Computers: Information Technology in Perspective Larry Long & Nancy Long Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Copyright 2002 Prentice Hall, Inc. Networks & Networking Chapter 6 Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Our Wired World 6.3 Quit People who understand information technology trends, such as digital convergence and global connectivity, are better prepared to cope with Monthly our increasingly wired society. Technology Update Digital Convergence 6.4 Quit DVDs Everything is Telephones becoming digitally Televisions compatible!! Computers Newspapers Collegecourses Textbooks on CD-ROM Serendipitous Banking/Finance Surfing: Online Books Connectivity 6.5 Quit Seeking ways to interface, or connect, a diverse set of hardware, software, and databases. Cooperative Processing 6.6 Quit Companies must cooperate Internally (for company resources) via Intracompany networking Intranets Externally (for world competition) via Intercompany networking Business-to-business (B2B) E-commerce (electronic commerce) Extranets Data Communications Channel 6.7 Quit Same as line, link or pipe Special hardware transmits the digital information between computers Transmission Media 6.8 Quit Bandwidth is channel capacity # of bits channel can transmit/second 56 K bps (bits per second) to 622 M bps Same as baud High bandwidth = Broadband Low bandwidth = Narrowband Broadband Access is high-speed Internet access Transmission Media 6.9 Quit Coaxial cable Wireless Twisted-pair wire Fiber optic cable Twisted-Pair Wire 6.10 Quit Telephone company services POTS (Plain old telephone service) 56 K bps ISDN (Integrated Services Digital Network) Line & Modem 128 K bps DSL (Digital Subscriber Line) Line & Modem 1.5 to 9 M bps Downstream rate Transmission Upstream rate Media Will compete with cable Coaxial Cable 6.11 Quit Coax: the cable in “cable television” Minimum signal distortion Has a very wide pipe Hundreds of times faster than POTS 100 times faster than ISDN Need a cable modem Wireless Communications 6.12 Quit Carries data via microwave or radio signals Transmission is line-of-sight Use transceivers/repeater stations Satellites Eliminate line-of-sight limitation Geosynchronous orbit Everyone has satellite access Need dish and modem Somewhat slower than DSL and Cable MMDS and LMDS (wireless at fiber optic-level speeds Fiber Optic Cable 6.13 Quit Carries data as laser- generated pulses of light Foundation transmission medium for Internet backbone Better for data security Future technology looks like very big “pipe” PC to PC: Wireless 6.14 Quit Wireless transceivers between PCs Alternative to running twisted-pair, coax, or fiber optics Hooks into USB or PCMCIA slot Limited range about 50 feet Use omnidirectional radio waves Limited channel capacity Common Carriers 6.15 Quit AT&T, MCI, Sprint, etc. Private Line - Leased Line Switched Line - Dial-Up Line Communications Protocols 6.16 Quit Rules that govern the way data are transmitted TCP/IP (Transmission Control Protocol/Internet Protocol Protocol Classifications 6.17 Quit Asynchronous Transmission Low speed Modem needed Transmitted as needed Start/stop bits used Synchronous Transmission High speed Source and destination in “synch” No start/stop bits needed Data Communications Hardware 6.18 Quit LAN Modem Modem Multiplexor Front-end Host Router Processor Computer Lines to more terminals Multiplexor LAN Modem vs. NIC 6.19 Quit Modulator-demodulator MODEM Converts digital to analog signals for transmission over phone lines Internal and external Usually a voice/data/fax modem Network Interface Card NIC Allows exchange of data via a LAN Special Function Devices 6.20 Quit Message is distributed among: Host or Server computer - in control Front-end Processor – establishes link or handshake Multiplexor - collects data from multiple devices and sends it along Network Address Routers 6.21 Quit Hardware and software used to ease the problems of linking incompatible networks Routes messages to proper destinations Backbone is a system of routers and transmission Serendipitous media that link computers. Surfing: Government Network Topologies 6.22 Quit Network Topology is a description of the possible physical connections within a network. It is a configuration of hardware and it shows which pairs of nodes can communicate. Networks Network Topologies 6.23 Quit Ring Star Bus Types of Networks 6.24 Quit WAN Wide Area Network Metropolitan Area Network MAN LAN Local Net Home Network Sharing Resources on a LAN 6.25 Quit Applications software Links to other LANs Communications capabilities I/O devices Storage devices Add-on boards Courtesy of Orbital Sciences Corporation LAN Overview 6.26 Quit One node at a time can send Token Access Method Ethernet Transmission media Twisted-pair, coax, and fiber optic LAN Servers File Server Print Server Communications Server LAN Software 6.27 Quit Operating Systems Peer to Peer LANs LANs with dedicated servers Client/Server Applications Software Shared software Groupware Networks on the Fly Portable networks Home and Small Office LAN 6.28 Quit InstallNICs Position switching hub Link PCs to hub Set up LAN software Networks & Networking The End Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc.