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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
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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
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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
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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