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8
TELECOMMUNICATIONS
AND NETWORKS
LEARNING OBJECTIVES
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DESCRIBE COMPONENTS OF
TELECOMMUNICATIONS SYSTEM
CALCULATE CAPACITY OF
TELECOMMUNICATIONS CHANNELS &
EVALUATE TRANSMISSION MEDIA
COMPARE TYPES OF NETWORKS &
NETWORK SERVICES
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LEARNING OBJECTIVES
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COMPARE ALTERNATIVE NETWORK
SERVICES
IDENTIFY APPLICATIONS FOR
SUPPORTING ELECTRONIC COMMERCE,
BUSINESS
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MANAGEMENT CHALLENGES
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TELECOMMUNICATIONS REVOLUTION
COMPONENTS, FUNCTIONS OF
TELECOMMUNICATIONS SYSTEM
COMMUNICATIONS NETWORKS
ELECTRONIC COMMERCE &
ELECTRONIC BUSINESS
TECHNOLOGIES
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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
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TELECOMMUNICATIONS
COMMUNICATING INFORMATION
VIA ELECTRONIC MEANS
OVER SOME DISTANCE
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INFORMATION SUPERHIGHWAY
NATIONAL / WORLDWIDE
HIGH SPEED
DIGITAL TELECOMMUNICATIONS
ACCESSIBLE BY GENERAL PUBLIC
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SYSTEM COMPONENTS
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COMPUTERS
TERMINALS: Input / output devices
COMMUNICATIONS CHANNELS
PROCESSORS: Modems, multiplexers, frontend processors
COMMUNICATIONS SOFTWARE
Routers, Hubs and Switches
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PROTOCOL
RULES & PROCEDURES
TO GOVERN TRANSMISSION
BETWEEN COMPONENTS
IN A NETWORK
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ANALOG SIGNAL
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CONTINUOUS WAVEFORM
PASSES THRU SYSTEM
VOICE COMMUNICATIONS
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DIGITAL SIGNAL
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DISCRETE WAVEFORM
TWO DISCRETE STATES:
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1-BIT & 0-BIT
ON / OFF PULSE
DATA COMMUNICATION
USES MODEM TO TRANSLATE ANALOG
TO DIGITAL, DIGITAL TO ANALOG
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0010111010011101001010101110111100100010000101111010110100111010010
COMMUNICATION
CHANNELS
MEANS BY WHICH DATA ARE TRANSMITTED:
 TWISTED WIRES: Copper Wires
 COAXIAL CABLE: Insulated Copper Wires
 FIBER-OPTIC CABLE
 MICROWAVE
 Radio Frequency
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FIBER OPTICS
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SUPER CLEAR GLASS STRANDS
FAST, LIGHT, DURABLE
TRILLIONS OF BITS PER SECOND, FULL
DUPLEX
EXPENSIVE, HARDER TO INSTALL
OFTEN USED AS BACKBONE OF NETWORKS
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SIGNAL
LASER
CABLE
PHOTO
DETECTOR
SIGNAL
FIBER OPTICS
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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
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WIRELESS TRANSMISSION
TECHNOLOGIES
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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
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WIRELESS TRANSMISSION
TECHNOLOGIES
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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
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ORBITING SATELLITES
MICROWAVE
TRANSMISSION
UPLINK
DOWNLINK
COMMUNICATIONS CHANNELS
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TRANSMISSION SPEED: Bits per Second
(BPS) or Baud
BANDWIDTH: Capacity of Channel;
Difference between Highest & Lowest
Frequencies
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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
COST
LOW
HIGH
COMMUNICATIONS PROCESSORS
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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
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NETWORK TOPOLOGIES
USER
USER
STAR
HOST
USER
USER
Host mainframe computers use this with terminals.
NETWORK TOPOLOGIES
USER
USER
USER
USER
USER
USER
Network
devices may
look like a star
configuration
BUS
Collision detection is required for multiple devices to share the
same bus. This creates some inefficiency.
NETWORK TOPOLOGIES
Device
Device
RING
Device
Device
A token is passed from device to device. Synchronizing access to the
ring. Single rings exists in older systems. Newer double rings are more
reliable.
LOCAL NETWORKS
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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
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LOCAL AREA NETWORK (LAN)
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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
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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
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VALUE-ADDED NETWORK
(VAN)
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PRIVATE, MULTIPATH, DATA ONLY
3rd PARTY MANAGED
USED BY SEVERAL ORGANIZATIONS
SUBSCRIPTION BASIS
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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
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PACKET SWITCHING (X.25)
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FORM OF Value Added Network
BREAKS DATA BLOCKS INTO SMALL
PACKETS (e.g.: 128 Bytes)
PACKETS ROUTED BY MOST
ECONOMICAL MEANS
REASSEMBLED AT DESTINATION
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FRAME RELAY
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PACKAGES DATA INTO BLOCKS
(FRAMES)
HIGH-SPEED TRANSMISSION
RELIABLE LINES
NO ERROR-CORRECTION ROUTINES
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ASYNCHRONOUS TRANSFER
MODE (ATM)
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CELL: 53 Groups of 8 Bytes Each
USES FIBER OPTICS CABLE
INDEPENDENT OF VENDOR HARDWARE
SPEEDS
CAN TIE LAN TO WAN
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INTEGRATED SERVICES
DIGITAL NETWORK (ISDN)
INTERNATIONAL STANDARD FOR
TRANSMITTING VOICE, VIDEO, DATA
OVER PUBLIC TELEPHONE LINES
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OTHER SERVICES:
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DIGITAL SUBSCRIBER LINE (DSL): enhancing
capacity over copper telephone lines
CABLE MODEM: modem for cable TV for highspeed access to Internet
T1 LINE: dedicated telephone connection, 24
channels @ 1.544 megabits per second
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OTHER SERVICES:
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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
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E-COMMERCE &
E-BUSINESS TECHNOLOGIES
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ELECTRONIC MAIL (e-mail)
GROUPWARE
VOICE MAIL
FACSIMILE MACHINES (fax)
TELECONFERENCING
DATACONFERENCING
VIDEOCONFERENCING
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E-COMMERCE &
E-BUSINESS TECHNOLOGIES
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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
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COMMERCIAL DIGITAL
INFORMATION SERVICES
PROVIDER
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
ELECTRONIC DATA
INTERCHANGE (EDI)
COMPUTER - TO - COMPUTER
EXCHANGE BETWEEN TWO
ORGANIZATIONS
OF STANDARD BUSINESS TRANSACTION
DOCUMENTS
SELLER
CUSTOMER
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ORDERS, PAYMENTS
COMPUTER
SHIPPING NOTICES, PRICE
UPDATES, INVOICES
COMPUTER
8
TELECOMMUNICATIONS
AND NETWORKS