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MANAGING
INFORMATION
TECHNOLOGY
FIFTH EDITION
CHAPTER 4
TELECOMMUNICATIONS
AND NETWORKING
E. Wainright Martin Carol V. Brown Daniel W. DeHayes
Jeffrey A. Hoffer William C. Perkins
THE NEED FOR NETWORKING
Sharing of technology resources
Sharing of data
Distributed data processing and
client/server systems
Enhanced communications
Marketing outreach
© 2005 Pearson Prentice-Hall
Chapter 4 - 2
Page 96-97
AN OVERVIEW OF
TELECOMMUNICATIONS
AND NETWORKING
Networking –
the electronic linking of geographically dispersed devices
Telecommunications –
communications (voice and data) at a distance
© 2005 Pearson Prentice-Hall
Chapter 4 - 3
Page 97-98
© 2005 Pearson Prentice-Hall
Chapter 4 - 4
Table 4.1 Functions of a
Telecommunications Network
Page 98
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Analog and Digital Signals
Analog network uses continuous voltage
varying as a function of time
Example: voice over telephone lines
Digital network directly transmits two discrete
states
Note: 0 for pulse off and 1 for pulse on
© 2005 Pearson Prentice-Hall
Chapter 4 - 5
Page 98-100
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Analog and Digital Signals
Modem
Device needed when transmitting data over analog
lines
Converts data from digital to analog to be sent over
analog telephone lines
Also reconverts data back to digital after data
transmission
Abbreviation for modulator/demodulator
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Page 99
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Analog and Digital Signals
© 2005 Pearson Prentice-Hall
Chapter 4 - 7
Figure 4.1 Use of Modem in Analog Network
Page 99
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Speed of Transmission
Bandwidth –
• difference between highest and lowest frequencies
(cycles per second) that can be transmitted on a
single medium
• common measure of a medium’s capacity
© 2005 Pearson Prentice-Hall
Chapter 4 - 8
Page 100
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Speed of Transmission
Hertz – cycles per second
Baud – number of signals sent per second
Bits per second (bps) – number of bits sent per
second
When each cycle sends one signal that transmits exactly
one bit of data (often the case), then the three terms are
identical
© 2005 Pearson Prentice-Hall
Chapter 4 - 9
Page 100
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Transmission Lines
Switched line system
Example: public telephone system
Uses switching centers to route signals along best
possible path to destination
Private (dedicated) lines
Leased from companies such as MCI, Sprint, AT&T
Use direct physical lines between source and
destination
© 2005 Pearson Prentice-Hall
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Page 101
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Transmission Lines
Simplex – data travels in one direction only
Half-duplex – data can travel in both directions,
but only one direction at a time
Full-duplex – data travels in both directions at the
same time
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Page 101
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Transmission Media
© 2005 Pearson Prentice-Hall
Chapter 4 - 12
Page 101
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Transmission Media
© 2005 Pearson Prentice-Hall
Chapter 4 - 13
Typical Speeds
Table 4.2 Telecommunications
Transmission Speeds
Page 101
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Transmission Media
© 2005 Pearson Prentice-Hall
Chapter 4 - 14
Figure 4.3 Construction of a Coaxial Cable
Page 102
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Transmission Media
Wireless –
broadcast technology in which radio signals are sent out
into the air
Cordless telephone
Microwave
Cellular phone
Satellite
Wireless LAN
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Page 102
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Transmission Media
© 2005 Pearson Prentice-Hall
Chapter 4 - 16
Figure 4.4 Satellite Communications
Page 102
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Transmission Lines
Fiber-optic cabling
Newest transmission medium
Transmits data by pulses of light through thin fiber
of glass
Much faster than other media
Thinner … requires less space
More secure … harder to tap
© 2005 Pearson Prentice-Hall
Chapter 4 - 17
Page 105-106
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Topology of Networks
Topology –
term used to describe the configuration or
arrangement of network devices and media
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Page 106
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Topology of Networks
© 2005 Pearson Prentice-Hall
Chapter 4 - 19
Figure 4.5 Network Topologies Page 106
More Complex Networks
© 2005 Pearson Prentice-Hall
Chapter 4 - 20
Figure 4.6 vBNS+ Network Map
Page 107
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Computer Telecommunications Networks
Private branch exchange (PBX) Networks
Local Area Networks (LANs)
Backbone Networks
Wide Area Networks (WANs)
Internet
Internet2
© 2005 Pearson Prentice-Hall
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Page 108
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Computer Telecommunications Networks
Emanates from a single medium or large computer
Usually arranged as a tree
Uses coaxial and twisted pair cabling
Controlled by central computer
Often has a front-end processor to handle all
aspects of telecommunications
© 2005 Pearson Prentice-Hall
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Page 108
© 2005 Pearson Prentice-Hall
Chapter 4 - 23
Figure 4.7 Computer
Telecommunications Network
Page 108
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Private Branch Exchanges (PBX)
Originally analog, today usually digital
Can serve as the central device in a star or ring
network
Can function as front-end processor for mainframe
© 2005 Pearson Prentice-Hall
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Page 109
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Private Branch Exchanges (PBX)
Advantages:
Can connect ALL telecommunications devices in a
building or campus
Can use existing telephone wiring
Can carry voice and data over same network
Has a high-potential throughput
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Page 109
© 2005 Pearson Prentice-Hall
Chapter 4 - 26
Figure 4.8 Schematic Representation
of a PBX
Page 109
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Local Area Networks
Owned by a single organization
Operate within area 2-3 miles in diameter
Contain a number of intelligent devices, usually
microcomputers, that can process data … based
on peer-to-peer relationship
No part of telephone system, have their own wiring
© 2005 Pearson Prentice-Hall
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Page 109
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Local Area Networks
LAN Topologies and Standards
Contention bus design … IEEE 802.3
Token bus design … IEEE 802.4
Token ring design … IEEE 802.5
Wireless design … IEEE 802.11
© 2005 Pearson Prentice-Hall
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Page 109
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Local Area Networks
Contention Bus Design (Ethernet)
Bus topology
Implemented with coax or twisted pair
Usually half-duplex
All devices contend for use of cable
Design now called Shared Ethernet … uses a
contention bus as its logical topology and
implemented with a physical star arrangement …
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Page 110
© 2005 Pearson Prentice-Hall
Chapter 4 - 30
Figure 4.9 Shared Ethernet Topology:
Logical Bus, Physical Star
Page 109
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Local Area Networks
Switched Ethernet
Newer variation, better performance, higher price
Uses switch instead of hub
Operates both logical and physical star
Each device has own dedicated circuit
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Page 110
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Local Area Networks
Token Bus
Employs bus topology, no contention
Uses single token passed around to all devices in
order
Device can only transmit when has token
Central to Manufacturing Automation Protocol
(MAP) – connects robots and other machines on
assembly line by a LAN
© 2005 Pearson Prentice-Hall
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Page 110
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Local Area Networks
Token Ring
Device attached to ring must seize token before
can send a message
Collisions cannot occur
Usual implementation is physical star, logical ring
© 2005 Pearson Prentice-Hall
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Page 111
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Local Area Networks
Wireless LAN
Known as Wi-Fi (wireless fidelity)
Growing in demand for corporate and home use
Use IEEE 802.11 standards with shared Ethernet
design
Requires use of wireless network interface card
(NIC)
Wireless Access Point (WAP) – radio transceiver that
acts as a hub
© 2005 Pearson Prentice-Hall
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Page 111
© 2005 Pearson Prentice-Hall
Chapter 4 - 35
Figure 4.10 Wireless Local Area Network
Topology
Page 112
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Backbone Network
In-between network that interconnects LANs in a single
organization with each other and with organization’s
WAN and the Internet
© 2005 Pearson Prentice-Hall
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Page 113
Major
corporate
network
Major ISP
Network Service Provider (NSP)
Network
Access Point
(NAP)
Network
Access Point
(NAP)
Network Service Provider (NSP)
Major
corporate
network
Major ISP
Regional ISP
The
backbone.
Major
corporate
network
Local ISP
Regional ISP
Local ISP
Regional ISP
Local ISP
Message A
Packet A1
Packet A2
Packet A3
Packet A3
Packet
Packet
Packet A1
Packet
Open
Packet
Packet A2
Packet
Packet
Packet
Open
Packet
Packet
Packet
Packet
Figure
2.16
Packet
switching.
Open
Packet
Packet A1
Packet A2
Message A
Packet A3
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Backbone network terminology:
Bridge – connects two LANs using same protocol
Router (gateway) – connects two or more LANs that
may use different protocols
Switch – connects more than two LANs using the
same protocols
© 2005 Pearson Prentice-Hall
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Page 113
© 2005 Pearson Prentice-Hall
Chapter 4 - 40
Figure 4.11 Sample Backbone Network
Page 112
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
Wide Area Networks (WANs)
Communicate voice and data across greater
distances
Usually owned by several organizations (including
user organization and common carrier)
Employ point-to-point transmission
Often rely on public telephone network
© 2005 Pearson Prentice-Hall
Chapter 4 - 41
Page 114
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of WANs
Switched-circuit
Direct distance dialing (DDD)
Wide Area Telephone Service (WATS)
Integrated Service Digital Network (ISDN)
Dedicated-circuit
Leased lines
Satellite
© 2005 Pearson Prentice-Hall
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Page 115
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of WANs
Packet-switched
Shared private lines using store-and-forward data
transmission
Permits multiple connections to exist
simultaneously over the same physical circuit
© 2005 Pearson Prentice-Hall
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Page 116
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of WANs
ATM – fast packet switching with short, fixed-length
packets
Virtual Private Networks (VPNs) – provide same as
private packet-switched network using the public
Internet
© 2005 Pearson Prentice-Hall
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Page 117
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Types of Networks
The Internet
Network of networks that use the TCP/IP protocol
Contain gateways to computers that do not use
TCP/IP
Provides four basic functions:
© 2005 Pearson Prentice-Hall
Electronic mail
Remote login
Discussion groups
Sharing of data resources
Chapter 4 - 45
Page 117-118
© 2005 Pearson Prentice-Hall
Chapter 4 - 46
Table 4.4 Internet Applications
Page 118
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
DSL, Cable Modem, and Satellite
Internet access services:
Digital subscriber line (DSL) – service offered by
telephone companies using copper wire already installed
in homes … moving data over wires without disturbing
voice traffic
Cable modem – connection obtained from cable TV
company using existing home coaxial cable
Satellite – most expensive, but may be only option for
customers in rural areas
© 2005 Pearson Prentice-Hall
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Page 120
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Intranets
Intranet –
a network operating within an organization that uses
the TCP/IP protocol
© 2005 Pearson Prentice-Hall
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Page 122
Intranet, Extranet, and VPN
Technologies
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Internet2 –
not-for-profit consortium of over 200 universities,
working with over 60 technology companies and the
U.S. government, to develop and deploy advanced
network applications and technologies
© 2005 Pearson Prentice-Hall
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Page 122
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Primary goals of Internet2:
Create a leading-edge network capability for the
national research community
Enable revolutionary Internet applications based on a
much higher-performance Internet that we have
today
Ensure the rapid transfer of new network services
and applications to the broader Internet community
© 2005 Pearson Prentice-Hall
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Page 123
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Network Protocols
Protocol –
agreed-upon set of rules governing communication
among layers or levels of a network
© 2005 Pearson Prentice-Hall
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Page 124
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Network Protocols
LAN protocols:
Contention bus
Token bus
Token ring
Wireless
IBM’s own protocol – Systems Network Architecture
(SNA)
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Page 124
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Network Protocols
International Organization for Standardization (ISO)
network protocol – Open Systems Interconnection
Reference Model (OSI)
Thought to become the only standard for networking
Gained momentum until Internet explosion
Transmission Control Protocol/Internet Protocol
(TCP/IP)
Has become the de facto standard for networking today
© 2005 Pearson Prentice-Hall
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Page 124-125
The TCP/IP Protocol Suite
Client workstation
Host server
Browser
Web server
Select page
Display page
Request page
(HTTP)
Pass page to
browser
(HTTP)
Retrieve page
Send page
(HTTP)
Pass request to
server (HTTP)
Application layer
Resolve
domain name
address(DMS)
Using TCP/IP
protocols to
download a
page.
Create packet
Assemble
packets
Transport layer
Create packet
Assemble
packets
Route packet
Check packet
Internet layer
Route packet
Check packet
Send packet
Accept packet
Network access
layer
Send packet
Accept packet
Page
Request
Internet
© 2005 Pearson Prentice-Hall
Chapter 4 - 57
Figure 4.17 Data Transmission
Based on OSI Model
Page 126
THE EXPLODING ROLE OF
TELECOMMUNICATIONS AND
NETWORKING
Online Operations
Connectivity
Electronic Data Interchange (EDI) and
Electronic Commerce
Marketing
© 2005 Pearson Prentice-Hall
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Page 128-129
THE TELECOMMUNICATIONS
INDUSTRY
Carriers
Own or lease the physical plant – cabling,
satellites, cellular towers, etc.
Sell service of transmitting communication
from one location to another
© 2005 Pearson Prentice-Hall
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Page 130
THE TELECOMMUNICATIONS
INDUSTRY
Equipment vendors
Manufacture and sell LAN software and
hardware
Includes routers, hubs, wireless access
points, digital switches, multiplexers, cellular
telephones, modems
© 2005 Pearson Prentice-Hall
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Page 130
THE TELECOMMUNICATIONS
INDUSTRY
Service providers
Operate networks and deliver services
through the network
Provide access to or services via the Internet
(such as AOL, Microsoft Network, Yahoo!,
and many ISPs
© 2005 Pearson Prentice-Hall
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Page 130