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					Guide to Networking Essentials, Fifth Edition   3-1




Chapter 3
Networking Media

At a Glance

Instructor’s Manual Table of Contents
   Overview

   Objectives

   Teaching Tips

   Quick Quizzes

   Class Discussion Topics

   Additional Projects

   Additional Resources

   Key Terms

   Technical Notes for Hands-On Projects
Guide to Networking Essentials, Fifth Edition                                           3-2


Lecture Notes

Overview
        Chapter 3 offers an introduction to networking media. Students learn about different
        cabling characteristics applied to physical media and about the primary cable types used
        in networking. They also learn about the components in a structured cabling installation
        and about wireless transmission techniques used in LANs and WANs.


Objectives
       Identify general cabling characteristics applied to physical media
       Describe the primary cable types used in networking
       Identify the components in a structured cabling installation
       Describe wireless transmission techniques used in LANs and WANs


Teaching Tips
Network Cabling: Tangible Physical Media
    1. Introduce the role of network media. Note that because all media must support the basic
       tasks of sending and receiving signals, you can view all networking media as doing the
       same thing; only the methods vary.

    2. Explain that each type of media has a unique design and usage, with associated cost,
       performance, and installation criteria.

General Cable Characteristics

    1. Briefly describe each of the following characteristics that apply to network cabling:
           a. Bandwidth rating
           b. Maximum segment length
           c. Maximum number of segments per internetwork
           d. Maximum number of devices per segment
           e. Interference susceptibility
           f. Connection hardware
           g. Cable grade
           h. Bend radius
           i. Material costs
           j. Installation costs

Baseband and Broadband Transmission

    1. Explain the difference between baseband and broadband transmission. Stress the
       differences between using repeaters and amplifiers to deal with signal ―attenuation‖.
Guide to Networking Essentials, Fifth Edition                                              3-3

    2. Simulation 3-1 helps students learn the difference between baseband and broadband
       communications.

The Importance of Bandwidth

    1. Describe the importance of bandwidth in computer networks.


Primary Cable Types
    1. Explain that all forms of cabling are similar, in that they provide a medium across
       which network information can travel in the form of a physical signal, whether it’s a
       type of electrical transmission or some sequence of light pulses.

    2. List the three primary cable types available.

Coaxial Cable

    1. Use Figure 3-1 to describe the components of a coaxial cable. Stress that this type of
       cable used to be the predominant form of network cable.


                 Stress that coaxial cable in LAN installations is obsolete. The majority of coaxial
                 cable used today is for carrying broadband signals for cable TV or from a home
Teaching         satellite dish to the satellite receiver. The information in this section about the
Tip              properties of coax refers to all types of coaxial cabling. Information on the use of
                 coaxial cable for a LAN is offered for historical purposes only. Keep in mind that
                 this type of cabling should not be used in new LAN installations.


    2. Note that coaxial cable is less susceptible to interference and attenuation than twisted-
       pair, but more susceptible than fiber-optic.


Teaching         For more information on coaxial cable, go to
Tip              http://en.wikipedia.org/wiki/Coaxial_cable.


    3. The Use of Coaxial Cable for Ethernet. Describe the role of thicknet and thinnet in
       Ethernet networks. Introduce the terms 10Base5 and 10Base2 and explain how to
       interpret them.

    4. Coaxial Cable in Cable Modem Applications. Note that coaxial cable in LANs has
       become obsolete. Use Figure 3-2 to describe the use of coaxial cable in cable modem
       applications.

    5. Other Coaxial Cable Types. Briefly describe the role of coaxial cable in ARCnet.
Guide to Networking Essentials, Fifth Edition                                             3-4

Twisted-Pair Cable

    1. Use Figure 3-3 to introduce twisted-pair and explain the difference between STP and
       UTP. Don’t forget to introduce the term crosstalk.


Teaching         For more information on twisted-pair cable, go to
Tip              http://en.wikipedia.org/wiki/Twisted_pair.


    2. Unshielded Twisted Pair. Describe the role of UTP in networking. Explain how to
       interpret the term 10BaseT.

    3. UTP Cabling Categories. Briefly describe the characteristics of UTP Categories 1
       through 6. You may introduce the non-standard Category 7 UTP. Note that of these
       categories of UTP cabling, Categories 5, 5e, and 6 are by far the most popular types.
       Note that Category 1 UTP is known as voicegrade, whereas Category 4 UTP is known
       as datagrade.

    4. Shielded Twisted Pair (STP). Describe the role of STP in networking. Note that STP
       enables support of higher bandwidth over longer distances than UTP. Stress that no set
       of standards for STP corresponds to the ANSI/TIA/EIA 568 Standard, yet it’s not
       unusual to find STP cables rated according to those standards.


                 Explain that another type of STP cabling is screened twisted pair (ScTP) or foil
Teaching         twisted pair (FTP). Both use 100 ohm, four-pair cabling, just like UTP. The
Tip              cabling is wrapped in a metal foil or screen. This type of cabling can be used in
                 place of UTP in electrically noisy environments.


    5. Use Figure 3-4 to introduce the RJ-45 and RJ-11 connectors.

    6. Note that typically, twisted-pair systems include the following elements, often in a
       wiring center (briefly describe each):
           a. Distribution racks and modular shelving
           b. Modular patch panels (see Figure 3-6)
           c. Wall plates (see Figure 3-5)
           d. Jack couplers

    7. Use Table 3-1 to summarize the common characteristics of Category 5, 5e, and 6 UTP
       cabling.

    8. Making Twisted Pair Cable Connections. Introduce the term patch cable. Use Figures
       3-7 and 3-8 to describe the TIA/EIA 568A and 568B standards. Don’t forget to
       introduce the term differential signal. Stress that you can use either standard, but you
       must stick to one throughout your network.
Guide to Networking Essentials, Fifth Edition                                             3-5

Fiber-Optic Cable

    1. Explain that fiber-optic cable trades electrical pulses for their optical equivalents, which
       are pulses of light. Note that because no electrical signals ever pass through the cable,
       fiber-optic media is as immune to interference as any medium can get. Stress that this
       characteristic also makes fiber-optic cables highly secure. Don’t forget to introduce the
       term electronic eavesdropping.


Teaching         For more information on optical fiber cable, go to
Tip              http://en.wikipedia.org/wiki/Optical_fiber.


    2. Note that today, commercial implementations of fiber-optic cables at 10 Gbps are in
       use.

    3. Use Figure 3-9 to describe the parts of a fiber-optic cable.

    4. Explain that in any fiber-optic cable, each light-conducting core can pass signals in only
       one direction.

    5. Use Table 3-2 to describe the fiber-optic cable characteristics.

    6. Use Figure 3-10 to briefly describe each of the available fiber-optic connectors. Don’t
       forget to describe the MIC and SMA connectors (not shown in the picture).

    7. Note that installation of fiber-optic networks is somewhat more difficult and time-
       consuming than copper media installation. Stress that because of the falling costs of
       fiber and the inherent advantages of this medium in interference immunity, high
       bandwidth capability, and increased security, fiber-optic cable is being used almost
       exclusively for all network backbone connections.

    8. Briefly describe the difference between single-mode and multimode fiber-optic cables.

Cable Selection Criteria

    1. Briefly describe each of the following criteria to be considered for a network
       installation:
           a. Bandwidth
           b. Budget
           c. Capacity
           d. Environmental considerations
           e. Placement
           f. Span
           g. Local requirement
           h. Existing cable plant

    2. Table 3-3 condenses the most important cabling information for the cable types covered
       so far in this chapter.
Guide to Networking Essentials, Fifth Edition                                             3-6

Quick Quiz 1
    1. What is attenuation?
       Answer: Each type of (networking) cable can transport data only so far before its signal
       begins to weaken beyond where it can be read accurately; this phenomenon is called
       attenuation.

    2. Baseband systems—such as Ethernet—can use special devices called
       ____________________ that receive incoming signals on one cable segment and
       refresh them before retransmitting them on another cable segment.
       Answer: repeaters

    3. For many years, coaxial cable—often called ―____________________‖ for short—was
       the predominant form of network cabling.
       Answer: coax

    4. Why are twisted-pair cables twisted?
       Answer: The most basic form of twisted-pair (TP) wiring consists of one or more pairs
       of insulated strands of copper wire twisted around one another. These twists are
       important because they cause the magnetic fields that form around a conducting wire to
       wrap around one another and improve TP’s resistance to interference. They also limit
       the influence of signals traveling on one wire over another (called crosstalk). In fact, the
       more twists per unit length, the better these characteristics become. It’s safe to say,
       therefore, that more expensive TP wire is usually more twisted than less expensive
       kinds.


Managing and Installing the Cable Plant
    1. Explain that the TIA/EIA developed the document ―568 Commercial Building Wiring
       Standard,‖ which specifies how network media should be installed to maximize
       performance and efficiency. Note that this standard defines what’s referred to as
       structured cabling.

Structured Cabling

    1. Explain the importance of structured cabling. Note that it relies on an extended star
       physical topology.

    2. Stress that structured cabling facilitates troubleshooting as well as network upgrades
       and expansion.
Guide to Networking Essentials, Fifth Edition                                              3-7

    3. Describe each of the six components of a cable plant (according the structured cabling
       standard):

            a. Work Area. Don’t forget to mention that the TIA/EIA 568 standard calls for at
               least one voice and one data outlet on each faceplate in each work area. Explain
               that the connection between a wall jack and the telecommunications closet is
               made with horizontal wiring.

             b. Horizontal Wiring. Stress that acceptable horizontal wiring types include four-
                pair UTP (Category 5e or 6) or two fiber-optic cables.

             c. Telecommunications Closet. Explain that the telecommunications closet (TC)
                provides connectivity to computer equipment in the nearby work area. Note that
                in small installations, the TC can also serve as the entrance facility. Use Figure
                3-11 to describe the relationship and connections between the work area,
                horizontal wiring, and telecommunications closet.

             d. Equipment Rooms. Note that the equipment room can be the main cross-connect
                of backbone cabling for the entire network, or it might serve as the connecting
                point for backbone cabling between buildings.

             e. Backbone Cabling. Note that it can also be called ―vertical cabling‖. Stress that
                it is frequently fiber-optic cable, but can also be UTP. Note that choice of single-
                mode or multimode fiber depends on the distance involved.

             f. Entrance Facilities. Note that the entrance facility can also serve as an
                equipment room and the main cross-connect for all backbone cabling. Explain
                that here is also where a connection to a WAN is made and the point where
                corporate LAN equipment ends and a third-party provider’s equipment and
                cabling begins—also known as the ―demarcation point‖.
Guide to Networking Essentials, Fifth Edition                                          3-8

Quick Quiz 2
    1. What is structured cabling?
       Answer: The TIA/EIA developed the document ―568 Commercial Building Wiring
       Standard,‖ which specifies how network media should be installed to maximize
       performance and efficiency. This standard defines what’s often referred to as structured
       cabling. Structured cabling specifies how cabling should be organized, regardless of the
       type of media or network architectures.

    2. According to the structured cabling standard, the ____________________, as the name
       suggests, is where computer workstations and other user devices are located—in short,
       the place where people work.
       Answer: work area

    3. According to the structured cabling standard, ____________________ runs from the
       work area’s wall jack to the telecommunications closet and is usually terminated at a
       patch panel.
       Answer: horizontal wiring

    4. According to the structured cabling standard, what is the role of backbone cabling?
       Answer: Backbone cabling (or vertical cabling) interconnects TCs and equipment
       rooms. This cabling runs between floors or wings of a building and between buildings
       to carry network traffic destined for devices outside the work area.


Wireless Networking: Intangible Media
    1. Describe the current importance of wireless networks.

    2. Explain that wireless networks are often used with wired networks to interconnect
       geographically dispersed LANs or groups of mobile users with stationary servers and
       resources on a wired LAN. Note that Microsoft calls networks that include both wired
       and wireless components hybrid networks.

The Wireless World

    1. Explain why wireless networks are frequently used (i.e., provide different scenarios in
       which wireless networks are very useful).

    2. Describe some common wireless applications.

    3. Figure 3-12 shows an example of using wireless in a home network.

    4. Students should see Simulation 3-2 to get an idea of how wireless networks operate.
Guide to Networking Essentials, Fifth Edition                                           3-9

Types of Wireless Networks

    1. Briefly describe each of the three main categories of wireless networks: LANs,
       extended LANs, and mobile computing.


Teaching         For more information on wireless LANs, go to
Tip              http://en.wikipedia.org/wiki/Wireless_LAN.


    2. Explain that an easy way to differentiate among these uses is to distinguish in-house
       from carrier-based facilities. Introduce the term communications carrier.

Wireless LAN Components

    1. Describe the role of the different wireless LAN components. Don’t forget to introduce
       the terms antenna, transceiver, and access point.

Wireless LAN Transmission

    1. Provide some background on how wireless LAN transmissions occur. In this part, you
       should talk about ―waves‖, ―electromagnetic spectrum‖, ―Hertz‖, etc.

    2. Explain that the frequency of the waves affects the amount and speed of data
       transmission.

    3. Note that commonly used frequencies for wireless data communications are: radio,
       microwave, and infrared. Briefly describe each of these.

    4. Explain that higher-frequency technologies often use tight-beam broadcasts and require
       a clear line of sight between sender and receiver.

    5. Note that wireless LANs make use of four primary technologies for transmitting and
       receiving data: infrared, laser, narrowband (single-frequency) radio, and spread-
       spectrum radio.

    6. Infrared LAN Technologies. Describe the role of infrared LAN technologies. Explain
       that there are four main kinds of infrared LANs: line of sight networks, reflective
       wireless networks, scatter infrared networks, and broadband optical telepoint networks.
       Don’t forget to introduce the terms virtual docking and IrDA.

    7. Laser-Based LAN Technologies. Describe the role of laser-based LAN technologies.
       Explain that to protect people from injury and avoid excess radiation, laser-based LAN
       devices are subject to many of the same limitations as infrared, but aren’t as susceptible
       to interference from visible light sources.
Guide to Networking Essentials, Fifth Edition                                          3-10

    8. Narrowband Radio LAN Technologies. Introduce narrowband radio. Note that it is also
       called ―single-frequency radio‖. Describe the role of the FCC. Use Table 3-4 to
       describe the characteristics of narrowband wireless LAN technologies. Use Table 3-5 to
       describe the characteristics of high-powered single-frequency radio networks.

    9. Spread-Spectrum LAN Technologies. Briefly explain how spread-spectrum works.
       Don’t forget to introduce the terms frequency hopping and direct-sequence modulation.
       Use Table 3-6 to describe the characteristics of spread-spectrum LANs.

802.11 Wireless Networking

    1. Provide an introduction to the 802.11 standard. Briefly describe the roles of 802.11b,
       802.11g, and 802.11a.


                 For more information on the 802.11 family of standards, go to
Teaching
                 http://grouper.ieee.org/groups/802/11/ and
Tip
                 http://en.wikipedia.org/wiki/IEEE_802.11.


    2. Note that most 802.11 networks incorporate wired Ethernet segments.

    3. Introduce the term hot spot.


                 Note that a newer technology, dubbed ―MIMO‖ for multiple-in, multiple-out, is
Teaching         available in some wireless products. This technology uses multiple antennas that
Tip              boost transfer rates to 108 Mbps and beyond. As you can see, there’s no end in
                 sight for the speed upgrades of wireless LANs.


Teaching
                 For a wealth of information on the 802.11 standards, see www.wi-fiplanet.com.
Tip

Wireless Extended LAN Technologies

    1. Explain that certain kinds of wireless networking equipment extend LANs beyond their
       normal cable-based distance limitations, or provide connectivity across areas where
       cables are not allowed (or able) to traverse. Explain that wireless bridges can connect
       networks up to three miles (4.4 km) apart.

    2. Use Table 3-7 to describe the characteristics of wireless extended LAN technologies.
Guide to Networking Essentials, Fifth Edition                                           3-11


                 Explain that wireless bridges always appear in pairs, and both devices function
                 together as a repeater—whatever comes in on the wired side of one device is
                 transmitted out the wired side of the other. These devices are sometimes called
Teaching
                 ―halfrepeaters,‖ a reference to the frequency ranges they use. Therefore, you
Tip
                 sometimes hear this equipment called ―optical half-repeaters‖ (for laser or
                 infrared versions) or ―radio half-repeaters‖ for their spread-spectrum
                 counterparts.


Wireless MAN: The 802.16 Standard

    1. Provide an introduction to the 802.16 (WiMax) standard.


                 For more information on the 802.16 family of standards, visit
Teaching
                 www.80216news.com/, http://en.wikipedia.org/wiki/802.16, and
Tip
                 http://standards.ieee.org/getieee802/802.16.html.


    2. Fixed WiMax: 802.16-2004. Provide an introduction to the 802.16-2004 (fixed WiMax)
       standard. Note that fixed WiMax can blanket an area up to a mile in radius, compared to
       just a few hundred feet for 802.11.

    3. Mobile WiMax: 802.16e. Provide an introduction to the 802.16e (mobile WiMax)
       standard. Stress that this technology is not yet widely adopted (as opposed to fixed
       WiMax). Stress that fixed WiMax is expected to be the dominant technology for the
       next several years, but mobile WiMax will win out in the end.

Microwave Networking Technologies

    1. Explain that microwave systems deliver higher transmission rates than radio-based
       systems do, but because the frequencies are so high, transmitters and receivers must
       share a common clear line of sight.

    2. Use Table 3-8 to describe the characteristics of terrestrial microwave.

    3. Use Table 3-9 to describe the characteristics of satellite microwave. Don’t forget to
       introduce the term geosynchronous. Note that most organizations can’t fund launching
       satellites, so most satellite microwave systems must lease frequencies on satellites
       operated by global communications carriers.
Guide to Networking Essentials, Fifth Edition                                            3-12


                 Explain that geosynchronous satellites orbit 50,000 km (23,000 miles) above
                 Earth. The distances are great enough to incur measurable transmission delays
Teaching
                 (called ―propagation delays‖) that vary between 0.5 and 5 seconds, depending on
Tip
                 the number of hops (jumps across network segments) between sender and
                 receiver.



Quick Quiz 3
    1. In a wireless LAN, a(n) ____________________ device includes an antenna and a
       transmitter to send and receive wireless traffic, but also connects to the wired side of the
       network.
       Answer: access point

    2. The ____________________ of the wave forms used for communication is measured in
       cycles per second usually expressed as hertz (Hz).
       Answer: frequency

    3. IrDA stands for ____________________.
       Answer: Infrared Device Association

    4. The 1997 ____________________ Wireless Networking Standard is also referred to as
       Wireless Fidelity (Wi-Fi).
       Answer: 802.11
Guide to Networking Essentials, Fifth Edition                                        3-13

Class Discussion Topics
    1. Have any of the students installed a wireless LAN at home? If so, ask them to discuss
       their experiences in class.

    2. How common are wireless networks in your area? Ask students to list businesses and
       institutions that they know have hot spots set up. Do they know what standard (802.11a,
       802.11b or 802.11g) they use? Do they charge for the use of the wireless LAN? If so,
       how much?


Additional Projects
    1. The 802.11 family of standards contains other standards besides those mentioned in this
       book. Ask students to compile a list of the standards in this family, including a brief
       description of each.

    2. There are special considerations that should be taken when installing and manipulating
       fiber-optic cables. Ask students to do some research to find out what these
       considerations are. They should summarize their findings in a written report.


Additional Resources
    1. Coaxial Cable:
       http://en.wikipedia.org/wiki/Coaxial_cable

    2. Twisted Pair:
       http://en.wikipedia.org/wiki/Twisted_pair

    3. Category 5 Cable:
       http://en.wikipedia.org/wiki/Category_5_cable

    4. Category 6 Cable:
       http://en.wikipedia.org/wiki/Category_6_cable

    5. RJ45:
       http://en.wikipedia.org/wiki/RJ-45

    6. Optical Fiber:
       http://en.wikipedia.org/wiki/Optical_fiber

    7. Structured Cabling:
       http://en.wikipedia.org/wiki/Structured_cabling

    8. Welcome to Belkin – Structured Cabling:
       http://catalog.belkin.com/IWCatSectionView.process?Section_Id=201488
Guide to Networking Essentials, Fifth Edition                                      3-14

    9. Wireless LAN:
       http://en.wikipedia.org/wiki/Wireless_LAN

    10. IEEE 802.11:
        http://grouper.ieee.org/groups/802/11/

    11. IEEE 802.11:
        http://en.wikipedia.org/wiki/IEEE_802.11

    12. 802.16 News:
        www.80216news.com/

    13. 802.16:
        http://en.wikipedia.org/wiki/802.16

    14. IEEE 802.16:
        http://standards.ieee.org/getieee802/802.16.html

    15. Wi-Fi Planet:
        www.wi-fiplanet.com/


Key Terms
     10Base2 — A designation for 802.3 Ethernet thin coaxial cable (also called thinnet,
      thinwire, or cheapernet). The 10 indicates a bandwidth of 10 Mbps, the Base indicates
      it’s a baseband transmission technology, and the 2 indicates a maximum segment length
      of 185 meters (originally 200, hence the ―2‖) for this cable type.
     10Base5 — A designation for 802.3 Ethernet thick coaxial cable (also called thicknet or
      thickwire). The 10 indicates a bandwidth of 10 Mbps, the Base indicates it’s a baseband
      transmission technology, and the 5 indicates a maximum segment length of 500 meters
      for this cable type.
     10BaseT — A designation for 802.3 Ethernet twisted-pair cable. The 10 indicates a
      bandwidth of 10 Mbps, the Base indicates it’s a baseband transmission technology, and
      the T indicates that the medium is twisted-pair. (Maximum segment length is around
      100 meters, or 328 feet, but the precise measurement depends on the manufacturer’s
      testing results for the cable.)
     802.11Wireless Networking Standard — An IEEE standard for wireless networking.
      A version of the 802.11 standard appeared late in 1997.
     access point device — The device that bridges wireless networking components and a
      wired network. It moves traffic between the wired and wireless sides as needed.
     American National Standards Institute (ANSI) — The U.S. representative in the
      International Organization for Standardization (ISO), a worldwide standards-making
      body. ANSI creates and publishes standards for networking, communications, and
      programming languages.
     amplifiers — Hardware devices that increase the power of electrical signals to maintain
      their original strength when transmitted across a large network.
Guide to Networking Essentials, Fifth Edition                                        3-15

     analog—The method of signal transmission used on broadband networks. Creating
      analog waveforms from computer-based digital data requires a special device called a
      digital-to-analog (d-to-a) converter; reversing the conversion requires an analog-to-
      digital (a-to-d) converter. Broadband networking equipment must include both kinds of
      devices to work.
     antenna — A tuned electromagnetic device that can send and receive broadcast signals
      at particular frequencies. In wireless networking devices, an antenna is an important
      part of a device’s sending and receiving circuitry.
     attached resource computing network (ARCnet) — A 2.5 Mbps LAN technology
      created by DataPoint Corporation in the late 1970s. ARCnet uses token-based
      networking technology and runs over several kinds of coaxial cable, twisted-pair, and
      fiber-optic cable.
     attenuation — The weakening of a signal as it travels the length of a medium, which
      eventually causes the signal to be unreadable.
     backbone cabling — The part of the cable plant that interconnects telecommunications
      closets and equipment rooms. Backbone cabling runs between floors or wings of a
      building and between buildings to carry network traffic destined for devices outside the
      work area.
     bandwidth — The range of frequencies that a communications medium can carry. For
      baseband networking media, the bandwidth also indicates the theoretical maximum
      amount of data that the medium can transfer. For broadband networking media, the
      bandwidth is measured by the variations that any single carrier frequency can carry,
      minus the analog-to-digital conversion overhead.
     baseband transmission — A technology that uses digital signals sent over a cable
      without modulation. It sends binary values (0s and 1s) as pulses of different voltage
      levels.
     bend radius — For network cabling, the maximum arc that a segment of cable can be
      bent over some unit length (typically, one foot or one meter) without incurring damage.
     broadband optical telepoint networks — An implementation of infrared wireless
      networking that supports broadband services equal to those a cabled network provides.
     broadband transmission — An analog transmission technique that can use multiple
      communication channels simultaneously. Each data channel is represented by
      modulation on a particular frequency band, and sending or receiving equipment must be
      tuned to that band.
     cable modem — A special-purpose networking device that permits a computer to send
      and receive networking signals, primarily for Internet access, by using two data
      channels on a broadband CATV network (one to send outgoing data, the other to
      receive incoming data). Cable modems can support bandwidth up to 1.544 Mbps, but
      upstream traffic (from computer to network) between 100 and 300 Kbps and
      downstream traffic (from network to computer) between 300 and 600 Kbps are more
      typical.
     cable plant — The combination of installed network cables, connectors, patch panels,
      wall jacks, and other media components.
     chips — Fixed-sized elements of data broadcast over a single frequency by using
      direct-sequence modulation. Also see direct-sequence modulation.
     cladding — A nontransparent layer of plastic or glass material inside fiber-optic cable;
      cladding surrounds the inner core of glass or plastic fibers. Cladding provides rigidity,
      strength, and a manageable outer diameter for fiber-optic cables.
Guide to Networking Essentials, Fifth Edition                                        3-16

     coaxial cable — A type of cable that uses a center conductor, wrapped by an insulating
      layer and surrounded by a braided wire mesh and an outer jacket or sheath, to carry
      high-bandwidth signals, such as network traffic or broadcast television frequencies.
      ―Coax‖ is often used as a shortened form of ―coaxial cable.‖
     communications carrier — A company that provides communications services for
      other organizations, such as a local phone company and long-distance telephone
      carriers. Most mobile computing technologies rely on the services of a communications
      carrier to handle wireless traffic from mobile units to a centralized wired network.
     conduit — Plastic or metal pipe laid specifically to provide a protected enclosure for
      cabling of any kind.
     crosstalk — A phenomenon that occurs when two wires lay against each other in
      parallel. Signals traveling down one wire can interfere with signals traveling down the
      other, and vice versa.
     datagrade — A designation for cabling of any kind; datagrade indicates that cabling is
      suitable for transporting digital data. When applied to twisted-pair cabling, ―datagrade‖
      indicates that the cable is suitable for voice or data traffic.
     differential signal — The use of two wires to carry a signal, where one wire carries a
      positive voltage signal and the other carries a negative voltage signal. Differential
      signals help mitigate the effects of noise and crosstalk. Also see electromagnetic
      interference (EMI) and crosstalk.
     direct-sequence modulation — The form of spread-spectrum data transmission that
      breaks data into fixed-length segments called chips, and transmits the data on multiple
      frequencies.
     dual-cable broadband — A broadband technique in which two cables are used; one is
      for transmitting, and one is for receiving.
     electromagnetic interference (EMI) — A form of interference, also referred to as
      ―noise,‖ caused by emissions from external devices, such as transformers or electrical
      motors, that can disrupt network transmissions over an electrical medium.
     electronic eavesdropping — The capability to ―listen‖ to signals passing through a
      communications medium by detecting its emissions. Eavesdropping on many wireless
      networking technologies is especially easy because they broadcast data into the
      atmosphere.
     Electronic Industries Alliance (EIA) — An industry trade group of electronics and
      networking manufacturers that collaborates on standards for wiring, connectors, and
      other common components.
     entrance facility — The location of the cabling and equipment that connects a
      corporate network to a third-party telecommunications provider.
     equipment room — An area that serves as a connection point for backbone cabling
      running between telecommunications closets; also houses servers, routers, switches, and
      other major network equipment.
     extended LANs — Microsoft’s name for the networks resulting from certain wireless
      bridges’ capability to expand the span of a LAN up to 25 miles.
     Federal Communications Commission (FCC) — Among other responsibilities, the
      FCC regulates access to broadcast frequencies throughout the electromagnetic
      spectrum, including those used for mobile computing and microwave transmissions.
      When these signals cover any distance (more than half a mile) and require exclusive use
      of a frequency, FCC requires a broadcast license. Many wireless networking
      technologies make use of unregulated frequencies set aside by the FCC. These
      frequencies don’t require licensing, but they must be shared with others.
Guide to Networking Essentials, Fifth Edition                                          3-17

     fiber-optic — A cabling technology that uses pulses of light sent along a light-
      conducting fiber at the heart of the cable to transfer information from sender to receiver.
      Fiber-optic cable can send data in only one direction, so two cables are required to
      permit network devices to exchange data in both directions.
     frequency hopping — The type of spread-spectrum data transmission that switches
      data across a range of frequencies over time. Frequency-hopping transmitters and
      receivers must be synchronized to hop at the same time to the same frequencies.
     geosynchronous — An orbital position relative to Earth where a satellite orbits at the
      same speed as Earth rotates. This orbit permits satellites to maintain a constant fixed
      position in relation to Earth stations, and represents the positioning technique used for
      microwave satellites.
     hertz (Hz) — A measure of broadcast frequencies in cycles per second; named after
      Heinrich Hertz, one of the inventors of radio communications.
     horizontal wiring — Network cabling that runs from the work area’s wall jack to the
      telecommunications closet and is usually terminated at a patch panel.
     hot spots — A term used in wireless networking for areas in which wireless access to a
      network or the Internet is possible. Often these areas are in nontraditional locations,
      such as outside cafes or college campus courtyards.
     infrared — The portion of the electromagnetic spectrum immediately below visible
      light. Infrared frequencies are popular for short- to medium-range (10 m to 40 m) point-
      to-point network connections.
     insertion loss — The weakening of signals that occurs on a cable segment each time a
      network device is attached. Necessary restrictions on the maximum number of devices
      keep the signals that traverse the network clean and strong enough to remain intelligible
      to all devices.
     Institute of Electrical and Electronics Engineers (IEEE) — An engineering
      organization that issues standards for electrical and electronic devices, including
      network interfaces, cabling, and connectors.
     IrDA devices — Devices that are compliant with the Infrared Device Association’s
      specifications for infrared components and devices.
     jack couplers — The female receptacles into which modular TP cables plug.
     latency — The amount of time a signal takes to travel from one end of a cable to the
      other.
     light-emitting diodes (LEDs) — A lower-powered alternative for emitting data at
      optical frequencies. LEDs are sometimes used for wireless LANs and for short-haul,
      fiber-optic based data transmissions.
     line-of-sight networks — Networks that require an unobstructed view, or clear line of
      sight, between the transmitter and receiver. Narrowband tight-beam transmitters and
      receivers must have an unobstructed path between them.
     locking connection (LC) — A type of fiber-optic connector that pushes on and pulls
      off using an RJ-45 style latching mechanism.
     maximum segment length — The longest cable segment that a particular networking
      technology permits. This limitation helps network designers and installers make sure the
      entire network can send and receive signals properly.
     mechanical transfer registered jack (MT-RJ) — A fiber-optic connector that
      provides a high-density connection using two fiber-optic cables.
     medium interface connector (MIC) — One of a number of fiber-optic cable connector
      types. MIC connectors feature a separate physical connector for each cable in a typical
      fiber-optic cable pair.
Guide to Networking Essentials, Fifth Edition                                       3-18

     mid-split broadband — A broadband technique in which two channels on different
      frequencies are used to transmit and receive signals via a single cable.
     mobile computing — A form of wireless networking that uses common carrier
      frequencies to permit networked devices to be moved freely within the broadcast
      coverage area yet remain connected to the network.
     narrowband radio — A type of broadcast-based networking technology that uses a
      single specific radio frequency to send and receive data. Low-powered, narrowband
      implementations don’t usually require FCC approval, but are limited to a 250-foot or so
      range; high-powered narrowband implementations do require FCC approval and
      licensing. Also called ―single-frequency radio.‖
     patch cable — A short length (1 to 20 feet) of network cable used to connect a
      computer’s network interface card to a jack in the work area, or to connect from a patch
      panel to a hub or switch in the wiring closet.
     patch panels — Elements of a wiring center in which separate cable runs are brought
      together. By making connections between any two points on the patch panel, the
      physical path of wires can be controlled and the sequence of wires managed.
     plenum-rated — Cable that has been burn-tested to make sure it doesn’t emit toxic
      fumes or large amounts of smoke when incinerated. Most building and fire codes
      require this designation for any cable to be run in plenum space.
     radio frequency interference (RFI) — Any interference caused by signals operating
      in the radio frequency range. This term has become generic for interference caused by
      broadcast signals of any kind.
     reflective wireless networks — An infrared wireless networking technology that uses a
      central optical transceiver to relay signals between end stations. All network devices
      must have an unobstructed view of this central transceiver, which explains why they’re
      usually mounted on the ceiling.
     registered jack 45 (RJ-45) — The eight-wire modular jack used for TP networking
      cables and PBX-based telephone systems.
     repeaters — Networking devices used to strengthen a signal suffering from attenuation.
      Also see attenuation.
     RJ-11 — The four-wire modular jack commonly used for home telephone handsets.
     satellite microwave — A microwave transmission system that uses geosynchronous
      satellites to send and relay signals between sender and receiver. Most companies that
      use satellite microwave lease access to the satellites for an exorbitant fee. Also see
      geosynchronous.
     scatter infrared networks — An infrared LAN technology that uses flat reflective
      surfaces, such as walls and ceilings, to bounce wireless transmissions between sender
      and receiver. Because bouncing introduces delays and attenuation, this variety of
      wireless LAN is the slowest and supports the narrowest bandwidth of any infrared
      technology.
     sheath — The outer layer of coating on a cable; sometimes also called a jacket.
     shielded twisted-pair (STP) — A variety of TP cable in which a foil wrap encloses
      each of one or more pairs of wires for additional shielding, and a wire braid or an
      additional layer of foil might enclose the entire cable for further shielding.
     shielding — Any layer of material included in cable to mitigate the effects of
      interference on the signal-carrying cables it encloses.
     spread-spectrum radio — A form of wireless networking technology that passes data
      by using multiple frequencies simultaneously.
Guide to Networking Essentials, Fifth Edition                                        3-19

     straight connection (SC) — A type of one-piece fiber-optic connector that’s pushed on
      yet makes a strong and solid contact with emitters and sensors.
     straight tip (ST) — The most common type of fiber-optic connector used in Ethernet
      networks with fiber backbones. These connectors come in pairs, one for each fiber-optic
      cable.
     structured cabling — A specification for how network media should be installed to
      maximize performance and efficiency.
     subminiature type A (SMA) — Another fiber-optic connector that twists on and
      comes in pairs.
     telecommunications closet (TC) — A small room or area housing equipment (such as
      patch panels, hubs, and switches) that provides connectivity to computer equipment in
      the nearby work area.
     Telecommunications Industries Association (TIA) — An industry consortium of
      telephone equipment, cabling, and communications companies that formulates hardware
      standards for equipment, cabling, and connectors used in phone systems and on
      networks.
     terrestrial microwave — A wireless microwave networking technology that uses line-
      of-sight communications between pairs of Earth-based transmitters and receivers to
      relay information. The large distances the signals must extend requires positioning
      microwave transmitters and receivers well above ground level on towers, on
      mountaintops, or atop tall buildings. This equipment is usually expensive.
     thicknet — A form of coaxial Ethernet that uses a rigid cable about 0.4 inches in
      diameter. Because of its common jacket color and its rigidity, this cable is sometimes
      called ―frozen yellow garden hose.‖ Also known as thickwire and 10Base5.
     thinnet — A form of coaxial Ethernet that uses a thin, flexible cable about 0.2 inches in
      diameter. Also known as thinwire, 10Base2, and cheapernet.
     transceiver — A compound word made from the words ―transmitter‖ and ―receiver‖ to
      describe a device that combines the functions of a transmitter and a receiver and
      integrates into a single device the circuitry needed to emit and receive signals on a
      medium.
     twisted-pair (TP) — A type of cabling in which two copper wires, each enclosed in
      some kind of sheath, are wrapped around each other. The twisting permits narrow-
      gauge wire, otherwise extraordinarily sensitive to crosstalk and interference, to carry
      higher-bandwidth signals over longer distances than is traditionally possible with
      straight wires. TP cabling is used for voice telephone circuits as well as networking.
     unshielded twisted-pair (UTP) — A form of TP cable that includes no additional
      shielding material in the cable composition. This cable encloses one or more pairs of
      twisted wires inside an outer jacket.
     virtual docking — One of numerous point-to-point wireless infrared technologies that
      enable portable computing devices to exchange data with desktop machines or allow
      data exchange between a computer and a handheld device or a printer. The ―virtual‖
      term is used because this capability replaces a cable between the two devices.
     voicegrade — A designation for cable (usually TP) that indicates it’s rated to carry only
      telephone traffic. Voicegrade cable is not recommended for network use.
     wall plates — A modular plate used to accommodate numerous outlets used for
      networking and voice applications.
     wireless — A network connection that depends on transmission at an electromagnetic
      frequency through the atmosphere to carry data transmissions from one networked
      device to another.
Guide to Networking Essentials, Fifth Edition                                          3-20

     wireless bridges — A pair of devices, typically narrowband and tight beam, that relay
      network traffic from one location to another. Wireless bridges that use spread-spectrum
      radio, infrared, and laser technologies are available and can span distances from
      hundreds of meters up to 25 miles.
     Wireless Fidelity (Wi-Fi) — A term used to indicate wireless networking, usually
      using one of the 802.11 wireless networking standards.
     wiring center — A set of racks with associated equipment that generally includes hubs,
      patch panels, backbone access units, and other network-management equipment, which
      brings TP-wired network cables together for routing, management, and control.
     work area — The space in a facility or office where computer workstations and other
      user devices are located.
     Worldwide Interoperability for Microwave Access (WiMax) — A wireless
      technology designed for wireless metropolitan area networks defined in standards
      802.16-2004 and 802.16e.


Technical Notes for Hands-On Projects
Hands-On Project 3-1: In this project, students analyze each of the following connectors: RJ-
   45, BNC, ST, SC, and MT-RJ.

Hands-On Project 3-2: This project requires a wire cutter and stripper, an RJ-45 crimp tool, 3 to
   4 feet of Category 5/5e or Category 6 cable (per student), two RJ-45 plugs (per student),
   and a patch cable checker (optional).

Hands-On Project 3-2: No special material, files, or software are required.

Hands-On Project 3-3: No special material, files, or software are required.

Hands-On Project 3-4: No special material, files, or software are required.

Hands-On Project 3-5: No special material, files, or software are required.

Hands-On Project 3-6: No special material, files, or software are required.

Hands-On Project 3-7: No special material, files, or software are required.

				
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