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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
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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
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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
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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
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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
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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
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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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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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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
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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
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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
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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
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KEY ELEMENTS OF
TELECOMMUNICATIONS AND
NETWORKING
Intranets
Intranet –
a network operating within an organization that uses
the TCP/IP protocol
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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
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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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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
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Page 124-125
© 2005 Pearson Prentice-Hall
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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
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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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