Ch08

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

TELECOMMUNICATIONS COMMUNICATING INFORMATION VIA ELECTRONIC MEANS OVER SOME DISTANCE *

8.6

© 2002 by Prentice Hall

INFORMATION SUPERHIGHWAY NATIONAL / WORLDWIDE HIGH SPEED DIGITAL TELECOMMUNICATIONS ACCESSIBLE BY GENERAL PUBLIC *

8.7

© 2002 by Prentice Hall

SYSTEM COMPONENTS • • • •

COMPUTERS TERMINALS: Input / output devices COMMUNICATIONS CHANNELS PROCESSORS: Modems, multiplexers, front-end processors • COMMUNICATIONS SOFTWARE * 8.8

© 2002 by Prentice Hall

PROTOCOL RULES & PROCEDURES TO GOVERN TRANSMISSION BETWEEN COMPONENTS IN A NETWORK * 8.9

© 2002 by Prentice Hall

ANALOG SIGNAL • • •

8.10

CONTINUOUS WAVEFORM PASSES THRU SYSTEM VOICE COMMUNICATIONS *

© 2002 by Prentice Hall

DIGITAL SIGNAL • DISCRETE WAVEFORM • TWO DISCRETE STATES: – 1-BIT & 0-BIT – ON / OFF PULSE

• DATA COMMUNICATION • USES MODEM TO TRANSLATE ANALOG TO DIGITAL, DIGITAL TO ANALOG 0010111010011101001010101110111100100010000101111010 * 01101100 8.11

© 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 * 8.12

© 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

8.13

© 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 * 8.14

© 2002 by Prentice Hall

WIRELESS TRANSMISSION TECHNOLOGIES

8.15

• 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

8.16

• 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

ORBITING SATELLITES

MICROWAVE TRANSMISSION

UPLINK

8.17

DOWNLINK

© 2002 by Prentice Hall

COMMUNICATIONS CHANNELS • TRANSMISSION SPEED: Bits per Second (BPS) or Baud • BANDWIDTH: Capacity of Channel; Difference between Highest & Lowest Frequencies *

8.18

© 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

8.19

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 * 8.20

© 2002 by Prentice Hall

NETWORK TOPOLOGIES USER

USER

STAR 8.21

HOST

USER

USER

© 2002 by Prentice Hall

NETWORK TOPOLOGIES USER

USER

USER

USER

USER

USER

BUS 8.22

© 2002 by Prentice Hall

NETWORK TOPOLOGIES USER

USER

RING 8.23

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 *

8.24

© 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 *

8.25

© 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 * 8.26

© 2002 by Prentice Hall

VALUE-ADDED NETWORK (VAN) • • • •

8.27

PRIVATE, MULTIPATH, DATA ONLY 3rd PARTY MANAGED USED BY SEVERAL ORGANIZATIONS SUBSCRIPTION BASIS *

© 2002 by Prentice Hall

NETWORK SERVICES • • • •

8.28

PACKET SWITCHING FRAME RELAY ASYNCHRONOUS TRANSFER MODE (ATM) INTEGRATED SERVICES DIGITAL NETWORK (ISDN) • SYMMETRIC DIGITAL SUBSCRIBER LINE • CABLE MODEM • T1 LINE *

© 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 * 8.29

© 2002 by Prentice Hall

FRAME RELAY • PACKAGES DATA INTO BLOCKS (FRAMES) • HIGH-SPEED TRANSMISSION • RELIABLE LINES • NO ERROR-CORRECTION ROUTINES * 8.30

© 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 *

8.31

© 2002 by Prentice Hall

INTEGRATED SERVICES DIGITAL NETWORK (ISDN) INTERNATIONAL STANDARD FOR TRANSMITTING VOICE, VIDEO, DATA OVER PUBLIC TELEPHONE LINES *

8.32

© 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 * 8.33 © 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 * 8.34 © 2002 by Prentice Hall

E-COMMERCE & E-BUSINESS TECHNOLOGIES • • • • • • •

8.35

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 * 8.36

© 2002 by Prentice Hall

COMMERCIAL DIGITAL INFORMATION SERVICES PROVIDER

8.37

TYPE OF SERVICE

AMERICA ONLINE

General interest / business information

PRODIGY

General interest / business information

MICROSOFT NETWORK

General interest / business information

DOW JONES NEWS RETRIEVAL

Business / financial information

DIALOG

Business / scientific / technical information

LEXIS

Legal research

NEXIS

News / business information

© 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

8.38

© 2002 by Prentice Hall

c h a p t e r

8

TELECOMMUNICATIONS AND NETWORKS

8.39

© 2002 by Prentice Hall