A form of local access where the provider is not the local
                                                                                               exchange carrier (LEC) but is authorized or permitted to
                                                                                               provide local access service.
Alternate Access Carriers                                                                      Local exchange carriers that compete directly with the
                                                                                               regional Bell operating companies (RBOCs). They are
                                                                                               normally found only in the larger metropolitan areas.
                                                                                               Examples are Teleport and Metropolitan Fiber Systems.
AM                                          Amplitude Modulation                               The technique of varying the amplitude or wavelength of a
                                                                                               carrier wave in direct proportion to the strength of the input
                                                                                               signal while maintaining a constant frequency and phase.
AMA                                         Automatic Messaging Accounting                     In OSS, the automatic collection, recording, and processing
                                                                                               of information relating to calls for billing purposes.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                        Page 10 of 150

                  Term                                        Description                                              Definition
AMADNS                                      AMA Data Networking System                         In OSS, the next generation (formerly Bellcore) system for
                                                                                               the collection and transport of AMA data from central office
                                                                                               switches to a billing system.
AMI                                         Alternative Mark Inversion                         Line-code type used on T1 and E1 circuits. In AMI, zeros
                                                                                               are represented by 01 during each bit cell, and ones are
                                                                                               represented by 11 or 00 alternately, during each bit cell.
                                                                                               AMI requires that the sending devices maintain ones
                                                                                               density. Ones density is not maintained independently of the
                                                                                               data stream. Sometimes called "Binary Coded Alternate
                                                                                               Mark Inversion."
AMITE                                                                                          The submarine cable between France and Morocco.
Amplitude                                                                                      Maximum value of an analog or a digital waveform.
AMPS                                        Advanced Mobile Phone Service                      A North American standard for mobile telephones.
Analog                                                                                         A device or method that uses nondiscrete variations in
                                                                                               frequency, amplitude, location, and so forth to symbolize or
                                                                                               carry sounds, signals, mathematical data, or other
                                                                                               information. Analog technology mimics information so that a
                                                                                               voice is represented as an electrical signal with frequency
                                                                                               and amplitude proportional to the pitch and volume of the
                                                                                               voice. Traditional telephone and video are both analog
                                                                                               technologies.
Analog Channel                                                                                 A channel that imposes no specified limits on transmitted
                                                                                               data. There are no discrete packages or pulses of
                                                                                               information.
Analog Loopback                                                                                A test that checks whether the modem or data terminal
                                                                                               equipment (DTE) is causing errors in data transmssion.
                                                                                               During an analog loopback, the system sends data between
                                                                                               the local modem and the local DTE. Errors in transmission
                                                                                               indicate a problem with the modem, DTE, or the interface
                                                                                               between them.
Analog Transmission                                                                            Signal transmission over wires or through the air in which
                                                                                               information is conveyed through the variation of some
                                                                                               combination of signal amplitude, frequency, and phase.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                        Page 11 of 150

                 Term                                            Description                                            Definition
ANC                                         All Number Calling                                 Telephone calling numbers containing all numerical digits
                                                                                               instead of a combination of two letters and five numbers.
ANI                                         Automatic Number Identification                    SS7 (signaling system 7) feature in which a series of digits,
                                                                                               either analog or digital, are included in the call, identifying
                                                                                               the telephone number of the calling device.
ANNIBAL                                                                                        The submarine cable between France and Tunisia.
Anonymous FTP                                                                                  Allows a user to retrieve documents, files, programs, and
                                                                                               other archived data from anywhere on the Internet without
                                                                                               having to establish a userid and password. By using the
                                                                                               special userid of anonymous, the network user will bypass
                                                                                               local security checks and will have access to publicly
                                                                                               accessible files on the remote system.
ANSI                                        American National Standards Institute              ANSI creates standards for networking and
                                                                                               communications. It is the U.S. representative to the
                                                                                               International Standards Organization (ISO)
ANTINEA                                                                                        The submarine cable between Senegal and Morocco.
Anycast                                                                                        In ATM, an address that can be shared by multiple end
                                                                                               systems. An anycast address can be used to route a
                                                                                               request to a node that provides a particular service.
ANZCAN                                                                                         The submarine cable that links Australia, New Zealand, and
                                                                                               Canada.
AOC                                         All Ones Code                                      A signal stream containing 15,360 or less zeros in one
                                                                                               second. When a device loses synchronization, it sends an
                                                                                               all ones code to keep the network up. It also sends this
                                                                                               code to tell the network there is a transmission problem.
AOS                                         Alternative Operator Services                      Business not associated with the telephone company that
                                                                                               provides operator services, for example, to private pay
                                                                                               phone companies.
AP                                          Access Point                                       A hardware device, or software used in conjunction with a
                                                                                               computer, that serves as a communications "hub" for
                                                                                               wireless clients and provides a connection to a wired LAN.
                                                                                               An AP can double the range of wireless clients and provide
                                                                                               enhanced security.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                            Page 12 of 150

                 Term                                         Description                                                Definition
APA                                         Access Provider Architecture                       The specifications of a system and the method in which its
                                                                                               subcomponents interconnect, interact, and cooperate.
                                                                                               Architectures are often described in multiple levels of
                                                                                               abstraction from low-level physical to higher-level logical
                                                                                               application and end-user views.
APD                                         Avalanche Photo Diode
API                                         Application Programming Interface                  A programming interface for accessing and administering
                                                                                               ISDN services
APLT                                        Advanced Private Line Termination                  An AT&T term referring to a private branch exchange (PBX)
                                                                                               user's ability to access all the services of an Enhanced
                                                                                               Private Switched Communications Services (EPCS)
                                                                                               network.
APNG                                                                                           The submarine cable between Australia and Papua New
                                                                                               Guinea.
APNIC                                       Asia Pacific Network Information Center            Nonprofit Internet registry organization for the Asia Pacific
                                                                                               region. The other Internet registries are currently IANA,
                                                                                               RIPE NCC and Inter NIC.
Apogee                                                                                         The point in a satellite's orbit that is farthest from the earth.
APOLLO                                                                                         The submarine cable between Greece and Cyprus.
APPC                                        Advanced Program-to-Program Communications         A set of IBM protocols also known as LU 6.2 and Type 2.1
                                                                                               architectures. It functions within SNA's APPN to support
                                                                                               peer to-peer communications between workstations
                                                                                               attached to SNA LANs and the applications running on
                                                                                               those workstations. It was added to SNA as part of the
                                                                                               "new" SNA to support peer to-peer networking, unlike the
                                                                                               traditional hierarchical SNA approach in which the
                                                                                               mainframe acts as host or master and treats the other
                                                                                               computer as a terminal or slave.
AppleTalk                                                                                      Apple Computer's proprietary local area network (LAN)
                                                                                               protocol suite for linking Macintoshes and peripheral
                                                                                               devices. AppleTalk is a carrier sense multiple
                                                                                               access/collision detection (CSMA/CA) network with 115
                                                                                               Kbps data rate and allows connecting up to 32 devices.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 13 of 150

                   Term                                       Description                                               Definition
Application software                                                                           A software program running on top of the operating system
                                                                                               (Windows, UNIX, Mac) that has been created to perform a
                                                                                               specific task for a user. Examples include word processing
                                                                                               software like Word/Word Perfect, spreadsheets like Excel or
                                                                                               Lotus 123, home finance packages like Quicken, etc.
APPN                                        Advanced Peer-to-Peer Networking                   Enhancement to the original IBM SNA architecture. APPN
                                                                                               handles session establishment between peer nodes,
                                                                                               dynamic transparent route calculation, and traffic
                                                                                               prioritization for APPC traffic.
APPN+                                                                                          Next generation APPN that reduces the label-swapping
                                                                                               routing algorithm with source routing. Also called "high-
                                                                                               performance routing"
APS                                         Automatic Protection Switching                     SONET switching mechanism that routes traffic from
                                                                                               working lines to protect them in case of a line card failure or
                                                                                               fiber cut.
AR(1)                                       Alternate Route                                    A secondary communications path to a destination when the
                                                                                               primary path is unavailable.
AR(1)                                       Access Rate                                        The data rate of the user access channel. The speed of the
                                                                                               access channel determines how rapidly (maximum rate) the
                                                                                               end user may inject data into the network.
ARD                                         Automatic Ring Down                                A private line connecting a station instrument in one location
                                                                                               to a station instrument in a distant location with automatic
                                                                                               two-way signaling. The automatic two-way signaling used
                                                                                               on these circuits causes the station instrument on one end
                                                                                               of the circuit to ring when the station instrument on the other
                                                                                               end goes off-hook. This circuit is sometimes called a "hot-
                                                                                               line" because urgent communications are typically
                                                                                               associated with this service. ARD circuits are commonly
                                                                                               used in the financial industry. ARD circuits also have one-
                                                                                               way signaling, where station A rings station B when station
                                                                                               A goes off hook, but station B cannot ring station A.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                          Page 14 of 150

                 Term                                          Description                                               Definition
ARIN                                        American Registry for Internet Numbers             Nonprofit organization for the purpose of administrating and
                                                                                               registrating IP numbers to the geographical areas currently
                                                                                               managed by Network Solutions (InterNIC). Those areas
                                                                                               include, but are not limited to, North America, South
                                                                                               America, South Africa, and the Caribbean.
ARM                                         Asynchronous Response Mode                         HDLC communication mode involving one primary station
                                                                                               and at least one secondary station, where either the primary
                                                                                               or one of the secondary stations can initiate transmissions.
ARP                                         Address Resolution Protocol                        This portion of the TCP/IP protocol maps an IP adress to
                                                                                               the physical address (Ethernet address) of the PC that it is
                                                                                               on, helping to identify PCs on an Ethernet LAN
ARPA                                        Advanced Research Projects Agency                  The U.S. Department of Defense agency that supports the
                                                                                               ARPAnet resource-sharing computer network.
ARPANET                                     Advanced Research Projects Agency Network          The Advanced Research Projects Agency Network
                                                                                               developed by the eponymous research agency in the 1960s
                                                                                               as the first, large scale, packet switched network. It is still I
                                                                                               in use today, connecting a large number of universities in
                                                                                               the US and Europe, as well as commercial users.
ARQ                                         Automatic Repeat Request                           Communication technique in which the receiving device
                                                                                               detects errors and requests retransmissions.
ARTEMIS                                                                                        The submarine cable between France and Greece.
ARU                                         Alarm Relay Unit
AS                                          Answer Supervision                                 An electrical signal the local telephone company at the
                                                                                               distant end of a long-distance call sends back up the line to
                                                                                               indicate positively the call has been answered by the called
                                                                                               party. The signal tells billing equipment to start timing the
                                                                                               call.
AS                                          Analog Signal                                      A signal, in the form of a continuous varying physical
                                                                                               quantity such as voltage, that reflects variations in some
                                                                                               quantity, such as loudness in the human voice.
ASAC                                        Any Service, Any Credit




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                        Page 15 of 150

                 Term                                          Description                                              Definition
ASAM                                        ATM Subscriber Access Multiplexer                  A telephone central office multiplexer that supports SDL
                                                                                               ports over a wide range of network interfaces. An ASAM
                                                                                               sends and receives subscriber data (often Internet services)
                                                                                               over existing copper telephone lines, concentrating all traffic
                                                                                               onto a single high-speed trunk for transport to the Internet or
                                                                                               the enterprice intranet. This device is similar to a DSLAM
                                                                                               (diferent manufacturers use different terms for similar
                                                                                               devices).
ASCII                                       American Standard Code For Information             ASCII is a character-encoding system for local area
                                            Interchange                                        networks (LANs). The 128 standard ASCII characters are
                                                                                               composed of seven bits, and have the values 0-127. The
                                                                                               extended ASCII character set contains another 128 values.
ASCU                                        Agent-Set Control Unit
ASEANIS                                                                                        The submarine cable between Indonesia and Singapore.
ASEANPS ASEAN                                                                                  The submarine cable between The Philippines and
                                                                                               Singapore.
ASI                                         ATM Service Interface
ASIC                                        Application Specific Integrated Circuit
ASIM                                                                                           Automated Security Incident Measurement. Monitoring of
                                                                                               network traffic and collection of information on networks by
                                                                                               detecting unauthorized network activity.
ASN                                         Auxiliary Signal Network
ASP                                         Application Service Provider                       A company providing IT services for users who do not want
                                                                                               to run all their own IT activities. ASPs run enterprise
                                                                                               software on their own computers; companies access this
                                                                                               over a telecommunications network. This field of activity can
                                                                                               be referred to as applications hosting.
ASR                                         Access Service Request                             A document or data transaction sent to the local exchange
                                                                                               carrier (LEC) to order the local access portion of a circuit.
ASSP                                        Application Specific Standard Product




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 16 of 150

                 Term                                         Description                                               Definition
Asynchronous Transmission                                                                      Term describing digital signals that are transmitted without
                                                                                               precise clocking. Such signals generally have diferent
                                                                                               frequencies and phase relationships. Asynchronous
                                                                                               transmissions usually encapsulate individual characters in
                                                                                               control bits (called start and stop bits) that designate the
                                                                                               beginning and end of each character.
ATB                                         All Trunks Busy                                    A single tone interrupted at a 60 or 120 impulses-per-minute
                                                                                               (ipm) rate that indicates all lines or trunks in a routing group
                                                                                               are busy.
ATC                                         Adaptive Transform Coding                          A voice coding technique used between 9.6 kbps and 32
                                                                                               kbps.
ATDM                                        Asynchronous Time-Division Multiplexing            Method of ending information that resembles normal TDM,
                                                                                               except that time slots are allocated as needed rather than
                                                                                               preassigned to specific transmitters.
ATLANTIS                                                                                       The submarine cable between Portugal and Brazil.
ATM                                         Asynchronous Transfer Mode                         A method of communications in which information is
                                                                                               transmitted in "cells". Transmission rates from 150 megabits
                                                                                               per second to 600 mbps are under consideration.
ATM Endpoint                                                                                   Point in an ATM network where an ATM connection is
                                                                                               initiated or terminated. ATM endpoints include ATM -
                                                                                               attached workstations, ATM-attached servers, ATM -to-LAN
                                                                                               switches, and ATM routers.
ATM Forum                                                                                      ATM standardization organisation
ATM Layer                                                                                      Service-independent sublayer of the data link layer in an
                                                                                               ATM network. The ATM layer receives the 48-byte payload
                                                                                               segments from the AAL and attaches a 5-byte header to
                                                                                               each, producing standard 53-byte ATM cells. These cells
                                                                                               are passed to the physical layer for transmission across the
                                                                                               physical medium.
ATM SWITCH                                  Asynchronous Transfer Mode Switch                  Switch using a transfer mode in which the information is
                                                                                               encapsulated into cells. It is asynchronous in the sense that
                                                                                               the recurrence of cells containing information from an
                                                                                               individual user is not necessarily periodic.



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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                          Page 17 of 150

                 Term                                         Description                                               Definition
ATMM                                        ATM Management                                     Process that runs on an ATM switch that controls VCI
                                                                                               translation and rate enforcement.
ATU-R/C                                     ADSL Termination Unit - Remote/Central Office
AU                                          Alternative Use                                    The ability to switch communications facilities from one type
                                                                                               to another, such as voice to data.
AUP                                         Acceptable Use Policy                              Many transit networks have policies that restrict the use to
                                                                                               which the network can be put. Enforcement of AUPs varies
                                                                                               with the network.
AUSM                                        ATM User Service Module
AUSTEL                                                                                         The Australian telecommunications regulatory body.
AUTOMATED ATTENDANT                                                                            A specialized form of an Interactive Voice Response
                                                                                               system.
Automatic Recovery                                                                             A system that permits restart of the switched message flow
                                                                                               after a fatal system failure. The recovery process is started
                                                                                               by an operator response when the system is reloaded, and
                                                                                               works from special records saved in the communications
                                                                                               data bank.
AVD                                         Alternate Voice Data                               A single transmission facility that can be used for either
                                                                                               voice or data.
AVI                                         Audio Video Interleave                             A specification that allows for the capture and storage of
                                                                                               video and waveform audio in a single data stream. Because
                                                                                               of speed and memory limitations, AVI offers only rough
                                                                                               animation, not full-motion video.
AVM                                         ATM Voice Multiplexer
AVR                                         Automated Voice Response                           A computer assisted answering system which provides pre-
                                                                                               recorded or real-time information based on touch tone
                                                                                               phone inputs from the customer. Benefits include immediate
                                                                                               access into the system (using an account number or
                                                                                               password) and 24 hour availability.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 18 of 150

                   Term                                       Description                                               Definition
AW                                          Administrative Weight                              Value set by the network administrator to indicate the
                                                                                               desirability of a network link. One of four link metrics
                                                                                               exchanged by PTSPs to determine the available resources
                                                                                               of an ATM network.
AWG                                         American Wire Gauge                                The US standard for wire size specification.
AWM                                         ATM Wireless Multiplexer                           Reunion base station node
B3ZS                                        Binary/Bipolar Three Zero Substitution
B8ZS                                        Binary 8-Zero Substitution                         Line-code type, used on T1 and E1 circuits, in which a
                                                                                               special code is substituted whenever 8 consecutive zeros
                                                                                               are sent over the link. This code is then interpreted at the
                                                                                               remote end of the connection. This technique guarantees
                                                                                               ones density independent of the data stream. Sometimes
                                                                                               called "bipolar 8-zero substitution."
Back Haul                                                                                      The indirect routing of a call through a network because it is
                                                                                               less expensive to do so. For example, a link between a
                                                                                               central office and a main microwave or multiplex station, or
                                                                                               between a ground satellite station, or submarine cable
                                                                                               terminal and switching center where forward distribution
                                                                                               occurs.
Backbone                                                                                       LAN or WAN connectivity between subnets across a high-
                                                                                               speed network. Often applied to a high-speed campus
                                                                                               network, such as ATM OC-12 or Gigabit Ethernet, that
                                                                                               interconnects lower-speed networks, such as ATM OC-3 or
                                                                                               Fast Ethernet. Fiber optic cable is often used.
Backbone Network                                                                               A network with a central cabling scheme linking it to other
                                                                                               networks. Hosts on networks linked to the backbone can
                                                                                               communicate with one another.
Backbone Router                                                                                Routers designed to be used to construct backbone
                                                                                               networks using leased lines. Typically do not have any built-
                                                                                               in digital dial-up WAN interfaces.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 19 of 150

                    Term                                      Description                                               Definition
Backward Learning                                                                              Algorithmic process used for routing traffic that surmises
                                                                                               information by assuming symmetrical network conditions.
                                                                                               For example, if node A receives a packet from node B
                                                                                               through intermediate node C, the backward-learning routing
                                                                                               algorithm will assume that A can optimally reach B through
                                                                                               C.
BALUN                                       Balanced, Unbalanced                               Device used for matching impedance between a balanced
                                                                                               and an unbalanced line, usually twisted-pair and coaxial
                                                                                               cable.
Bandpass filter                                                                                A circuit designed to allow only frequencies within a specific
                                                                                               range to pass. The cutoff frequencies must be finite and
                                                                                               nonzero. The band of frequencies between the cutoff
                                                                                               frequencies is the passband.
Bandwidth                                                                                      A circuit's capacity to carry communications signals,
                                                                                               measured by the range of frequencies (expressed in hertz)
                                                                                               the circuit carries. (2) The information-carrying capacity of a
                                                                                               computer or communications channel, such as a telephone
                                                                                               line, measured in bits per second. (3) The range of
                                                                                               frequencies available for signaling; the difference between
                                                                                               the highest and lowest frequencies of a band, expressed in
                                                                                               hertz.
Bandwidth Reservation                                                                          Process of assigning bandwidth to users and applications
                                                                                               served by a network. Involves assigning priority to different
                                                                                               flows of traffic on how critical and delay-sensitive they are.
                                                                                               This makes the best use of available bandwidth, and if the
                                                                                               network becomes congested, lower-priority traffic can be
                                                                                               dropped. Sometimes called "bandwidth allocation."
BAPI                                                                                           The submarine cable between Barcelona, Spain and Pisa,
                                                                                               Italy.
BARGEN                                                                                         The submarine cable between Barcelona, Spain and
                                                                                               Genoa, Italy.
BARO                                                                                           The submarine cable between Barcelona, Spain and Rome,
                                                                                               Italy.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                          Page 20 of 150

                  Term                                        Description                                              Definition
Base Station                                                                                   In cellular communications, and installation, located within a
                                                                                               cell that houses the equipment needed to set up and
                                                                                               complete calls on cellular phones, i.e. FM radio transmitter
                                                                                               and receiver, antenna, and computer. The base station
                                                                                               works with the subscriber's handset and the Mobile
                                                                                               Switching Center to complete a call.
Base Transceiver Station                                                                       In cellular communications, the component that consists of
                                                                                               all radio transmission and reception equipment, it provides
                                                                                               coverage to a geographic area, and is controlled by a Base
                                                                                               Station Controller.
Baseband                                                                                       Describing the band of frequencies occupied by a signal
                                                                                               below the point that the signal is modulated as an analog
                                                                                               carrier frequency. Also known as "narrowband."
Baud                                                                                           A unit of modulation rate, equal to the maximum number of
                                                                                               signal events or symbols that can be transmitted per
                                                                                               second. A signal event is a change in an information-
                                                                                               bearing signal or waveform, which represents some number
                                                                                               of encoded bits. The term baud should not be used as a
                                                                                               synonym for bits per second (though many people do) since
                                                                                               at speeds above 2,400 bits per second multiple bits are sent
                                                                                               in each baud and, therefore, the baud rate does not equal
                                                                                               the bit rate.
BBS                                         Bulletin Board System                              A computer system that functions as a centralized
                                                                                               information source and message system for a particular
                                                                                               group of users.
Bc                                          Committed Burst                                    Negotiated tariff metric in Frame Relay Internetworks. The
                                                                                               maximum amount of data (in bits) that a Frame Relay
                                                                                               Internetwork is committed to accept and transmit at the CIR.
BCD                                         Binary-Coded Decimal                               A code compression scheme in which two binary bits
                                                                                               replace the three zone bits and four binary bits replace the
                                                                                               nine data bits.
BCH                                         Bose-Chaudhuri-Hocquenghem                         A forward error correction technique with low-overhead,
                                                                                               often used for videoconferencing as in H.261.




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                    Page 21 of 150

                 Term                                          Description                                            Definition
B-Channel Bundling                                                                             A B-channel is a "bearer" channel, one of the fundamental
                                                                                               components of the ISDN inerface. The B channel is circuit-
                                                                                               switched and can carry 64,000bps of voice or data in either
                                                                                               direction. Bundling is based on Digital Speed Interpolation
                                                                                               (DSI), a technique used to squeeze more voice
                                                                                               conversations onto a single line.
BDCS                                        Broadband Digital Cross-Connect System             SONET DCS capable of cross-connecting DS-3, STS -1 and
                                                                                               STS-3c signals.
Be                                          Excess Burst                                       Negotiated tariff metric in Frame Relay Internetworks. The
                                                                                               number of bits that a Frame Relay will attempt to transmit
                                                                                               after Bc is accommodated. Be data is, in general, delivered
                                                                                               with a lower probability than Bc data because Be data can
                                                                                               be marked as DE by the network.
Beacon                                                                                         A condition where no data can pass on a Token Ring or
                                                                                               fiber-distributed data interface (FDDI) network.
Beacon Frame                                                                                   A specialized frame in token-passing networks, sent to
                                                                                               indicate and recover from a break in the ring.
Beaconing                                                                                      Token Ring process to recover the network when any
                                                                                               attached station has sensed that the ring is inoperable
                                                                                               because of a hard error Stations can withdraw from the ring
                                                                                               if needed. A station detecting a ring failure upstream
                                                                                               transmits (beacons) a special MAC frame used to isolate
                                                                                               the location of the error using beacon transmit and beacon
                                                                                               repeat modes.
BECN                                        Backward Explicit Congestion Notification          Bit set by a Frame Relay network in frames traveling in the
                                                                                               opposite direction of frames encountering a congested path.
                                                                                               DTE receiving frames with the BECN bit set can request
                                                                                               that higher-level protocols take flow control action as
                                                                                               appropriate.
B-ED                                        Best-Effort Delivery                               Describes a network system that does not use a
                                                                                               sophisticated acknowledgment system to guarantee reliable
                                                                                               delivery of information.




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 22 of 150

                 Term                                          Description                                              Definition
BEMS                                        Business Exchange Measured Service                 A usage-sensitive rating structure for business local service
                                                                                               in which business customers pay a reduced flat rate for
                                                                                               access to the telephone network and a separate per-minute
                                                                                               charge for their outgoing local calling. Incoming calls, long
                                                                                               distance calls, operator-handled and directory assistance
                                                                                               calls, and local calls internal to a business's own system are
                                                                                               excluded.
BER                                         Bit Error Rate                                     Ratio of received bits that contain errors.
BER(1)                                      Basic Encoding Rules                               Rules for encoding data units described in the ISO ASN.1
                                                                                               standard.
BER(2)                                                                                         The submarine cable between the U.S. and Bermuda.
BERT                                        Bit Error Rate Tester                              Device that determines the BER on a given communications
                                                                                               channel.
BGA                                         Ball Grid Array                                    Chip package
BGP                                         Border Gateway Protocol                            Interdomain routing protocol that replaces EGP. BGP
                                                                                               exchanges reachability information with other BGP systems.
BGP4                                        BGP Version 4                                      Version 4 of the predominant interdomain routing protocol
                                                                                               used on the Internet. BGP4 supports CIDR and uses route
                                                                                               aggregation mechanisms to reduce the size of routing
                                                                                               tables.
BICI                                        Broadband Inter-Carrier Interface                  ITU -T standard that defines the protocols and procedures
                                                                                               needed for establishing, maintaining, and terminating
                                                                                               broadband switched virtual connections between public
                                                                                               networks.
Binary                                                                                         Numbering system characterized by ones and zeros (1 =
                                                                                               on, 0 = off).
Binary digit                                                                                   The smallest entity of digital information possible.
BinHex                                      Binary Hexadecimal                                 Method for converting binary files into ASCII for
                                                                                               transmission by applications, such as email, that can only
                                                                                               handle ASCII.




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                        Page 23 of 150

                   Term                                        Description                                              Definition
BIP                                         Bit Interleaved Parity                             In ATM, a method used to monitor errors on a link. A check
                                                                                               bit or word is sent in the link overhead for the previous block
                                                                                               or frame. Bit errors in the payload can then be detected and
                                                                                               reported as maintenance information.
Biphase Coding                                                                                 Bipolar coding scheme originally developed for use in
                                                                                               Ethernet. Clocking information is embedded into and
                                                                                               recovered from the synchronous data stream without the
                                                                                               need for separate clocking leads. The biphase signal
                                                                                               contains no direct current energy.
Bipolar                                                                                        A 2-state code where successive "1" signals alternate
                                                                                               between positive and negative polarity. (2) Electrical
                                                                                               characteristic denoting a circuit with both negative and
                                                                                               positive polarity.
BISDN                                       Broadband Integrated Services Digital Network      A packet switching technique that uses packets of fixed
                                                                                               length, resulting in lower processing and higher speeds.
B-ISDN                                      Broadband Integrated Services Digital Networks     The new generation of ISDN which carries digital data,
                                                                                               voice, and video over SONET networks. B-ISDN allows
                                                                                               Asynchrous Transfer Mode (ATM) and Synchronous
                                                                                               Transfer Mode (STM) services to operate on the same
                                                                                               network.
Bit                                         Binary digit                                       Contraction of the term Binary digit
Bit Interleaving                                                                               A form of Time Division Multiplexing (TDM) for synchronous
                                                                                               protocols, including HDLC, SDLC, BiSync and X.25 Bit
                                                                                               inter-leaving retains the sequence and number of bits, so
                                                                                               that correct synchronization is achieved between both ends.
Black Hole                                                                                     Routing term for an area of the Internetwork where packets
                                                                                               enter, but do not emerge, due to adverse conditions or poor
                                                                                               system configuration within a portion of the network.
BLAST                                       Bell Labs Layered Space Time
BLEC                                        Building Local Exchange Carrier                    A company that supplies communications services to office
                                                                                               blocks. A term used in the U.S. In Europe the term BSP
                                                                                               (building service provider) is more commonly used.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                        Page 24 of 150

                 Term                                         Description                                               Definition
BLERT                                       Block Error Rate Test/Tester                       A method or device used to measure the quality of the block
                                                                                               transmission, the pattern of block transmission, and the
                                                                                               number of block errors received. The figures obtained are
                                                                                               used to compute the block error rate.
BLOB                                        Binary Large Object                                Massive image files to be moved across local area networks
                                                                                               (LANs).
Block                                                                                          A collection of transmitted data that is treated as a complete
                                                                                               and separate identity. Blocks typically have a specific
                                                                                               address, control routing, and error checking data.
Block Error                                                                                    One or more bits in a 1-second window are in error (for
                                                                                               DDS). Block size varies for other applications.
Block Length                                                                                   The total number of records, words, or characters contained
                                                                                               in one block.
Block Size                                                                                     This term, when used with either error control or data
                                                                                               compression protocols, refers to the number of characters
                                                                                               to be sent at one time. If error control is used, the codes are
                                                                                               sent immediately following this block.
Blocking                                                                                       In a switching system, a condition in which no paths are
                                                                                               available to complete a circuit. The term is also used to
                                                                                               describe a situation in which one activity cannot begin until
                                                                                               another is completed.
Blower                                                                                         Internal cooling fan used in larger router and switch chassis.
BLSR                                        Bidirectional Line Switch Ring                     SONET ring architecture that provides working and
                                                                                               protection fibers between nodes. If the working fiber
                                                                                               between nodes is cut, traffic is automatically routed onto the
                                                                                               protection fiber.
Bluetooth                                                                                      A short-range wireless connection standard. Its aim is to link
                                                                                               a wide range of computers, electronics and telecoms
                                                                                               devices. The technology uses a low-power, two-way radio
                                                                                               link, which is built into a microchip.
BNI                                         Broadband Network Interface
BNM                                         Broadband Network Module



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                          Page 25 of 150

                 Term                                            Description                                             Definition
BNN                                         Boundary Network Node                              In SNA terminology, a subarean node that provides
                                                                                               boundary function support for adjacent peripheral nodes.
                                                                                               This support includes sequencing, pacing, and address
                                                                                               translation.
BOC                                         Bell Operating Company                             The local (or regional) telephone company that owns and
                                                                                               operates lines to customer locations and Class 5 Central
                                                                                               Office switches.
BOOTP                                       Bootstrap Protocol                                 Protocol used by a network node to determine the IP
                                                                                               address of its Ethernet interfaces, in order to affect net work
                                                                                               booting.
BORSCHT                                     Battery supply, Overvoltage protection, Ringing    The functions required in any telephone line card.
                                            current, Supervision, Coding, Hybrid conversion,
                                            Testing
BOT                                         Build-Operate-Transfer Agreement
BP(1)                                       Bypass                                             The ability of a station or port to be optically or electronically
                                                                                               isolated from a ring network while maintaining the integrity
                                                                                               of the ring. The direct connection to customer-premises
                                                                                               equipment by an interexchange carrier (IC).
BP(2)                                       Break-Even Point                                   The usage level at which the total cost of a service with a
                                                                                               high monthly fee and low per-minute costs becomes equal
                                                                                               to the total cost of another service with a low monthly fee
                                                                                               and high per-minute cost. The service with the high monthly
                                                                                               fee is cheaper at usage levels above the BP.
BPDU                                        Bridge Protocol Data Unit                          Spanning-Tree Protocol hello packet that is sent out at
                                                                                               configurable intervals to exchange information among
                                                                                               bridges in the network.
BPI                                         Baseline Privacy Interface
Bps                                         Bits per second                                    The number of binary digits transmitted over a
                                                                                               communications channel in one second. For example,
                                                                                               Ethernet is a 10-Mbps network, Token Ring is a 4-Mbps or
                                                                                               16-Mbps network, and fiber-distributed data interface (FDDI)
                                                                                               is a 100-Mbps network.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                     Page 26 of 150

                 Term                                           Description                                            Definition
BPV                                         Bipolar Violation                                  A condition which occurs when an AMI-coded signal
                                                                                               contains a pulse of the same polarity as the previous pulse
                                                                                               and which is not part of a bipolar zero substitution code.
BPV Code                                                                                       A specific BPV sequence purposely introduced to the local
                                                                                               loop for network control.
BPV Rate                                                                                       The rate of erroneous received data bits to total received
                                                                                               data bits. This rate excludes framing bits, CRC-6 bits, or
                                                                                               data link bits.
BPVR                                        Bipolar Violation Ratio                            The number of accumulated BPVs in the last monitored
                                                                                               interval divided by the number of bits in that interval. Any
                                                                                               one second where there is an LOS condition is not included
                                                                                               in this computation.
BRA                                         Basic Rate Access                                  BRA provides ISDN users with access to two 64Kbit/s data
                                                                                               channels, It is defined in ITU -TS Recommendation I.420
                                                                                               which covers a 2B + D-channel where the B channel is a
                                                                                               64Kbit/s channel, and the D-channel is a 16Kbit/s signaling
                                                                                               channel.
BRACAN                                                                                         The submarine cable between Brazil and the Canary
                                                                                               Islands.
BRC                                         Block Redundancy Check                             The information added to a transmitted block to verify
                                                                                               accuracy of data before it is accepted. Block check data is
                                                                                               developed by the sender as a predefined function of
                                                                                               information in the block. The receiver performs the same
                                                                                               function on the received data, and compares the calculated
                                                                                               and received block checks. The block is accepted only if the
                                                                                               comparison is exact.
BRF                                         Bridge Relay Function
BRI                                         Basic Rate Interface                               An ISDN subscriber line, consisting of two 64kbit/s B
                                                                                               channels, or "bearer" channels, and one 16kbit/s D channel,
                                                                                               used for both data and signalling purposes.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 27 of 150

                    Term                                      Description                                               Definition
Bridge                                                                                         Device that connects and passes packets between two
                                                                                               network segments that use the same communications
                                                                                               protocol. Bridges operate at the data link layer (Layer 2) of
                                                                                               the OSI reference model. In general, a bridge will filter,
                                                                                               forward, or flood an incoming frame based on the MAC
                                                                                               address of that frame.
Broadband                                                                                      A service or system requiring transmission channels
                                                                                               capable of supporting rates greater than the ISDN primary
                                                                                               rate or circuits that carry data at rates that range from 1.544
                                                                                               million bits per second (megabits) to billions of bits per
                                                                                               second (gigabits). (2) LAN terminology: A coaxial cable on
                                                                                               which analog signaling is used. Also called wideband. (3)
                                                                                               Telecommunications terminology: Any channel having a
                                                                                               bandwidth greater than a voice-grade channel (4 kHz). (4)
                                                                                               Transmission system that multiplexes multiple independent
                                                                                               signals onto one cable.
Broadband Network                                                                              A network that enables a device to transmit a large amount
                                                                                               of information (including voice, data, and video) on the
                                                                                               same cable over long distances.
Broadcast                                                                                      Data packet that will be sent to all nodes on a network.
                                                                                               Broadcasts are identified by a broadcast address.
Broadcast Address                                                                              Special address reserved for sending a message to all
                                                                                               stations. Generally, a broadcast address is a MAC
                                                                                               destination address of all ones.
Broadcast Domain                                                                               Set of all devices that will receive broadcast frames
                                                                                               originating from any device within the set. Broadcast
                                                                                               domains are typically bounded by routers because routers
                                                                                               do not forward broadcast frames.
Broadcast Search                                                                               Propagation of a search request to all network nodes if the
                                                                                               location of a resource is unknown to the requester.
Broadcast Storm                                                                                Undesirable network event in which many broadcasts are
                                                                                               sent simultaneously across all network segments. A
                                                                                               broadcast storm uses substantial network bandwidth and,
                                                                                               typically, causes network time-outs.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 28 of 150

                 Term                                         Description                                              Definition
Brouter                                                                                        A device that combines the dynamic routing capability of an
                                                                                               internetwork router with the ability of a bridge to
                                                                                               interconnect local area networks.
BRUS                                                                                           The submarine cable between Brazil and the U.S.
BSC                                         Binary Synchronous Communication                   Character-oriented data link layer protocol for half-duplex
                                                                                               applications. A form of telecommunication line control that
                                                                                               uses a standard set of transmission control characters and
                                                                                               control character sequences, for binary synchronous
                                                                                               transmission of binary-coded data between stations.
BSGL                                        Branch Systems General License                     A license which must be obtained by any organization
                                                                                               seeking to link its own private network to the Public
                                                                                               Switched Telephone Network (PSTN). A separate license
                                                                                               must be held for each individual site.
BSP                                         Building Service Provider                          A company that supplies communications services to office
                                                                                               blocks. A term used in the Europe. In the U.S. the term
                                                                                               BLEC (building local exchange carrier) is more commonly
                                                                                               used.
BSS                                         Base Station Subsystem
BT                                          Burst Tolerance                                    Parameter defined by the ATM Forum for ATM traffic
                                                                                               management. For VBR connections, BT determines the size
                                                                                               of the maximum burst of contiguous cells that can be
                                                                                               transmitted.
BTAM                                        Basic Telecommunications Access Method             An access method that supports read/write communications
                                                                                               between remote devices.
Burst                                                                                          A sequence of signals counted as one unit in accordance
                                                                                               with some specific criterion or measure.
Burst Mode                                                                                     A method of transmitting data. When a device uses burst
                                                                                               mode, it collects and sends data in a single high-speed
                                                                                               transmission, rather than one character at a time.
BUS                                         Broadcast and Unknown Server                       Multicast server used in ELANs that is used to flood traffic
                                                                                               addressed to an unknown destination and to forward
                                                                                               multicast and broadcast traffic to the appropriate clients.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 29 of 150

                 Term                                         Description                                               Definition
Bus Topology                                                                                   A linear network topology. A bus network is a local area
                                                                                               network (LAN) in which all workstations are connected to a
                                                                                               single cable. All workstations receive all transmissions on
                                                                                               the cable. Each workstation selects those transmissions
                                                                                               addressed to it based on the address information contained
                                                                                               in the transmission. A bus network is the simplest and most
                                                                                               common LAN topology.
Busy                                                                                           The lines over which a call is to be transmitted are already
                                                                                               in use. Slow busy signals (60 times per minute) indicate the
                                                                                               receiving telephone is busy or off-hook. Fast busy signals
                                                                                               (120 times per minute) indicate that the network facilities are
                                                                                               congested with too many calls.
Butt-Sett                                                                                      A hand-carried test telephone used to monitor, dial, and talk
                                                                                               on conventional analog telephone lines. So named because
                                                                                               the craft person could clip onto a telephone line and "butt in"
                                                                                               to a conversation.
BVI                                         Bridge Group Virtual Interface
BWA                                         Broadband Wireless Access                          A service providing two-way, broadband, data, voice,
                                                                                               multimedia and information services using (mostly)
                                                                                               millimetre wave radio links. BWA is similar to LMDS except
                                                                                               that in most cases it excludes video broadcast as a service.
BXM                                         Broadband Switch Module
Byte                                                                                           8 bits of data, also called an octet.
Byte Reversal                                                                                  Process of storing numeric data with the least-significant
                                                                                               byte first. Used for integers and addresses on devices with
                                                                                               Intel microprocessors.
Byte Stuffing                                                                                  A technique which increases the speed of a digital stream
                                                                                               by repeating bytes and transmitting them at a faster rate.
                                                                                               This technique does not increase the information content of
                                                                                               the stream.
C Band                                                                                         The 4 GHz to 6 GHz portion of the electromagnetic
                                                                                               spectrum used for satellite transmission.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                         Page 30 of 150

                 Term                                           Description                                             Definition
C Conditioning                                                                                 A type of line conditioning that controls attenuation,
                                                                                               distortion, and delay distortion so they lie within specific
                                                                                               limits.
C/S                                         Client/Server                                      A distributed computing model in which clients request data
                                                                                               and processing from servers. Servers usually have higher
                                                                                               capacity than clients. C/S exploits less expensive hardware
                                                                                               than host-based computing. But, C/S application design and
                                                                                               resource management must be more sophisticated.
CA(1)                                       Certification Authority
CA(2)                                       Call Appearance
Cablehead                                                                                      The point where a marine cable connects to terrestrial
                                                                                               facilities.
CAC(1)                                      Connection Admission Control                       Set of actions taken by each ATM switch during connection
                                                                                               setup in order to determine whether a connection's
                                                                                               requested QoS will violate the QoS guarantees for
                                                                                               established connections. CAC is also used when routing a
                                                                                               connection request through an ATM network.
CAC(2)                                      Carrier Access Code                                The sequence an end user dials to obtain access to the
                                                                                               switched services of a carrier.
Caching                                                                                        Form of replication in which information learned during a
                                                                                               previous transaction is used to process later transactions.
CAD/CAM                                     Computer-Aided Design/Computer-Aided               A computer and its related software and terminals used to
                                            Manufacture                                        design and manufacture things. CAD terminals are often run
                                                                                               over LANs and/or WANs.
CAF                                         Controllable ATM Fabric
CAI                                         Common Air Interface                               The CT2 international mobile communications standard
                                                                                               which allows any compliant equipment to be used on any
                                                                                               network of the same type. CAI compliant telepoint handsets
                                                                                               from different vendors may therefore be used on a telepoint
                                                                                               network. Vendors with CAI compliant systems include
                                                                                               Northern Telecom and GPT.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                    Telecom / IS Glossary                                                      Page 31 of 150

                   Term                                         Description                                              Definition
Call Park                                                                                       A feature that enables calls to be transferred to a busy
                                                                                                extension; the call can be connected to the extension when
                                                                                                it is free.
Call Pickup                                                                                     Calls directed to one station can be picked up by another
                                                                                                station line within a preset pickup group by dialing a special
                                                                                                code.
Call Setup Time                                                                                 Time required to establish a switched call between DTE
                                                                                                devices.
Callback Queuing                                                                                The user's extension rings when a non-busy trunk is
                                                                                                available if outgoing calls cannot be completed due to busy
                                                                                                trunk groups, signaling that the call can now be placed.
CALLER ID                                   Caller Identification                               Phone company feature which identifies the customer on
                                                                                                the line as the call is received.
CAM(1)                                      Content Addressable Memory                          A memory device that stores and retrieves data based on a
                                                                                                key value, as opposed to an address or name.
CAM(2)                                                                                          The submarine cable between Portugal and Madeira
CAMEL                                       Customised Applications for Mobile Networks         CAMEL is a GSM feature name for including IN (Intelligent
                                            Enhanced Logic                                      Network) functions into a GSM system. CAMEL is used
                                                                                                when roaming between networks, allowing the home
                                                                                                network to monitor and control calls made by its
                                                                                                subscribers. The feature allows numbers dialled to be
                                                                                                modified during call set-up, and monitoring of call answer
                                                                                                and cleardown. Possible applications include pre-paid
                                                                                                roaming services, fraud control, special numbers (e.g. 123
                                                                                                for voicemail works everywhere) and closed user groups
                                                                                                (office extension numbers work everywhere). CAMEL has
                                                                                                been standardised in three phases, the first of which is
                                                                                                starting to be deployed now.
CANBER                                                                                          The submarine cable between Canada and Bermuda
CANTAT                                                                                          The submarine cable between Canada and the U.K.
CAP(1)                                      CAMEL Application Part
CAP(2)                                      Carrierless Amplitude Modulation/Phase Modulation   A line coding protocol



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                          Page 32 of 150

                 Term                                          Description                                              Definition
CAP(3)                                      Competitive Access Provider                        A company that provides network links between the
                                                                                               customer and the interexchange carrier or even directly to
                                                                                               the Internet service provider. CAPs operate private
                                                                                               networks independent of local exchange carriers.
Capacity                                                                                       The highest possible reliable transmission speed that can
                                                                                               be carried on a channel, circuit, or piece of equipment.
                                                                                               Capacity may be expressed as raw speed or as net
                                                                                               throughput.
CAPACITY PROVISIONING                                                                          Process focused on market-based capacity planning and
                                                                                               deployment of software-configurable network components.
Capt ure                                                                                       The act of removing a token from the ring for the purpose of
                                                                                               frame transmission. (2) To 'catch' text that is being sent to
                                                                                               your computer from a BBS and put it in a buffer or a file.
Carrier(1)                                                                                     Electromagnetic wave or alternating current of a single
                                                                                               frequency, suitable for modulation by another, data-bearing
                                                                                               signal.
Carrier(2)                                                                                     A long-distance company that uses primarily its own
                                                                                               transmission facilities, as opposed to resellers that lease or
                                                                                               buy most or all transmission facilities from carriers.
Carrierband                                                                                    A single-channel broadband.
CAS                                         Channel Associated Signaling
CAT                                         Carrier Access Tariff                              The CAT -- which all interexchange carriers, including
                                                                                               telephone companies must pay for access to the utility
                                                                                               (local) network -- consists of one or more network access
                                                                                               components (charges for switching and aggregation,
                                                                                               recovery of start-up costs, etc.) and a contribution
                                                                                               component to subsidize the rates for basic local telephone
                                                                                               service.
Catenet                                                                                        Network in which hosts are connected to diverse networks,
                                                                                               which themselves are connected with routers. The Internet
                                                                                               is a prominent example of a catenet.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                          Page 33 of 150

                 Term                                            Description                                              Definition
CATV                                        Cable Television                                     Communication system where multiple channels of
                                                                                                 programming material are transmitted to homes using
                                                                                                 broadband coaxial cable. Formerly called Community
                                                                                                 Antenna Television.
CBAC                                        Context-Based Access Control                         Protocol that provides internal users with secure access
                                                                                                 control for each application and for all traffic across network
                                                                                                 perimeters. CBAC enhances security by scrutinizing both
                                                                                                 source and destination addresses and by tracking each
                                                                                                 application's connection status.
CBDS                                        Connectionless Broadband Data Service                European high-speed, packet-switched, datagram-based
                                                                                                 WAN networking technology.
CBR                                         Constant Bit Rate                                    QoS class defined by the ATM Forum for ATM networks.
                                                                                                 CBR is used for connections that depend on precise
                                                                                                 clocking to ensure undistorted delivery.
CBX                                         Computerized Branch Exchange
CCB                                         Call Control Block
CCC                                         Clear Channel Capability                             The bandwidth of a data transmission path available to the
                                                                                                 end users after control and signaling bits are accounted for.
                                                                                                 For example, in a 64Kbps channel, all 64Kbps is available
                                                                                                 for data transmission.
CCIR                                        Consultative Committee on International Radio        An international committee that defined the 625-line
                                                                                                 television system used in Western Europe. The US system
                                                                                                 uses 525 lines, while ISDN (integrated services digital
                                                                                                 network) TV uses 1,125 lines.
CCIS                                                                                             A digital technology used by AT&T to enhance their
                                                                                                 Integrated Services Digital Network (ISDN). CCIS uses a
                                                                                                 separate data line to route interoffice signals to provide
                                                                                                 faster call set-up and efficient use of trunks.
CCITT                                       Consultative Committee on International Telegraphy   International organization responsible for the development
                                            and Telephony                                        of communications standards. Now called the ITU-T.
CCP                                                                                              Compression Control Protocol. Used to negotiate
                                                                                                 compression methods over PPP links.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                       Page 34 of 150

                 Term                                         Description                                              Definition
CCR                                         Common Control Redundancy                          A feature that allows configuration of a redundant common
                                                                                               control unit; in the event of the main control failure, the
                                                                                               redundant unit automatically switches on.
CCS                                         Common Channel Signaling                           Signaling system used in telephone networks that separates
                                                                                               signaling information from user data. A specified channel is
                                                                                               exclusively designated to carry signaling information for all
                                                                                               other channels in the system.
CCSA                                        Common Control Switching Arrangement               The use of carrier switches under a carrier's control as part
                                                                                               of a customer's private network. The carrier's software
                                                                                               controls the customer's calls over private lines rented by the
                                                                                               customer. Switch control and switching functions is
                                                                                               performed in common for all users.
CCSA Access                                                                                    A private branch exchange (PBX) feature that allows a user
                                                                                               to gain entry to a common control switching arrangement
                                                                                               (CCSA).
CCTA                                        Central Computer & Telecommunications Agency       The Government Center for Information Systems.
CD                                          Carrier Detect                                     Signal that indicates whether an interface is active. Also, a
                                                                                               signal generated by a modem indicating that a call has been
                                                                                               connected.
CDC                                         Call Directing Code                                A character string used to address a terminal for automatic
                                                                                               routing of messages in teletype systems.
CDDI                                        Copper Distributed Data Interface                  Implementation of FDDI protocols over STP and UTP
                                                                                               cabling. CDDI transmits over relatively short distances
                                                                                               (about 90 yards [100 meters]), providing data rates of 100
                                                                                               Mbps using a dual-ring architecture to provide redundancy.
                                                                                               Based on the ANSI TPPMD standard.
CDF                                         Channel Definition Format                          Technology for "push" applications on the World Wide Web.
                                                                                               CDF is an application of XML.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                       Page 35 of 150

                 Term                                          Description                                              Definition
CDMA                                        Code Division Multiple Access                      A digital cellular phone service that offers up to 20 times
                                                                                               more call-handling capacity than conventional cellular
                                                                                               systems by assigning a special electronic code to each
                                                                                               signal, allowing more calls to occupy the same space and
                                                                                               be spread over an entire frequency band. Developed by
                                                                                               Qualcomm Inc., which promotes CDMA as an alternative to
                                                                                               Time Division Multiple Access technology.
CDPD                                        Cellular Digital Packet Data                       A system that transmits packets of data over cellular
                                                                                               networks without interfering with voice transmission.
CDR                                         Call Data Record                                   Information sent from a circuit switch to track the time and
                                                                                               duration of a call or the amount of packets or data; event
                                                                                               record which may include transaction ID, type of
                                                                                               transaction, destination/origination, start time, duration or
                                                                                               end time (packets or seconds).
CDSL                                        Consumer DSL                                       Ttrademarked version of DSL, slower than ADSL (1 Mbps
                                                                                               downstream, probably less upstream) but has the
                                                                                               advantage that a "splitter" does not need to be installed at
                                                                                               the user's end.
CDV                                         Cell Delay Variation                               Component of cell transfer delay, which is induced by
                                                                                               buffering and cell scheduling. CDV is a QoS delay
                                                                                               parameter associated with CBR and VBR service.
CDVT                                        Cell Delay Variation Tolerance                     In ATM, a QoS parameter for managing traffic that is
                                                                                               specified when a connection is set up. In CBR
                                                                                               transmissions, CDVT determines the level of jitter that is
                                                                                               tolerable for the data samples taken by the PCR.
CE                                          Conditioning Equipment                             Equipment that provides modifications or adjustments
                                                                                               necessary to match transmission levels and impedances.
                                                                                               CE also equalizes transmission and delay to bring circuit
                                                                                               losses, levels, and distortion within established standards.
Cell                                                                                           A fixed-length transmission unit which forms the basis of
                                                                                               ATM. Each cell is 53 bytes in length, divided into a 48-byte
                                                                                               payload and a 5-byte header.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                           Page 36 of 150

                 Term                                          Description                                              Definition
Cell Relay                                                                                     A packet transmission system that uses fixed-length cells
                                                                                               which can be processed and switched at very high speeds,
                                                                                               making it possible to use a single transmission scheme for
                                                                                               voice, data, and video traffic on local- and wide-area
                                                                                               networks.
Cell Switching                                                                                 A feature that enables a caller to move from one location to
                                                                                               another without losing the connection. The cellular system is
                                                                                               designed to switch calls to a new call without a noticeable
                                                                                               drop in the connection. While not noticeable in voice
                                                                                               communications, the 300 milliseconds required for cell
                                                                                               switching can cause problems in data transmission. Cell
                                                                                               switching is sometimes referred to as handing off.
Cellular                                                                                       A networking technology which breaks up geographical
                                                                                               areas into clusters of small honeycomb-shaped cells. The
                                                                                               network consists of one low-powered output cell site per
                                                                                               cell, cellular handsets, and the MSC, which all exchange
                                                                                               information to connect cellular subscribers.
CELP                                        Code Excited Linear Prediction Compression         Compression algorithm used in low bit-rate voice encoding.
CEPT                                        Conférence Européenne des Postes et des            Association of the 26 European PTTs that recommends
                                            Télécommunications                                 communication specifications to the ITU-T.
CER                                         Cell Error Ratio                                   In ATM, the ratio of transmitted cells that have errors to the
                                                                                               total cells sent in a transmission for a specific period of time.
CERN                                        European Laboratory for Particle Physics           Birthplace of the World Wide Web.
CES                                         Circuit Emulation Service                          Enables users to multiplex or concentrate multiple circuit
                                                                                               emulation streams for voice and video with packet data on a
                                                                                               single high-speed ATM link without a separate ATM access
                                                                                               multiplexer.
CFA                                         Carrier Facility Assignment                        An identifier for the circuit assignments a local exchange
                                                                                               carrier (LEC) uses at the point where it interconnects with
                                                                                               other facilities. (2) An identifier for the telephone company
                                                                                               network point where an interexchange carrier (IEC)
                                                                                               connects.
CFRAD                                       Cisco Frame Relay Access Device



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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                         Page 37 of 150

                   Term                                       Description                                              Definition
CGI                                         Common Gateway Interface                           Programs use the CGI specifications to communicate with
                                                                                               Web servers and produce interactive, 'intelligent' Web
                                                                                               pages, Such programs are often referred to as CGIs, or CGI
                                                                                               scripts.
Channel                                                                                        A portion of a line's bandwidth. A line contains a fixed
                                                                                               number of channels. Each line can contain switched
                                                                                               channels only, nailed-up channels only, or a combination of
                                                                                               switched and nailed-up channels.
Channel Aggregator                                                                             Channel aggregators, also known as inverse multiplexers,
                                                                                               are devices that allow very large amounts of data to be sent
                                                                                               down the narrow band channels of ISDN. The aggregator
                                                                                               effectively pulls together ISDN channels at one end to form
                                                                                               a higher bandwidth and then re-synchronizes the
                                                                                               information at the other end. Re-synchronization is
                                                                                               necessary because during transmission the ISDN channels
                                                                                               may send the information along different routes, meaning it
                                                                                               arrives at its destination at fractionally different times.
Channel Capacity                                                                               A measure of the maximum amount of data that a channel
                                                                                               can manage.
Channel Extender                                                                               A device that increases the distance a mainframe can
                                                                                               communicate with other mainframes and input/output
                                                                                               devices, such as remote terminals, tape drives, and high-
                                                                                               speed printers at local channel speeds over T1/T3 lines.
Channel Grade                                                                                  The relative bandwidth of a channel: narrowband, voice
                                                                                               grade, or wideband.
Channel Termination                                                                            The equipment such as multiplexers and channelizers,
                                                                                               required to provide a connection point for one channel. A
                                                                                               recurring charge rate element is levied on each channel
                                                                                               termination for dedicated circuits.
Channelize                                                                                     To subdivide or break out a broadband transmission system
                                                                                               into multiple communications channels.
Channelized E1                                                                                 Access link operating at 2.048 Mbps that is subdivided into
                                                                                               30 B-channels and 1 D-channel. Supports DDR, Frame
                                                                                               Relay, and X.25.



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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                          Page 38 of 150

                   Term                                       Description                                               Definition
Channelized T1                                                                                 Access link operating at 1.544 Mbps that is subdivided into
                                                                                               24 channels (23 B-channels and 1 D-channel) of 64 Kbps
                                                                                               each. The individual channels or groups of channels
                                                                                               connect to different destinations. Supports DDR, Frame
                                                                                               Relay, and X.25. Also called fractional T1.
Channelized Testing                                                                            The isolation and testing of a particular data path out of
                                                                                               many such paths included in a conglomerate data signal.
CHAP                                        Challenge Handshake Authentication Protocol        This security protocol allows access between data
                                                                                               communications systems prior to and during data
                                                                                               transmission. CHAP uses challenges to verify that a user
                                                                                               has access to a system.
Character Interleaving                                                                         A form of TDM used for asynchronous protocols. This can
                                                                                               be used either with extra channels, or by carrying RS232-C
                                                                                               control signals.
Character Parity                                                                               The process of adding a redundant overhead bit to a
                                                                                               character to provide error detection capability.
Chat Script                                                                                    String of text that defines the login "conversation" that
                                                                                               occurs between two systems. Consists of expect-send pairs
                                                                                               that define the string that the local system expects to
                                                                                               receive from the remote system and what the local system
                                                                                               should send as a reply.
Cheapernet                                                                                     Thin wire Ethernet.
Chinapac                                                                                       China' s public data network.
Choke Packet                                                                                   Packet sent to a transmitter to tell it that congestion exists
                                                                                               and that it should reduce its sending rate.
CICS                                        Customer Information Control System                IBM application subsystem allowing transactions entered at
                                                                                               remote terminals to be processed concurrently by user
                                                                                               applications.
CID(1)                                      Craft Interface Device                             Terminal or PC-based interface that enables the
                                                                                               performance of local maintenance operations.
CID(2)                                      Channel ID                                         Designates the Frame Relay subchannel ID for Voice over
                                                                                               Frame Relay.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 39 of 150

                    Term                                      Description                                               Definition
CIDR                                        Classless Inter-Domain Routing                     An address aggregation process that simplifies routing.
CIR                                         Committed Information Rate                         The minimum bandwidth guaranteed to be available if
                                                                                               required on a virtual circuit. This value is also known as
                                                                                               guaranteed bandwidth.
Circuit                                                                                        A path for the transmission of electromagnetic signals to
                                                                                               include all conditioning and signaling equipment. (2) A
                                                                                               switched or dedicated communications path with a
                                                                                               specifiedtransmission speed or bandwidth capacity.
Circuit Grade                                                                                  The data-carrying ability of a circuit measured in speed or
                                                                                               type of signal, such as broadband, voice grade, subvoice,
                                                                                               and telegraph.
Circuit Steering                                                                               Mechanism used by some ATM switches to eavesdrop on a
                                                                                               virtual connection and copy its cells to another port where
                                                                                               an ATM analyzer is attached. Also known as "port
                                                                                               snooping."
Circuit Switching                                                                              Switching system in which a dedicated physical circuit path
                                                                                               must exist between sender and receiver for the duration of
                                                                                               the "call." Used heavily in the telephone company network.
CIT                                         Computer Integrated Telephony                      The linking of telephone and IT systems to provide a
                                                                                               seamless service to customers, whatever their means of
                                                                                               contact.
CIX                                         Commercial Internet Exchange                       A connection point between the commercial Internet service
                                                                                               providers. Pronounced "kicks."
CLASS                                       Custom Local Area Signalling Services              A set of intelligent services for residential and small-
                                                                                               business subscribers, including call forwarding, call waiting
                                                                                               and three-party conferencing, provided by Bell companies
                                                                                               and increasingly in other countries outside the USA.
Class of Office                                                                                A rank assigned to a switching office, according to its
                                                                                               functions, relationships to other switching offices, and
                                                                                               transmission requirements, in the telephone network.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                        Page 40 of 150

                 Term                                           Description                                             Definition
CLAW                                        Common Link Access for Workstations                Data link layer protocol used by channel-attached RISC
                                                                                               System/6000 series systems and by IBM 3172 devices
                                                                                               running TCP/IP off-load. CLAW improves efficiency of
                                                                                               channel use and allows the CIP to provide the functionality
                                                                                               of a 3172 in TCP/IP environments and support direct
                                                                                               channel attachment. The output from TCP/IP mainframe
                                                                                               processing is a series of IP datagrams that the router can
                                                                                               switch without modifications.
Clear Channel                                                                                  Channel that uses out-of-band signaling (as opposed to in-
                                                                                               band signaling), so the channel's entire bit rate is available.
CLEC                                        Competitive Local Exchange Carrier                 A company that provides local dial-tone services as well as
                                                                                               long-distance, data, and Internet services, usually to
                                                                                               businesses.
CLI(1)                                      Command Line Interface                              Interface that allows the user to interact with the operating
                                                                                               system by entering commands and optional arguments. The
                                                                                               UNIX operating system and DOS provide CLIs.
CLI(2)                                      Command Language Interpreter                       Basic Cisco IOS configuration and management interface.
CLI(3)                                      Calling Line Identification                        A service available on digital phone networks that tells the
                                                                                               person being called which number is calling them. The
                                                                                               central office equipment identifies the phone number of the
                                                                                               caller, enabling information about the caller to be sent along
                                                                                               with the call itself.
CLI(4)                                      Called Line Identification                         A facility provided by a switched network in which the
                                                                                               network confirms for the calling terminal, the telephone
                                                                                               number of the line to which the call has been connected.
Client                                                                                         Any computer connected to a network that requests
                                                                                               services (files, print capability) from another member of the
                                                                                               network.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                        Page 41 of 150

                  Term                                           Description                                            Definition
Client/Server Computing                                                                        The division of an application into two parts, with one part
                                                                                               running on a server and the other running on a PC or
                                                                                               workstation. It can be described as an architecture for LAN
                                                                                               application programs. The rationale behind client/server
                                                                                               computing is to exploit the local, desk top processing power
                                                                                               leaving the server to govern the centrally held inforation.
                                                                                               This should not be confused with PCs holding their own files
                                                                                               on a LAN, as here the client or PC is carrying out its own
                                                                                               application tasks. Nevrtheless, such systems are helping
                                                                                               the market move in the direction of true client/server
                                                                                               computing, the advantages of which include less network
                                                                                               traffic and more flexibility.
Clipping                                                                                       This occurs when the first words during a telephone
                                                                                               conversation are broken off or "clipped," because the line is
                                                                                               being shared by many conversations. This usually occurs
                                                                                               on overseas channels.
CLNP                                        Connectionless Network Protocol                    OSI network layer protocol that does not require a circuit to
                                                                                               be established before data is transmitted.
CLNS                                        Connectionless Network Service                     OSI network layer service that does not require a circuit to
                                                                                               be established before data is transmitted. CLNS routes
                                                                                               messages to their destinations independently of any other
                                                                                               messages.
Closed End                                                                                     The end of a line, such as a wide area telecommunications
                                                                                               service (WATS) 800 or a foreign exchange line, from which
                                                                                               all calls are directed to or from a single point. Private lines
                                                                                               normally have two closed ends.
CLP                                         Cell Loss Priority                                 Traffic, which is unlikely to be dropped. Cells with CLP = 1
                                                                                               are best-effort traffic, which might be dropped in congested
                                                                                               conditions in order to free up resources to handle insured
                                                                                               traffic.
CLR                                         Cell Loss Ratio                                    In ATM, the ratio of discarded cells to cells that are
                                                                                               successfully transmitted. CLR can be set as a QoS
                                                                                               parameter when a connection is set up.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                             Page 42 of 150

                     Term                                     Description                                                Definition
Cluster Controller                                                                             Generally, an intelligent device that provides the
                                                                                               connections for a cluster of terminals to a data link. (2) In
                                                                                               SNA, a programmable device that controls the input/output
                                                                                               operations of attached devices.
CM                                          Configuration Management                           In fiber-distributed data interface (FDDI), that portion of
                                                                                               connection management that provides for the configuration
                                                                                               of physical layer protocol (PHY) and media access control
                                                                                               (MAC) entities within a node.
CMA                                         Construction and Maintenance Agreement             An agreement for the ownership, construction and
                                                                                               maintenance of expensive facilities, such as transoceanic
                                                                                               cables and related equipment. CMAs are usually between
                                                                                               multiple carriers, but may be between a carrier and a
                                                                                               government.
C-Message Noise                                                                                Noise level measured on a channel in the absence of signal
                                                                                               (voiceband).
CMIP                                        Common Management Information Protocol             OSI network management protocol created and
                                                                                               standardized by ISO for the monitoring and control of
                                                                                               heterogeneous networks.
CMIS                                        Common Management Information Services             Network management protocol.
CMNS                                        Connection-Mode Network Service                    Extends local X.25 switching to a variety of media (Ethernet,
                                                                                               FDDI, Token Ring).
CMOS                                        Complementary Metal Oxide Semiconductor
CMT                                         Connection Management                              FDDI process that handles the transition of the ring through
                                                                                               its various states (off, active, connect, and so on), as
                                                                                               defined by the ANSI X3T9.5 specification.
CMTS                                        Cable Modem Termination System                     Any DOCSIS-compliant headend cable router.
CNCA                                        Carrier Non-Compatible Applications                Applications which rely on metallic facilities (i.e., copper)
                                                                                               with direct current continuity to provide service. Certain
                                                                                               older applications, such as some provided by alarm
                                                                                               companies, energy monitoring companies and other users
                                                                                               of telemetry, could not generally be multiplexed, carried
                                                                                               over digital facilities (i.e., fiber optics) or transported over
                                                                                               radio facilities.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                          Page 43 of 150

                  Term                                        Description                                              Definition
CNMS                                        Customer Network Management System                  A network management system to provide customers with
                                                                                               network monitoring and service request capabilities. This
                                                                                               system is located at the customer's facility.
C-Notched Noise                                                                                Noise level measured with a 1004-Hz signal present, but
                                                                                               removed at the measurement end (voiceband).
CO                                          Central Office                                     Local telephone company office to which all local loops in a
                                                                                               given area connect and in which circuit switching of
                                                                                               subscriber lines occurs.
CO FRAD                                     Central Office Frame Relay Access Device
Coaxial Cable                                                                                  Cable consisting of a hollow outer cylindrical conductor that
                                                                                               surrounds a single inner wire conductor. Two types of
                                                                                               coaxial cable are currently used in LANs: 50-ohm cable,
                                                                                               which is used for digital signaling, and 75-ohm cable, which
                                                                                               is used for analog signaling and high-speed digital signaling.
COBOL                                       Common Business-Oriented Language                  A high-level programming language adopted in 1960 for use
                                                                                               on minicomputers and mainframes in business
                                                                                               environments.
CoDec                                       Coder-Decoder                                      Integrated circuit device that typically uses pulse code
                                                                                               modulation to transform analog signals into a digital bit
                                                                                               stream and digital signals back into analog signals. (2) In
                                                                                               Voice over IP, Voice over Frame Relay, and Voice over
                                                                                               ATM, a DSP software algorithm used to
                                                                                               compress/decompress speech or audio signals.
Coding                                                                                         Electrical techniques used to convey binary signals.
CO-LAN                                      Central Office-based Local Area Network            A collection of computers on one or several business
                                                                                               premises interconnected through public telephone lines and
                                                                                               acting as a single, physically-connected network.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                         Page 44 of 150

                   Term                                       Description                                              Definition
Collaborative Working                                                                          A process that enables a group of distant participants to
                                                                                               jointly view, discuss, and edit documents while using
                                                                                               communications and computing resources. This can be
                                                                                               considered an extension of conventional audio/video
                                                                                               conferencing which employs media communications and
                                                                                               information access. Collaborative working represents a case
                                                                                               of complex and dynamic communication that encompasses
                                                                                               a number of participants, connections, information types,
                                                                                               systems, and functions.
Collapsed Backbone                                                                             Nondistributed backbone in which all network segments are
                                                                                               interconnected by way of an internetworking device. A
                                                                                               collapsed backbone might be a virtual network segment
                                                                                               existing in a device such as a hub, a router, or a switch.
Collection Hub                                                                                 A collection point for data from a number of end offices.
                                                                                               Data is combined into a single bit stream for transmission
                                                                                               back to the hub office. A collection hub does not have test
                                                                                               capability, MJUs, or analog extension equipment.
Collocation                                                                                    The placement of in-service, customer telecommunications
                                                                                               equipment at a carrier's central office (CO), point of
                                                                                               presence (POP), or other network location.
COLUMBUS                                                                                       A submarine cable between Spain and Venezuela.
Common Carrier                                                                                 Licensed, private utility company that supplies
                                                                                               communication services to the public at regulated prices.
Communication Server                                                                           Communications processor that connects asynchronous
                                                                                               devices to a LAN or WAN through network and terminal
                                                                                               emulation software. Performs only asynchronous routing of
                                                                                               IP and IPX.
Community String                                                                               Text string that acts as a password and is used to
                                                                                               authenticate messages sent between a management station
                                                                                               and a router containing an SNMP agent. The community
                                                                                               string is sent in every packet between the manager and the
                                                                                               agent. Also called a "community name."
COMPAC                                                                                         The submarine cable that links Canada, Fiji, New Zealand
                                                                                               and Australia.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                            Page 45 of 150

                     Term                                     Description                                               Definition
Companding                                                                                     Contraction derived from the opposite processes of
                                                                                               compression and expansion. Part of the PCM process
                                                                                               whereby analog signal values are logically rounded to
                                                                                               discrete scale-step values on a nonlinear scale. The
                                                                                               decimal step number is then coded in its binary equivalent
                                                                                               prior to transmission. The process is reversed at the
                                                                                               receiving terminal using the same nonlinear scale.
Compression                                                                                    The running of a data set through an algorithm that reduces
                                                                                               the space required to store or the bandwidth required to
                                                                                               transmit the data set.
Concatenation                                                                                  The connection of transmission channels in a chain.
Concentration                                                                                  A technique used to get the most out of a composite
                                                                                               multiplexer link. Usually a statistical multiplexer, or
                                                                                               concentrator, is used to focus channel inputs on to the
                                                                                               composite ink by removing the portions of the transmission
                                                                                               carrying no data.
Concentrator                                                                                   A network device used in fiber-distributed data interface
                                                                                               (FDDI) and token ring networks to provide connections
                                                                                               between multiple stations, allowing them to communicate
                                                                                               with other stations on the network. It provides a logical star
                                                                                               topology while stations are physically connected as a ring.
                                                                                               The concentrator is the center of the star topology and can
                                                                                               actively bypass a port connected to it. A fiber-distributed
                                                                                               data interface (FDDI) concentrator has at least two physical
                                                                                               layer entities and may or may not have one or more media
                                                                                               access control (MAC) entities. In Ethernet networks, a
                                                                                               similar function is performed by a repeater.
Configuration Tool                                                                             Element management service tool with a GUI.
Congestion                                                                                     Traffic in excess of network capacity.
Congestion Avoidance                                                                           Mechanism by which an ATM network controls traffic
                                                                                               entering the network to minimize delays. In order to use
                                                                                               resources most efficiently, lower-priority traffic is discarded
                                                                                               at the edge of the network if conditions indicate that it
                                                                                               cannot be delivered.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                          Page 46 of 150

                 Term                                          Description                                              Definition
Congestion Collapse                                                                            Condition in which the retransmission of frames in an ATM
                                                                                               network results in little or no traffic successfully arriving at
                                                                                               the destination. Congestion collapse frequently occurs in
                                                                                               ATM networks composed of switches that do not have
                                                                                               adequate and effective buffering mechanisms complimented
                                                                                               by intelligent packet discard or ABR congestion feedback
                                                                                               mechanisms.
CONP                                        Connection-Oriented Network Protocol               OSI protocol providing connection-oriented operation to
                                                                                               upper-layer protocols.
CONS                                        Connection-Oriented Network Service
Cookie                                                                                         Piece of information sent by a Web server to a Web browser
                                                                                               that the browser is expected to save and send back to the
                                                                                               Web server whenever the browser makes additional
                                                                                               requests of the Web server.
COPS                                        Common Open Policy Service                         Quality-of-service (QoS) policy exchange protocol proposed
                                                                                               as an IETF standard for communicating network QoS policy
                                                                                               information.
CORBA                                       Common Object Request Broker Architecture          A set of specifications for management object modelling and
                                                                                               for interactions between objects.
Core Gateway                                                                                   Primary routers in the Internet.
Core Router                                                                                    In a packet-switched star topology, a router that is part of
                                                                                               the backbone and that serves as the single pipe through
                                                                                               which all traffic from peripheral networks must pass on its
                                                                                               way to other peripheral networks.
COS                                         Corporation for Open Systems                       Organization that promulgates the use of OSI protocols
                                                                                               through conformance testing, certification, and related
                                                                                               activities.
CoS                                         Class of Service                                   Indication of how an upper-layer protocol requires a lower-
                                                                                               layer protocol to treat its messages. In SNA subarea
                                                                                               routing, COS definitions are used by subarea nodes to
                                                                                               determine the optimal route to establish a given session. A
                                                                                               COS definition comprises a virtual route number and a
                                                                                               transmission priority field. Also called "ToS."



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                          Page 47 of 150

                    Term                                      Description                                               Definition
COSINE                                      Cooperation for Open Systems Interconnection       European project financed by the EC to build a
                                            Networking in Europe                               communication network between scientific and industrial
                                                                                               entities in Europe. The project ended in 1994.
COT                                         Continuity Test                                    Requirement of the SS7 protocol specifications. It tests the
                                                                                               bearer channels' status using either loopback or tone
                                                                                               detection and generation. Used to test individual DS0
                                                                                               channels via either loopback or tone detection and
                                                                                               generation.
Count to Infinity                                                                              Problem that can occur in routing algorithms that are slow to
                                                                                               converge, in which routers continuously increment the hop
                                                                                               count to particular networks. Typically, some arbitrary hop-
                                                                                               count limit is imposed to prevent this problem.
CPC                                         Calling Party Category
CPCS(1)                                     Common Part Convergence Sublayer                   One of the two sublayers of any AAL. The CPCS is service-
                                                                                               independent and is further divided into the CS and the SAR
                                                                                               sublayers. The CPCS is responsible for preparing data for
                                                                                               transport across the ATM network, including the creation of
                                                                                               the 48-byte payload cells that are passed to the ATM layer.
CPCS(2)                                     Call Processing Control System
CPE                                         Customer Premises Equipment                        Terminating equipment, such as terminals, telephones, and
                                                                                               modems, supplied by the telephone company, installed at
                                                                                               customer sites, and connected to the telephone company
                                                                                               network.
CPI-C                                       Common Programming Interface for                   Platform-independent API developed by IBM and used to
                                            Communications                                     provide portability in APPC applications
CPS                                         Characters Per Second                              The number of bytes or characters sent over the phone
                                                                                               lines in 1 second.
CPSS                                        Control Packet Switching System                    A signalling protocol that supports exchange of information
                                                                                               on private-line services and virtual circuits, operating in time
                                                                                               division multiplexing, X.25, X.75, frame relay and ATM
                                                                                               systems.
CPU                                         Central Processing Unit
CQ                                          Custom Queuing


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 48 of 150

                 Term                                          Description                                             Definition
CQL                                         Card Query Language
Crankback                                                                                      A mechanism used by ATM networks when a connection
                                                                                               setup request is blocked because a node along a selected
                                                                                               path cannot accept the request. In this case, the path is
                                                                                               rolled back to an intermediate node, which attempts to
                                                                                               discover another path to the final destination using GCAC.
CRC                                         Cycle Redundancy Check                             Error-checking technique in which the frame recipient
                                                                                               calculates a remainder by dividing frame contents by a
                                                                                               prime binary divisor and compares the calculated remainder
                                                                                               to a value stored in the frame by the sending node.
CREDFACS                                    Conduit, Raceway, Equipment Ducts, and             The infrastructure used in cabling.
                                            FACilitieS.
CRM                                         Customer Relationship Management                   The use of software systems to target and serve customers
                                                                                               by using data intelligently. Products can be tailored to
                                                                                               individual needs.
CRS                                         Customer Reservation System
CRT                                         Cathode Ray Tube
Cryptography                                                                                   The coding of communications to ensure privacy.
CS                                          Convergence Sublayer                               Part of AAL
CS1                                         Capability Set 1                                   A set of service-independent building blocks for the creation
                                                                                               of IN services developed by the European
                                                                                               Telecommunications Standards Institute and the CCITT.
CSCF                                        Call State Control Function
CSDN                                        Circuit Switched Digital Network
CSI                                         Called Subscriber Identification                   An identifier whose coding format contains the telephone
                                                                                               number from a remote fax terminal.
CSM                                         Customer Service Manage                            Also known as Customer Account / Operations Manager,
                                                                                               employee responsible for developing customer care
                                                                                               standards, plans, and processes, then managing the
                                                                                               customer care department and CAS employees.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 49 of 150

                Term                                         Description                                                Definition
CSMA/CA                                    Carrier Sense Multiple Access/Collision Avoidance   Is the principle medium access method employed by IEEE
                                                                                               802.11 WLANs. It is a "listen before talk": method of
                                                                                               minimizing (but not eliminating) collisions caused by
                                                                                               simultaneous transmission by multiple radios. IEEE 802.11
                                                                                               states collision avoidance method rather than collision
                                                                                               detection must be used, because the standard employs half
                                                                                               duplex radios—radios capable of transmission or
                                                                                               reception—but not both simultaneously. Unlike conventional
                                                                                               wired Ethernet nodes, a WLAN station cannot detect a
                                                                                               collision while transmitting. If a collision occurs, the
                                                                                               transmitting station will not receive an ACKnowledge packet
                                                                                               from the intended receive station. For this reason, ACK
                                                                                               packets have a higher priority than all other network traffic.
                                                                                               After completion of a data transmission, the receive station
                                                                                               will begin transmission of the ACK packet before any other
                                                                                               node can begin transmitting a new data packet. All other
                                                                                               stations must wait a longer pseudo randomized period of
                                                                                               time before transmitting. If an ACK packet is not received,
                                                                                               the transmitting station will wait for a subsequent
                                                                                               opportunity to retry transmission.
CSMA/CD                                    Carrier Sense Multiple Access/Collision Detection   The LAN access method used in Ethernet. When a device
                                                                                               wants to gain access to the network, it checks to see if the
                                                                                               network is free. If it is not, it waits a random amount of time
                                                                                               before retrying. If the network is free and two devices
                                                                                               access the line at exactly the same time, their signals
                                                                                               collide. When the collision is detected, they both back off
                                                                                               and each wait a random amount of time before retrying.
CSMA/CD                                    Carrier Sense Multiple Access with Collision        A contention-based network access method in which any
                                           Detection                                           computer may attempt to communicate at any time. Since
                                                                                               there is no centralized force controlling the medium, a
                                                                                               device must first sense whether or not the medium is in use.
                                                                                               If the medium is unused the device then transmits. If two
                                                                                               computers sense that a channel is open and transmit at the
                                                                                               same time, the result is a collision, after which there is a
                                                                                               random pause determined individually by each transmitting
                                                                                               machine. Each machine then senses the line again and, if it
                                                                                               is available, retransmits.
CSPDN                                      Circuit Switched Public Data Network


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                                                                  Telecom / IS Glossary                                                       Page 50 of 150

                 Term                                          Description                                             Definition
CSU                                         Channel Service Unit                               A device used to connect a digital phone line coming in from
                                                                                               the phone company to network access equipment located
                                                                                               on the customer premises. A CSU may also be built into the
                                                                                               network interface of the network access equipment.
CSU/DSU                                     Channel Service Unit / Data Service Unit           Manages digital transmission, monitors signals for
                                                                                               problems, responds to Central Office commands. It
                                                                                               performs many of the functions that modems do, but it does
                                                                                               not have to convert digital signals to/from analogue, since
                                                                                               the end device and the underlying transmission facility are
                                                                                               both digital.
CT2                                         Capability Set 2                                   A specification for the digital second generation of cordless
                                                                                               telephones (a British digital cordless communications
                                                                                               system).
CTD                                         Cell Transfer Delay                                In ATM, the elapsed time between a cell exit event at the
                                                                                               source UNI and the corresponding cell entry event at the
                                                                                               destination UNI for a particular connection. The CTD
                                                                                               between the two points is the sum of the total inter-ATM
                                                                                               node transmission delay and the total ATM node processing
                                                                                               delay.
CTI                                         Computer Telephony Integration                     Name given to the merger of traditional telecommunications
                                                                                               (PBX) equipment with computers and computer
                                                                                               applications. The use of Caller ID to automatically retrieve
                                                                                               customer information from a database is an example of a
                                                                                               CTI application.
CTIA                                        Cellular Telecommunications Industry Association   An organization that promotes cellular technology,
                                                                                               addresses common cellular concerns, provides a forum for
                                                                                               exchange of information, as well as a lobbying voice in the
                                                                                               legislature.
C-TPS                                       Cut-Through Packet Switching                       Packet switching approach that streams data through a
                                                                                               switch so that the leading edge of a packet exits the switch
                                                                                               at the output port before the packet finishes entering the
                                                                                               input port. A device using cut-through packet switching
                                                                                               reads, processes, and forwards packets as soon as the
                                                                                               destination address is looked up and the outgoing port
                                                                                               determined.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                          Page 51 of 150

                   Term                                       Description                                               Definition
CTR                                         Customer Premise Transceiver                       Reunion CPE radio and antenna
CTS                                         Clear-to-Send                                      The signal transmitted to a sending modem to start the data
                                                                                               transmission process.
CU(1)                                       Control Unit                                       A device that concentrates data from several terminals onto
                                                                                               a single communications line.
CU(2)                                       Control Unit                                       The central processor of a telephone switching device.
CUG                                         Closed User Group                                  A subgroup of network users that is treated as an entity.
                                                                                               Member can communicate only with other members of that
                                                                                               subgroup.
CVSD                                        Continuously Variable Slope Delta Modulation       A type of delta modulation in which the step size of an
                                                                                               approximated signal are progressively increased or
                                                                                               decreased as required to make the approximated signal
                                                                                               closely match the input analog wave.
CW                                          Continuous Wave
D-4                                                                                            A data transmission format comprised of 12 frames of 192
                                                                                               bits each. A single 193rd bit is used for link control and error
                                                                                               checking. D-4, also known as SF, has been superseded by
                                                                                               the ESF format as the industry standard. However, ESF is
                                                                                               not backward compatible and there is a large base of
                                                                                               channel banks and DS -1 multiplexers that are D-4 based.
                                                                                               D-4 is still the default private line formatting technique.
D-4 Channel Bank                                                                               A multiplexer used to convert 24 voice grade analog or data
                                                                                               channels into a DS-1 This is the most common type of
                                                                                               channel bank. The D-4 is not equipped for software-
                                                                                               controlled provisioning or remote circuit testing.
DAA                                         Data Access Agreement.                             Data communications equipment furnished or approved by
                                                                                               a common carrier that permits attachment of privately
                                                                                               owned data terminal and communications equipment to the
                                                                                               common carrier's network.
DAC                                         Dual Attached Concentrator                         FDDI or CDDI concentrator capable of attaching to both
                                                                                               rings of an FDDI or CDDI network. It can also be dual-
                                                                                               homed from the master ports of other FDDI or CDDI
                                                                                               concentrators.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 52 of 150

                   Term                                       Description                                               Definition
DACS                                        Digital Access and Cross-connect System            Used to interconnect both low and high-speed digital
                                                                                               transmission circuits, while providing access to individual
                                                                                               voice and data channels embedded within these circuits.
Dark Fiber                                                                                     An inactive fiber-optic strand without electronics or
                                                                                               optronics. Dark fiber is not connected transmitters, receivers
                                                                                               and regenerators.
DARPA                                       Defense Advanced Research Projects Agency.
DAS                                         Dynamically Assigned Socket                        Socket that is dynamically assigned by DDP upon request
                                                                                               by a client. In an AppleTalk network, the sockets numbered
                                                                                               128 to 254 are allocated as DASs.
DAS                                         Dual Attachment Station                            Device attached to both the primary and the secondary
                                                                                               FDDI rings. Dual attachment provides redundancy for the
                                                                                               FDDI ring: if the primary ring fails, the station can wrap the
                                                                                               primary ring to the secondary ring, isolating the failure and
                                                                                               retaining ring integrity.
Dassill                                                                                        A message based signaling system following the
                                                                                               International Standards Organization (ISO) based model
                                                                                               developed by BT to provide multi-line IDA interconnection to
                                                                                               the BT network.
Data Compression                                                                               A method of reducing the amount of data to be transmitted
                                                                                               by applying an algorithm to the basic data at source. A
                                                                                               decompression algorithm expands the data back to its
                                                                                               original state at the other end of the link. Digital video
                                                                                               requires up to 45 Mbps for reasonable performances but
                                                                                               with compression can achieve the same in one to three
                                                                                               Mbps.
Data Stream                                                                                    All data transmitted through a communications line in a
                                                                                               single read or write operation.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                        Page 53 of 150

                 Term                                         Description                                               Definition
DBM                                         Dynamic Buffer Management                          Frame Relay and ATM service modules are equipped with
                                                                                               large buffers and the patented Dynamic Buffer Management
                                                                                               scheme for allocating and scaling traffic entering or leaving
                                                                                               a node on a per-VC basis. The WAN switch dynamically
                                                                                               assigns buffers to individual virtual circuits based upon the
                                                                                               amount of traffic present and service-level agreements. This
                                                                                               deep pool of available buffers readily accommodates large
                                                                                               bursts of traffic into the node.
DCD                                         Data Carrier Detect                                A process that tells the computer whether or not the modem
                                                                                               is connected to another modem.
DCE(1)                                      Data Communications Equipment (EIA expansion)
DCE(2)                                      Data Circuit-Terminating Equipment (ITU-T          Devices and connections of a communications network that
                                            expansion)                                         comprise the network end of the user-to-network interface.
                                                                                               The DCE provides a physical connection to the network,
                                                                                               forwards traffic, and provides a clocking signal used to
                                                                                               synchronize data transmission between DCE and DTE
                                                                                               devices. Modems and interface cards are examples of DCE.
DCOM                                        Distributed Component Object Model                 Protocol that enables software components to communicate
                                                                                               directly over a network. Developed by Microsoft and
                                                                                               previously called Network OLE, DCOM is designed for use
                                                                                               across multiple network transports, including Internet
                                                                                               protocols such as HTTP.
DCS                                         Digital Cross-Connect System                       A digital switching facility interconnection device allowing
                                                                                               reconfiguration of lower levels of capacity within a circuit
                                                                                               without the need for manual changes in the
                                                                                               interconnections.
DCT                                         Discrete Cosine Transform
DDM                                         Distributed Data Management                        Software in an IBM SNA environment that provides peer-to-
                                                                                               peer communication and file sharing. One of three SNA
                                                                                               transaction services.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                      Page 54 of 150

                 Term                                         Description                                              Definition
DDR                                         Dial-on-Demand Routing                             Technique whereby a router can automatically initiate and
                                                                                               close a circuit-switched session as transmitting stations
                                                                                               demand. The router spoofs keepalives so that end stations
                                                                                               treat the session as active. DDR permits routing over ISDN
                                                                                               or telephone lines using an external ISDN terminal adaptor
                                                                                               or modem.
DDS                                         Digital Data Service                               A private line channel at 56 or 64Kbps
DECT(1)                                     Digital European Cordless Telephone
DECT(2)                                     Digital Enhanced Cordless Telecommunications       A wireless communications standard used in Europe, the
                                                                                               Mid-East and Africa.
Dedicated Line                                                                                 Communications line that is indefinitely reserved for
                                                                                               transmissions, rather than switched as transmission is
                                                                                               required.
Default Route                                                                                  Routing table entry that is used to direct frames for which a
                                                                                               next hop is not explicitly listed in the routing table.
DEK                                         Data Encryption Key                                Used for the encryption of message text and for the
                                                                                               computation of message integrity checks (signatures).
Demodulation                                                                                   Process of returning a modulated signal to its original form.
                                                                                               Modems perform demodulation by taking an analog signal
                                                                                               and returning it to its original (digital) form.
Demultiplexing                                                                                 Separating of multiple input streams that were multiplexed
                                                                                               into a common physical signal back into multiple output
                                                                                               streams.
DEN                                         Document Enabled Networking
DES(1)                                      Destination End Station
DES(2)                                      Data Encryption Standard                           Standard cryptographic algorithm developed by the U.S.
                                                                                               National Bureau of Standards.
DFB                                         Distributed Feed-Back
DG-I                                                                                           The European Commission's directorate general on external
                                                                                               relations and trade negotiations.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                        Page 55 of 150

                   Term                                       Description                                              Definition
DG-IV                                                                                          The European Commission's directorate general on
                                                                                               competition.
DG-XIII                                                                                        The European Commission's directorate general for
                                                                                               telecommunications, information industries and innovation.
DHCP                                        Dynamic Host Configuration Protocol                Provides a mechanism for allocating IP addresses
                                                                                               dynamically so that addresses can be reused when hosts
                                                                                               no longer need them.
DHTML                                       Dynamic Hypertext Mark-up Language
DIA                                         Document Interchange Architecture                  Defines the protocols and data formats needed for the
                                                                                               transparent interchange of documents in an SNA network.
                                                                                               One of three SNA transaction services.
Dial Backup                                                                                    Feature that provides protection against WAN downtime by
                                                                                               allowing the network administrator to configure a backup
                                                                                               serial line through a circuit-switched connection.
Dial String                                                                                    The sequence of numbers sent to a device, such as a
                                                                                               modem, that can dial a telephone number.
Differential Encoding                                                                          Digital encoding technique whereby a binary value is
                                                                                               denoted by a signal change rather than a particular signal
                                                                                               level.
Digital Cross Connect                                                                          An electronic switching system, found in telephone central
                                                                                               offices, that switches groups of signals from one route to
                                                                                               another, without the need to demultiplex them. An optical
                                                                                               cross connect is an optical switch that routes wavelength
                                                                                               channels from one fiber route to another without first
                                                                                               converting them into electricity and back.
DIN                                         Deutsche Industrie Norm                            German national standards organization.
DIN Connector                               Deutsche Industrie Norm Connector                  Multipin connector used in some Macintosh and IBM PC-
                                                                                               compatible computers, and on some network processor
                                                                                               panels.
Direct Route                                                                                   A route that can reach a destination without going through
                                                                                               any intervening routers.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                       Page 56 of 150

                   Term                                          Description                                             Definition
DISA                                        Defense Information Systems Agency                 Formerly DCA. U.S. military organization responsible for
                                                                                               implementing and operating military information systems,
                                                                                               including the DDN.
Distortion Delay                                                                               Problem with a communication signal resulting from
                                                                                               nonuniform transmission speeds of the components of a
                                                                                               signal through a transmission medium.
DL                                          Downlink                                           Data/RF propagation away from the BTR; transmission
                                                                                               direction from the central facility to the customer.
DLC                                         Digital Loop Carrier                               Equipment that concentrates analog loop lines, digitizing
                                                                                               and multiplexing calls for transmission to the central office.
DLCI                                        Data-Link Connection Identifier                    Value that specifies a PVC or SVC in a Frame Relay
                                                                                               network. In the basic Frame Relay specification, DLCIs are
                                                                                               locally significant (connected devices might use different
                                                                                               values to specify the same connection). In the LMI extended
                                                                                               specification, DLCIs are globally significant (DLCIs specify
                                                                                               individual end devices).
DLL                                         Dynamic Link Library
DLSw                                        Data Link Switching                                Involves using routers at field offices and headquarters to
                                                                                               encapsulate SNA traffic in TCP/IP, and then transmit that
                                                                                               traffic over a leased-line or frame relay network.
DMA                                         Direct Memory Access                               Transfer of data from a peripheral device, such as a hard
                                                                                               disk drive, into memory without that data passing through
                                                                                               the microprocessor. DMA transfers data into memory at
                                                                                               high speeds with no processor overhead.
DME                                         Differential Manchester Encoding                   Digital coding scheme where a mid-bit-time transition is
                                                                                               used for clocking, and a transition at the beginning of each
                                                                                               bit time denotes a zero. This coding scheme is used by
                                                                                               IEEE 802.5 and Token Ring networks.
DMS                                         Digital Multiplexer System
DMT                                         Discrete Multitone                                 A line coding protocol.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 57 of 150

                 Term                                          Description                                              Definition
DNA                                         Digital Network Architecture                       Network architecture developed by Digital Equipment
                                                                                               Corporation. The products that embody DNA (including
                                                                                               communications protocols) are collectively referred to as
                                                                                               DECnet.
DNS                                         Domain Name System                                 System used in the Internet for translating names of network
                                                                                               nodes into addresses.
DNSIX                                       Department of Defense Intelligence Information     Collection of security requirements for networking defined
                                            System Network Security for Information Exchange   by the U.S. Defense Intelligence Agency.
Domain                                                                                         In IS-IS, a logical set of networks. (2) In SNA, an SSCP and
                                                                                               the resources it controls. (3) In the Internet, a portion of the
                                                                                               naming hierarchy tree that refers to general groupings of
                                                                                               networks based on organization-type or geography. (4)
                                                                                               Networking system developed by Apollo Computer (now
                                                                                               part of Hewlett-Packard) for use in its engineering
                                                                                               workstations.
DOWNSTREAM                                                                                     Downlink, data/RF propagation away from the BTR;
                                                                                               transmission direction from the central facility to the
                                                                                               customer.
DPNSS                                       Digital Private Network Signalling System          A British protocol for PBX-to-PBX communications.
DQDB                                        Distributed Queue Dual Bus                         Data-link layer communication protocol, specified in the
                                                                                               IEEE 802.6 standard, designed for use in MANs. DQDB,
                                                                                               which permits multiple systems to interconnect using two
                                                                                               unidirectional logical buses, is an open standard that is
                                                                                               designed for compatibility with carrier transmission
                                                                                               standards, and is aligned with emerging standards for
                                                                                               BISDN. SIP is based on DQDB.
DRAM                                        Dynamic Random-Access Memory                       RAM that stores information in capacitors that must be
                                                                                               periodically refreshed. Delays can occur because DRAMs
                                                                                               are inaccessible to the processor when refreshing their
                                                                                               contents. However, DRAMs are less complex and have
                                                                                               greater capacity than SRAMs.
DS-0                                        Digital Signal Level 0                             Framing specification used in transmitting digital signals
                                                                                               over a single channel at 64-kbps on a T1 facility.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                      Page 58 of 150

                 Term                                           Description                                             Definition
DS-1                                        Digital Signal Level                               Framing specification used in transmitting digital signals at
                                                                                               1.544-Mbps on a T1 facility (in the United States) or at
                                                                                               2.108-Mbps on an E1 facility (in Europe).
DS-1/DTI                                    DS-1 Domestic Trunk Interface                      Interface circuit used for DS-1 applications with 24 trunks.
DS-3                                        Digital Signal Level 3                             Framing specification used for transmitting digital signals at
                                                                                               44.736 Mbps on a T3 facility.
DSAP                                        Destination Service Access Point                   SAP of the network node designated in the Destination field
                                                                                               of a packet.
DSL                                         Digital Subscriber Line                            Public network technology that delivers high bandwidth over
                                                                                               conventional copper wiring at limited distances. There are
                                                                                               four types of DSL: ADSL, HDSL, SDSL, and VDSL. All are
                                                                                               provisioned via modem pairs, with one modem located at a
                                                                                               central office and the other at the customer site. Because
                                                                                               most DSL technologies do not use the whole bandwidth of
                                                                                               the twisted pair, there is room remaining for a voice
                                                                                               channel.
DSLAM                                       Digital Subscriber Line Access Multiplexer
DS-n                                                                                           North America PDH transmission speed
DSP                                         Digital Signal Processor                           A DSP analyzes and processes analog signals, converting
                                                                                               them to a digital format.
DSR                                         Data Set Ready                                     EIA/TIA-232 interface circuit that is activated when DCE is
                                                                                               powered up and ready for use.
DSSS                                        Direct-Sequencing Spread-Spectrum                  A spread-spectrum techniques that operate over the radio
                                                                                               airwaves in the unlicensed ISM band (industrial, scientific,
                                                                                               and medical). DSSS uses a radio transmitter to spread data
                                                                                               packets over a fixed range of the frequency band. WECA’s
                                                                                               focus is on the use of DSSS for 11 Mbps high rate wireless
                                                                                               LAN communications.
DSU                                         Data Service Unit                                  Device used in digital transmission that adapts the physical
                                                                                               interface on a DTE device to a transmission facility such as
                                                                                               T1 or E1. The DSU is also responsible for such functions as
                                                                                               signal timing.
DSX-1                                                                                          Crossconnection point for DS-1 signals.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 59 of 150

                 Term                                         Description                                              Definition
DTE                                         Data Terminal Equipment                            Device at the user end of a user-network interface that
                                                                                               serves as a data source, destination, or both. DTE connects
                                                                                               to a data network through a DCE device (for example, a
                                                                                               modem) and typically uses clocking signals generated by
                                                                                               the DCE. DTE includes such devices as computers,
                                                                                               protocol translators, and multiplexers.
DTH                                         Direct-To-Home
DTMF                                        Dual Tone Multi-Frequency                          Use of two simultaneous voice-band tones for dialing (such
                                                                                               as touch tone).
Dual Homing                                                                                    Network topology in which a device is connected to the
                                                                                               network by way of two independent access points (points of
                                                                                               attachment). One access point is the primary connection,
                                                                                               and the other is a standby connection that is activated in the
                                                                                               event of a failure of the primary connection.
DVMRP                                       Distance Vector Multicast Routing Protocol         Internetwork gateway protocol, largely based on RIP, that
                                                                                               implements a typical dense mode IP multicast scheme.
                                                                                               DVMRP uses IGMP to exchange routing datagrams with its
                                                                                               neighbors.
DVRA                                        Distance Vector Routing Algorithm                  Class of routing algorithms that iterate on the number of
                                                                                               hops in a route to find a shortest-path spanning tree.
                                                                                               Distance vector routing algorithms call for each router to
                                                                                               send its entire routing table in each update, but only to its
                                                                                               neighbors. Distance vector routing algorithms can be prone
                                                                                               to routing loops, but are computationally simpler than link
                                                                                               state routing algorithms.
DWDM                                        Dense Wavelength Division Multiplexing             Using optical multiplexers and optical amplifiers, DWDM
                                                                                               combines multiple optical signals so they can be amplified
                                                                                               as a group and transported over a single fiber to increase
                                                                                               capacity.
DXI                                                                                            An SMDS interface between the customer and the network
                                                                                               used at low speeds, typically 64 kbps. The data passes
                                                                                               through the interface in full frames. The carrier's equipment
                                                                                               converts the messages to small packets.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 60 of 150

                  Term                                         Description                                              Definition
Dynamic Route                                                                                  A path to another network that the router learns by means of
                                                                                               dynamic updates from other routers, rather than by means
                                                                                               of a static specification in a configured profile. Routers that
                                                                                               use Routing Information Protocol (RIP) broadcast their
                                                                                               entire routing tables every 30 seconds, updating other
                                                                                               routers about which routes are usable. Hosts that run
                                                                                               Internet Control Message Protocol (ICMP) can also send
                                                                                               ICMP redirects to offer a better path to a destination
                                                                                               network. Open Shortest Path First (OSPF) routers
                                                                                               propagate link-state changes as they occur in order to
                                                                                               update their routing tables.
Dynamic Routing                                                                                A routing technique that enables a message's route to
                                                                                               change as the message proceeds along the network.
E.164                                                                                          ITU -T recommendation for international telecommunication
                                                                                               numbering, especially in ISDN, BISDN, and SMDS. An
                                                                                               evolution of standard telephone numbers. (2) Name of the
                                                                                               field in an ATM address that contains numbers in E.164
                                                                                               format.
E1                                                                                             European standard of the T1, a digital circuit with
                                                                                               standardized characteristics that operate at 2.048 Mbps.
                                                                                               This standard is widely used in Europe as a rough
                                                                                               equivalent of a DS-1, (E1 provides thirty 64Kbps channels -
                                                                                               six more than a DS-1).
E3                                                                                             Wide-area digital transmission scheme used predominantly
                                                                                               in Europe that carries data at a rate of 34.368 Mbps. E3
                                                                                               lines can be leased for private use from common carriers.
EA                                                                                             Electro Absorptive
EAI                                         Enterprise Application Integration                 Integrating IT systems with new applications; a
                                                                                               sophisticated approach to middleware.
EAP                                         Extensible Authentication Protocol                 EAP is a PPP extension that provides support for additional
                                                                                               authentication methods within PPP.
EARN                                        European Academic Research Network                 European network connecting universities and research
                                                                                               institutes. EARN merged with RARE to form TERENA.
eBILLS                                                                                         Electronic Bills


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 61 of 150

                 Term                                         Description                                               Definition
E-bone                                      European Backbone                                  Pan-European network backbone service.
EBPP                                        Electronic Bill Presentation and Payment           EBPP provides companies the ability to send bills
                                                                                               electronically over the Internet to their customers.
Echo                                                                                           A signal that determines whether a node can receive and
                                                                                               acknowledge data transmissions. A host sends an echo
                                                                                               request packet. If the destination is properly connected and
                                                                                               receives the echo request packet, it sends back an echo
                                                                                               reply packet.
Echo Canceller                                                                                 A chip that identifies and erases echoes occurring in
                                                                                               satellite and terrestrial long-distance phone calls of about
                                                                                               2,000 miles and beyond.
Echoplex                                                                                       Mode in which keyboard characters are echoed on a
                                                                                               terminal screen upon return of a signal from the other end of
                                                                                               the line indicating that the characters were received
                                                                                               correctly.
ECP                                         Encryption Control Protocol                        Used to negotiate data encryption over PPP links.
ECTF                                        Enterprise Computer Telephony Forum
EDA                                         Electronic Design Automation
EDGE                                        Enhanced Data for GSM Evolution                    Uses a new modulation schema to enable data throughput
                                                                                               speeds of up to 384kbit/s using existing GSM infrastructure.
Edge Device                                                                                    Physical device that is capable of forwarding packets
                                                                                               between legacy interfaces (such as Ethernet and Token
                                                                                               Ring) and ATM interfaces based on data-link and network
                                                                                               layer information. An edge device does not participate in the
                                                                                               running of any network layer routing protocol, but it obtains
                                                                                               forwarding descriptions using the route distribution protocol.
EDI                                         Electronic Data Interchange                        A term for data communications systems and technologies
                                                                                               used to automate common paper-based business
                                                                                               transactions and exchange standardized business forms,
                                                                                               direct from one computer to another. This technology is
                                                                                               most often used for data communication between major
                                                                                               buyers of a product and large suppliers of that product.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                        Page 62 of 150

                 Term                                          Description                                             Definition
EDIFACT                                     Electronic Data Interchange for Administration,    Data exchange standard administered by the United
                                            Commerce, and Transport                            Nations to be a multi-industry EDI standard.
EDNS                                        Enterprise Defined Network Services                The managed data network services offering planned by
                                                                                               Infonet.
EECM                                        End-to-End Call Manager
EEPROM                                      Electrically Erasable Programmable Read-Only       EPROM that can be erased using electrical signals applied
                                            Memory                                             to specific pins.
EFCI                                        Explicit Forward Congestion Indication             In ATM, one of the congestion feedback modes allowed by
                                                                                               ABR service. A network element in an impending
                                                                                               congestion state or in a congested state can set the EFCI.
                                                                                               The destination end-system can implement a protocol that
                                                                                               adaptively lowers the cell rate of the connection based on
                                                                                               the value of the EFCI.
EFF                                         Electronic Frontier Foundation                     Foundation established to address social and legal issues
                                                                                               arising from the impact on society of the increasingly
                                                                                               pervasive use of computers as the means of communication
                                                                                               and information distribution.
EFR                                         Enhanced Full Rate                                 Speech codec defined specifically for speech quality
                                                                                               purposes with an improved coding algorithms for higher
                                                                                               tolerance to interference.
EFT                                         Electronic Fund Transfer
EGP                                         Exterior Gateway Protocol                          A routing protocol used by gateways in two-level Internets.
                                                                                               EGP is used in the Internet core system.
EIA                                         Electronic Industries Association                  Group that specifies electrical transmission standards. The
                                                                                               EIA and TIA have developed numerous well-known
                                                                                               communications standards, including EIA/TIA-232 and
                                                                                               EIA/TIA-449.
EISA                                        Extended Industry Standard Architecture            A specification for a PC-bus architecture featuring a 32-bit
                                                                                               input/output bus. In competition with IBM's Micro Channel
                                                                                               Architecture.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                          Page 63 of 150

                     Term                                     Description                                              Definition
ELAN                                        Emulated LAN                                       ATM network in which an Ethernet or Token Ring LAN is
                                                                                               emulated using a client-server model. ELANs are composed
                                                                                               of an LEC, an LES, a BUS, and an LECS. Multiple ELANs
                                                                                               can exist simultaneously on a single ATM network. ELANs
                                                                                               are defined by the LANE specification.
ELMI                                        Enhanced Local Management Interface
EMA                                         Enterprise Management Architecture                 Digital Equipment Corporation network management
                                                                                               architecture, based on the OSI network management
                                                                                               model.
EMA                                         Electronic Messaging Association                   Forum devoted to standards and policy work, education,
                                                                                               and development of electronic messaging systems such as
                                                                                               e-mail, voice mail, and facsimile.
EMI                                         Electromagnetic Interference                       Interference by electromagnetic signals that can cause
                                                                                               reduced data integrity and increased error rates on
                                                                                               transmission channels.
EMP                                         Electromagnetic Pulse                              Caused by lightning and other high-energy phenomena.
                                                                                               Capable of coupling enough energy into unshielded
                                                                                               conductors to destroy electronic devices.
E-n                                                                                            Europe PDH transmission speed
Encoder                                                                                        Device that modifies information into the required
                                                                                               transmission format.
Encryption                                                                                     Application of a specific algorithm to data so as to alter the
                                                                                               appearance of the data making it incomprehensible to those
                                                                                               who are not authorized to see the information.
End-to End Delay                                                                               An asynchronous transfer mode (ATM) routing metric that
                                                                                               measures the time it takes a cell to get from one end of a
                                                                                               connection to the other
Enterprise Network                                                                             Large and diverse network connecting most major points in
                                                                                               a company or other organization. Differs from a WAN in that
                                                                                               it is privately owned and maintained.
EOM                                         End of Message                                     Indicator that identifies the last ATM cell containing
                                                                                               information from a data packet that was segmented.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                        Page 64 of 150

                  Term                                        Description                                               Definition
EOT                                         End of Transmission                                Generally, a character that signifies the end of a logical
                                                                                               group of characters or bits.
EPD                                         Early Packet Discard                               Mechanism used by some ATM switches for discarding a
                                                                                               complete AAL5 frame when a threshold condition, such as
                                                                                               imminent congestion, is met. EPD prevents congestion that
                                                                                               would otherwise jeopardize the switch's ability to properly
                                                                                               support existing connections with a guaranteed service.
EPOC                                                                                           The operating system for wireless devices, such as
                                                                                               handheld organisers, that was developed by Psion.
EPROM                                       Erasable Programmable Read-Only Memory             Nonvolatile memory chips that are programmed after they
                                                                                               are manufactured, and, if necessary, can be erased by
                                                                                               some means and reprogrammed.
Equalization                                                                                   Technique used to compensate for communications channel
                                                                                               distortions.
ER                                          Explicit Rate                                      In ATM, an RM cell used to limit the ACR for a transmission
                                                                                               to a specific value. Usually the source initially sets the ER
                                                                                               initially to a requested rate, such as the PCR. Later, any
                                                                                               network element in the path can reduce the ER to a value
                                                                                               that the element can sustain.
ERP                                         Enterprise Resource Planning                       The linking of a company's various business operations and
                                                                                               functions by means of complex software. ERP is now being
                                                                                               rapidly extended to the growing number of e-business
                                                                                               applications being developed over the Internet, connecting
                                                                                               customer, supply chain and other activities.
Error Control                                                                                  Technique for detecting and correcting errors in data
                                                                                               transmissions.
Error-Correcting Code                                                                          Code having sufficient intelligence and incorporating
                                                                                               sufficient signaling information to enable the detection and
                                                                                               correction of many errors at the receiver.
Error-Detecting Code                                                                           Code that can detect transmission errors through analysis of
                                                                                               received data based on the adherence of the data to
                                                                                               appropriate structural guidelines.
ES                                          End System                                         Generally, an end-user device on a network. Nonrouting
                                                                                               host or node in an OSI network.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                          Page 65 of 150

                    Term                                      Description                                               Definition
ESA                                         Encapsulating Security Payload                     A mechanism which provides confidentiality and integrity
                                                                                               protection to IP datagrams.
ESD                                         Electrostatic Discharge                            Discharge of stored static electricity that can damage
                                                                                               electronic equipment and impair electrical circuitry, resulting
                                                                                               in complete or intermittent failures.
ESF                                         Extended SuperFrame                                Framing type used on T1 circuits that consists of 24 frames
                                                                                               of 192 bits each, with the 193rd bit providing timing and
                                                                                               other functions. ESF is an enhanced version of SF.
ESI                                         End System Identifier                              Identifier that distinguishes multiple nodes at the same level
                                                                                               when the lower level peer group is partitioned (usually an
                                                                                               IEEE 802 address).
ESMTP                                       Extended Simple Mail Transfer Protocol             Extended version of the Simple Mail Transfer Protocol
                                                                                               (SMTP), which includes additional functionality such as
                                                                                               delivery notification and session delivery. ESMTP is
                                                                                               described in RFC 1869, "SMTP Service Extensions."
ESP                                         Extended Services Processor
Ethernet                                                                                       The most widely used LAN access method, which is defined
                                                                                               by the IEEE 802.3 standard. Ethernet is normally a shared
                                                                                               media LAN meaning all devices on the network segment
                                                                                               share total bandwidth. Ethernet networks operate at
                                                                                               10Mbps using CSMA/CD to run over 10BaseT cables. (2)
                                                                                               The most common layer-two protocol used in LANs.
                                                                                               Ethernet is a 10 Mbps CSMA/CD standard originally
                                                                                               developed by Xerox to run on thick coaxial cabling. It has
                                                                                               evolved and now runs primarily on twisted pair cabling. (3)
                                                                                               An older broadband technology that carries data over
                                                                                               coaxial cable, twisted pair, etc. in LANs and transmits data
                                                                                               over a very limited area. An Ethernet LAN has a
                                                                                               transmission speed of up to 10 megabits per second,
                                                                                               although each individual user sees only a portion of that line
                                                                                               speed as real throughput.
Ethernet Meltdown                                                                              Event that causes saturation, or near saturation, on an
                                                                                               Ethernet. It usually results from illegal or misrouted packets
                                                                                               and typically lasts only a short time.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                           Page 66 of 150

                 Term                                         Description                                               Definition
ETSI                                        European Telecommunications Standards Institute    An international standards body, comparable to ANSI, that
                                                                                               recommends standards for telephony, ISDN, wireless,
                                                                                               plesiochronous, and synchronous transport in Europe.
Excess Rate                                                                                    In ATM, traffic in excess of the insured rate for a given
                                                                                               connection. Specifically, the excess rate equals the
                                                                                               maximum rate minus the insured rate. Excess traffic is
                                                                                               delivered only if network resources are available and can be
                                                                                               discarded during periods of congestion.
Expansion                                                                                      The process of running a compressed data set through an
                                                                                               algorithm that restores the data set to its original size.
External Route                                                                                 A route imported into the Open Shortest Path First (OSPF)
                                                                                               database from outside the router's Autonomous System
                                                                                               (AS)
EXTRANET                                                                                       A private web site, intended for use only by those business
                                                                                               partners and select customers you choose to grant access
                                                                                               to.
EXZ                                         Excessive Zeros
Fallback                                                                                       Mechanism used by ATM networks when rigorous path
                                                                                               selection does not generate an acceptable path. The
                                                                                               fallback mechanism attempts to determine a path by
                                                                                               selectively relaxing certain attributes, such as delay, in order
                                                                                               to find a path that meets some minimal set of desired
                                                                                               attributes.
FAN                                         Flexible Access Network                            A technology offering variable bandwidth, rapid service
                                                                                               provisioning, service variety and customer control. FAN on
                                                                                               second reference.
Fantail                                                                                        Panel of I/O connectors that attaches to an equipment rack,
                                                                                               providing easy access for data connections to a networking.
FAQ                                                                                            Frequently Asked Question
FARNET                                      Federation of American Research NETworks
Fast Ethernet                                                                                  A LAN transmission standard with a data rate of 100Mbps.
                                                                                               A workstation with a 10-Mbps (10Base-T) Ethernet card can
                                                                                               be connected to a Fast Ethernet network.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 67 of 150

                 Term                                          Description                                             Definition
FCC                                         Federal Communications Commission                  A regulatory authority for telecommunication in the US.
FCS                                         Frame Check Sequence                               Extra characters added to a frame for error control
                                                                                               purposes. Used in HDLC, Frame Relay, and other data link
                                                                                               layer protocols.
FDD                                         Frequency Division Duplex
FDDI                                        Fiber Distributed Data Interface                   The American National Standards Institute standard for 100-
                                                                                               megabit-per-second local area networks.
FDDI II                                     Fiber Distributed Data Interface II                ANSI standard that enhances FDDI. FDDI II provides
                                                                                               isochronous transmission for connectionless data circuits
                                                                                               and connection-oriented voice and video circuits.
FDM                                         Frequency Division Multiplexing                    Method by which the available transmission frequency
                                                                                               range is divi ded into narrower bands; each of these bands is
                                                                                               used for a separate channel. This allows several signals to
                                                                                               be sent over the same transmission medium.
FEC                                         Forward Error Correction                           An error correction technique in which redundant bits are
                                                                                               transmitted along with the payload enabling the receiving
                                                                                               station to detect error and to correct the message.
FECN                                        Forward Explicit Congestion Notification           Bit set by a Frame Relay network to inform DTE receiving
                                                                                               the frame that congestion was experienced in the path from
                                                                                               source to destination. DTE receiving frames with the FECN
                                                                                               bit set can request that higher-level protocols take flow-
                                                                                               control action as appropriate.
FEP                                         Front -End Processor                               Device or board that provides network interface capabilities
                                                                                               for a networked device.
FFD                                         Flexible access network Four Dragons               South Korea, Hong Kong, Singapore, Taiwan.
FHSS                                        Frequency-Hopping Spread-Spectrum                  A spread-spectrum techniques that operate over the radio
                                                                                               airwaves in the unlicensed ISM band (industrial, scientific,
                                                                                               and medical). FHSS uses a technique by which the signal
                                                                                               transmitted hops among several frequencies at a specific
                                                                                               rate and sequence as a way of avoiding interference.
                                                                                               WECA’s focus is on the use of DSSS for 11 Mbps high rate
                                                                                               wireless LAN communications.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 68 of 150

                 Term                                          Description                                              Definition
File Transfer                                                                                  Category of popular network applications that allow files to
                                                                                               be moved from one network device to another.
Filter                                                                                         Generally, a process or device that screens network traffic
                                                                                               for certain characteristics, such as source address,
                                                                                               destination address, or protocol, and determines whether to
                                                                                               forward or discard that traffic based on the established
                                                                                               criteria.
Firewall                                                                                       A hardware/software tool that allows a network
                                                                                               administrator to determine what type of users can access
                                                                                               the resources on the network. The firewall provides a
                                                                                               mechanism to monitor and funnel data from authorized
                                                                                               users (only) through the firewall to and from the network. A
                                                                                               firewall may be a software program that runs on UNIX or
                                                                                               other platforms, or it may be a part of a proprietary
                                                                                               operating system. A firewall by itself does not perform the
                                                                                               routing function.
FLAG                                        Fiber-optic Link Around the Globe                  A proposal by a consortium led by Nynex Corp. to extend a
                                                                                               25,000-kilometer cable from the United Kingdom to eastern
                                                                                               Asia via the Middle East.
Flapping                                                                                       Routing problem where an advertised route between two
                                                                                               nodes alternates (flaps) back and forth between two paths
                                                                                               due to a network problem that causes intermittent interface
                                                                                               failures.
F-Link                                                                                         SS7 fully associated link. An SS7 signaling link directly
                                                                                               associated with a link carrying traffic.
Flip-Chip BGA                               Flip Chip Ball Grid Array
Flooding                                                                                       Traffic passing technique used by switches and bridges in
                                                                                               which traffic received on an interface is sent out all of the
                                                                                               interfaces of that device except the interface on which the
                                                                                               information was originally received.
Flow                                                                                           Stream of data traveling between two endpoints across a
                                                                                               network (for example, from one LAN station to another).
                                                                                               Multiple flows can be transmitted on a single circuit.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                      Page 69 of 150

                    Term                                         Description                                           Definition
Flow Control                                                                                   Technique for ensuring that a transmitting entity, such as a
                                                                                               modem, does not overwhelm a receiving entity with data.
                                                                                               When the buffers on the receiving device are full, a
                                                                                               message is sent to the sending device to suspend the
                                                                                               transmission until the data in the buffers has been
                                                                                               processed. In IBM networks, this technique is called pacing.
FLS                                         Fallback/fall-forward Line Sensing                 A feature that enables a high-speed analog modem to
                                                                                               monitor the quality of the phone line and to step down to the
                                                                                               next lower speed if the line quality deteriorates. The modem
                                                                                               falls forward to the next higher speed as line quality
                                                                                               improves.
FLT                                         Full Line Terminal                                 Multiplexer that terminates a SONET span.
FM                                          Frequency Modulation                               Modulation technique in which signals of different
                                                                                               frequencies represent different data values.
FNC                                         Federal Networking Council                         Group responsible for assessing and coordinating U.S.
                                                                                               federal agency networking policies and needs.
FOIRL                                       Fiber-Optic Interrepeater Link                     Fiber-optic signaling methodology based on the IEEE 802.3
                                                                                               fiber-optic specification. FOIRL is a precursor of the
                                                                                               10BaseFL specification, which is designed to replace it.
Forward Channel                                                                                Communications path carrying information from the call
                                                                                               initiator to the called party.
Forward Delay Interval                                                                         Amount of time an interface spends listening for topology
                                                                                               change information after that interface is activated for
                                                                                               bridging and before forwarding actually begins.
Forwarding                                                                                     Process of sending a frame toward its ultimate destination
                                                                                               by way of an internetworking device.
FOTS                                        Fiber Optics Transmission Systems                  Vendor-proprietary fiber-optic transmission equipment.
Fourier Transform                                                                              Technique used to evaluate the importance of various
                                                                                               frequency cycles in a time series pattern.
FPGA                                        Field Programmable Gate Array




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                         Page 70 of 150

                  Term                                        Description                                              Definition
FQDN                                        Fully Qualified Domain Name                        FQDN is the full name of a system, rather than just its host
                                                                                               name. For example, aldebaran is a host name, and
                                                                                               aldebaran.interop.com is an FQDN.
FR                                          Frame Relay
FRAD                                        Frame Relay Access Device                          Any network device that provides a connection between a
                                                                                               LAN and a Frame Relay WAN.
Fragment                                                                                       Piece of a larger packet that has been broken down to
                                                                                               smaller units.
Fragmentation                                                                                  Process of breaking a packet into smaller units when
                                                                                               transmitting over a network medium that cannot support the
                                                                                               original size of the packet.
Frame                                                                                          A segment of a digital signal that has a repetitive
                                                                                               characteristic in that corresponding elements of successive
                                                                                               frames represent the same things. In a time-division
                                                                                               multiplex system, a frame is a sequence of time slots, each
                                                                                               containing a sample from one of the channels served by the
                                                                                               multiplex system; the frame is repeated at the sampling
                                                                                               rate, and each channel occupies the same sequence
                                                                                               position in successive frames.
Frame Relay                                                                                    The emerging standard for high-speed data
                                                                                               communications, offering users transmission speeds of
                                                                                               2.048 megabits per second and higher. It allows faster
                                                                                               speeds than the X.25 packet switching standard because it
                                                                                               does away with elaborate error-correction and routing
                                                                                               information. Its main application is interconnecting local
                                                                                               area networks. (2) Connection-oriented, fast packet
                                                                                               technology for either public or private local or wide area
                                                                                               networks; implemented as a permanent virtual circuit. More
                                                                                               efficient than X.25.
Frame Relay Bridging                                                                           Bridging technique that uses the same spanning-tree
                                                                                               algorithm as other bridging functions, but allows packets to
                                                                                               be encapsulated for transmission across a Frame Relay
                                                                                               network.
Framed Protocol                                                                                A synchronous protocol that encapsulates data into frames.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                          Page 71 of 150

                    Term                                        Description                                             Definition
FRASM                                       Frame Relay Access Service Module
Freephone                                                                                      The European term for toll-free 800 services.
Frequency                                                                                      Number of cycles per unit of time, measured in units called
                                                                                               Hertz (Hz). One Hz equals one cycle per second.
Frequency Hopping                                                                              A transmission technology in which packets of information
                                                                                               hop along the clearest frequencies in a bandwidth.
FTAM                                        File Transfer Access and Management                The standard for the transfer of whole files or parts of files
                                                                                               between end systems.
FTP                                         File Transfer Protocol                             A feature of the Internet that allows users to transfer files
                                                                                               from other hosts.
FTP Server                                                                                     A server that a user can contact in order to transfer files by
                                                                                               means of the File Transfer Protocol (FTP) over a TCP/IP
                                                                                               network.
FTPF                                        File Transfer Protocol Filter
Full Duplex                                                                                    Capability for simultaneous data transmission between a
                                                                                               sending station and a receiving station.
Full Status Reporting                                                                          In frame relay, a link-management message function that
                                                                                               provides the user device with the complete status of all
                                                                                               permanent virtual circuits (PVCs) configured on the link.
FUNI                                        Frame User Network Interface
FXO                                         Foreign Exchange Office                            An FXO interface connects to the Public Switched
                                                                                               Telephone Network's (PSTN) central office and is the
                                                                                               interface offered on a standard telephone. Cisco's FXO
                                                                                               interface is an RJ-11 connector that allows an analog
                                                                                               connection to be directed at the PSTN's central office or to a
                                                                                               station interface on a PBX.
FXS                                         Foreign Exchange Station                           An FXS interface connects directly to a standard telephone
                                                                                               and supplies ring, voltage, and dial tone. Cisco's FXS
                                                                                               interface is an RJ-11 connector that allows connections to
                                                                                               basic telephone service equipment, keysets, and PBXes.
G.711                                                                                          Audio codec 64 kbps, narrow band (8kHz)



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                     Page 72 of 150

                 Term                                         Description                                              Definition
G.722                                                                                          Audio codec 64 kbps, wide band (16kHz)
G.723-1                                                                                        Audio codec 5-3/6.3 kbps, narrow band (8kHz)
G.726                                                                                          Audio codec 16 kbps, narrow band (8kHz)
G.728                                                                                          Audio codec 16kbps, narrow band (8kHz)
G.729                                                                                          Audio codec 8 kbps, narrow band (8kHz)
GAI                                         GSM Ansi-136 Interoperability Team
GAP                                         Generic Access Profile
GASP                                        Gatekeeper Synchronization Protocol
Gatekeeper                                                                                     Telecommunications: H.323 entity on a LAN that provides
                                                                                               address translation and control access to the LAN for H.323
                                                                                               terminals and gateways. The gatekeeper can provide other
                                                                                               services to the H.323 terminals and gateways, such as
                                                                                               bandwidth management and locating gateways. A
                                                                                               gatekeeper maintains a registry of devices in the multimedia
                                                                                               network. The devices register with the gatekeeper at startup
                                                                                               and request admission to a call from the gatekeeper.
Gateway                                                                                        Gateways are points of entrance to and exit from a
                                                                                               communications network. Viewed as a physical entity, a
                                                                                               gateway is that node that translates between two otherwise
                                                                                               incompatible networks or network segments. Gateways
                                                                                               perform code and protocol conversion to facilitate traffic
                                                                                               between data highways of differing architecture. In OSI
                                                                                               terms, a gateway is a device that provides mapping at all
                                                                                               seven layers of the OSI model. A gateway can be thought of
                                                                                               as a function within a system that enables communications
                                                                                               with the outside world.
GB                                          Gigabyte                                           Approximately 1,000,000,000 bytes.
Gb                                          Gigabit                                            Approximately 1,000,000,000 bits.
GBps                                        Gigabytes Per Second
Gbps                                        Gigabits Per Second




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                          Page 73 of 150

                 Term                                          Description                                              Definition
GCAC                                        Generic Connection Admission Control               In ATM, a PNNI algorithm designed for CBR and VBR
                                                                                               connections. Any node can use GCAC to calculate the
                                                                                               expected CAC behavior of another node given than node's
                                                                                               advertised link metrics and the QoS of a connection setup
                                                                                               request.
GCRA                                        Generic Cell Rate Algorithm                        In ATM, an algorithm that defines conformance with respect
                                                                                               to the traffic contract of the connection. For each cell arrival,
                                                                                               the GCRA determines whether the cell conforms to the
                                                                                               traffic contract.
GEA                                         Gigabit Ethernet Alliance
GEN                                         Global European Network                            BT, Deutsche Telekom, France Telecom, Telecom Italia and
                                                                                               Telefonica were the originators of this fiber optic network to
                                                                                               connect the capitals of their respective countries.
GEO                                         Geostationary Earth Orbit
GGP                                         Gateway-to-Gateway Protocol                        MILNET protocol specifying how core routers (gateways)
                                                                                               should exchange reachability and routing information. GGP
                                                                                               uses a distributed shortest-path algorithm.
GGSN                                        Gateway GPRS Support
GHz                                         Gigahertz
GIBN                                        Global Interoperability of Broadband Networks
GIS                                         Geographical Information System
GIX                                         Global Internet eXchange                           Common routing exchange point which allows pairs of
                                                                                               networks to implement agreed-upon routing policies. The
                                                                                               GIX is intended to allow maximum connectivity to the
                                                                                               Internet for networks all over the world.
GMDSS                                       Global Maritime Distress & Safety System
GNS                                         Get Nearest Server                                 Request packet sent by a client on an IPX network to locate
                                                                                               the nearest active server of a particular type. An IPX
                                                                                               network client issues a GNS request to solicit either a direct
                                                                                               response from a connected server or a response from a
                                                                                               router that tells it where on the internetwork the service can
                                                                                               be located. GNS is part of the IPX SAP.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 74 of 150

                 Term                                          Description                                              Definition
Goodput                                                                                        Generally referring to the measurement of actual data
                                                                                               successfully transmitted from the sender(s) to receiver(s).
                                                                                               This is often a more useful measurement than the number
                                                                                               of ATM cells per second throughput of an ATM switch if that
                                                                                               switch is experiencing cell loss that results in many
                                                                                               incomplete, and therefore unusable, frames arriving at the
                                                                                               recipient.
Gopher                                                                                         Distributed document delivery system. The Internet Gopher
                                                                                               allows a neophyte user to access various types of data
                                                                                               residing on multiple hosts in a seamless fashion.
GoS                                         Grade of Service                                   Measure of telephone service quality based on the
                                                                                               probability that a call will encounter a busy signal during the
                                                                                               busiest hours of the day.
GPRS                                        General Packet Radio Service                       Part of the GSM Phase 2+ development and offers packet
                                                                                               switching within GSM, enabling users to send and receive
                                                                                               data at speeds up to 115kbit/s over a permanent connection
                                                                                               when required.
GPS                                         Global Positioning Satellite/Global Positioning    A system that uses radio signals between a vessel or
                                            System                                             vehicle on Earth to pinpoint the location of the vehicle or
                                                                                               vessel.
GRE                                         Generic Routing Encapsulation
Grooming                                                                                       The process of separating and segregating
                                                                                               telecommunications channels, as by combing, such that the
                                                                                               broadest channel possible can be assembled and sent
                                                                                               across the longest practical link. The aim is to minimize de-
                                                                                               multiplexing traffic and reshuffling it electrically.
Ground Station                                                                                 Collection of communications equipment designed to
                                                                                               receive signals from (and usually transmit signals to)
                                                                                               satellites.
GSM                                         Global System for Mobile Communications            Formerly stood for Groupe Speciale Mobile. Digital cellular
                                                                                               telephone standard.
GSMP                                        Global Service Management Platform
GSN                                         GPRS Support Node



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 75 of 150

                 Term                                          Description                                              Definition
GSO                                         Geostationary Satellite Orbit
GSS                                         Generic Service State
GSTN                                        General Switched Telephone Network
Guard Band                                                                                     Unused frequency band between two communications
                                                                                               channels that provides separation of the channels to
                                                                                               prevent mutual interference.
GUI                                         Graphical User Interface                           User environment that uses pictorial as well as textual
                                                                                               representations of the input and output of applications and
                                                                                               the hierarchical or other data structure in which information
                                                                                               is stored. Conventions such as buttons, icons, and windows
                                                                                               are typical, and many actions are performed using a
                                                                                               pointing device (such as a mouse). Microsoft Windows and
                                                                                               the Apple Macintosh are prominent examples of platforms
                                                                                               using a GUI.
H Channel                                   High-Speed Channel                                 Full-duplex ISDN primary rate channel operating at 384
                                                                                               Kbps.
H.320                                                                                          Suite of ITU -T standard specifications for videoconferencing
                                                                                               over circuit-switched media such as ISDN, fractional T-1,
                                                                                               and switched-56 lines.
H.323                                                                                          Extension of ITU-T standard H.320 that enables
                                                                                               videoconferencing over LANs and other packet-switched
                                                                                               networks, as well as video over the Internet.
H.323 RAS                                   Registration, Admission, and Status                The RAS signaling protocol performs registration,
                                                                                               admissions, bandwidth changes, and status and disengage
                                                                                               procedures between the VoIP gateway and the gatekeeper.
H0 Channel                                                                                     In switched-384 data service, a circuit consisting of 6 B
                                                                                               channels, or 384 Kbps.
HACMP                                       High-Availability Cluster Multiprocessing
Hairpin                                                                                        Telephony term that means to send a call back in the
                                                                                               direction that it came from. For example, if a call cannot be
                                                                                               routed over IP to a gateway that is closer to the target
                                                                                               telephone, the call is typically sent back out the local zone,
                                                                                               back the way it came from.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                        Page 76 of 150

                 Term                                          Description                                             Definition
Half-duplex                                                                                    A transmission mode which permits transmission in both
                                                                                               directions, but only one direction at a time.
Handoff                                                                                        A call in progress is automatically passed from one cell or
                                                                                               zone to another without dropping the call as the user
                                                                                               moves.
Handshake                                                                                      Sequence of messages exchanged between two or more
                                                                                               network devices to ensure transmission synchronization.
Hard Hand-Off                                                                                  The switch over from digital CDMA to analog during a call
HBD3                                                                                           Line code type used on E1 circuits.
HBN                                         High Bandwidth Networking                          The ability to connect nodes and devices over a network
                                                                                               that can handle digital services at the rate of 150 Mbps or
                                                                                               more.
HCDS or HiCap                               High-Capacity Digital Services                     Service that uses DS1 digital facilities to provide
                                                                                               communications channels to customers at 1.544 Mbps.
HDB -3-Code                                 High Density Bipolar –3-Code                       For binary signals
HDL                                         Hardware Description Language
HDLC                                        High-Level Data Link Control                       A synchronous, bit-oriented Link Layer for data
                                                                                               transmission. Frame relay is an example of an HDLC-based
                                                                                               packet protocol.
HDML                                        Hand-held Dynamic Mark-up Language
HDSL                                        High-bit-rate Digital Subscriber Line              One of four DSL technologies. HDSL delivers 1.544 Mbps of
                                                                                               bandwidth each way over two copper twisted pairs.
                                                                                               Because HDSL provides T1 speed, telephone companies
                                                                                               have been using HDSL to provision local access to T1
                                                                                               services whenever possible. The operating range of HDSL
                                                                                               is limited to 12,000 feet (3658.5 meters), so signal repeaters
                                                                                               are installed to extend the service. HDSL requires two
                                                                                               twisted pairs, so it is deployed primarily for PBX network
                                                                                               connections, digital loop carrier systems, interexchange
                                                                                               POPs, Internet servers, and private data networks.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                       Page 77 of 150

                   Term                                        Description                                              Definition
HDTV                                        High-Definition Television                         Expected to be a driving force in broadband technology; of
                                                                                               great concern to telecoms carriers, which are counting on
                                                                                               being the principal providers of support services for HDTV
                                                                                               satellite transmission and for the distribution of signals via
                                                                                               fiber-optic cables.
Headend                                                                                        End point of a broadband network. All stations transmit
                                                                                               toward the headend; the headend then transmits toward the
                                                                                               destination stations.
Header                                                                                         Control information placed before data when encapsulating
                                                                                               that data for network transmission.
HEC                                         Header Error Control                               Algorithm for checking and correcting an error in an ATM
                                                                                               cell. Using the fifth octet in the ATM cell header, ATM
                                                                                               equipment will check for an error and correct the contents of
                                                                                               the header. The check character is calculated using a CRC
                                                                                               algorithm allowing a single bit error in the header to be
                                                                                               corrected or multiple errors to be detected.
HEPnet                                      High-Energy Physics Network                        Research network that originated in the United States, but
                                                                                               that has spread to most places involved in high-energy
                                                                                               physics. Well-known sites include Argonne National
                                                                                               Laboratory, Brookhaven National Laboratory, Lawrence
                                                                                               Berkeley Laboratory, and the SLAC.
Heterogeneous Network                                                                          Network consisting of dissimilar devices that run dissimilar
                                                                                               protocols and in many cases support dissimilar functions or
                                                                                               applications.
HFC                                         Hybrid Fiber-Coaxial                               Technology being developed by the cable TV industry to
                                                                                               provide two-way, high-speed data access to the home using
                                                                                               a combination of fiber optics and traditional coaxial cable.
HiCap                                                                                          See HCDS
Hierarchical Addressing                                                                        Scheme of addressing that uses a logical hierarchy to
                                                                                               determine location. For example, IP addresses consist of
                                                                                               network numbers, subnet numbers, and host numbers,
                                                                                               which IP routing algorithms use to route the packet to the
                                                                                               appropriate location.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                          Page 78 of 150

                   Term                                       Description                                              Definition
Hierarchical Routing                                                                           The complex problem of routing on large networks can be
                                                                                               simplified by reducing the size of the networks. This is
                                                                                               accomplished by breaking a network into a hierarchy of
                                                                                               networks, where each level is responsible for its own
                                                                                               routing.
HIPPI                                       High-Performance Parallel Interface                High-performance interface standard defined by ANSI.
                                                                                               HIPPI is typically used to connect supercomputers to
                                                                                               peripherals and other devices.
HLR                                         Home Location Register
HNCSD                                       High Speed Circuit Switched Data
Homologation                                                                                   Conformity of a product or specification to international
                                                                                               standards, such as ITU -T, CSA, TUV, UL, or VCCI. Enables
                                                                                               portability across company and international boundaries.
Hookflash                                                                                      Short on-hook period usually generated by a telephone-like
                                                                                               device during a call to indicate that the telephone is
                                                                                               attempting to perform a dial-tone recall from a PBX.
                                                                                               Hookflash is often used to perform call transfer.
Hop                                                                                            The transmission of a data packet between two network
                                                                                               nodes - for example between two routers.
Hop Count                                                                                      In data networking, measurement of the distance between a
                                                                                               source and destination. It is used to compare route length. If
                                                                                               a packet passes through six routers between source and
                                                                                               destination nodes, the hop count for the packet will be six
                                                                                               when it arrives at its destination.
Hop Off                                                                                        Point at which a call transitions from H.323 to non-H.323,
                                                                                               typically at a gateway.
Host                                                                                           Computer system on a network. Similar to node, except that
                                                                                               host usually implies a computer system, whereas node
                                                                                               generally applies to any networked system, including
                                                                                               access servers and routers.
Host Number                                                                                    Part of an IP address that designates which node on the
                                                                                               subnetwork is being addressed. Also called a "host
                                                                                               address."



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                            Page 79 of 150

                 Term                                         Description                                                Definition
HP/PN                                       Hybrid Private/Public Networking                   The creation of a network using both private leased lines
                                                                                               and public switched facilities (digital dial-up bandwidth). The
                                                                                               goals of combining both networking technologies are
                                                                                               increased performance and flexibility at reduced cost.
HPR                                         High Performance Routing                           Second-generation routing algorithm for APPN. HPR
                                                                                               provides a connectionless layer with nondisruptive routing of
                                                                                               sessions around link failures, and a connection-oriented
                                                                                               layer with end-to-end flow control, error control, and
                                                                                               sequencing.
HSCSD                                       High Speed Circuit Switched Data                   An enhancement to the GSM mobile communications
                                                                                               system that enables up to four 14.4 Kbps channels to be
                                                                                               combined to provide 57.6 Kbps data transfer. Part of GSM
                                                                                               Phase 2, HSCSD is suited for videoconferencing and
                                                                                               multimedia transmission.
HSSI                                        High-Speed Serial Interface                        A serial interface that operates at speeds up to 52Mbps at
                                                                                               distances up to 50 feet. It is similar to, but faster than, RS -
                                                                                               232 and V.35 serial interfaces.
HTML                                        HyperText Markup Language                          The authoring language used to create hypertext
                                                                                               documents for the World Wide Web. Like the Standard
                                                                                               Generalized Markup Language (SGML), on which it is
                                                                                               based, HTML identifies the types of information in a
                                                                                               document rather than the exact way it is to be presented.
                                                                                               The presentation is left to the software that converts the
                                                                                               contents to a suitable format for viewing.
HTTP                                        HyperText Transport Protocol                       The application protocol for moving hypertext files across
                                                                                               the Internet. This protocol requires an HTTP client program
                                                                                               on one end of a connection and an HTTP server on the
                                                                                               other.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                           Page 80 of 150

                 Term                                         Description                                               Definition
Hub                                                                                            Generally, a term used to describe a device that serves as
                                                                                               the center of a star-topology network. (2) Hardware or
                                                                                               software device that contains multiple independent but
                                                                                               connected modules of network and internetwork equipment.
                                                                                               Hubs can be active (where they repeat signals sent through
                                                                                               them) or passive (where they do not repeat, but merely split,
                                                                                               signals sent through them). (3) In Ethernet and IEEE 802.3,
                                                                                               an Ethernet multiport repeater, sometimes called a
                                                                                               concentrator.
Hybrid LAN                                                                                     A hybrid network is one in which some links are capable of
                                                                                               sending and receiving only analog signals while others
                                                                                               handle digital signals only. Another definition is the division
                                                                                               of a network into public and private sections.
Hz                                          Hertz                                              Measure of frequency. Synonymous with cycles per second.
                                                                                               (2) The international unit for measuring frequency,
                                                                                               equivalent to the older unit of cycles per second. One
                                                                                               megahertz (MHz) is one million hertz. One gigahertz (GHz)
                                                                                               is one billion hertz. The standard US electrical power
                                                                                               frequency is 60 Hz, the AM broadcast radio frequency band
                                                                                               is 535 - 1605 kHz, the FM broadcast radio frequency band
                                                                                               is 88 -108 MHz, and wireless 802.11b LANs operate at 2.4
                                                                                               GHz.
I/O                                         Input/Output
I420                                                                                           BT's basic-rate integrated services digital network offering.
                                                                                               See also IDA.
IAB(1)                                      Internet Architecture Board                        Board of internetwork researchers who discuss issues
                                                                                               pertinent to Internet architecture. Responsible for appointing
                                                                                               a variety of Internet -related groups such as the IANA, IESG,
                                                                                               and IRSG. The IAB is appointed by the trustees of the
                                                                                               ISOC.
IAB(2)                                      Internet Advertising Bureau                        Self-regulating body to establish internet advertising
                                                                                               standards.
IAD                                         Integrated Access Device




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                      Page 81 of 150

                 Term                                             Description                                           Definition
IAHC                                        Internet International Ad Hoc Committee            Coalition of participants from the broad Internet community,
                                                                                               working to satisfy the requirement for enhancements to the
                                                                                               Internet's global DNS. Organizations naming members to
                                                                                               the committee include Internet Society (ISOC), Internet
                                                                                               Assigned Numbers Authority (IANA), Internet Architecture
                                                                                               Board (IAB), Federal Networking Council (FNC),
                                                                                               International Telecommunication Union (ITU), International
                                                                                               Trademark Association (INTA), and World Intellectual
                                                                                               Property Organization (WIPO).
IANA                                        Internet Assigned Numbers Authority                Organization operated under the auspices of the ISOC as a
                                                                                               part of the IAB. IANA delegates authority for IP address-
                                                                                               space allocation and domain-name assignment to the
                                                                                               InterNIC and other organizations. IANA also maintains a
                                                                                               database of assigned protocol identifiers used in the TCP/IP
                                                                                               stack, including autonomous system numbers.
IAP                                         Internet Access Provider
IAS                                         Internet Authentication Service                    A RADIUS Server which performs connection authentication
                                                                                               and accounting for dial-up and VPN remote access.
ICD                                         International Code Designator                      One of two ATM address formats developed by the ATM
                                                                                               Forum for use by private networks. Adapted from the
                                                                                               subnetwork model of addressing in which the ATM layer is
                                                                                               responsible for mapping network layer addresses to ATM
                                                                                               addresses.
ICR                                         Initial Cell Rate
ICT                                         Information communication technology
IDA                                                                                            BT's proprietary basic rate integrated services digital
                                                                                               network offering. See also I420.
IDEA                                        International Data Encryption Algorithm            A private key encryption-decryption algorithm.
IDI                                         Initial Domain Identifier                          Portion of an NSAP or NSAP-format ATM address that
                                                                                               specifies the address allocation and administration
                                                                                               authority.
IDP                                         Initial Domain Part                                Part of a CLNS address that contains an authority and
                                                                                               format identifier, and a domain identifier



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                       Page 82 of 150

                 Term                                          Description                                              Definition
IDPR                                        Inter-Domain Policy Routing                         Interdomain routing protocol that dynamically exchanges
                                                                                                policies between autonomous systems. IDPR encapsulates
                                                                                                interautonomous system traffic and routes it according to
                                                                                                the policies of each autonomous system along the path.
                                                                                                IDPR is currently an IETF proposal.
IDS                                         Intrusion Detection System                          Hardware and/or software which detects unauthorised
                                                                                                access.
IE                                          Information Element
IEC(1)                                      International Electrotechnical Commission           Industry group that writes and distributes standards for
                                                                                                electrical products and components.
IEC(2)                                      Inter-Exchange Carrier                              Common carrier providing communications channels
                                                                                                between local telephone companies (LECs, or Local
                                                                                                Exchange Carriers). Also known as long distance carriers.
IEEE                                        Institute of Electrical and Electronics Engineers   An organization that maintains the standards for 10BaseT
                                                                                                and other communications standards.
IEEE 802.11                                                                                     IEEE 802.xx is a set of specifications for LANs from The
                                                                                                Institute of Electrical and Electronic Engineers (IEEE). Most
                                                                                                wired networks conform to 802.3, the specification for
                                                                                                CSMA/CD based Ethernet networks or 802.5, the
                                                                                                specification for token ring networks. 802.11 defines the
                                                                                                standard for wireless LANs encompassing three
                                                                                                incompatible (non-interoperable) technologies: Frequency
                                                                                                Hopping Spread Spectrum (FHSS), Direct Sequence
                                                                                                Spread Spectrum (DSSS), and Infrared. WECA’s focus is
                                                                                                on 802.11b, an 11 Mbps high rate DSSS standard for
                                                                                                wireless networks.
IEPG                                        Internet Engineering Planning Group                 Group, primarily composed of Internet service operators,
                                                                                                whose goal is to promote a globally coordinated Internet
                                                                                                operating environment. Membership is open to all.
IESG                                        Internet Engineering Steering Group                 Organization, appointed by the IAB, that manages the
                                                                                                operation of the IETF.
IETF                                        Internet Engineering Task Force                     Task force consisting of over 80 working groups responsible
                                                                                                for developing Internet standards. The IETF operates under
                                                                                                the auspices of ISOC.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                         Page 83 of 150

                 Term                                             Description                                              Definition
IFIP                                        International Federation for Information Processing   Research organization that performs OSI prestandardization
                                                                                                  work. Among other accomplishments, IFIP formalized the
                                                                                                  original MHS model.
IGMP                                        Internet Group Management Protocol                    Used by IP hosts to report their multicast group
                                                                                                  memberships to an adjacent multicast router
IGP                                         Internet Gateway Protocol                             Generic term applied to any protocol used to propagate
                                                                                                  network reach and routing information within autonomous
                                                                                                  system.
IGRP                                        Interior Gateway Routing Protocol
IKE                                         Internet Key Exchange
ILEC                                        Incumbent Local Exchange Carrier
IMA                                         Invere Multiplexing over ATM                          Standard protocol defined by the ATM Forum in 1997.
IMA Group                                                                                         Physical links grouped to form a higher-bandwidth logical
                                                                                                  link whose rate is approximately the sum of the individual
                                                                                                  link rates.
IMAP                                        Internet Message Access Protocol                      Method of accessing e-mail or bulletin board messages kept
                                                                                                  on a mail server that can be shared. IMAP permits client
                                                                                                  electronic mail applications to access remote message
                                                                                                  stores as if they were local without actually transferring the
                                                                                                  message.
IMEI                                        International Mobile Equipment Identification
IMT                                         Inter-Machine Trunk
IMT-2000                                    International Mobile Telecommunications-2000          ITU concept of a family of technological solutions that will
                                                                                                  enable the implementation of third generation wireless
                                                                                                  communications.
IN                                          Intelligent Network                                   An upgraded version of the current switched telephone
                                                                                                  network that allows for the quick and easy introduction of
                                                                                                  new, enhanced services.
INA                                         Information Networking Architecture                   Bellcore object-oriented architecture for the management of
                                                                                                  ATM and SONET equipment and services in an operating
                                                                                                  company environment.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                         Page 84 of 150

                      Term                                     Description                                              Definition
INAP                                        Intelligent Network Application Protocol
INASoft                                                                                        Bellcore implementation of INA.
In-Band Signaling                                                                              Transmission within a frequency range normally used for
                                                                                               information transmission.
INE                                         Intelligent Network Element                        Network element that can be provisioned from a remote
                                                                                               OSS.
Informtion Element                                                                             In ATM, the portion of a signaling packet that carries
                                                                                               information, such as addresses, used in the UNI
                                                                                               specification.
Infrared                                                                                       Electromagnetic waves whose frequency range is above
                                                                                               that of microwaves, but below that of the visible spectrum.
                                                                                               LAN systems based on this technology represent an
                                                                                               emerging technology.
Infrastructure Mode                                                                            A client setting providing connectivity to an AP. As
                                                                                               compared to Ad-Hoc Mode where PCs communicate
                                                                                               directly with each other, clients set in Infrastructure Mode all
                                                                                               pass data through a central AP. The AP not only mediates
                                                                                               wireless network traffic in the immediate neighborhood, but
                                                                                               also provides communication with the wired network. See
                                                                                               AD-Hoc and AP.
INLSP                                       Integrated Net Layer Security Protocol
Insured Burst                                                                                  In an ATM network, the largest burst of data above the
                                                                                               insured rate that will be temporarily allowed on a PVC and
                                                                                               not tagged by the traffic policing function for dropping in the
                                                                                               case of network congestion. The insured burst is specified
                                                                                               in bytes or cells.
Insured Rate                                                                                   Long-term data throughput, in bits or cells per second, that
                                                                                               an ATM network commits to support under normal network
                                                                                               conditions. The insured rate is 100 percent allocated; the
                                                                                               entire amount is deducted from the total trunk bandwidth
                                                                                               along the path of the circuit.
Insured Traffic                                                                                Traffic within the insured rate specified for an ATM PVC.
                                                                                               This traffic should not be dropped by the network under
                                                                                               normal network conditions.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 85 of 150

                     Term                                      Description                                             Definition
INTAP                                       Interoperability Technology Association for        Technical organization that has the official charter to
                                            Information Processing                             develop Japanese OSI profiles and conformance tests.
Integrated                                                                                     Routing protocol based on the OSI routing protocol IS-IS,
                                                                                               but with support for IP and other protocols. Integrated IS-IS
                                                                                               implementations send only one set of routing updates,
                                                                                               making it more efficient than two separate implementations.
                                                                                               Formerly called Dual IS-IS.
Inter-Area Routing                                                                             Term used to describe routing between two or more logical
                                                                                               areas.
Interexchange                                                                                  Refers to non-local voice or data transmission.
Interface                                                                                      Boundary between adjacent layers of the OSI model. (2)
                                                                                               Connection between two systems or devices. (3) In routing
                                                                                               terminology, a network connection. (4) In telephony, a
                                                                                               shared boundary defined by common physical
                                                                                               interconnection characteristics, signal characteristics, and
                                                                                               meanings of interchanged signals.
Interference                                                                                   Unwanted communication channel noise.
INTERNET                                                                                       Interconnected Networks, a worldwide collection of
                                                                                               computers, the links between them, and standards about
                                                                                               how information will be shared over those links; a public site
                                                                                               for customers.
Internet Telephony                                                                             Generic term used to describe various approaches to
                                                                                               running voice telephony over IP.
Internetwork                                                                                   Collection of networks interconnected by routers and other
                                                                                               devices that functions (generally) as a single network.
                                                                                               Sometimes called an internet, which is not to be confused
                                                                                               with the Internet.
InterNIC                                                                                       Organization that serves the Internet community by
                                                                                               supplying user assistance, documentation, training,
                                                                                               registration service for Internet domain names, and other
                                                                                               services. Formerly called NIC.
Interoperability                                                                               Ability of computing equipment manufactured by different
                                                                                               vendors to communicate with one another successfully over
                                                                                               a network.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                    Telecom / IS Glossary                                                     Page 86 of 150

                     Term                                       Description                                            Definition
Intra-Area Routing                                                                             Term used to describe routing within a logical area.
Intranet                                                                                       A private internetwork inside a company or agency that
                                                                                               uses the same kind of software running on the Internet, but
                                                                                               only for internal purposes. A corporate intranet uses the
                                                                                               internet as its backbone, but the firewall surrounding the
                                                                                               intranet prevents unauthorized access. Like the Internet,
                                                                                               intranets are used to share information.
Inverse ARP                                 Inverse Address Resolution Protocol                Method of building dynamic routes in a network. Allows an
                                                                                               access server to discover the network address of a device
                                                                                               associated with a virtual circuit.
Inverse Multiplexing                                                                           Process whereby physical links are grouped to form a
                                                                                               higher-bandwidth logical link whose rate is approximately
                                                                                               the sum of the individual link rates.
IOC                                         Independent Operating Company                      Independently owned company providing local telephone
                                                                                               services to residential and business customers in a
                                                                                               geographic area not served by an RBOC.
IOCC                                        I/O Channel Controller
IONL                                        Internal Organization of the Network Layer         OSI standard for the detailed architecture of the network
                                                                                               layer. Basically, it partitions the network layer into
                                                                                               subnetworks interconnected by convergence protocols
                                                                                               (equivalent to internet working protocols), creating what the
                                                                                               Internet community calls a catenet or internet.
IP ADDRESS                                  Internet Protocol Address                          A 32-bit address assigned to a host. The IP address has a
                                                                                               host component and a network component.
IP Spoofing                                                                                    An attack whereby a system attempts to impersonate
                                                                                               another system by using its IP network address.
IP(1)                                       Internet Protocol                                  The layer-three protocol used in the TCP/IP set of protocols
                                                                                               which support the Internet and many private networks. IP
                                                                                               provides a connectionless datagram delivery service for
                                                                                               transport-layer protocols such as TCP and UDP.
IP(2)                                       Intellectual Property
IPC                                         Interprocess Communication



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                       Page 87 of 150

                 Term                                            Description                                           Definition
IPCP                                        Internet Protocol Control Protocol                 Responsible for configuring, enabling, and disabling the IP
                                                                                               protocol modules on both ends of a point-t o-point link. The
                                                                                               IP Control Protocol is tied to PPP, and is activated only
                                                                                               when PPP reaches the network layer to protocol phase. If
                                                                                               IPCP packets are received prior to this phase, they should
                                                                                               be discarded. Elements of IPCP include packet
                                                                                               encapsulation, code fields and timeouts.
IPSO                                        IP Security Option                                 U.S. government specification that defines an optional field
                                                                                               in the IP packet header that defines hierarchical packet
                                                                                               security levels on a per interface basis.
IPv6                                        IP version 6                                       Replacement for the current version of IP (version 4). IPv6
                                                                                               includes support for flow ID in the packet header, which can
                                                                                               be used to identify flows. Formerly called IPng (next
                                                                                               generation).
IR                                          Internet Registry                                  IR was delegated the responsibility of network address and
                                                                                               autonomuous system identifiers from the IANA, which has
                                                                                               the discretionary authority to delegate portions of its
                                                                                               responsibility.
IRB                                         Integrated Routing and Bridging
IRC                                         Internet Relay Chat                                World-wide "party line" protocol that allows one to converse
                                                                                               with others in real time. IRC is structured as a network of
                                                                                               servers, each of which accepts connections from client
                                                                                               programs, one per user.
IRIDIUM                                                                                        A Motorola communications system comprising a
                                                                                               constellation of 66 low-earth-orbiting (LEO) satellites
                                                                                               forming a mobile wireless system allowing subscribers to
                                                                                               place and receive calls from any location in the world.
IRN                                         Intermediate Routing Node                          In SNA, a subarea node with intermediate routing capability
IRSG                                        Internet Research Steering Group                   Group that is part of the IAB and oversees the activities of
                                                                                               the IRTF.
IRTF                                        Internet Research Task Force                       Community of network experts that considers Internet-
                                                                                               related research topics. The IRTF is governed by the IRSG
                                                                                               and is considered a subsidiary of the IAB.
IS(1)                                       Intermediate System                                Routing node in an OSI network.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 88 of 150

                  Term                                          Description                                            Definition
IS(2)                                       In-Service                                         As fully operational and capable of providing service to a
                                                                                               requesting entity.
ISA                                         Industry-Standard Architecture                     16-bit bus used for Intel-based personal computers.
ISA (or PCI)                                                                                   A local bus standard for connecting peripherals to a
                                                                                               personal computer. Within a computer, the bus is the
                                                                                               transmission path on which signals and data transfers occur
                                                                                               between the CPU, system memory, and attached devices
                                                                                               such as a network card, sound card, or CD-ROM drive.
Isarithmic Flow                                                                                Flow control technique that permits travel through the
                                                                                               network. Isarithmic flow control is not commonly
                                                                                               implemented.
ISDN                                        Integrated Services Digital Networks               A CCITT standard developed to cover a range of voice,
                                                                                               data, and image services. It is intended to provide end-to-
                                                                                               end, simultaneous handling of voice and data on a single
                                                                                               link. Access channels include Basic Rate Interface (BRI)
                                                                                               and Primary Rate Interface (PRI)
ISE                                         Integrated Services Internet                       IETF proposal for enhancing IP to allow it to support
                                                                                               integrated or multimedia services, including traffic
                                                                                               management mechanisms that closely match the traffic
                                                                                               management mechanisms of ATM.
IS-IS                                       Intermediate System-to-Intermediate System         OSI link-state hierarchical routing protocol based on
                                                                                               DECnet Phase V routing, whereby ISs (routers) exchange
                                                                                               routing information based on a single metric, to determine
                                                                                               network topology.
ISL                                         Inter-Switch Link
ISM                                         Internetwork Status Monitor
ISO                                         International Organization for Standardization     International organization that is responsible for a wide
                                                                                               range of standards, including those relevant to networking.
                                                                                               ISO developed the OSI reference model, a popular
                                                                                               networking reference model.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 89 of 150

                    Term                                       Description                                             Definition
ISO Network Model                                                                              The International Standards Organization (ISO) has
                                                                                               developed a network model that consists of seven different
                                                                                               levels, or layers. By standardizing these layers, and the
                                                                                               interfaces in between, different portions of a given protocol
                                                                                               can be modified or changed as technologies advance, or
                                                                                               systems requirements are altered. The seven layers are: 1.
                                                                                               Physical, 2. Data Link, 3. Network, 4. Transport, 5. Session,
                                                                                               6. Presentation, 7. Application. The IEEE 802.11 Standard
                                                                                               encompasses the physical layer (PHY) and the lower
                                                                                               portion of the data link layer. The lower portion of the data
                                                                                               link layer is often referred to as the Medium Access
                                                                                               Controller (MAC) sublayer.
ISOC                                        Internet Society                                   International nonprofit organization, founded in 1992, that
                                                                                               coordinates the evolution and use of the Internet. In
                                                                                               addition, ISOC delegates authority to other groups related to
                                                                                               the Internet, such as the IAB. ISOC is headquartered in
                                                                                               Reston, Virginia, (United States).
ISP                                         Internet Service Provider                          A company that provides access to the Internet. By
                                                                                               establishing points-of-presence (POPs) containing remote
                                                                                               access servers and additional devices, as well as a suite of
                                                                                               user software packages, the Internet service provider acts
                                                                                               as a commercial Internet on-ramp. Providers typically
                                                                                               charge a monthly fee and supply technical support and
                                                                                               advice to customers.
ISSI                                        Inter-Switching System Interface                   Standard interface between SMDS switches.
ISUP                                        ISDN User Part
ITM                                         Isochronous Transmission                           Asynchronous transmission over a synchronous data link.
                                                                                               Isochronous signals require a constant bit rate for reliable
                                                                                               transport.
ITSP                                        Internet Service Telephony Provider
ITU                                         International Telecommunications Union             A group of representatives from 161 countries
                                                                                               headquartered in Geneva, Switzerland. The ITU publishes
                                                                                               recommendations that influence telecom engineers,
                                                                                               designers, manufacturers, and service providers around the
                                                                                               world.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 90 of 150

                 Term                                          Description                                             Definition
ITU -R                                                                                         ITU groups for Radiocommunication
ITU -T                                      International Telecommunication Union              International body that develops worldwide standards for
                                            Telecommunication Standardization Sector           telecommunications technologies. The ITU-T carries out the
                                                                                               functions of the former CCITT.
IVPN                                        International Virtual Private Networks
IVR                                         Interactive Voice Response                         Term used to describe systems that provide information in
                                                                                               the form of recorded messages over telephone lines in
                                                                                               response to user input in the form of spoken words or more
                                                                                               commonly DTMF signaling. Examples include banks that
                                                                                               allow you to check your balance from any telephone and
                                                                                               automated stock quote systems.
IVS                                         Interactive Videocommunications Systems
IVSN                                        Integrated Virtual Services Node
IXC                                         Inter-Exchange Carrier                             Common carrier providing long distance connectivity
                                                                                               between LATAs. The three major IXCs are AT&T, MCI, and
                                                                                               Sprint, but several hundred IXCs offer long distance service
                                                                                               in the United States.
Jabber                                                                                         Error condition in which a network device continually
                                                                                               transmits random, meaningless data onto the network. (2)
                                                                                               In IEEE 802.3, a data packet whose length exceeds that
                                                                                               prescribed in the standard.
JADSL                                                                                          ADSL for ISDN
JANET                                       Joint Academic Network                             X.25 WAN connecting university and research institutions in
                                                                                               the United Kingdom.
Java                                                                                           An object-oriented programming language developed by
                                                                                               Sun Microsystems, Inc. used to create applets that can be
                                                                                               distributed over the World Wide Web. Java programs run
                                                                                               inside a Java-enabled Web browser, otherwise they run
                                                                                               inside a Java Virtual Machine (JVM).
JCCR                                        Joint Committee on Cellular Roaming




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                          Page 91 of 150

                 Term                                           Description                                              Definition
JDBC                                        Java Database Connectivity                         Java API that enables Java programs to execute SQL
                                                                                               statements. This allows Java programs to interact with any
                                                                                               SQL-compliant database. Since nearly all relational
                                                                                               database management systems (DBMSs) support SQL, and
                                                                                               because Java itself runs on most platforms, JDBC makes it
                                                                                               possible to write a single database application that can run
                                                                                               on different platforms and interact with different DBMSs.
                                                                                               JDBC is similar to ODBC, but is designed specifically for
                                                                                               Java programs, whereas ODBC is language-independent.
                                                                                               JDBC was developed by JavaSoft, a subsidiary of Sun
                                                                                               Microsystems.
JEEC                                        Joint ETSI/ECMA Committee
Jitter                                                                                         Analog communication line distortion caused by the
                                                                                               variation of a signal from its reference timing positions. Jitter
                                                                                               can cause data loss, particularly at high speeds.
JPEG                                        Joint Photographic Experts Group                   A common graphics format for compressing still images,
                                                                                               widely used in web publication.
JTACS                                       Japanese TACS System
Jumper                                                                                         Electrical switch consisting of a number of pins and a
                                                                                               connector that can be attached to the pins in a variety of
                                                                                               different ways. Different circuits are created by attaching the
                                                                                               connector to different pins.
JUNET                                       Japan UNIX Network                                 Nationwide, noncommercial network in Japan, designed to
                                                                                               promote communication between Japanese and other
                                                                                               researchers.
JvNCnet                                     John von Neumann Computer Network                  Regional network, owned and operated by Global
                                                                                               Enterprise Services, Inc., composed of T1 and slower serial
                                                                                               links providing midlevel networking services to sites in the
                                                                                               Northeastern United States.
KA                                          Keep Alive Signal                                  An unframed all ones pattern sent in the non-test direction
                                                                                               during circuit testing.
KA9Q                                                                                           Popular implementation of TCP/IP and associated protocols
                                                                                               for amateur packet radio systems.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                       Page 92 of 150

                   Term                                       Description                                               Definition
Karn's Algorithm                                                                               Algorithm that improves round-trip time estimations by
                                                                                               helping transport layer protocols distinguish between good
                                                                                               and bad round-trip time samples.
KB                                          Kilobyte                                           1,024 bytes
Kb                                          Kilobit                                            1,024 bits
KBps                                        Kilobytes per second
Kbps                                        Kilobits per second
KDC                                         Key Distribution Center
KDS                                         Key Distribution Service
Kermit                                                                                         Popular file-transfer and terminal-emulation program.
kHz                                         Kilohertz
KMC                                         Key Management Center
KTS                                         Key Telephone System
Ku-band                                                                                        The frequency band from 11.7 to 12.7 gigahertz used for a
                                                                                               variety of satellite communications services.
kVA                                         Kilovoltampere
L2F Protocol                                Layer 2 Forwarding Protocol                        Protocol that supports the creation of secure virtual private
                                                                                               dial-up networks over the Internet.
Label Swapping                                                                                 Routing algorithm used by APPN in which each router that a
                                                                                               message passes through on its way to its destination
                                                                                               independently determines the best path to the next router.
LAN                                         Local Area Network                                 A network that uses dedicated in-house links to connect a
                                                                                               group of organizational users within an office, a building, or
                                                                                               a campus without using facilities from a telephone company
                                                                                               or other outside carrier.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 93 of 150

                 Term                                         Description                                              Definition
LAN Switch                                                                                     High-speed switch that forwards packets between data-link
                                                                                               segments. Most LAN switches forward traffic based on MAC
                                                                                               addresses. This variety of LAN switch is sometimes called a
                                                                                               frame switch. LAN switches are often categorized according
                                                                                               to the method they use to forward traffic: cut-through packet
                                                                                               switching or store-and-forward packet switching. Multilayer
                                                                                               switches are an intelligent subset of LAN switches.
LAN/WAN Connectivity                                                                           This is the practical set of tools, from OS layer protocols to
                                                                                               support services that make a remote access device an
                                                                                               effective link between LANs and WANs. An effective remote
                                                                                               access server must include a host of communications and
                                                                                               translation protocols to fulfill this function.
LANE                                        LAN emulation                                      Technology that allows an ATM network to function as a
                                                                                               LAN backbone. The ATM network must provide multicast
                                                                                               and broadcast support, address mapping (MAC-to-ATM),
                                                                                               SVC management, and a usable packet format. LANE also
                                                                                               defines Ethernet and Token Ring ELANs.
LANE UNI                                    LANE User-Network Interface
LAPB                                        Link Access Procedure, Balanced                    Data link layer protocol in the X.25 protocol stack. LAPB is a
                                                                                               bit-oriented protocol derived from HDLC.
LAPD                                        Link Access Procedure on the D channel             ISDN data link layer protocol for the D channel. LAPD was
                                                                                               derived from the LAPB protocol and is designed primarily to
                                                                                               satisfy the signaling requirements of ISDN basic access.
LAPM                                        Link Access Procedure for Modems
LASER                                       Light Amplification by Stimulated Emission of      Analog transmission device in which a suitable active
                                            Radiation                                          material is excited by an external stimulus to produce a
                                                                                               narrow beam of coherent light that can be modulated into
                                                                                               pulses to carry data. Networks based on laser technology
                                                                                               are sometimes run over SONET
LAT                                         Local-Area Transport                               A network virtual terminal protocol developed by Digital
                                                                                               Equipment Corporation.
LATA                                        Local Access and Transport Area                    LATAs are geographic regions within the United States that
                                                                                               define areas within which Bell operating companies can
                                                                                               offer exchange and exchange-access services.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                       Page 94 of 150

                    Term                                       Description                                             Definition
Latency                                                                                        Delay between the time a device requests access to a
                                                                                               network and the time it is granted permission to transmit.
LATS                                        Loop Access Test System                            A relay connection matrix that provides access to individual
                                                                                               customer four-wire local loops and/or to DS0 (64 kbps)
                                                                                               circuits. The matrix is only at DDS hub offices.
Layer 3 Switching                                                                              Emerging Layer 3 switching technology that integrates
                                                                                               routing with switching to yield very high routing throughput
                                                                                               rates in the millions-of-packets- per-second range. The
                                                                                               movement to Layer 3 switching is designed to address the
                                                                                               downsides of the current generation of layer 2 switches,
                                                                                               which are functionally equivalent to bridges. These
                                                                                               downsides for a large, flat network include being subject to
                                                                                               broadcast storms, spanning tree loops, and address
                                                                                               limitations.
LCI                                         Logical Channel Identifier
LCN                                         Logical Channel Number
LCP                                         Link Control Protocol                              Protocol that establishes, configures, and tests data-link
                                                                                               connections for use by PPP.
LCR                                         Least Cost Routing
LCV                                         Line Code Violation
LDAP                                        Lightweight Directory Access Protocol
LDC                                         Long Distance Carrier
LDCELP                                      Low-Delay CELP                                     CELP voice compression algorithm providing 16 Kbps, or
                                                                                               4:1 compression.
LE_ARP                                      LAN Emulation Address Resolution Protocol          Protocol that provides the ATM address that corresponds to
                                                                                               a MAC address.
Leased Line                                                                                    A transmission facility which is leased by an end user from a
                                                                                               public carrier, and which is dedicated to that user's traffic.
                                                                                               Typically, frequency synchronization is maintained from one
                                                                                               end of the circuit to the other. Leased line circuits are
                                                                                               generally used less in recent times, while public data
                                                                                               networks are more common.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                       Page 95 of 150

                 Term                                           Description                                             Definition
LEC(1)                                      Local Exchange Carrier                             Local telephone company, providing connections between
                                                                                               local points or to long distance carriers for extended
                                                                                               connections.
LEC(2)                                      LAN Emulation Client                               Entity in an end system that performs data forwarding,
                                                                                               address resolution, and other control functions for a single
                                                                                               ES within a single ELAN. An LEC also provides a standard
                                                                                               LAN service interface to any higher-layer entity that
                                                                                               interfaces to the LEC. Each LEC is identified by a unique
                                                                                               ATM address, and is associated with one or more MAC
                                                                                               addresses reachable through that ATM address.
LECS                                        LAN Emulation Configuration Server                 Entity that assigns individual LANE clients to particular
                                                                                               ELANs by directing them to the LES that corresponds to the
                                                                                               ELAN. There is logically one LECS per administrative
                                                                                               domain, and this serves all ELANs within that domain.
LEO                                         Low Earth Orbit satellite
LES                                         LAN Emulation Server                               Entity that implements the control function for a particular
                                                                                               ELAN. There is only one logical LES per ELAN, and it is
                                                                                               identified by a unique ATM address.
Line of Sight                                                                                  Characteristic of certain transmission systems such as
                                                                                               laser, microwave, and infrared systems in which no
                                                                                               obstructions in a direct path between transmitter and
                                                                                               receiver can exist.
Line Speed                                                                                     The speed of the physical wire attached to the interface or
                                                                                               interface hardware. The line speed is 10Mbps for Ethernet
                                                                                               and 1.544Mbps for T1.
LIS                                         Logical IP Subnet                                  A group of IP nodes (such as hosts and routers) that
                                                                                               connects to a single ATM network and belongs to the same
                                                                                               IP subnet
LLB                                         Line LoopBack
LLC                                         Logical Link Control                               Higher of the two data link layer sublayers defined by the
                                                                                               IEEE. The LLC sublayer handles error control, flow control,
                                                                                               framing, and MAC-sublayer addressing. The most prevalent
                                                                                               LLC protocol is IEEE 802.2, which includes both
                                                                                               connectionless and connection-oriented variants.


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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                             Page 96 of 150

                 Term                                          Description                                                Definition
LLC2                                        Logical Link Control, Type 2                       Connection-oriented OSI LLC-sublayer protocol
LMDS                                        Local Multipoint Distribution Services             A digital wireless cable system that provides two-way
                                                                                               transmission in the 28 gigahertz range of the spectrum. It
                                                                                               depends on line of sight and requires a transmitter every
                                                                                               few miles.
LMI                                         Local Management Interface Set                     Set of enhancements to the basic Frame Relay
                                                                                               specification. LMI includes support for a keepalive
                                                                                               mechanism, which verifies that data is flowing; a multicast
                                                                                               mechanism, which provides the network server with its local
                                                                                               DLCI and the multicast DLCI; global addressing, which
                                                                                               gives DLCIs global rather than local significance in Frame
                                                                                               Relay networks; and a status mechanism, which provides
                                                                                               an on-going status report on the DLCIs known to the switch.
                                                                                               Known as LMT in ANSI terminology.
LMOS                                        Loop Maintenance Operations System                 A testing system for voice grade telephone service that
                                                                                               records customer trouble reports and tracks subsequent
                                                                                               maintenance activities.
LNM                                         LAN Network Manager                                SRB and Token Ring management package provided by
                                                                                               IBM. Typically running on a PC, it monitors SRB and Token
                                                                                               Ring devices, and can pass alerts up to NetView.
Load Balancing                                                                                 In routing, the ability of a router to distribute traffic over all
                                                                                               its network ports that are the same distance from the
                                                                                               destination address. Good load-balancing algorithms use
                                                                                               both line speed and reliability information. Load balancing
                                                                                               increases the use of network segments, thus increasing
                                                                                               effective network bandwidth.
Local Bridge                                                                                   Bridge that directly interconnects networks in the same
                                                                                               geographic area.
Local Loop                                                                                     The physical wires that run from the subscriber's telephone
                                                                                               set, PBX, or key telephone system, to the telephone
                                                                                               company central office. Increasingly, the local loop now
                                                                                               goes from the main distribution frame in the basement to the
                                                                                               telephone company. The subscriber is responsible for
                                                                                               getting his wires from the box in the basement to this phone,
                                                                                               PBX, or key system.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 97 of 150

                  Term                                        Description                                              Definition
LocalTalk                                                                                      Apple Computer's proprietary baseband protocol that
                                                                                               operates at the data link and physical layers of the OSI
                                                                                               reference model. LocalTalk uses CSMA/CD and supports
                                                                                               transmissions at speeds of 230.4 Kbps.
Logical Channel                                                                                Nondedicated, packet-switched communications path
                                                                                               between two or more network nodes. Packet switching
                                                                                               allows many logical channels to exist simultaneously on a
                                                                                               single physical channel.
Looping                                                                                        A test procedure in which the received signal returns to its
                                                                                               source.
LOS                                         Loss Of Signal                                     The absence of pulses lasting for one millisecond or more.
LSRP                                        Link-State Routing Protocol                        A sophisticated method of determining the shortest paths
                                                                                               through the network.
LUNI                                        LAN Emulation User-to-Network Interface            The ATM Forum standard for LAN emulation on ATM
                                                                                               networks. Defines the interface between the LEC and the
                                                                                               LAN Emulation Server components.
MAC                                         Media Access Control                               In a WLAN network card, the MAC is radio controller
                                                                                               protocol. It corresponds to the ISO Network Model's level 2
                                                                                               Data Link layer. The IEEE 802.11 standard specifies the
                                                                                               MAC protocol for medium sharing, packets formats and
                                                                                               addressing, and error detection. (2) Lower of the two
                                                                                               sublayers of the data link layer defined by the IEEE. The
                                                                                               MAC sublayer handles access to shared media, such as
                                                                                               whether token passing or contention will be used.
MAC Address                                                                                    Standardized data link layer address that is required for
                                                                                               every port or device that connects to a LAN. Other devices
                                                                                               in the network use these addresses to locate specific ports
                                                                                               in the network and to create and update routing tables and
                                                                                               data structures. MAC addresses are 6 bytes long and are
                                                                                               controlled by the IEEE. Also known as a hardware address,
                                                                                               MAC-layer address, and physical address.




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 98 of 150

                 Term                                         Description                                              Definition
MAC Address Learning                                                                           Service that characterizes a learning bridge, in which the
                                                                                               source MAC address of each received packet is stored so
                                                                                               that future packets destined for that address can be
                                                                                               forwarded only to the bridge interface on which that address
                                                                                               is located. Packets destined for unrecognized addresses
                                                                                               are forwarded out every bridge interface. This scheme helps
                                                                                               minimize traffic on the attached LANs. MAC address
                                                                                               learning is defined in the IEEE 802.1 standard.
MAC Spoofing                                                                                   An attack whereby a system attempts to impersonate
                                                                                               another system by using its MAC address.
MAE                                         Metropolitan Access Exhange                        One of a number of Internet exchange points.
Mail Gateway                                                                                   Machine that connects two or more electronic mail systems
                                                                                               (especially dissimilar mail systems on two different
                                                                                               networks) and transfers messages between them.
                                                                                               Sometimes the mapping and translation can be quite
                                                                                               complex, and generally it requires a store-and-forward
                                                                                               scheme whereby the message is received from one system
                                                                                               completely before it is transmitted to the next system after
                                                                                               suitable translations.
MAN                                         Metropolitan Area Network                          Typically, they support transmission speeds from 1.5
                                                                                               megabits per second to 45 mbps. They can carry greater
                                                                                               volumes of information further distances than local area
                                                                                               networks and can support voice, video and data
                                                                                               transmissions because of their high bandwidths.
MAP                                         Mobile Application Platform
MAP/TOP                                     Manufacturing Automation Protocol/Technical and
                                            Office Protocol .
MARS                                        Multicast Address Resolution Server                Mechanism for supporting IP multicast. A MARS serves a
                                                                                               group of nodes (known as a cluster); each node in the
                                                                                               cluster is configured with the ATM address of the MARS.
                                                                                               The MARS supports multicast through multicast messages
                                                                                               of overlaid point -to-multipoint connections or through
                                                                                               multicast servers.




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                          Page 99 of 150

                 Term                                         Description                                               Definition
MAU                                         Maximum Attachment Unit                            Device used in Ethernet and IEEE 802.3 networks that
                                                                                               provides the interface between the AUI port of a station and
                                                                                               the common medium of the Ethernet. The MAU, which can
                                                                                               be built into a station or can be a separate device, performs
                                                                                               physical layer functions including the conversion of digital
                                                                                               data from the Ethernet interface, collision detection, and
                                                                                               injection of bits onto the network. Sometimes referred to as
                                                                                               a media access unit, also abbreviated MAU, or as a
                                                                                               transceiver. In Token Ring, a MAU is known as a
                                                                                               multistation access unit and is usually abbreviated MSAU to
                                                                                               avoid confusion.
Maximum Burst                                                                                  Specifies the largest burst of data above the insured rate
                                                                                               that will be allowed temporarily on an ATM PVC, but will not
                                                                                               be dropped at the edge by the traffic policing function, even
                                                                                               if it exceeds the maximum rate. This amount of traffic will be
                                                                                               allowed only temporarily; on average, the traffic source
                                                                                               needs to be within the maximum rate. Specified in bytes or
                                                                                               cells.
Maximum Rate                                                                                   Maximum total data throughput allowed on a given virtual
                                                                                               circuit, equal to the sum of the insured and uninsured traffic
                                                                                               from the traffic source. The uninsured data might be
                                                                                               dropped if the network becomes congested. The maximum
                                                                                               rate, which cannot exceed the media rate, represents the
                                                                                               highest data throughput the virtual circuit will ever deliver,
                                                                                               measured in bits or cells per second.
MB                                          Megabytes
Mb                                          Megabit                                            1,048,576 bits or 1,204 kilobits.
M-Bone(1)                                   Multimedia Backbone
M-Bone(2)                                   Multicast Bone                                     A virtual network layered on top of the Internet to support IP
                                                                                               multicast routing across point-to-point links. Because
                                                                                               multicasting is a fast and inexpensive way to communicate
                                                                                               information to multiple hosts, the M-Bone is used for
                                                                                               transmitting audio and video on the Internet in real time.
Mbps                                        Megabits per second




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                      Page 100 of 150

                Term                                          Description                                             Definition
MBS                                        Maximum Burst Size                                 In an ATM signaling message, burst tolerance is conveyed
                                                                                              through the MBS, which is coded as a number of cells. The
                                                                                              burst tolerance together with the SCR and the GCRA
                                                                                              determine the MBS that can be transmitted at the peak rate
                                                                                              and still be in conformance with the GCRA.
MCA                                        Micro Channel Architecture                         IBM's PC-bus architecture featuring a 32-bit input/output
                                                                                              bus. In competition with Extended Industry Standard
                                                                                              Architecture.
MCCOI                                      Multimedia Communications Community Of Interest
MCDV                                       Maximum Cell Delay Variation                       In an ATM network, the maximum two-point CDV objective
                                                                                              across a link or node for the specified service category. One
                                                                                              of four link metrics exchanged using PTSPs to determine
                                                                                              the available resources of an ATM network. There is one
                                                                                              MCDV value for each traffic class.
MCLR                                       Maximum Cell Loss Ratio                            In an ATM network, the maximum ratio of cells that do not
                                                                                              successfully transit a link or node compared with the total
                                                                                              number of cells that arrive at the link or node. One of four
                                                                                              link metrics exchanged using PTSPs to determine the
                                                                                              available resources of an ATM network. The MCLR applies
                                                                                              to cells in the CBR and VBR traffic classes whose CLP bit is
                                                                                              set to zero.
MCNS                                       Multimedia Cable Network System Partners Ltd       Consortium of cable companies providing service to the
                                                                                              majority of homes in the United States and Canada. This
                                                                                              consortium drives a standard with the goal of having
                                                                                              interoperable cable modems.
MCTD                                       Maximum Cell Transfer Delay                        In an ATM network, the sum of the MCDV and the fixed
                                                                                              delay component across the link or node. One of four link
                                                                                              metrics exchanged using PTSPs to determine the available
                                                                                              resources of an ATM network. There is one MCTD value for
                                                                                              each traffic class.
MCU                                        Multipoint Control Unit                            Endpoint on the LAN that provides the capability for three or
                                                                                              more terminals and gateways to participate in a multipoint
                                                                                              conference.




    This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
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                                                                  Telecom / IS Glossary                                                      Page 101 of 150

                    Term                                         Description                                           Definition
MDIS                                        Mobile Data Intermediate System                    A system to handle authentication, directory services,
                                                                                               packet switching, and gateway services to landline data
                                                                                               networks.
MDN                                         Message Disposition Notification                   Message returned to the originator of an e-mail message
                                                                                               indicating that the e-mail message has been opened.
MDNS                                        Managed Data Network Service
Message Switching                                                                              Switching technique involving transmission of messages
                                                                                               from node to node through a network. The message is
                                                                                               stored at each node until such time as a forwarding path is
                                                                                               available.
Metasignalling                                                                                 Signalling for signalling channels, used to set up a
                                                                                               connection
MG                                          Media Gateway
MGC                                         Media Gateway Controller
MHRP                                        Multi Host Routing Protocol
MHz                                         Megahertz                                          One million Hertz.
MIB                                         Management Information Base                        Database of network management information that is used
                                                                                               and maintained by a network management protocol such as
                                                                                               SNMP or CMIP. The value of a MIB object can be changed
                                                                                               or retrieved using SNMP or CMIP commands, usually
                                                                                               through a GUI network management system. MIB objects
                                                                                               are organized in a tree structure that includes public
                                                                                               (standard) and private (proprietary) branches.
MICP                                        Mobile Internetworking Control Protocol
Microfilter                                                                                    Device that prevents data frequencies (intended for a data
                                                                                               device such as a router) from traveling over the telephone
                                                                                               line and interfering with telephone calls.
MID                                         Message Identifier                                 In ATM, used to identify ATM cells that carry segments from
                                                                                               the same higher-layer packet.
Mid-Level Network                                                                              Makes up the second level of the Internet hierarchy. They
                                                                                               are the transit networks that connect the stub networks to
                                                                                               the backbone networks.


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                                                                 Telecom / IS Glossary                                                      Page 102 of 150

                 Term                                          Description                                             Definition
MIME                                        Multipurpose Internet Mail Extensions              The standard for attaching non-ASCII files to Internet mail
                                                                                               messages. These files include graphics, spreadsheets,
                                                                                               formatted word-processor documents, audio files, and other
                                                                                               binary data.
MIPS                                        Million Instructions Per Second
MIX                                         Multiservice Interchange
MMDS                                        Multichannel Multipoint Distribution Services
MMF                                         MultiMode Fiber
MMoIP                                       Multimedia Mail over IP
MMP                                         Multichassis Multilink PPP                         Extends MLP support across multiple routers and access
                                                                                               servers. MMP enables multiple routers and access servers
                                                                                               to operate as a single, large dial-up pool, with a single
                                                                                               network address and ISDN access number. MMP correctly
                                                                                               handles packet fragmenting and reassembly when a user
                                                                                               connection is split between two physical access devices.
MP                                          Multilink PPP                                      A proposed standard for inverse multiplexing, a method of
                                                                                               combining individually dialed channels into a single, higher
                                                                                               speed data stream. MP is an extension of PPP that
                                                                                               supports the ordering of data packets across multiple
                                                                                               channels.
MP3                                         MPEG Audio layer 3                                 A popular digital compression format for music files.
MPEG                                        Motion Picture Experts Group                       Standard for compressing video. MPEG1 is a bit stream
                                                                                               standard for compressed video and audio optimized to fit
                                                                                               into a bandwidth of 1.5 Mbps. MPEG2 is intended for higher
                                                                                               quality video-on-demand applications and runs at data rates
                                                                                               between 4 and 9 Mbps. MPEG4 is a low-bit-rate
                                                                                               compression algorithm intended for 64-kbps connections.
MPEG-4 CELP                                                                                    Audio codec 5—12/11-24 kbps




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                                                                 Telecom / IS Glossary                                                          Page 103 of 150

                 Term                                          Description                                                 Definition
MPLS                                        MultiProtocol Label Switching                         A specification for layer 3 switching from the IETF. Similar to
                                                                                                  Cisco's tag switching, MPLS uses labels, or tags, that
                                                                                                  contain forwarding information, which are attached to IP
                                                                                                  packets by a router that sits at the edge of the network
                                                                                                  known as a label edge router (LER). The routers in the core
                                                                                                  of the network, known as label switch routers (LSRs),
                                                                                                  examine the label more quickly than if they had to look up
                                                                                                  destination addresses in a routing table. When fully
                                                                                                  implemented on the Internet, MPLS is expected to deliver
                                                                                                  the quality of service (QoS) required to adequately support
                                                                                                  realtime voice and video as well as service level
                                                                                                  agreeements (SLAs) that guarantee bandwidth. Following in
                                                                                                  the tradition of the "dumb network," MPLS enables more
                                                                                                  decisions to be made at the periphery of the network.
MPP                                         Multichannel Point-to Point Protocol                  A protocol that extends the capabilities of MP to support
                                                                                                  inverse multiplexing, session management, and bandwidth
                                                                                                  management. MPP allows you to combine up to 30
                                                                                                  individual channels into a single high-speed connection.
MPU                                                                                               Microprocessor Unit
MSC                                         Mobile Switching Center                               This contains all the control and switching elements for a
                                                                                                  cellular system, housed by the Mobile Telephone Switching
                                                                                                  Office.
MSDT                                        Multi-Services Distant Terminal                       Device that terminates broadband services, including video,
                                                                                                  at the end user's location.
MSISDN                                      Mobile Subscriber International Subscriber iDentity
                                            Number
MSO                                         Multiple Service Operator                             Cable service provider that also provides other services
                                                                                                  such as data and/or voice telephony.
MSP                                         MultiService Platform                                 Multiservice Platform
MSSs                                        Mobile Satellite Services
MTA(1)                                      Message Transfer Agent                                OSI application process used to store and forward
                                                                                                  messages in the X.400 Message Handling System.
                                                                                                  Equivalent to Internet mail agent.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                     Page 104 of 150

                    Term                                        Description                                            Definition
MTA(2)                                      Mail Transfer Agent                                Software that implements SMTP and provides storage for
                                                                                               mail messages to be forwarded or delivered to a local user.
                                                                                               MTAs implement SMTP (RFC 821).
MTBF                                        Mean-Time-Between-Failure                          An average of the time from the point when a problem
                                                                                               occurs to the time when the last problem occurred with a
                                                                                               specific piece of equipment or an entire system.
MTP                                         Multicast Transport Protocol
MTTR                                        Mean-Time-To-Restore                               An average of the outage time from the point when a
                                                                                               problem occurs to the point when service is restored.
MTU(1)                                      Multi-tenant unit Office                           Office blocks occupied by many companies, usually small-
                                                                                               or medium-sized enterprises (SMEs)
MTU(2)                                      Maximum Transmission Unit                          Maximum packet size, in bytes, that a particular interface
                                                                                               can handle.
Multicast                                                                                      A form of broadcast in which a packet is delivered to a pre-
                                                                                               defined subset of all possible destinations. A specific
                                                                                               multicast destination address is used.
Multicast Network                                                                              A network in which a router sends packets to all addresses
                                                                                               on a subscriber list. This type of network is different from
                                                                                               both a unicast network (in which the router sends packets to
                                                                                               one user at a time) and a broadcast network (in which the
                                                                                               router sends packets to all users, whether they appear on a
                                                                                               subscription list or not). The M-Bone is an example of a
                                                                                               multicast network.
Multicast Router                                                                               Router used to send IGMP query messages on their
                                                                                               attached local networks. Host members of a multicast group
                                                                                               respond to a query by sending IGMP reports noting the
                                                                                               multicast groups to which they belong. The multicast router
                                                                                               takes responsibility for forwarding multicast datagrams from
                                                                                               one multicast group to all other networks that have
                                                                                               members in the group.
Multihoming                                                                                    Addressing scheme in IS-IS routing that supports
                                                                                               assignment of multiple area addresses.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                            Page 105 of 150

                    Term                                       Description                                                  Definition
Multiplexer                                                                                        In general, a multiplexer optimises the use of
                                                                                                   communications facilities by configuring and bringing
                                                                                                   together many channels for efficient transmission on a
                                                                                                   network.
Multipoint                                                                                         Circuit that has points served by three or more switches.
                                                                                                   Single communications channel (typically a leased
                                                                                                   telephone circuit) to which two or more stations or logical
                                                                                                   units are attached although only one can transmit at a time.
                                                                                                   Such arrangements usually require a polling mechanism
                                                                                                   under the control of a master station to ensure that only one
                                                                                                   device transmits at a time.
Multipoint Access                                                                                  User access in which more than one terminal equipment is
                                                                                                   supported by a single network termination.
Multiprotocol Routing                                                                              The ability to route multiple network protocols, including IP,
                                                                                                   IPX, and Appletalk.
Multi-Tenant                                                                                       Multiple customers sharing a common CTR.
MUNDI                                       Multiplexed Network for Distributive and Interactive
                                            services .
MVNO                                        Mobile Virtual Network Operators                       Mobile Virtual Network Operators
MVS                                         Multiple Virtual Storage                               An IBM operating system that runs on IBM System/370-
                                                                                                   based mainframes.
MX Device                                   Mail Exchange Record                                   DNS resource record type indicating which host can handle
                                                                                                   e-mail for a particular domain
NADF                                        North American Directory Forum                         Collection of organizations that offer, or plan to offer, public
                                                                                                   directory services in North America, based on the CCITT
                                                                                                   X.500 Recommendations.
NADN                                        Nearest Active Downstream Neighbor                     In Token Ring or IEEE 802.5 networks, the closest
                                                                                                   downstream network device from any given device that is
                                                                                                   still active.
Nagle's Algorithm                                                                                  Actually two separate congestion control algorithms that can
                                                                                                   be used in TCP-based networks. One algorithm reduces the
                                                                                                   sending window; the other limits small datagrams.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                        Page 106 of 150

                 Term                                         Description                                              Definition
Nailed-Up Line                                                                                 A line rented from the phone company for exclusive use, 24
                                                                                               hours per day, seven days per week. The connection exists
                                                                                               between two predetermined points and cannot be switched
                                                                                               to other locations. A nailed-up line is also called a leased
                                                                                               line.
NAK                                         Negative Acknowledgement                           A packet sent from a receiver to a sender, informing the
                                                                                               sender that the data is missing or corrupt. When a device
                                                                                               receives a packet, it sends back a packet to the sending
                                                                                               device. If all the data arrived without corruption, the packet
                                                                                               is an acknowledgement (ACK). If some of the data is
                                                                                               missing or corrupt, a NAK results requesting that the sender
                                                                                               retransmits the data.
Name Server                                                                                    In data communications, a server connected to a network
                                                                                               that transforms host names into network addresses.
NANOG                                       North American Network Operator's Group            Primary forum for information exchange among U.S.
                                                                                               exchange point participants, Internet service providers, and
                                                                                               end users.
NAPs                                        Network Access Points                              Where ISPs agree to drop down their lines and establish
                                                                                               peering arrangements and let their customers communicate.
Narrowband                                                                                     Digital communication at the 64 Kbps or lower rate. Also
                                                                                               known as "baseband."
NAS                                         Network Access Server                              Cisco platform (or collection of platforms such as an
                                                                                               AccessPath system which interfaces between the packet
                                                                                               world (e.g. the Internet) and the circuit world (e.g. the
                                                                                               PSTN).




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                         Page 107 of 150

                 Term                                         Description                                              Definition
NAT                                         Network Address Translation                        Mechanism for reducing the need for globally unique IP
                                                                                               addresses. NAT allows an organization with addresses that
                                                                                               are not globally unique to connect to the Internet by
                                                                                               translating those addresses into globally routable address
                                                                                               space. (2) The translation of an Internet Protocol address
                                                                                               (IP address) used within one network to a different IP
                                                                                               address known within another network. One network is
                                                                                               designated the internal network and the other is the
                                                                                               external. The internal network then appears as one entity to
                                                                                               the outside world. In the case of wireless LANs with an
                                                                                               outside Internet connection, the NAT capability of Internet
                                                                                               sharing software allows the sharing of one Internet
                                                                                               connection among all the wireless PCs connected.
NAU                                         Network Addressable Unit                           SNA term for an addressable entity. Examples include LUs,
                                                                                               PUs, and SSCPs. NAUs generally provide upper-level
                                                                                               network services.
NAUN                                        Nearest Active Upstream Meighbor                   In Token Ring or IEEE 802.5 networks, the closest
                                                                                               upstream network device from any given device that is still
                                                                                               active.
NBMA                                        NonBroadcast MultiAccess                           Term describing a multiaccess network that either does not
                                                                                               support broadcasting (such as X.25) or in which
                                                                                               broadcasting is not feasible (for example, an SMDS
                                                                                               broadcast group or an extended Ethernet that is too large).
NCCs                                        New Common Carriers                                Those companies competing with NTT in Japan's domestic
                                                                                               long distance market.
NCOP                                        Network Code Of Practice                           Specifications designed to ensure the quality of private
                                                                                               networks connected to public switched telephone networks.
NCP(1)                                      Network Control Protocol                           Series of protocols for establishing and configuring different
                                                                                               network layer protocols, such as for AppleTalk over PPP.
NCP(2)                                      Network Control Program                            In SNA, a program that routes and controls the flow of data
                                                                                               between a communications controller (in which it resides)
                                                                                               and other network resources.
NCSA                                        National Center for Supercomputing Applications
NCSC                                        National Computer Security Center.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                        Page 108 of 150

                    Term                                       Description                                              Definition
NDIS                                        Network Driver Interface Specification.
NDSs                                        NetWare Directory Services
NE                                          Network Element                                    In OSS, a single piece of telecommunications equipment
                                                                                               used to perform a function or service integral to the
                                                                                               underlying network.
NEMS                                        Network Element Management Server
NetBEUI                                     NetBIOS Extended User Interface                    Enhanced version of the NetBIOS protocol used by network
                                                                                               operating systems such as LAN Manager, LAN Server,
                                                                                               Windows for Workgroups, and Windows NT. NetBEUI
                                                                                               formalizes the transport frame and adds additional
                                                                                               functions. NetBEUI implements the OSI LLC2 protocol.
NetBIOS                                     Network Basic Input/Output System                  A transport protocol connecting network hardware with the
                                                                                               network operating system. There are a variety of NetBIOS
                                                                                               implementations, many of which do not work together.
NetView, NetView/PC                                                                            NetView is IBM's host-based network management product.
                                                                                               NetView/PC is an IBM product that runs on personal
                                                                                               computers and provides limited network management
                                                                                               functions.
NetWare                                                                                        Novell's network operating system.
NETWORK CONNECTION                                                                             Medium used to connect one system element to another;
                                                                                               could be wire, cable, fibre optic, infrared, radio frequency,
                                                                                               etc.
Network Indicator                                                                              Determines the type of call that is being placed: 0 =
                                                                                               international, 1 = reserved, 2= national, and 3 = national
                                                                                               spare.
Network Layer                                                                                  Layer 3 of the OSI reference model. This layer provides
                                                                                               connectivity and path selection between two end systems.
                                                                                               The network layer is the layer at which routing occurs.
Network Provisioning                                                                           Takes place once a service order is generated including
                                                                                               assignment of bandwidth, IP address, trunking facilities, hub
                                                                                               routing, site survey, workforce management, etc.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                      Page 109 of 150

                 Term                                         Description                                              Definition
NFS                                         Network File System                                As commonly used, a distributed file system protocol suite
                                                                                               developed by Sun Microsystems that allows remote file
                                                                                               access across a network. In actuality, NFS is simply one
                                                                                               protocol in the suite. NFS protocols include NFS, RPC,
                                                                                               XDR, and others. These protocols are part of a larger
                                                                                               architecture that Sun refers to as ONC.
NHRP                                        Next Hop Resolution Protocol                       Protocol used by routers to dynamically discover the MAC
                                                                                               address of other routers and hosts connected to a NBMA
                                                                                               network. These systems can then directly communicate
                                                                                               without requiring traffic to use an intermediate hop,
                                                                                               increasing performance in ATM, Frame Relay, SMDS, and
                                                                                               X.25 environments.
NHS                                         Next Hop Server                                    Server defined by the NHRP protocol that maintains next-
                                                                                               hop resolution cache tables containing the IP-to-ATM
                                                                                               address mappings of associated nodes and nodes that are
                                                                                               reachable through routers served by the NHS.
NIC(1)                                      Network Interface Card                             Board that provides network communication capabilities to
                                                                                               and from a computer system.
NIC(2)                                      Network Information Center
NIS                                         Network Information Service                        Protocol developed by Sun Microsystems for the
                                                                                               administration of network-wide databases. The service
                                                                                               essentially uses two programs: one for finding a NIS server
                                                                                               and one for accessing the NIS databases.
N-ISDN                                      Narrowband ISDN                                    Communication standards developed by the ITU -T for
                                                                                               baseband networks. Based on 64-kbps B channels and 16-
                                                                                               or 64-kbps D channels.
NIST                                        National Institute of Standards and Technology.
NMS                                         Network Management System                          System responsible for managing at least part of a network.
                                                                                               An NMS is generally a reasonably powerful and well-
                                                                                               equipped computer such as an engineering workstation.
                                                                                               NMSs communicate with agents to help keep track of
                                                                                               network statistics and resources.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                        Page 110 of 150

                 Term                                           Description                                             Definition
NN                                          Network Node                                       SNA intermediate node that provides connectivity, directory
                                                                                               services, route selection, intermediate session routing, data
                                                                                               transport, and network management services to LEN nodes
                                                                                               and ENs. The NN contains a CP that manages the
                                                                                               resources of both the NN itself and those of the ENs and
                                                                                               LEN nodes in its domain. NNs provide intermediate routing
                                                                                               services by implementing the APPN PU 2.1 extensions.
NNI                                         Network-to-Network Interface                       The interface between two networks. This could be two
                                                                                               different carriers (for example between an LEC and an IEC),
                                                                                               or between a customer network and an IEC network.
NOA                                         Nature of Address
NOC                                         Network Operations Center                          Organization responsible for maintaining a network.
Node                                                                                           Endpoint of a network connection or a junction common to
                                                                                               two or more lines in a network. Nodes can be processors,
                                                                                               controllers, or workstations. Nodes, which vary in routing
                                                                                               and other functional capabilities, can be interconnected by
                                                                                               links, and serve as control points in the network. Node is
                                                                                               sometimes used generically to refer to any entity that can
                                                                                               access a network, and is frequently used interchangeably
                                                                                               with device. See also host. (2) H.323 entity that uses RAS
                                                                                               to communicate with the gatekeeper (for example, an
                                                                                               endpoint such as a terminal, proxy, or gateway). (3) In
                                                                                               SNA, the basic component of a network and the point at
                                                                                               which one or more functional units connect channels or data
                                                                                               circuits.
NOS                                         Network Operating System                           An operating system for networks or the software that runs
                                                                                               on local area networks. It manages the continual
                                                                                               conversation between all computers on a network.
NPI                                         Number Plan Identification
NRM                                         Normal Response Mode                               HDLC mode for use on links with one primary station and
                                                                                               one or more secondary stations. In this mode, secondary
                                                                                               stations can transmit only if they first receive a poll from the
                                                                                               primary station.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 111 of 150

                 Term                                           Description                                             Definition
NRZ                                         Nonreturn to Zero                                  Signals that maintain constant voltage levels with no signal
                                                                                               transitions (no return to a zero-voltage level) during a bit
                                                                                               interval.
NRZI                                        Nonreturn to Zero Inverted                         Signals that maintain constant voltage levels with no signal
                                                                                               transitions (no return to a zero-voltage level), but interpret
                                                                                               the presence of data at the beginning of a bit interval as a
                                                                                               signal transition and the absence of data as no transition.
NSAP                                        Network Service Access Point                       Network addresses, as specified by ISO. An NSAP is the
                                                                                               point at which OSI Network Service is made available to a
                                                                                               transport layer (Layer 4) entity.
NSP                                         Network Service Provider                           An NSP is a company that provides Internet connectivity to
                                                                                               Internet Service Providers (ISPs) and other organizations
                                                                                               requiring high-speed access to the Internet.
NT-1                                        Network Termination 1                              In ISDN, a device that provides the interface between
                                                                                               customer premises equipment and central office switching
                                                                                               equipment.
NTP                                         Network Time Protocol                              Protocol built on top of TCP that assures accurate local
                                                                                               time-keeping with reference to radio and atomic clocks
                                                                                               located on the Internet. This protocol is capable of
                                                                                               synchronizing distributed clocks within milliseconds over
                                                                                               long time periods.
NTS                                         Number Translation Services
NTSC                                        National Television Standards Committee            The TV standard used primarily in North America and Japan
                                                                                               with 525 lines transmitted at 60 interlaced half-frames per
                                                                                               second
NVRAM                                       NonVolatile RAM                                    RAM that retains its contents when a unit is powered off.
NVT ASCII                                   Network Virtual Terminal ASCII Nailed Line
NYSERNet                                                                                       Network in New York (United States) with a T1 backbone
                                                                                               connecting NSF, many universities, and several commercial
                                                                                               concerns.
OA&M                                        Operations, Administration and Maintenance         Implementation of a modern, integrated and computerised
                                                                                               OA&M system is seen as a prerequisite for provision of AIN-
                                                                                               type services.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                     Page 112 of 150

                 Term                                           Description                                            Definition
OADM                                        Optical Add Drop Multiplexer
OAM                                         Operation, Administration and Maintenance
OBC                                         Out-of-Band Connection                             A remote link, or a link outside connected networks,
                                                                                               established over a modem. It is useful when network
                                                                                               communications are not available.
OBM                                         Optimized Bandwidth Management                     Cisco wide-area switches ensure fair and cost-efficient
                                                                                               bandwidth utilization using various techniques. ABR and
                                                                                               Optimized Banwidth Management are used for ATM and
                                                                                               Frame Relay traffic. ABR is a standards-based ATM traffic
                                                                                               management mechanism, and ForeSight is Cisco's
                                                                                               implementation that mirrors ABR capabilities for Frame
                                                                                               Relay traffic. ABR and Optimized Bandwidth Management
                                                                                               optimize real-time traffic performance and throughput, and
                                                                                               minimize data loss. Bandwidth management for voice is
                                                                                               achieved through the use of standards-based voice
                                                                                               compression and silence suppression mechanisms for
                                                                                               circuit data services.
OC                                          Optical Carrier                                    A hierarchy of optical signals used to classify speeds, or
                                                                                               capacities, of fiber lines, especially as related to the SONET
                                                                                               standard. The basic speed is OC-1 (52Mbps). An OC-48
                                                                                               fiber line has a capacity of 2.5 gigabits a second and an
                                                                                               OC-192 line 10 gigabits a second.
OC3c SONET                                                                                     A SONET-based fiber-optic User-to-Network Interface
                                                                                               (UNI), either public or private, operating at 155.52 Mbps
                                                                                               over single-mode and multimode optical fiber.
OC-n                                        Optical Carrier-bit rate                           Bit rate of North America Sonet hierarchy
Octet                                                                                          Eight data bits
ODA                                         Open Document Architecture                         ISO standard that specifies how documents are represented
                                                                                               and transmitted electronically. Formerly called Office
                                                                                               Document Architecture.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                        Page 113 of 150

                 Term                                         Description                                               Definition
ODBC                                        Open DataBase Connectivity                         Standard application programming interface for accessing
                                                                                               data in both relational and nonrelational database
                                                                                               management systems. Using this application programming
                                                                                               interface, database applications can access data stored in
                                                                                               database management systems on a variety of computers
                                                                                               even if each database management system uses a different
                                                                                               data storage format and programming interface. ODBC is
                                                                                               based on the call level interface specification of the X/Open
                                                                                               SQL Access Group and was developed by Digitial
                                                                                               Equipment Corporation, Lotus, Microsoft, and Sybase.
ODI                                         Open Data-Link Interface                           Novell specification providing a standardized interface for
                                                                                               NICs (network interface cards) that allows multiple protocols
                                                                                               to use a single NIC.
ODSI                                        Open Directory Services Interface
OEM                                         Original Equipment Manufacturer
OFDM                                        Orthogonal Frequency-Division Multiplexing.
OIM                                         OSI Internet Management                            Group tasked with specifying ways in which OSI network
                                                                                               management protocols can be used to manage TCP/IP
                                                                                               networks.
OLE                                         Object Link Embedding technology
OLO                                         Other Licenced Operator
OMG                                         Object Management Group
ONA                                         Open Network Architecture                          An FCC-mandated plan for AT&T and the Bell companies,
                                                                                               by which the companies must give network interconnection
                                                                                               of the same quality
ONP                                         Open Network Provision                             The European Commission's proposed set of technical
                                                                                               interfaces, usage conditions and tariff principles for opening
                                                                                               public networks to competition. Comparable to Open
                                                                                               Network Architecture in the United States.
ONPCCP                                      ONP Consultative and Co-ordination Platform




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 114 of 150

                  Term                                         Description                                              Definition
Open System                                                                                    Any system based on publicly available standards for
                                                                                               subsystem interaction that facilitates multivendor and
                                                                                               multitechnology integration. Open systems are portable,
                                                                                               scaleable, and interoperable.
OPXC                                        Optical Path Cross Connect
OSI                                         Open Systems Interconnection                       A model for computer networking based on the seven-layer
                                                                                               OSI reference model, defined by the International
                                                                                               Organisation for Standardisation, which lets computers from
                                                                                               different manufacturer communicate using local or wide
                                                                                               area networks.
OSI Network Address                                                                            Address, consisting of up to 20 octets, used to locate an
                                                                                               OSI Transport entity. The address is formatted into two
                                                                                               parts: an Initial Domain Part that is standardized for each of
                                                                                               several addressing domains and a Domain Specific Part
                                                                                               that is the responsibility of the addressing authority for that
                                                                                               domain.
OSPF                                        Open Shortest Path First                           A routing protocol.
OSS                                         Operations Support System                          Network management system supporting a specific
                                                                                               management function, such as alarm surveillance and
                                                                                               provisioning, in a carrier network. Many OSSs are large
                                                                                               centralized systems running on mainframes or
                                                                                               minicomputers.
OUI                                         Organizational Unique Identifier                   3 octets assigned by the IEEE in a block of 48-bit LAN
                                                                                               addresses.
Out-of-Band Signaling                                                                          Transmission using frequencies or channels outside the
                                                                                               frequencies or channels normally used for information
                                                                                               transfer. Out -of-band signaling is often used for error
                                                                                               reporting in situations in which in-band signaling can be
                                                                                               affected by whatever problems the network might be
                                                                                               experiencing.
Overflow                                                                                       The process of dialling additional bandwidth to
                                                                                               accommodate peak traffic loads, and reducing the total
                                                                                               bandwidth during times of reduced traffic loads.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                         Page 115 of 150

                     Term                                     Description                                               Definition
PABX                                        Private Automatic Branch Exchange                  Telephone switch for use inside a corporation. PABX is the
                                                                                               preferred term in Europe, while PBX is used in the United
                                                                                               States.
PACE                                        Priority Access Control Enabled
Packet                                                                                         A short fixed-length section of data, transmitted as a unit in
                                                                                               an electronic communications network.
Packet Switching                                                                               Networking method in which nodes share bandwidth with
                                                                                               each other by sending packets.
PAD                                         Packet Assembler/Disassembler                      Device used to connect simple devices (like character-mode
                                                                                               terminals) that do not support the full functionality of a
                                                                                               particular protocol to a network. PADs buffer data and
                                                                                               assemble and disassemble packets sent to such end
                                                                                               devices.
PAP                                         Password Authentication Protocol                   Authentication protocol that allows PPP peers to
                                                                                               authenticate one another. The remote router attempting to
                                                                                               connect to the local router is required to send an
                                                                                               authentication request. Unlike CHAP, PAP passes the
                                                                                               password and host name or username in the clear
                                                                                               (unencrypted). PAP does not itself prevent unauthorized
                                                                                               access, but merely identifies the remote end. The router or
                                                                                               access server then determines if that user is allowed
                                                                                               access. PAP is supported only on PPP lines.
PARC                                        Palo Alto Research Center                          Research and development center operated by XEROX. A
                                                                                               number of widely-used technologies were originally
                                                                                               conceived at PARC, including the first personal computers
                                                                                               and LANs.
Parity Check                                                                                   Process for checking the integrity of a character. A parity
                                                                                               check involves appending a bit that makes the total number
                                                                                               of binary 1 digits in a character or word (excluding the parity
                                                                                               bit) either odd (for odd parity) or even (for even parity).
Path Control Layer                                                                             Layer 3 in the SNA architectural model. This layer performs
                                                                                               sequencing services related to proper data reassembly. The
                                                                                               path control layer is also responsible for routing.
                                                                                               Corresponds roughly with the network layer of the OSI
                                                                                               model.


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                                                                Telecom / IS Glossary                                                        Page 116 of 150

                 Term                                          Description                                             Definition
Payload                                                                                        Portion of a cell, frame, or packet that contains upper-layer
                                                                                               information (data).
PBX                                         Private Branch Exchange                            Digital or analog telephone switchboard located on the
                                                                                               subscriber premises and used to connect private and public
                                                                                               telephone networks.
PCBs                                        Printed Circuit Boards
PCI (or ISA)                                                                                   A local bus standard for connecting peripherals to a
                                                                                               personal computer. Within a computer, the bus is the
                                                                                               transmission path on which signals and data transfers occur
                                                                                               between the CPU, system memory, and attached devices
                                                                                               such as a network card, sound card, or CD-ROM drive.
PCI(1)                                      Protocol Control Information Control               Control information added to user data to comprise an OSI
                                                                                               packet. The OSI equivalent of the term header.
PCI(2)                                      Personal Computer Interface Bus
PCM                                         Pulse Code Modulation                              Transmission of analog information in digital form through
                                                                                               sampling and encoding the samples with a fixed number of
                                                                                               bits.
PCN(1)                                      Personal Communications Number                     A telephone number in a PCS which is permanently
                                                                                               assigned to a subscriber regardless of the person's location
                                                                                               or service provider. The PCN remains static even if the user
                                                                                               changes handsets or phones.
PCN(2)                                      Personal Communications Network                    Mobile telephone networks that permit two-way
                                                                                               communications over small, inexpensive handsets.
PCR                                         Peak Cell Rate                                     The maximum rate at which ATM cells can be transmitted
                                                                                               across a virtual circuit, specified in cells per second and
                                                                                               defined by the interval between the transmission of the last
                                                                                               bit of one cell and the first bit of the next.
PCS(1)                                      Personal Communications Services                   Services for digital Radio Frequency (RF) equipment
                                                                                               conveying both voice and data over wireless networks.
PCS(2)                                      Port Concentrator Switch
PDA                                         Personal Digital Assistant                         A portable organiser, increasingly with Internet access and
                                                                                               e-mail functions.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                       Page 117 of 150

                  Term                                           Description                                            Definition
PDC                                         Personal Digital Cellular
PDH                                         Plesiochronous Digital Hierarchy                   The transmission technology for transmitting multiple
                                                                                               channels of traffic from one point to another.
PDN                                         Public Data Network                                Network operated either by a government (as in Europe) or
                                                                                               by a private concern to provide computer communications
                                                                                               to the public, usually for a fee. PDNs enable small
                                                                                               organizations to create a WAN without all the equipment
                                                                                               costs of long-distance circuits.
PDU(1)                                      Protocol Data Unit                                 OSI term for packet
PDU(2)                                      Protocol Data Unit                                 E.g., a 53-byte ATM cell
Peak Rate                                                                                      Maximum rate, in kilobits per second, at which a virtual
                                                                                               circuit can transmit.
Peer Group                                                                                     Collection of ATM nodes that share identical topological
                                                                                               databases and exchange full link state information with each
                                                                                               other. Peer groups are arranged hierarchically to prevent
                                                                                               excessive PTSP traffic.
PEM                                         Privacy Enhanced Mail                              Internet e-mail that provides confidentiality, authentication,
                                                                                               and message integrity using various encryption methods.
                                                                                               Not widely deployed in the Internet.
Peripheral Node                                                                                In SNA, a node that uses local addresses and is therefore
                                                                                               not affected by changes to network addresses. Peripheral
                                                                                               nodes require boundary function assistance from an
                                                                                               adjacent subarea node.
PGT-10                                                                                         The Conference of European Postal and
                                                                                               Telecommunications administrations' general tariff
                                                                                               principles study group.
PHS                                         Personal Handyphone Services
PHY                                         Physical Layer                                     One of two sublayers of the FDDI physical layer. (2) In
                                                                                               ATM, the physical layer provides for the transmission of
                                                                                               cells over a physical medium that connects two ATM
                                                                                               devices. The PHY is comprised of two sublayers: PMD and
                                                                                               TC.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 118 of 150

                   Term                                        Description                                              Definition
Physical Resource Allocations                                                                  The process of procuring, storing, and allocating physical
                                                                                               hardware such as CTR, BTR, cards, NIU, etc.
PHYSNET                                     Physics Network                                    Group of many DECnet-based physics research networks,
                                                                                               including HEPnet.
PIM                                         Protocol Independent Multicast                     Multicast routing architecture that allows the addition of IP
                                                                                               multicast routing on existing IP networks. PIM is unicast
                                                                                               routing protocol independent and can be operated in two
                                                                                               modes: dense and sparse.
PIM DM                                      PIM Dense Mode                                     One of the two PIM operational modes. PIM dense mode is
                                                                                               data-driven and resembles typical multicast routing
                                                                                               protocols. Packets are forwarded on all outgoing interfaces
                                                                                               until pruning and truncation occurs. In dense mode,
                                                                                               receivers are densely populated, and it is assumed that the
                                                                                               downstream networks want to receive and will probably use
                                                                                               the datagrams that are forwarded to them. The cost of using
                                                                                               dense mode is its default flooding behavior.
PIM SM                                      PIM Sparse Mode                                    One of the two PIM operational modes. PIM sparse mode
                                                                                               tries to constrain data distribution so that a minimal number
                                                                                               of routers in the network receive it. Packets are sent only if
                                                                                               they are explicitly requested at the RP (rendezvous point).
                                                                                               In sparse mode, receivers are widely distributed, and the
                                                                                               assumption is that downstream networks will not necessarily
                                                                                               use the datagrams that are sent to them. The cost of using
                                                                                               sparse mode is its reliance on the periodic refreshing of
                                                                                               explicit join messages and its need for RPs.
PIN                                         P-doped Intrinsic N-doped
Ping                                        Packet Internet Groper                             ICMP echo message and its reply. Often used in IP
                                                                                               networks to test the reachability of a network device.
PINX                                        Private Integrated Services Network Exchange       A PBX or key system which, in a BRI voice application, uses
                                                                                               QSIG signaling.
PKC                                         Public Key Cryptology
PKI                                         Public Key Infrastructure




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                    Page 119 of 150

                   Term                                           Description                                          Definition
PLAR                                        Private Line, Automatic Ringdown                   Leased voice circuit that connects two single endpoints
                                                                                               together. When either telephone handset is taken off-hook,
                                                                                               the remote telephone automatically rings.
PLCP                                        Physical Layer Convergence Procedure               Specification that maps ATM cells into physical media, such
                                                                                               as T3 or E3, and defines certain management information.
PLIM                                        Physical Layer Interface Module
PLMN                                        Public Land Mobile Network
PLP                                         Packet Level Protocol                              Network layer protocol in the X.25 protocol stack.
PLSP                                        PNNI Link State Packets
PMD                                         Physical Medium Dependent                          Sublayer of the FDDI physical layer that interfaces directly
                                                                                               with the physical medium and performs the most basic bit
                                                                                               transmission functions of the network.
PMP                                         Point-to-Multipoint
PNNI                                        Private Network Node Interface                     ATM Forum specification for signaling to establish point-t o-
                                                                                               point and point-to-multipoint connections across an ATM
                                                                                               network. The protocol is based on the ATM Forum UNI
                                                                                               specification with additional mechanisms for source routing,
                                                                                               crankback, and alternate routing of call setup requests.
PNO                                         Public Network Operator
POET                                        Packet Over E3/T3
Point-to-Multipoint Connection                                                                 One of two fundamental connection types. In ATM, a point-
                                                                                               to-multipoint connection is a unidirectional connection in
                                                                                               which a single source end-system (known as a root node)
                                                                                               connects to multiple destination end-systems (known as
                                                                                               leaves).
POINT-TO-POINT                                                                                 A connection with only two endpoints; a communications
                                                                                               line connected directly from one point to one other point as
                                                                                               opposed to multi-point lines.
Point-to-Point Connection                                                                      One of two fundamental connection types. In ATM, a point-
                                                                                               to-point connection can be a unidirectional or bidirectional
                                                                                               connection between two ATM end-systems.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                     Page 120 of 150

                     Term                                       Description                                             Definition
POLICING                                                                                       Usage/network parameter control
Policy Routing                                                                                 Routing scheme that forwards packets to specific interfaces
                                                                                               based on user-configured policies. Such policies might
                                                                                               specify that traffic sent from a particular network should be
                                                                                               forwarded out one interface, while all other traffic should be
                                                                                               forwarded out another interface.
POOH                                        Path Overhead                                      Alarm indication and quality control within SDI network
POONA                                       Passive Optical Network
POP(1)                                      Post Office Protocol                               Protocol that client e-mail applications use to retrieve mail
                                                                                               from a mail server.
POP(2)                                      Point of Presence                                  In OSS, a physical location where an interexchange carrier
                                                                                               installed equipment to interconnect with an LEC (local
                                                                                               exchange carrier).
POS                                         Packet over Sonet
POSI                                        Promoting Conference for OSI                       Group of executives from the six major Japanese computer
                                                                                               manufacturers and Nippon Telephone and Telegraph that
                                                                                               sets policies and commits resources to promote OSI.
POTS                                        Plain Old Telephone System
PPP                                         Point-to-Point Protocol                            Successor to SLIP that provides router-to-router and host-
                                                                                               to-network connections over synchronous and
                                                                                               asynchronous circuits.
Predictive Dialler                                                                             Equipment which makes simultaneous calls to the numbers
                                                                                               in a database, then as "live" answers are received, callers
                                                                                               are instantly transferred to a Formus representative.
                                                                                               Eliminates wasted time due to busy signals, rings-but no
                                                                                               answer, operator intercepts because of disconnected
                                                                                               numbers, answering machines, etc.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                        Page 121 of 150

                 Term                                         Description                                               Definition
Primary rate                                                                                   This description of services and interfaces offered to
                                                                                               integrated services digital network customers is not
                                                                                               capitalised. In Europe, the primary rate interface operates at
                                                                                               2.048 megabits per second and has 30 64-kilobit-per-
                                                                                               second B, or bearer channels, and one 64 kbps D, or
                                                                                               signalling, channel. The North American equivalent
                                                                                               operates at 1.544 megabits per second and has 23 64-kbps
                                                                                               B channels and one 64-kbps signalling channel.
PRMD                                        Private Management Domain
PROM                                        Programmable Read-Only Memory                      ROM that can be programmed using special equipment.
                                                                                               PROMs can be programmed only once.
Protocol Stack                                                                                 Set of related communications protocols that operate
                                                                                               together and, as a group, address communication at some
                                                                                               or all of the seven layers of the OSI reference model. Not
                                                                                               every protocol stack covers each layer of the model, and
                                                                                               often a single protocol in the stack will address a number of
                                                                                               layers at once. TCP/IP is a typical protocol stack.
Provisioning                                                                                   Processes associated with establishing customer service.
Proxy                                                                                          The mechanism whereby one system acts for another
                                                                                               system in responding to protocol requests.
PSE                                         Packet Switch Exchange
PSN                                         Packet Switched Network                            Network that uses packet-switching technology for data
                                                                                               transfer.
PSP                                         Personal Software Products
PSTN                                        Public Switched Telephone Network                  General term referring to the variety of telephone networks
                                                                                               and services in place worldwide.
PTI                                         Payload Type Indentifier                           3-bit descriptor in the ATM cell header indicating the type of
                                                                                               payload that the cell contains. Payload types include user
                                                                                               and management cells; one combination indicates that the
                                                                                               cell is the last cell of an AAL5 frame.
PTM                                         Plesiochronous Transmission                        Term describing digital signals that are sourced from
                                                                                               different clocks of comparable accuracy and stability.



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                                                                  Telecom / IS Glossary                                                       Page 122 of 150

                 Term                                            Description                                            Definition
PTSE                                        PNNI Topology State Element                        Collection of PNNI information that is flooded among all
                                                                                               logical nodes within a peer group.
PTSP                                        PNNI Topology State Packet                         Type of PNNI routing packet used to exchange reachability
                                                                                               and resource information among ATM switches to ensure
                                                                                               that a connection request is routed to the destination along
                                                                                               a path that has a high probability of meeting the requested
                                                                                               QoS. Typically, PTSPs include bidirectional information
                                                                                               about the transit behavior of particular nodes (based on
                                                                                               entry and exit ports) and current internal state.
PTT                                         Postal Telephone and Telegraph
PVC                                         Permanent Virtual Circuit                          A connection in a connection-oriented network which is
                                                                                               established through configuration, rather than dynamically.
PVN                                         Private Virtual Network
PVP                                         Permanent Virtual Path                             Virtual path that consists of PVCs.
PVP Tunneling                               Permanent Virtual Path Tunneling                   Method of linking two private ATM networks across a public
                                                                                               network using a virtual path. The public network
                                                                                               transparently trunks the entire collection of virtual channels
                                                                                               in the virtual path between the two private networks.
Q-2931                                                                                         Signalling protocol (layer 3) for B-ISDN (similar to Q-931)
QAM                                         Quadrature Amplitude Modulation                    Method of modulating digital signals onto a radio-frequency
                                                                                               carrier signal involving both amplitude and phase coding.
                                                                                               QAM is a modulation scheme mostly used in the
                                                                                               downstream direction.
QI                                          Quality Index
QLLC                                        Qualified Logical Link Control                     Data link layer protocol defined by IBM that allows SNA data
                                                                                               to be transported across X.25 networks.
QoS                                         Quality of Service                                 The requirements a network must provide to an individual
                                                                                               flow of information (e.g., a voice call, an interactive video
                                                                                               conference, a data file transfer) so that the information is
                                                                                               optimally delivered.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                        Page 123 of 150

                 Term                                         Description                                               Definition
QoS Parameters                              Quality of Service Parameters                      Parameters that control the amount of traffic the source in
                                                                                               an ATM network sends over an SVC. If any switch along the
                                                                                               path cannot accommodate the requested QoS parameters,
                                                                                               the request is rejected, and a rejection message is
                                                                                               forwarded back to the originator of the request.
QRS                                         Quasi-Random Signal                                A digital test signal consisting of a bit sequence that
                                                                                               approximates a random signal.
QRSS                                        Quasi-Random Signal Sequence
Quantization                                                                                   The process that divides the continuous range of values of a
                                                                                               signal into non-overlapping (but not necessarily equal) sub-
                                                                                               ranges. It then assigns a discrete value of the output to
                                                                                               each sub-range. Whenever the signal value falls within a
                                                                                               given sub-range, output has the corresponding discrete
                                                                                               value.
QUIPU                                                                                          Software package developed to study the OSI Directory and
                                                                                               provide extensive pilot capabilities.
RAC                                         Relay Access Card
RACE                                        Research on Advanced Communications in Europe      Project sponsored by the EC for the development of
                                                                                               broadband networking capabilities.
Radio Channel                                                                                  Actual cellular Radio Frquency (RF) channel as identified in
                                                                                               the United States by the Federal Communications FCC. For
                                                                                               analog, the channel is 30KHz wide. In CDMA, the radio
                                                                                               chanel is 1.25 MHz wide.
RADIUS                                      Remote Authentication Dial-In User Service         Database for authenticating modem and ISDN connections
                                                                                               and for tracking connection time.
RADSL                                                                                          Rate-Adaptive DSL. ADSL technology from Westell in
                                                                                               which software is able to determine the rate at which signals
                                                                                               can be transmitted on a given customer phone line and
                                                                                               adjust the delivery rate accordingly.
RAM                                         Random Access Memory                               A solid-state memory device used for transient memory
                                                                                               storage. Allows you to enter and retrieve information from
                                                                                               any storage position.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                       Page 124 of 150

                 Term                                         Description                                              Definition
RARE                                        Réseaux Associés pour la Recherche Européenne      Association of European universities and research centers
                                                                                               designed to promote an advanced telecommunications
                                                                                               infrastructure in the European scientific community.
RARP                                        Reverse Address Resolution Protocol                Protocol in the TCP/IP stack that provides a method for
                                                                                               finding IP addresses based on MAC addresses.
Rate Queue                                                                                     In ATM, a value associated with one or more virtual circuits
                                                                                               that defines the speed at which an individual virtual circuit
                                                                                               transmits data to the remote end. Each rate queue
                                                                                               represents a portion of the overall bandwidth available on
                                                                                               an ATM link. The combined bandwidth of all configured rate
                                                                                               queues should not exceed the total available bandwidth.
RBOC                                        Regional Bell Operating Company                    There are seven (also known as Baby Bells) which own the
                                                                                               local exchange carriers in the US following the
                                                                                               divestiture/breakup of AT&T (‘Ma Bell’) in 1984.
RCP                                         Remote Copy Protocol                               Protocol that allows users to copy files to and from a file
                                                                                               system residing on a remote host or server on the network.
                                                                                               The RCP protocol uses TCP to ensure the reliable delivery
                                                                                               of data.
RDBMS                                       Relational Database Management System              A structured computer information storage and retrieval
                                                                                               system where the basic unit is a Table with Rows and
                                                                                               Columns. Data is defined, accessed and modified with SQL
                                                                                               statements.
RDI                                         Remote Defect Identifiaction                       In ATM, when the physical layer detects loss of signal or cell
                                                                                               synchronization, RDI cells are used to report a VPC/VCC
                                                                                               failure. RDI cells are sent upstream by a VPC/VCC endpoint
                                                                                               to notify the source VPC/VCC endpoint of the downstream
                                                                                               failure.
Real time                                                                                      A transmission or data processing operating mode by which
                                                                                               data is entered in an interactive session; pertaining to an
                                                                                               application whereby response to input is fast enough to
                                                                                               affect subsequent input such as a process-control system;
                                                                                               describing processing in which the results are used to
                                                                                               influence an ongoing process.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 125 of 150

                   Term                                       Description                                               Definition
Redundancy                                                                                     In internetworking, the duplication of devices, services, or
                                                                                               connections so that, in the event of a failure, the redundant
                                                                                               devices, services, or connections can perform the work of
                                                                                               those that failed. (2) In telephony, the portion of the total
                                                                                               information contained in a message that can be eliminated
                                                                                               without loss of essential information or meaning.
Redundant System                                                                               Computer, router, switch, or other system that contains two
                                                                                               or more of each of the most important subsystems, such as
                                                                                               two disk drives, two CPUs, or two power supplies.
Reed Solomon Code                                                                              Error correction code for bit errors, e.g., in AAL-1 type
                                                                                               transmission
Remote Bridge                                                                                  Bridge that connects physically disparate network segments
                                                                                               via WAN links.
RF                                          Radio Frequency                                    Refers to wireless transmission of radio signals as opposed
                                                                                               to wires or cables to carry signals; refers to a frequency
                                                                                               band which is higher then audio frequencies, but lower than
                                                                                               the infrared frequencies. (2) A range of electromagnetic
                                                                                               frequencies above sound and below visible light, generally
                                                                                               in the 30Khz to 300GHz range, used for all broadcast
                                                                                               transmission including AM and FM radio, television, short-
                                                                                               wave, microwave, and satellite transmissions.
RF ENGINEER                                                                                    Employee working within the RF engineering department
                                                                                               involved with cell layout, RF system design, identifying
                                                                                               target buildings for antenna installation, planning in-building
                                                                                               distribution, and implementation of new services; provide a
                                                                                               direct input to civil engineering and customer activations;
                                                                                               typical tasks might include provisioning IP addresses,
                                                                                               VPI/VCI, and DLCI, putting hubs in place, frequency reuse
                                                                                               planning, and RF network engineering.
RFI                                         Radio Frequency Interference                       Disruption of signal by radio waves at the same frequency
                                                                                               as the desired signal.
RHC                                         Regional Holding Company
RIM                                         Request Initialization Mode




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                                                                Telecom / IS Glossary                                                       Page 126 of 150

                 Term                                         Description                                              Definition
Ring                                                                                           Connection of two or more stations in a logically circular
                                                                                               topology. Information is passed sequentially between active
                                                                                               stations. Token Ring, FDDI, and CDDI are based on this
                                                                                               topology.
RIP                                         Routing Information Protocol                       An IAB protocol which is used by IP routers to determine the
                                                                                               optimal path along which to move a packet.
RISC                                        Reduced Instruction Set Computing
RLM                                         Redundant Link Manager
RM                                          Resource Management                                Management of critical resources in an ATM network. Two
                                                                                               critical resources are buffer space and trunk bandwidth.
                                                                                               Provisioning can be used to allocate network resources in
                                                                                               order to separate traffic flows according to service
                                                                                               characteristics.
RMON                                        Remote Monitoring
RNC                                         Radio Network Controller
Roaming                                                                                        Moving seamlessly from one AP coverage area to another
                                                                                               with no loss in connectivity.
ROSE                                        Remote Operation Service Element                   A international-standard protocol that serves as an interface
                                                                                               between software applications on different nodes.
Router                                                                                         A sophisticated, protocol-sensitive device that examines
                                                                                               data packets and finds the best route for them between
                                                                                               sender and receiver. Selects the cheapest, fastest, or least
                                                                                               busy of all available routes.
RPF                                         Reverse Path Forwarding                            Multicasting technique in which a multicast datagram is
                                                                                               forwarded out of all but the receiving interface if the
                                                                                               receiving interface is the one used to forward unicast
                                                                                               datagrams to the source of the multicast datagram.
RR                                          Relative Rate                                      In ATM, one of the congestion feedback modes provided by
                                                                                               ABR service. In RR mode, switches set a bit in forward and
                                                                                               backward RM cells to indicate congestion.
RSA                                         Rivest, Shamir, and Adelman                        Public-key cryptographic system named after its inventors. It
                                                                                               may be used for encryption and authentication.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                       Page 127 of 150

                 Term                                         Description                                              Definition
RSH                                         Remote Shell Protocol                              Protocol that allows a user to execute commands on a
                                                                                               remote system without having to log in to the system. For
                                                                                               example, rsh can be used to remotely examine the status of
                                                                                               a number of access servers without connecting to each
                                                                                               communication server, executing the command, and then
                                                                                               disconnecting from the communication server.
RSM                                         Route Switch Module
RSP                                         Route/Switch Processor
RSRB                                        Remote Source-Route Bridging                       SRB over WAN links.
RSVP                                        Resource Reservation Protocol                      Protocol that supports the reservation of resources across
                                                                                               an IP network. Applications running on IP end systems can
                                                                                               use RSVP to indicate to other nodes the nature (bandwidth,
                                                                                               jitter, maximum burst, and so forth) of the packet streams
                                                                                               they want to receive.
RTCP                                        RTP Control Protocol                               Protocol that monitors the QOS of an IPv6 RTP connection
                                                                                               and conveys information about the on-going session.
RTP(1)                                      Routing Table Protocol                             VINES routing protocol based on RIP. Distributes network
                                                                                               topology information and aids VINES servers in finding
                                                                                               neighboring clients, servers, and routers. Uses delay as a
                                                                                               routing metric.
RTP(2)                                      Real-Time Transport Protocol                       One of the IPv6 protocols. RTP is designed to provide end-
                                                                                               to-end network transport functions for applications
                                                                                               transmitting real-time data, such as audio, video, or
                                                                                               simulation data, over multicast or unicast network services.
                                                                                               RTP provides services such as payload type identification,
                                                                                               sequence numbering, timestamping, and delivery
                                                                                               monitoring to real-time applications.
RTP(3)                                      Rapid Transport Protocol                           Provides pacing and error recovery for APPN data as it
                                                                                               crosses the APPN network. With RTP, error recovery and
                                                                                               flow control are done end-to-end rather than at every node.
                                                                                               RTP prevents congestion rather than reacts to it.




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 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                        Page 128 of 150

                 Term                                         Description                                               Definition
RTSP                                        Real Time Streaming Protocol                       Enables the controlled delivery of real-time data, such as
                                                                                               audio and video. Sources of data can include both live data
                                                                                               feeds, such live audio and video, and stored content, such
                                                                                               as pre-recorded events. RTSP is designed to work with
                                                                                               established protocols, such as RTP and HTTP.
RTU                                         Radio Termination Unit
rt-VBR                                      Real Time Variable Bit Rate                        A form of ATM transmission in which clock frequency can
                                                                                               vary, but maximum delay and maximum variation of delay
                                                                                               between cells are guaranteed. A typical use is real-time
                                                                                               videoconferencing.
RU                                          Request/Response Unit                              Request and response messages exchanged between
                                                                                               NAUs in an SNA network.
RUDP                                        Reliable User Data Protocol
RX                                                                                             Number of Receive Slots
S/T Interface                                                                                  A physical interface in an ISDN Basic Rate service which
                                                                                               uses two copper pairs.
SAA                                         Systems Application Architecture                   An IBM blueprint for letting software applications written for
                                                                                               one IBM processor run on all IBM processors.
SAC                                         Single-Attached Concentrator                       FDDI or CDDI concentrator that connects to the network by
                                                                                               being cascaded from the master port of another FDDI or
                                                                                               CDDI concentrator.
SAP(1)                                      Service Access Point                               Field defined by the IEEE 802.2 specification that is part of
                                                                                               an address specification. Thus, the destination plus the
                                                                                               DSAP define the recipient of a packet. The same applies to
                                                                                               the SSAP.
SAP(2)                                      Service Advertising Protocol                       IPX protocol that provides a means of informing network
                                                                                               clients, via routers and servers, of available network
                                                                                               resources and services.
SAR                                         Segmentation and Reassembly                        Sublayer of 53-byte cells
SAS(1)                                      Single Attachment Station                          Device attached only to the primary ring of an FDDI ring.




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                                                                 Telecom / IS Glossary                                                      Page 129 of 150

                 Term                                           Description                                            Definition
SAS(2)                                      Statically Assigned Socket                         Socket that is permanently reserved for use by a designated
                                                                                               process. In an AppleTalk network, SASs are numbered 1 to
                                                                                               127; they are reserved for use by specific socket clients and
                                                                                               for low-level built-in network services.
SCE                                         Service Creation Environment                       A key goal of IN developers is an SCE, which makes it easy
                                                                                               for telecoms operators, third-party service providers and,
                                                                                               perhaps, users to build services.
SCP                                         Service Control Point                              A computer database that holds information on IN services
                                                                                               and subscribers and is separated from the switch, making it
                                                                                               easier to introduce new services on the network.
SCR                                         Sustainable Cell Rate                              Parameter defined by the ATM Forum for ATM traffic
                                                                                               management. For VBR connections, SCR determines the
                                                                                               long-term average cell rate that can be transmitted.
SDH                                         Synchronous Digital Hierarchy                      European standard that defines a set of rate and format
                                                                                               standards that are transmitted using optical signals over
                                                                                               fiber. SDH is similar to SONET, with a basic SDH rate of
                                                                                               155.52 Mbps, designated at STM-1.
SDLC                                        Synchronous Data Link Control                      SNA data link layer communications protocol. SDLC is a bit-
                                                                                               oriented, full-duplex serial protocol that has spawned
                                                                                               numerous similar protocols, including HDLC and LAPB.
SDLS                                        Single-Line Digital Subscriber Line                One of four DSL technologies. SDSL delivers1.544 Mbps
                                                                                               both downstream and upstream over a single copper
                                                                                               twisted pair. The use of a single twisted pair limits the
                                                                                               operating range of SDSL to 10,000 feet (3048.8 meters).
SDSL                                        Symmetric DSL                                      Similar to HDSL with a single twisted-pair line, carrying
                                                                                               1.544 Mbps (U.S. and Canada) or 2.048 Mbps (Europe)
                                                                                               each direction on a duplex line.
SDU                                         Service Data Unit                                  Unit of information from an upper-layer protocol that defines
                                                                                               a service request to a lower-layer protocol.
Sea-Me-We 2                                                                                    A fiber optic cable to run between Singapore and Europe,
                                                                                               through the Middle East.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                        Page 130 of 150

                 Term                                         Description                                                Definition
Segment                                                                                        In a LAN using a bus topology, a segment is a continuous
                                                                                               electrical circuit that is often connected to other such
                                                                                               segments with repeaters. Section of a network that is
                                                                                               bounded by bridges, routers, or switches. (2) Term used in
                                                                                               the TCP specification to describe a single transport layer
                                                                                               unit of information.
SerDes                                                                                         Serializer/Deserializer
SET                                         Secure Electronic Transaction                      Automates the authorisation, verification, fraud detection
                                                                                               and settlement processes of credit card transactions over
                                                                                               the Internet.
SF                                          Super Frame                                        Common framing type used on T1 circuits. SF consists of
                                                                                               12 frames of 192 bits each, with the 193rd bit providing error
                                                                                               checking and other functions. SF is superseded by ESF, but
                                                                                               is still widely used.
SGCP                                        Simple Gateway Control Protocol                    Controls Voice over IP gateways by an external call control
                                                                                               element (called a call-agent). This has been adapted to
                                                                                               allow SGCP to control switch ATM Circuit Emulation Service
                                                                                               circuits (called endpoints in SGCP). The resulting system
                                                                                               (call-agents and gateways) allows for the call-agent to
                                                                                               engage in Common Channel Signalling (CCS) over a 64-
                                                                                               Kbps CES circuit, governing the interconnection of bearer
                                                                                               channels on the CES interface.
SGML                                        Standard Generalised Mark -up Language             International standard for the definition of system-
                                                                                               independent, device-independent methods of representing
                                                                                               text in electronic form.
SGMP                                        Simple Gateway Monitoring Protocol                 Network management protocol that was considered for
                                                                                               Internet standardization and lat er evolved into SNMP.
SGSN                                        Serving GPRS Support Node
SIBs                                        Service Independent Building Blocks                Creation of SIBs will in theory make it easier for non-
                                                                                               software specialists to create new services by mixing and
                                                                                               matching SIBs.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                        Page 131 of 150

                   Term                                        Description                                              Definition
Signaling Packet                                                                               Generated by an ATM -connected device that wants to
                                                                                               establish a connection with another such device. The
                                                                                               signaling packet contains the ATM NSAP address of the
                                                                                               desired ATM endpoint, as well as any QoS parameters
                                                                                               required for the connection. If the endpoint can support the
                                                                                               desired QoS, it responds with an accept message, and the
                                                                                               connection is opened.
SIM                                         Subscriber Identification Module                   A plastic card which is placed in the back of a mobile phone
                                                                                               and allows you to store information on your phone.
SIM Toolkit                                 Subscriber Identity Module Application Toolkit     Extends the customisation of the SIM card through the
                                                                                               development of mobile phone resident applications, such as
                                                                                               menu structures.
Simplex                                                                                        Capability for transmission in only one direction between a
                                                                                               sending station and a receiving station. Broadcast television
                                                                                               is an example of a simplex technology.
SLA                                         Service Level Agreement                            The minimum quality of service the provider is committed to
                                                                                               providing and should include the CIR, response time in case
                                                                                               of problems, and other details outlining what minimum you
                                                                                               are agreeing to accept.
SLIP                                        Serial Line Internet Protocol                      Standard protocol for point-to-point serial connections using
                                                                                               a variation of TCP/IP
Slotted Ring                                                                                   LAN architecture based on a ring topology in which the ring
                                                                                               is divided into slots that circulate continuously. Slots can be
                                                                                               either empty or full, and transmissions must start at the
                                                                                               beginning of a slot.
SMA                                         Service Management Architecture
SMB                                         Server Message Block                               File-system protocol used in LAN manager and similar
                                                                                               NOSs to package data and exchange information with other
                                                                                               systems.
SMDS                                        Switched Multimegabit Data Service                 A high-speed data service developed by Bellcore (Bell
                                                                                               Communications Research Inc.).
SMI                                         Structure of Management Information
SMP                                         Symmetric Multiprocessing


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                       Page 132 of 150

                 Term                                          Description                                             Definition
SMRP                                        Simple Multicast Routing Protocol                  Specialized multicast network protocol for routing
                                                                                               multimedia data streams on enterprise networks. SMRP
                                                                                               works in conjunction with multicast extensions to the
                                                                                               AppleTalk protocol.
SMS(1)                                      Short Messaging Service
SMS(2)                                      Service Management System                          The SMS allows provision and updating of information on
                                                                                               subscribers and services in near-real time for billing and
                                                                                               administrative purposes.
SMTP                                        Simple Mail Transfer Protocol
SN                                          Service Node                                       Used to refer generally to an element in an advanced public
                                                                                               networking architecture at which service requests, including
                                                                                               service switching, are processed.
SNA                                         Systems Network Architecture                       IBM's masterplan for communications among its computer
                                                                                               systems. The plan is implemented in IBM hardware and
                                                                                               software products.
SNAP                                        Subnetwork Access Protocol                         Internet protocol that operates between a network entity in
                                                                                               the subnetwork and a network entity in the end system.
                                                                                               SNAP specifies a standard method of encapsulating IP
                                                                                               datagrams and ARP messages on IEEE networks. The
                                                                                               SNAP entity in the end system makes use of the services of
                                                                                               the subnetwork and performs three key functions: data
                                                                                               transfer, connection management, and QoS selection.
Sniffer                                                                                        A program to capture data from a computer network.
SNMP                                        Simple Network Management Protocol                 An application-layer protocol that facilitates the exchange of
                                                                                               management information between network devices. It is part
                                                                                               of the Transmission Control Protocol/Internet Protocol
                                                                                               (TCP/IP) protocol suite. SNMP enables network
                                                                                               administrators to manage network performance, find and
                                                                                               solve network problems, and plan for network growth.
SNPA                                        Subnetwork Point of Attachment                     Data link layer address (such as an Ethernet address, X.25
                                                                                               address, or Frame Relay DLCI address). SNPA addresses
                                                                                               are used to configure a CLNS route for an interface.
SOA                                         System on a Chip



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                      Page 133 of 150

                 Term                                           Description                                             Definition
Soft Hand-Off                                                                                  Occurs when two or more logical connections on a packet
                                                                                               pipe are utilized by the same selector.
SOH                                         Section Overhead                                   First nine bytes of an STM-1 transmission frame
SONET                                       Synchronous Optical Network                        A building block for the forthcoming broadband integrated
                                                                                               services digital network, Sonet is the first global
                                                                                               transmission standard. It allows for the multiplexing of a
                                                                                               range of signals from asynchronous data and voice, high or
                                                                                               low-speed data or voice, and on-demand services such as
                                                                                               videoconferencing. It also provides for sophisticated
                                                                                               network management techniques and increased customer
                                                                                               control. Developed by Bell Communications Research Inc.
                                                                                               Also known as Synchronous Digital Hierarchy
SPF                                         Shortest Path First Algorithm                      Routing algorithm that iterates on length of path to
                                                                                               determine a shortest-path spanning tree. Commonly used in
                                                                                               link-state routing algorithms. Sometimes called Dijkstra's
                                                                                               algorithm.
SPID                                        Service Profile Identifier                         Number that some service providers use to define the
                                                                                               services to which an ISDN device subscribes. The ISDN
                                                                                               device uses the SPID when accessing the switch that
                                                                                               initializes the connection to a service provider.
Spoofing                                                                                       Scheme used by routers to cause a host to treat an
                                                                                               interface as if it were up and supporting a session. The
                                                                                               router spoofs replies to keepalive messages from the host in
                                                                                               order to convince that host that the session still exists.
                                                                                               Spoofing is useful in routing environments such as DDR, in
                                                                                               which a circuit-switched link is taken down when there is no
                                                                                               traffic to be sent across it in order to save toll charges. (2)
                                                                                               The act of a packet illegally claiming to be from an address
                                                                                               from which it was not actually sent. Spoofing is designed to
                                                                                               foil network security mechanisms such as filters and access
                                                                                               lists.
SPP                                         Sequenced Packet Protocol                          Provides reliable, connection-based, flow-controlled packet
                                                                                               transmission on behalf of client processes. Part of the XNS
                                                                                               protocol suite.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                    Page 134 of 150

                 Term                                           Description                                             Definition
SQE                                         Signal Quality Error                               Transmission sent by a transceiver back to the controller to
                                                                                               let the controller know whether the collision circuitry is
                                                                                               functional.
SQL                                         Structured Query Language
SR/TLB                                      Source-Route Translational Bridging                Method of bridging where source-route stations can
                                                                                               communicate with transparent bridge stations with the help
                                                                                               of an intermediate bridge that translates between the two
                                                                                               bridge protocols.
SRAM                                                                                           Type of RAM that retains its contents for as long as power is
                                                                                               supplied. SRAM does not require constant refreshing, like
                                                                                               DRAM.
SRB                                         Source-Route Bridging                              Method of bridging originated by IBM and popular in Token
                                                                                               Ring networks. In an SRB network, the entire route to a
                                                                                               destination is predetermined, in real time, prior to the
                                                                                               sending of data to the destination.
SRT                                         Source-Route Transparent Bridging                  IBM bridging scheme that merges the two most prevalent
                                                                                               bridging strategies: SRB and transparent bridging. SRT
                                                                                               employs both technologies in one device to satisfy the
                                                                                               needs of all ENs. No translation between bridging protocols
                                                                                               is necessary.
SS7                                         Signalling System 7                                The industry standard that lets telephone company
                                                                                               switches, database servers, other equipment and switching
                                                                                               software pass commands and data for advanced network
                                                                                               services. (A protocol that uses out-of-band signalling to give
                                                                                               the user greater control of high-speed digital data links.)
SSCS                                        Service Specific Convergence Sublayer
SSID                                        Service Set Identifier                             Wireless network name.
SSL                                         Secure Socket Layer                                Encryption technology for the Web used to provide secure
                                                                                               transactions such as the transmission of credit card
                                                                                               numbers for e-commerce.
SSP                                         Service Switching Point                            A switch that can recognise IN calls and route and connect
                                                                                               them under the direction of an SCP.
SSSO                                        Specialised Satellite Services Operator


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                      Page 135 of 150

                 Term                                          Description                                             Definition
SST                                         Spread Spectrum Technology                         This technique sends a message as a series of computer
                                                                                               codes. However, since the signal is stretched out over a
                                                                                               broad frequency band, the receiver only needs to receive a
                                                                                               part of the transmitted signal to reconstruct the original
                                                                                               message.
STM                                         Synchronous Transfer Mode                          B-ISDN communications method that transmits a group of
                                                                                               different data streams synchronized to a single reference
                                                                                               clock.
STM -1                                      Synchronous Transport Module level 1               One of a number of SDH formats that specifies the frame
                                                                                               structure for the 155.52-Mbps lines used to carry ATM cells.
STP                                         Shielded Twisted Pair                              Cable type
STPs                                        Signal Transfer Points
STS-n                                       Synchronous Transport Signal                       Module, Sonet hierarchy types
Subarea                                                                                        Portion of an SNA network that consists of a subarea node
                                                                                               and any attached links and peripheral nodes.
Subarea Node                                                                                   SNA communication controller or host that handles
                                                                                               complete network addresses.
Subnetwork                                                                                     In IP networks, a network sharing a particular subnet
                                                                                               address. Subnetworks are networks arbitrarily segmented
                                                                                               by a network administrator in order to provide a multilevel,
                                                                                               hierarchical routing structure while shielding the subnetwork
                                                                                               from the addressing complexity of attached networks.
                                                                                               Sometimes called a subnet. (2) In OSI networks, a
                                                                                               collection of ESs and ISs under the control of a single
                                                                                               administrative domain and using a single network access
                                                                                               protocol.
SuperNOS                                                                                       A single microkernal operating system that blends NetWare
                                                                                               and UnixWare.
SVC                                         Switched Virtual Circuit                           A connection in a connection-oriented network which is
                                                                                               established dynamically, rather than through network
                                                                                               configuration. An SVC is set up through a protocol which
                                                                                               operates between a switch and an end station, and between
                                                                                               switches.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                         Page 136 of 150

                   Term                                       Description                                               Definition
T1                                                                                             Trunk Type One, a digital transmission channel that carries
                                                                                               data at the 1.544 MBps rate (DS -1 level); in a digital service
                                                                                               it is used primarily for short-haul links. A dedicated T1 can
                                                                                               support as many as (130) IP voice calls vs. 24 simultaneous
                                                                                               calls as in today's carrier networks.
T3                                                                                             Digital WAN carrier facility. T3 transmits DS-3-formatted
                                                                                               data at 44.736 Mbps through the telephone switching
                                                                                               network.
TABS                                        Telemetry Asynchronous Block Serial                AT&T polled point-t o-point or multipoint communication
                                                                                               protocol that supports moderate data transfer rates over
                                                                                               intra-office wire pairs.
TAC                                         Terminal Access Controller                         Internet host that accepts terminal connections from dial-up
                                                                                               lines.
TACACS                                      Terminal Access Controller Access Control System   Authentication protocol, developed by the DDN community,
                                                                                               that provides remote access authentication and related
                                                                                               services, such as event logging. User passwords are
                                                                                               administered in a central database rather than in individual
                                                                                               routers, providing an easily scalable network security
                                                                                               solution.
TACS                                        Total Access Communications System                 An analog cellular phone technology. Used in the United
                                                                                               Kingdom and Italy.
Tag Switching                                                                                  High-performance, packet-forwarding technology that
                                                                                               integrates network layer (Layer 3) routing and data link layer
                                                                                               (Layer 2) switching and provides scalable, high-speed
                                                                                               switching in the network core. Tag switching is based on the
                                                                                               concept of label swapping, in which packets or cells are
                                                                                               assigned short, fixed-length labels that tell switching nodes
                                                                                               how data should be forwarded.
Tagged Traffic                                                                                 ATM cells that have their CLP bit set to 1. If the network is
                                                                                               congested, tagged traffic can be dropped to ensure delivery
                                                                                               of higher-priority traffic.
Tandem Switching                                                                               Dynamic switching of voice calls between VoFR, VoATM, or
                                                                                               VoHDLC PVCs and subchannels; also called tandeming.
                                                                                               Tandem switching is often encountered in multi-hop VoFR
                                                                                               call connection paths.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 137 of 150

                 Term                                          Description                                              Definition
TAT-12                                                                                         A Trans-Atlantic undersea fiber optic cable system.
TAT-8                                                                                          The first transoceanic fiber optic cable that was installed in
                                                                                               1988.
TAT-9                                                                                          A Transatlantic fiber optic cable linking the United States
                                                                                               with both the United Kingdom and France. Associated with
                                                                                               TAT G-1. Both TAT-9 and TAT G-1 are mutually restoring,
                                                                                               meaning they will serve as back-ups to each other.
TATG-1                                                                                         The first high-speed Trans-Atlantic fiber optic cable to link
                                                                                               the USA with Germany. Associated with TAT-9.
TAXI 4B/5B                                  Transparent Asynchronous Transmitter/Receiver      Encoding scheme used for FDDI LANs as well as for ATM.
                                            Interface 4-byte/5-byte                            Supports speeds of up to 100 Mbps over multimode fiber.
                                                                                               TAXI is the chipset that generates 4B/5B encoding on
                                                                                               multimode fiber.
T-BGA                                       Tape-automated bonding Ball Grid Array package
TC                                          Transmission Convergence                           Sublayer of the ATM physical layer that transforms the flow
                                                                                               of cells into a steady flow of bits for transmission over the
                                                                                               physical medium. Part of layer 1 of B-ISDN
TCAP                                        Transaction Capabilities Application Part
TCC                                         Terminating Call Control
TCL Interface                               Tool Command Line Interface
TCP/IP                                      Transmission Control Protocol/Internet Protocol    A set of communications protocols developed by the U.S.
                                                                                               Department of Defense, now considered a de facto
                                                                                               standard for local area networks.
TD-CDMA                                     Time Division Code Division Multiple Access
TDD                                         Time Division Duplex
TDM                                         Time Division Multiplexing                         A method of multiplexing in which multiple information
                                                                                               streams "take turns" with a single communications channel.
                                                                                               Each stream is allocated a specific percentage of the
                                                                                               common channel.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 138 of 150

                 Term                                          Description                                              Definition
TDMA                                        Time Division Multiple Access                      One of several technologies used to separate multiple
                                                                                               conversation transmissions over a finite frequency allocation
                                                                                               of through-the-air bandwidth. Allocates a discrete amount of
                                                                                               frequency bandwidth to each user, to permit many
                                                                                               simultaneous conversations. However, each caller is
                                                                                               assigned a specific timeslot for transmission. See also Code
                                                                                               Division Multiple Access (CDMA).
TDR                                         Time Domain Reflectometer                          Device capable of sending signals through a network
                                                                                               medium to check cable continuity and other attributes.
                                                                                               TDRs are used to find physical layer network problems.
TE                                          Terminal Equipment                                 Any ISDN-compatible device that can be attached to the
                                                                                               network, such as a telephone, fax, or computer.
TEI                                         Terminal Endpoint Identifier                       Field in the LAPD address that identifies a device on an
                                                                                               ISDN interface.
Telco                                       Telephone Company
Telematics                                                                                     A wireless communications system designed for the
                                                                                               collection and dissemination of data. Applications include
                                                                                               vehicle-based electronic systems: mobile telephony, vehicle
                                                                                               tracking and positioning, on-line navigation and information
                                                                                               services and emergency assistance. Static applications
                                                                                               include stock control (automatic ordering), and monitoring of
                                                                                               utilities meters.
Telemetry                                                                                      Capability of transmitting or retrieving data over long
                                                                                               distance communication links, such as satellite or
                                                                                               telephone.
Telephony                                                                                      Science of converting sound to electrical signals and
                                                                                               transmitting it between widely removed points.
Telescript                                                                                     Intelligent agent technology developed by General Magic
                                                                                               Inc.
Telnet                                                                                         Standard terminal emulation protocol in the TCP/IP protocol
                                                                                               stack. Telnet is used for remote terminal connection,
                                                                                               enabling users to log in to remote systems and use
                                                                                               resources as if they were connected to a local system.
Terabit                                                                                        One trillion bits.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                     Page 139 of 150

                  Term                                            Description                                          Definition
TERENA                                      Trans -European Research and Education             Organization that promotes information and
                                            Networking Association                             telecommunications technologies development in Europe.
                                                                                               Formed by the merger of EARN and RARE.
Terminal Server                                                                                Communications processor that connects asynchronous
                                                                                               devices such as terminals, printers, hosts, and modems to
                                                                                               any LAN or WAN that uses TCP/IP, X.25, or LAT protocols.
                                                                                               Terminal servers provide the internetwork intelligence that is
                                                                                               not available in the connected devices.
TFTP                                        Trivial File Transfer Protocol                     A simplified version of FTP that transfers files but does not
                                                                                               provide password protection or user-directory capability. It is
                                                                                               associated with the TCP/IP family of protocol. TFTP
                                                                                               depends on the connectionless datagram delivery service,
                                                                                               UDP
THEnet                                      Texas Higher Education Network                     Regional network comprising over 60 academic and
                                                                                               research institutions in the Texas (United States) area.
Thinnet                                                                                        Term used to define a thinner, less expensive version of the
                                                                                               cable specified in the IEEE 802.3 10Base2 standard.
Throughput                                                                                     The actual speed of a network.
TIA                                         Telecommunications Industries Association          The group responsible for setting telecommunications
                                                                                               standards in the United States.
TIC                                         Token Ring Interface Coupler                       Controller through which an FEP connects to a Token Ring.
TID                                         Terminal Identifier
Timeout                                                                                        Event that occurs when one network device expects to hear
                                                                                               from another network device within a specified period of
                                                                                               time, but does not. The resulting timeout usually results in a
                                                                                               retransmission of information or the dissolving of the
                                                                                               session between the two devices.
TIOS                                        Transpath Input and Output Subsystem
TIRKS                                       Trunk Information Record Keeping System            Bellcore OSS that provides record keeping for interoffice
                                                                                               trunk facilities.
TLAN                                        Transparent Local Area Network




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                         Page 140 of 150

                  Term                                        Description                                               Definition
TLS                                         Transport Level Security                           TLS provides for mutual authentication, integrity-protected
                                                                                               negotiation and key exchange between two endpoints.
TMN                                         Telecommunication Management Network               ITU -T generic model for transporting and processing
                                                                                               OAM&P information for a telecommunications network.
Token-ring                                                                                     Refers to a generic type of LAN architecture. The token-ring
                                                                                               concept involves a data signal, or token, that passes around
                                                                                               a ring configuration from station to station, with no central
                                                                                               control element.
TOP                                         Technical Office Protocol                          OSI-based architecture developed for office
                                                                                               communications.
Topology                                                                                       Describes how a network is structured.
ToS                                         Type of Service
TR VLAN                                     Token Ring Virtual LAN
Traceroute                                                                                     A superset of PING used to evaluate the hops taken from
                                                                                               one end of a link to the other.
Traffic Profile                                                                                Set of CoS attribute values assigned to a given port on an
                                                                                               ATM switch. The profile affects numerous parameters for
                                                                                               data transmitted from the port including rate, cell drop
                                                                                               eligibility, transmit priority, and inactivity timer.
Traffic Shaping                                                                                Shaping of the cell stream to improve the load of an ATM
                                                                                               line. (2) Use of queues to limit surges that can congest a
                                                                                               network. Data is buffered and then sent into the network in
                                                                                               regulated amounts to ensure that the traffic will fit within the
                                                                                               promised traffic envelope for the particular connection.
                                                                                               Traffic shaping is used in ATM, Frame Relay, and other
                                                                                               types of networks. Also known as metering, shaping, and
                                                                                               smoothing.
Tri-Band                                                                                       Specific to handsets, a tri-band cellular phone will operate
                                                                                               on three different frequencies, depending on the available
                                                                                               network. Outside America, the GSM frequencies used are
                                                                                               900MHz and 1800MHz. 'American GSM', or PCS, operates
                                                                                               at 1900MHz. The introduction of tri-band phones is a further
                                                                                               step towards true worldwide roaming.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                     Page 141 of 150

                 Term                                            Description                                            Definition
TRISL                                       Token Ring Inter-Switch Link
TRUNK                                                                                          Transport facility connecting two switch entities (typically
                                                                                               called long haul transport).
TSAPI                                       Telephony Services Applications Programming
                                            Interface.
TSF                                         Telephone Service Factor
TSI                                         Transmitting Subscriber Information                Frame that can be sent by the caller with the caller's
                                                                                               telephone number that can be used to screen calls.
TSL                                         Trans -Soviet Line                                 Formerly Trans-Siberian Line.
TSP                                         Tag-Switched Path
TTL                                         Time-To-Live                                       An IETF specification that calls for a minimum default value
                                                                                               of 64 hops before a data packet expires.
TTPS                                        Trusted Third-Party Services
TU                                          Tributary Unit                                     Tributary Unit, virtual container in SDH in combination with
                                                                                               its pointer
TUD                                         Trunk Up-Down                                      Protocol used in ATM networks that monitors trunks and
                                                                                               detects when one goes down or comes up. ATM switches
                                                                                               send regular test messages from each trunk port to test
                                                                                               trunk line quality. If a trunk misses a given number of these
                                                                                               messages, TUD declares the trunk down. When a trunk
                                                                                               comes back up, TUD recognizes that the trunk is up,
                                                                                               declares the trunk up, and returns it to service.
TUG                                         Tributary Unit Group                               Additional TU-1s
TULIP                                       TCP and UDP over Lightweight IP                    Proposed protocol for running TCP and UDP applications
                                                                                               over ATM.
TUNIP                                       TCP and UDP over Nonexistent IP                    Proposed protocol for running TCP and UPD applications
                                                                                               over ATM.
Turret Systems                                                                                 Communications switchboards used by the financial
                                                                                               community. They have phones, speed-dial buttons, and
                                                                                               monitors.
TVR                                         Teletel Vitesse Rapide                             A 9.6-kbps videotex service to handle low-resolution photos.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                     Page 142 of 150

                 Term                                            Description                                            Definition
Twisted Pair                                                                                   Relatively low-speed transmission medium consisting of two
                                                                                               insulated wires arranged in a regular spiral pattern. The
                                                                                               wires can be shielded or unshielded. Twisted pair is
                                                                                               common in telephony applications and is increasingly
                                                                                               common in data networks.
TX                                                                                             Number Transceive Slots
U Interface                                                                                    A physical interface in an ISDN Basic Rate service which
                                                                                               uses a single copper pair.
UART                                        Universal Asynchronous Receiver/Transmitter        Integrated circuit, attached to the parallel bus of a computer,
                                                                                               used for serial communications. The UART translates
                                                                                               between serial and parallel signals, provides transmission
                                                                                               clocking, and buffers data sent to or from the computer.
UASs                                        Unavailable seconds                                Count of seconds for which the monitored entity is
                                                                                               unavailable.
UBR                                         Unspecified Bit Rate                               A form of ATM transmission in which an information stream
                                                                                               is supported on whatever bandwidth is available after other
                                                                                               connection types have been satisfied. No congestion control
                                                                                               is provided. UBR is commonly used to support information
                                                                                               streams originating in LAN switches with ATM uplinks.
UCM                                         Universal Call Model
UDLP                                        UniDirectional Link Protocol                       Protocol used by inexpensive, receive-only antennas to
                                                                                               receive data via satellite.
UDP                                         User Datagram Protocol                             A transport-layer protocol that provides connectionless
                                                                                               service without packet acknowledgment.
UDSL                                        Unidirectional DSL                                 Is a proposal from a European company. It's a unidirectional
                                                                                               version of HDSL.
U-DSL                                       U Interface - Digital Subscriber Loop
UKERNA                                      UK Education and Research Networking Association
UL                                                                                             Transmission direction from the customer toward the central
                                                                                               facility.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                        Page 143 of 150

                    Term                                      Description                                              Definition
U-Law                                                                                          An International Telecommunication Union-
                                                                                               Telecommunication Standardization Sector (ITU-T)
                                                                                               standard used for sampling data by means of Pulse Coded
                                                                                               Modulation (PCM). U-Law is most commonly used in North
                                                                                               America and Japan.
ULP                                         Upper-Layer Protocol                               Protocol that operates at a higher layer in the OSI reference
                                                                                               model, relative to other layers. ULP is sometimes used to
                                                                                               refer to the next-highest protocol (relative to a particular
                                                                                               protocol) in a protocol stack.
U-MSC                                       UMTS Mobile Switching Centre
UMTS                                        Universal Mobile Telecommunications System
Unbalanced Configuration                                                                       HDLC configuration with one primary station and multiple
                                                                                               secondary stations.
UNI                                         User-to-Network Interface                          The reference point where the protocols for compatibility
                                                                                               between customer premises equipment (CPE) and a carrier
                                                                                               network must be defined. A UNI specification defines in
                                                                                               detail the Layer 1 and Layer 2 and perhaps Layer 3
                                                                                               protocols which are required for CPE and carrier equipment
                                                                                               to interoperate.
Unicast Network                                                                                A network in which a router sends packets to one user at a
                                                                                               time.
Unified Messaging                                                                              Provides an individual user access, through their mobile
                                                                                               terminal, to all the recognised messaging formats including
                                                                                               voice mail, facsimile, pager, SMS and email.
Uninsured Traffic                                                                              Traffic within the excess rate (the difference between the
                                                                                               insured rate and maximum rate) for an ATM VCC. This
                                                                                               traffic can be dropped by the network if congestion occurs.
Unipolar                                                                                       A signal stream in which all one bits are the same voltage
                                                                                               polarity. Zero bits normally are zero volts.
Unity Gain                                                                                     In broadband networks, the balance between signal loss
                                                                                               and signal gain through amplifiers.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                     Page 144 of 150

                 Term                                         Description                                               Definition
UNIX                                                                                           A multiuser, multitasking operating system originally
                                                                                               developed by AT&T Bell Labs that runs on a wide variety of
                                                                                               computer systems.
UNMA                                        Unified Network Management Architecture
Upstream                                                                                       Set of frequencies used to send data from a subscriber to
                                                                                               the headend.
UPT                                         Universal Personal Telecommunications              A relatively advanced IN system.
URL                                         Universal Resource Locator                         A path that takes you directly to the desired site on the
                                                                                               World Wide Web; also known as an internet address.
USB                                         Universal Serial Bus
USENET                                                                                         Initiated in 1979, one of the oldest and largest cooperative
                                                                                               networks, with over 10,000 hosts and a quarter of a million
                                                                                               users. Its primary service is a distributed conferencing
                                                                                               service called news.
U-SIM                                       UMTS Subscriber Identity Module
USO                                         Universal Service Obligation
USSD                                        Unstructured Supplementary Service Data            A method of transmitting messages via the GSM network in
                                                                                               an interactive, open session environment. It is GSM based,
                                                                                               therefore it works on all existing GSM mobile phones. It is
                                                                                               also supported in SIM Application toolkit and WAP.
USTA                                        United States Telephone Association
UTOPIA                                      Universal Test & Operation PHY Interface for ATM
UTP                                         Unshielded Twisted Pair                            A cable medium with one or more pairs of twisted insulated
                                                                                               copper conductors bound in a single plastic sheath. Now
                                                                                               becoming the most common method of bringing telephone
                                                                                               and data to the desktop.
UTP Cable                                   Unshielded Twisted Pair Cable                      Two paired wires with wire twisted two or more times per
                                                                                               inch to help cancel out noise.
UTP-n                                       Unshielded Twisted Pair of category n
UTRA                                        UMTS Terrestrial Radio Access



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                     Page 145 of 150

                 Term                                           Description                                            Definition
UTRAN                                       UMTS Terrestrial Radio Access Network
UUCP                                        UNIX-to-UNIX Copy Program                          Protocol stack used for point-to-point communication
                                                                                               between UNIX systems.
Uudecode                                    UNIX-to-UNIX Decode                                Method of decoding ASCII files that were encoded using
                                                                                               uuencode.
Uuencode                                    UNIX-to-UNIX Encoding                              Method of converting binary files to ASCII so that they can
                                                                                               be sent over the Internet via e-mail. The name comes from
                                                                                               its use by the UNIX operating system's uuencode
                                                                                               command.
UUI                                         User-to-User Indentification                       A field within ISDN protocol which can provide end-to-end
                                                                                               information exchange (telephone number, credit card
                                                                                               number, login ID, etc.)
UVM                                         Universal Voice Module
UVM-C                                       Universal Voice Module-Channelized
UVM-U                                       Universal Voice Module-Unchannelized
UWB                                         Ultra Wide Band
V.110                                                                                          A rate adaption standard, based on fixed frames, that
                                                                                               subdivides the ISDN channel so that it can carry one lower-
                                                                                               speed data channel.
VAD                                         Voice Activity Detection                           When enabled on voice port or a dial peer, silence is not
                                                                                               transmitted over the network, only audible speech. When
                                                                                               VAD is enabled, the sound quality is slightly degraded, but
                                                                                               the connection monopolizes much less bandwidth.
VAN                                         Value-Added Network
VANS                                        Value Added Network Services
VAR                                         Value-Added Reseller
VB                                          Virtual Bandwidth                                  Channel capacity calculated to allow for the over
                                                                                               subscription of channel usage.
VBI                                         Vertical Blanking Intervals




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                   Telecom / IS Glossary                                                      Page 146 of 150

                 Term                                           Description                                             Definition
VBR                                         Variable Bit Rate                                  QoS class defined by the ATM Forum for ATM networks.
                                                                                               VBR is subdivided into a real time (RT) class and non-real
                                                                                               time (NRT) class. VBR (RT) is used for connections in
                                                                                               which there is a fixed timing relationship between samples.
                                                                                               VBR (NRT) is used for connections in which there is no
                                                                                               fixed timing relationship between samples, but that still need
                                                                                               a guaranteed QoS.
VC                                          Virtual Circuit                                    A link that behaves like a dedicated point-to-point line or a
                                                                                               system that delivers packets in sequence, as would happen
                                                                                               on an actual point-to-point network.
VCC                                         Virtual Channel Connection                         Logical circuit, made up of VCLs, that carries data between
                                                                                               two end points in an ATM network. Sometimes called a
                                                                                               "virtual circuit connection."
VCD                                         Virtual Circuit Descriptor
VCI                                         Virtual Channel Identifier                         16-bit field in the header of an ATM cell. The VCI, together
                                                                                               with the VPI, is used to identify the next destination of a cell
                                                                                               as it passes through a series of ATM switches on its way to
                                                                                               its destination. ATM switches use the VPI/VCI fields to
                                                                                               identify the next network VCL that a cell needs to transit on
                                                                                               its way to its final destination. The function of the VCI is
                                                                                               similar to that of the DLCI in Frame Relay. Logical channel
                                                                                               number in B-ISDN, part of cell header
VCL                                         Virtual Channel Link                               Connection between two ATM devices. A VCC is made up
                                                                                               of one or more VCLs.
VC-n                                        Virtual Container                                  E.g., STM-1 uses VC-4 container
VDSL                                        Very High Bit Rate Digital Subscriber Line         An assymetric DSL technology that offers about eight times
                                                                                               the performance of ADSL. The downside is that it requires a
                                                                                               fiber-optic line from the central office (CO) to the
                                                                                               subscriber's neighborhood. Because infrastructure changes
                                                                                               are required in the local loop, VDSL is considered a
                                                                                               specialized and long-term technology.
VDT                                         Video Display Terminal
VERONICA                                    Very Easy Rodent Oriented Netwide Index to         Gopher utility that effectively searches Gopher services
                                            Computer Archives                                  based on a user's list of keywords.


     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                Telecom / IS Glossary                                                        Page 147 of 150

                  Term                                         Description                                              Definition
VF                                          Variance Factor                                    One of three link attributes exchanged using PTSPs to
                                                                                               determine the available resources of an ATM network. VF is
                                                                                               a relative measure of CRM normalized by the variance of
                                                                                               the aggregate cell rate on the link.
Virtual Ring                                                                                   Entity in an SRB network that logically connects two or more
                                                                                               physical rings together either locally or remotely. The
                                                                                               concept of virtual rings can be expanded across router
                                                                                               boundaries.
VLAN                                        Virtual Local Area Network                         In a a switched network, a logical collection of devices, such
                                                                                               as all the workstations and servers with a particular IP
                                                                                               subnet address, which are grouped into a broadcast
                                                                                               domain.
VLI                                         Virtual LAN Internetwork                           Internetwork composed of VLANs.
VLR                                         Visitor Location Register                          A database that stores the necessary information to handle
                                                                                               calls while mobile subscrbers are visiting outside their home
                                                                                               areas.
VLSI                                        Very Large Systems Integration
VLSM                                        Variable-Length Subnet Mask                        Ability to specify a different subnet mask for the same
                                                                                               network number on different subnets. VLSM can help
                                                                                               optimize available address space.
VMAC                                        Virtual Media Access Control
VNS                                         Virtual Network Service
VoATM                                       Voice Over ATM                                     Voice over ATM enables a router to carry voice traffic (for
                                                                                               example, telephone calls and faxes) over an ATM network.
                                                                                               When sending voice traffic over ATM, the voice traffic is
                                                                                               encapsulated using a special AAL5 encapsulation for
                                                                                               multiplexed voice.
VoATM Dial Peer                                                                                Dial peer connected via an ATM network. VoATM peers
                                                                                               point to specific VoATM devices.
VOD                                         Video-On-Demand
VoFR                                        Voice-over-Frame Relay                             A term applied to a set of facilities for managing the delivery
                                                                                               of voice information using frame relay.



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                  Telecom / IS Glossary                                                       Page 148 of 150

                 Term                                           Description                                             Definition
VoHDLC                                      Voice Over HDLC                                    Voice over HDLC enables a router to carry live voice traffic
                                                                                               (for example, telephone calls and faxes) back-to-back to a
                                                                                               second router over a serial line.
Voiceband                                                                                      A transmission channel with a nominal 4-kHz bandwidth
                                                                                               suitable for voice transmission.
VoIP                                        Voice over Internet Protocol                       A category of hardware and software that allows people to
                                                                                               use the Internet to make telephone calls. Currently, VoIP
                                                                                               does not offer the same quality of telephone service as
                                                                                               direct telephone connections. Also known as Internet
                                                                                               telephony, and Voice over the Internet.
VP                                          Virtual Path                                       Contains virtual circuits that are to be switched together to a
                                                                                               common destination such as an inter-exchange carrier.
VPDN                                        Virtual Private Dial-up Network
VPI                                         Virtual Path Identifier                             8-bit field in the header of an ATM cell. The VPI, together
                                                                                               with the VCI, is used to identify the next destination of a cell
                                                                                               as it passes through a series of ATM switches on its way to
                                                                                               its destination. ATM switches use the VPI/VCI fields to
                                                                                               identify the next VCL that a cell needs to transit on its way
                                                                                               to its final destination. The function of the VPI is similar to
                                                                                               that of the DLCI in Frame Relay.
VPL                                         Virtual Path Link                                  Within a virtual path, a group of unidirectional VCLs with the
                                                                                               same end points. Grouping VCLs into VPLs reduces the
                                                                                               number of connections to be managed, thereby decreasing
                                                                                               network control overhead and cost. A VPC is made up of
                                                                                               one or more VPLs.
VPN                                         Virtual Private Network                            A restricted network that uses pubic wires to connect nodes.
                                                                                               A VPN provides a way to encapsulate, or "tunnel", private
                                                                                               data cheaply, reliably, and securely through a public
                                                                                               network, usually the Internet.
VRML                                        Virtual Reality Modeling Language                  Specification for displaying 3-dimensional objects on the
                                                                                               World Wide Web.
VSAT                                        Very Small Aperture Terminal
VSI                                         Virtual Switch Interface



     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                                 Telecom / IS Glossary                                                       Page 149 of 150

                 Term                                          Description                                             Definition
VTAM                                        Virtual Telecommunications Access Method           Set of programs that control communication between LUs.
                                                                                               VTAM controls data transmission between channel-attached
                                                                                               devices and performs routing functions.
VT-n                                        Virtual Tributary Level n                          SONET format for mapping a lower-rate signal into a
                                                                                               SONET payload. For example, VT-1.5 is used to transport a
                                                                                               DS-1 signal.
VTP                                         Virtual Terminal Protocol                          An application for establishing a virtual terminal connection
                                                                                               across a network.
WAIS                                        Wide Area Information Server                       Distributed database protocol developed to search for
                                                                                               information over a network. WAIS supports full-text
                                                                                               databases, which allow an entire document to be searched
                                                                                               for a match (as opposed to other technologies that only
                                                                                               allow an index of key words to be searched).
WAN                                         Wide Area Network                                  A network which covers a larger geographical area than a
                                                                                               single end user location, and in which telecommunications
                                                                                               links are implemented, normally leased from service
                                                                                               provider(s).
WAP                                         Wireless Application Protocol                      Standard to enable mobile device users to view web pages
                                                                                               easily. It is intended to simplify wireless access to e-mail
                                                                                               and enable web transactions to be carried out.
W-CDMA                                      Wideband Code Division Multiplex Access
W-DCS                                       Wideband Digital Crossconnect System               SONET DCS capable of crossconnecting DS-1 and VT1.5
                                                                                               signals.
WDM                                         Wavelength Division Multiplexing                   Optical transmission technique in which two or more
                                                                                               wavelengths (each carrying its own information), are
                                                                                               combined for transmission over a single optical fiber. At the
                                                                                               receiving end, the wavelengths are separated and directed
                                                                                               to separate receivers.




     This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
 While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.
                                                               Telecom / IS Glossary                                                       Page 150 of 150

                Term                                         Description                                              Definition
WEB HOSTING                                                                                   A service designed to allow customers to establish a
                                                                                              presence on the web without the overhead normally
                                                                                              associated with maintaining their own server and network
                                                                                              connection. By placing their information on a provider's
                                                                                              server, customers receive all the benefits of a high speed
                                                                                              network connection, high performance server, round the
                                                                                              clock monitoring and emergency facilities at a fraction of
                                                                                              what it would cost them to acquire these resources on their
                                                                                              own.
WECA                                       Wireless Ethernet Compatibility Alliance
WEP                                        Wired Equivalent Privacy                           WEP data encryption is defined by the 802.11 standard to
                                                                                              prevent (i) access to the network by "intruders" using similar
                                                                                              wireless LAN equipment and (ii) capture of wireless LAN
                                                                                              traffic through eavesdropping. WEP allows the administrator
                                                                                              to define a set of respective "Keys" for each wireless
                                                                                              network user based on a "Key String" passed through the
                                                                                              WEP encryption algorithm. Access is denied by anyone who
                                                                                              does not have an assigned key.
WFQ                                        Weighted Fair Queuing                              Congestion management algorithm that identifies
                                                                                              conversations (in the form of traffic streams), separates
                                                                                              packets that belong to each conversation, and ensures that
                                                                                              capacity is shared fairly between these individual
                                                                                              conversations. WFQ is an automatic way of stabilizing
                                                                                              network behavior during congestion and results in increased
                                                                                              performance and reduced retransmission.




    This selected list of terms has been cumulated from a number of publicly available sources and is intended as a complementary reference only.
While every attempt is made to ensure the accuracy of the definitions, Comm-sult Worldwide declines any responsibility with respect to any use thereof.

				
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