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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
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Page 97-98
© 2005 Pearson Prentice-Hall
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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
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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
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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
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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
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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
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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
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KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Transmission Media
© 2005 Pearson Prentice-Hall
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Typical Speeds
Table 4.2 Telecommunications
Transmission Speeds
Page 101
KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Transmission Media
© 2005 Pearson Prentice-Hall
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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
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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
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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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KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Topology of Networks
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Figure 4.5 Network Topologies Page 106
More Complex Networks
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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
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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
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Page 108
© 2005 Pearson Prentice-Hall
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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
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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
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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
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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
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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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© 2005 Pearson Prentice-Hall
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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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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
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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
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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
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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
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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
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Page 113
© 2005 Pearson Prentice-Hall
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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
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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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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
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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
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Page 117-118
© 2005 Pearson Prentice-Hall
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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
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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
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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
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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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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
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Page 130