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c h a p t e r 8 TELECOMMUNICATIONS AND NETWORKS 8.1 © 2002 by Prentice Hall LEARNING OBJECTIVES 8.2 • DESCRIBE COMPONENTS OF TELECOMMUNICATIONS SYSTEM • CALCULATE CAPACITY OF TELECOMMUNICATIONS CHANNELS & EVALUATE TRANSMISSION MEDIA • COMPARE TYPES OF NETWORKS & NETWORK SERVICES * © 2002 by Prentice Hall LEARNING OBJECTIVES • COMPARE ALTERNATIVE NETWORK SERVICES • IDENTIFY APPLICATIONS FOR SUPPORTING ELECTRONIC COMMERCE, BUSINESS * 8.3 © 2002 by Prentice Hall MANAGEMENT CHALLENGES • TELECOMMUNICATIONS REVOLUTION • COMPONENTS, FUNCTIONS OF TELECOMMUNICATIONS SYSTEM • COMMUNICATIONS NETWORKS • ELECTRONIC COMMERCE & ELECTRONIC BUSINESS TECHNOLOGIES * 8.4 © 2002 by Prentice Hall MANAGEMENT CHALLENGES 1. MANAGING LOCAL AREA NETWORKS: Must be carefully administered, monitored, vulnerable to interruption, data loss, viruses 2. MANAGING BANDWIDTH: While costs per unit are dropping and capacity is growing, sudden demand can overwhelm system * 8.5 © 2002 by Prentice Hall INFORMATION SUPERHIGHWAY NATIONAL / WORLDWIDE HIGH SPEED DIGITAL TELECOMMUNICATIONS ACCESSIBLE BY GENERAL PUBLIC * 8.6 © 2002 by Prentice Hall SYSTEM COMPONENTS • • • • COMPUTERS TERMINALS: Input / output devices COMMUNICATIONS CHANNELS PROCESSORS: Modems, multiplexers, front-end processors • COMMUNICATIONS SOFTWARE * 8.7 © 2002 by Prentice Hall PROTOCOL RULES & PROCEDURES TO GOVERN TRANSMISSION BETWEEN COMPONENTS IN A NETWORK * 8.8 © 2002 by Prentice Hall COMMUNICATION CHANNELS MEANS BY WHICH DATA ARE TRANSMITTED: • TWISTED WIRES: Copper Wires • COAXIAL CABLE: Insulated Copper Wires • FIBER-OPTIC CABLE • MICROWAVE * 8.9 © 2002 by Prentice Hall FIBER OPTICS • SUPER CLEAR GLASS STRANDS • FAST, LIGHT, DURABLE • TRILLIONS OF BITS PER SECOND, FULL DUPLEX • EXPENSIVE, HARDER TO INSTALL • OFTEN USED AS BACKBONE OF NETWORKS PHOTO * SIGNAL LASER CABLE SIGNAL DETECTOR 8.10 © 2002 by Prentice Hall FIBER OPTICS • BACKBONE: Fiber optics cable carries light signals to distribution nodes, which use copper wires to user • DENSE WAVE DIVISION MULTIPLEXING (DWDM): Next-generation, uses many colors, (up to 160) each a channel, increases capacity of a fiber to 6.4 terabits per second * 8.11 © 2002 by Prentice Hall WIRELESS TRANSMISSION TECHNOLOGIES 8.12 • PAGERS: Small pager beeps when receives short message • CELLULAR TELEPHONE: Device uses radio waves to reach antennas within areas called cells • MOBILE DATA NETWORKS: Radio based data network using hand-held computers, cheap, efficient * © 2002 by Prentice Hall WIRELESS TRANSMISSION TECHNOLOGIES 8.13 • PERSONAL COMMUNICATION SERVICE: Cellular; lower power; higher frequency. Smaller phones not shielded by buildings, tunnels • PERSONAL DIGITAL ASSISTANT: Pen sized, hand-held, digital communicator • SMART PHONE: Wireless, voice, text, Internet * © 2002 by Prentice Hall SPEEDS & COST OF MEDIA MEDIUM TWISTED WIRE SPEED 300 BPS - 10 MBPS MICROWAVE 256 KBPS - 100 MBPS SATELLITE 256 KBPS - 100 MBPS COAXIAL CABLE 56 KBPS - 200 MBPS FIBER OPTICS 500 KBPS - 6.4 TBPS BPS: BITS PER SECOND KBPS: KILOBITS PS, MBPS: MEGABITS PS, GBPS: GIGABITS PS, TBPS: TERABITS PS 8.14 COST LOW HIGH © 2002 by Prentice Hall COMMUNICATIONS PROCESSORS • FRONT- END PROCESSOR: Minicomputer manages communication for host computer • CONCENTRATOR: Computer collects messages for batch transmission to host computer • CONTROLLER: Computer controls interface between CPU and peripheral devices • MULTIPLEXER: Allows channel to carry multiple sources simultaneously * 8.15 © 2002 by Prentice Hall NETWORK TOPOLOGIES USER USER STAR 8.16 HOST USER USER © 2002 by Prentice Hall NETWORK TOPOLOGIES USER USER USER USER USER USER BUS 8.17 © 2002 by Prentice Hall NETWORK TOPOLOGIES USER USER RING 8.18 USER USER © 2002 by Prentice Hall LOCAL NETWORKS • PRIVATE BRANCH EXCHANGE (PBX): firm’s central switching system • LOCAL AREA NETWORK (LAN): dedicated channels; limited distance (less than 2000 foot radius); higher capacity than PBX. Can share expensive hardware & software * 8.19 © 2002 by Prentice Hall LOCAL AREA NETWORK (LAN) • GATEWAY: Connection to other networks • ROUTER: Forwards data to other networks • NETWORK OPERATING SYSTEM (NOS): Manages file server; routes communications on network • PEER - TO - PEER: In some small networks all computers have equal power * 8.20 © 2002 by Prentice Hall WIDE - AREA NETWORK (WAN) Network spans large geographic distances. Can include cable, satellite, microwave • SWITCHED LINES: Route determined by current traffic • DEDICATED LINES: Constantly available for high-volume traffic * 8.21 © 2002 by Prentice Hall VALUE-ADDED NETWORK (VAN) • • • • 8.22 PRIVATE, MULTIPATH, DATA ONLY 3rd PARTY MANAGED USED BY SEVERAL ORGANIZATIONS SUBSCRIPTION BASIS * © 2002 by Prentice Hall NETWORK SERVICES • • • • PACKET SWITCHING FRAME RELAY ASYNCHRONOUS TRANSFER MODE (ATM) INTEGRATED SERVICES DIGITAL NETWORK (ISDN) • SYMMETRIC DIGITAL SUBSCRIBER LINE • CABLE MODEM • T1 LINE * 8.23 © 2002 by Prentice Hall PACKET SWITCHING (X.25) • FORM OF Value Added Network • BREAKS DATA BLOCKS INTO SMALL PACKETS (e.g.: 128 Bytes) • PACKETS ROUTED BY MOST ECONOMICAL MEANS • REASSEMBLED AT DESTINATION * 8.24 © 2002 by Prentice Hall FRAME RELAY • PACKAGES DATA INTO BLOCKS (FRAMES) • HIGH-SPEED TRANSMISSION • RELIABLE LINES • NO ERROR-CORRECTION ROUTINES * 8.25 © 2002 by Prentice Hall ASYNCHRONOUS TRANSFER MODE (ATM) • CELL: 53 Groups of 8 Bytes Each • USES FIBER OPTICS CABLE • INDEPENDENT OF VENDOR HARDWARE SPEEDS • CAN TIE LAN TO WAN * 8.26 © 2002 by Prentice Hall INTEGRATED SERVICES DIGITAL NETWORK (ISDN) INTERNATIONAL STANDARD FOR TRANSMITTING VOICE, VIDEO, DATA OVER PUBLIC TELEPHONE LINES * 8.27 © 2002 by Prentice Hall OTHER SERVICES: • DIGITAL SUBSCRIBER LINE (DSL): enhancing capacity over copper telephone lines • CABLE MODEM: modem for cable TV for high-speed access to Internet • T1 LINE: dedicated telephone connection, 24 channels @ 1.544 megabits per second * 8.28 © 2002 by Prentice Hall OTHER SERVICES: • BROADBAND: High-speed transmission, multiple channels • NETWORK CONVERGENCE: Enables simultaneous transmission of voice, data, video. Attractive for multimedia applications: Video collaboration, voice-data call centers, distance learning, unified messaging * 8.29 © 2002 by Prentice Hall E-COMMERCE & E-BUSINESS TECHNOLOGIES • • • • • • • 8.30 ELECTRONIC MAIL (e-mail) GROUPWARE VOICE MAIL FACSIMILE MACHINES (fax) TELECONFERENCING DATACONFERENCING VIDEOCONFERENCING * © 2002 by Prentice Hall E-COMMERCE & E-BUSINESS TECHNOLOGIES • DIGITAL INFORMATION SERVICES: Commercial service provides desired mix • DISTANCE LEARNING: Education, training delivered over a distance, can include printed material, teleconferencing, interactive multimedia, Web sites * 8.31 © 2002 by Prentice Hall ELECTRONIC DATA INTERCHANGE (EDI) COMPUTER - TO - COMPUTER EXCHANGE BETWEEN TWO ORGANIZATIONS OF STANDARD BUSINESS TRANSACTION DOCUMENTS SELLER CUSTOMER * ORDERS, PAYMENTS COMPUTER SHIPPING NOTICES, PRICE COMPUTER UPDATES, INVOICES 8.32 © 2002 by Prentice Hall c h a p t e r 8 TELECOMMUNICATIONS AND NETWORKS 8.33 © 2002 by Prentice Hall