Computers:
Information Technology in Perspective, 11e
Larry Long and Nancy Long
Chapter 7
Networks and Networking
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Objectives
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Once you have read and studied this chapter, you will
have learned:
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How the application of the concept of connectivity is affecting
your life.
Alternatives and sources of data transmission services that have
enabled the networking of our world.
The function and operation of data communications hardware.
The various kinds of network topologies, essential local area
network concepts and terminology, and the scope and potential
of home networking.
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Why this chapter is important to you!
Learning about data communications and
networking before going online will save
you both time and money
 Learning about networks is not just for the
office anymore; more and more homes are
being networked everyday
 Understanding about networks can save a
lot of frustration
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Our Wired World
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Understanding
information technology
trends will help people
cope with our increasingly
wired society
People are knowledge
workers by day
By night, people surf the
Internet
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Digital Convergence
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Everything is becoming
digitally compatible:
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DVDs
Telephones
Televisions
Computers
Newspapers
College courses
Textbooks on CD-ROM
Banking/Finance
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Connectivity
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Connectivity means:
 Accessing
information
from one department
to the next
 Sharing a printer
 Communicating with
suppliers
 Sending a holiday
newsletter via e-mail
 Networking your home
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The Era of Cooperative Processing
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Internally (for company
resources) via
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Intracompany networking
Intranets
Externally (for world
competition) via
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Intercompany networking
Business-to-business (B2B)
E-commerce (electronic
commerce)
Extranets
VPS
Tunneling
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The Data Communications
Channel
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A communications
channel is the medium
through which digital
information must pass
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Same as line, link, or pipe
Requires special hardware
that transmits the digital
information between
computers
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Transmission Media: Twisted-Pair Wire
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Twisted-pair wire contains
two insulated copper
wires twisted around
each other
One twisted-pair line
provides POTS
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Plain old telephone service:
analog line that permits
voice service
Another service is DSL

Digital subscriber line
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Transmission Media: Coaxial Cable
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Coax: the cable in “cable
television”
Minimum signal distortion
Has a very wide pipe
Hundreds of times faster
than POTS
100 times faster than
ISDN
Need a cable modem
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Transmission Media: Wireless
Communication
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Carries data via
microwave or radio
signals
Transmission is line-ofsight
Use transceivers/repeater
stations
Satellites
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Eliminates line-of-sight
limitation
Geosynchronous orbit set
at 22,300 miles above
earth
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Transmission Media: Without Wires
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Wireless transceivers between
PCs
Alternative to running twistedpair, coax, or fiber optics
Hooks into USB, PCI, or
PCMCIA slot
Limited range about 50 feet
Use omnidirectional radio
waves
Limited channel capacity
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The Future of Wireless
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Multichannel Multiport
Distribution Service
(MMDS)
Local Multiport
Distribution Service
(LMDS)
Wireless at fiber opticlevel speeds
Will provide Internet
service at 1 G bps
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Transmission Media: Fiber Optic Cable
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Carries data as lasergenerated pulses of light
Foundation transmission
medium for Internet
backbone
Better for data security
Future technology looks
like very big “pipe”
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Common Carriers
AT&T, MCI, Sprint,
etc.
 Private Line Leased Line
 Switched Line Dialup Line
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Controlling Transmissions over
Communications Channels

Communication
protocols
 Rules
that govern the
way data are
transmitted
 TCP/IP (Transmission
Control
Protocol/Internet)
Protocol
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Asynchronous and Synchronous
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Asynchronous
Transmission
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Low speed
Modem needed
Transmitted as needed
Start/stop bits used
Synchronous
Transmission
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High speed
Source and destination in
“synch”
No start/stop bits needed
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Data Communications Hardware
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Data communication hardware
is used to transmit digital
information
There are many devices that
enable data communication
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Concentrators
Hubs
Bridges
Routers
Brouters
NIC
Modems
And more…
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The Standard Telephone-Link Modem
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Modulator-demodulator
Converts digital signals to
analog signals for
transmission over phone
lines
Internal and external
Usually a voice/data/fax
modem
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Other Modems

Cable modem
 Supports
cable
Internet

DSL modem
 High-speed
Internet
connection using fiberoptic cable
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Network Interface Cards
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Allows exchange of
data via a LAN
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Routers
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Hardware and software
used to ease the
problems of linking
incompatible networks
Routes messages to
proper destinations
Backbone is a system of
routers and transmission
media that link computers
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Terminals
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Enables both input and
output from a remote
computer system
Dumb and smart
terminals
Examples:
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VDT (hospitals and
airports)
Windows terminals
Telephone terminals
Special function (ATMs)
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Networks
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Networks are about
sharing and
communicating
Networks allow
printers, data, Internet
access, and more to
be shared
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Network Topologies
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Network topology is a
description of the
possible physical
connections within a
network
It is a configuration of
hardware and it shows
which pairs of nodes can
communicate
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Network Topology - Star
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Uses Category 5 cable (cat 6 is on
the way)
Cat 5 cable uses an RJ-45
connector for the NIC card
Easy to install/not that expensive
Computers are concentrated into
a star pattern using hubs or
switches
Hubs broadcast data to all devices
Switches can be used instead of
hubs
Switches can help segment data
traffic but are more expensive
If there is a break in the cable it
does not disturb the other
computers
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Network Topology - Ring
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Uses different hardware
More expensive
Complex to install
Data is passed around
the ring until it reaches
its destination
Best at passing data
with less collisions
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Network Topology - Bus
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Least expensive/easiest to setup
Uses coax cable
Computers are daisy chained together in a linear bus
Data packets are sent along the coax cables
All computers hear data sent out
A BNC connector is used for the NIC card
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Types of Networks
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Local Area Network (LAN)

Small network
 Usually confined to a building
or an office floor
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Wide Area Network (WAN)
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Two or more LANs connected
together
The Internet is an example
Metropolitan Area Network
(MAN)
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Covers a large area, such as a
city
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LAN Overview
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One node at a time can
send
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Transmission media
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Token access method
Ethernet
Twisted-pair, coax, and
fiber optic
LAN Servers
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File server
Print server
Communications Server
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LAN Software
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Operating Systems
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Applications Software
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Peer-to-Peer LANs
LANs with dedicated
servers
Client/Server
Shared software
Groupware
Networks on the Fly
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Portable networks
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Home Network
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Home networks are becoming
more popular
Home networks are typically
peer-to-peer
A router keeps track of all the
computers inside the home
network
The computers are configured
with fake IP addresses that
allows them to communicate
Setup for a home computer is
fairly easy
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Summary
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Our Wired World
The Data
Communications
Channel
Data Communications
Hardware
Networks
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