copyright prentice hall, inc. 1 computers: information technology in perspective, 11e larry long and...
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Copyright Prentice Hall, Inc. 1
Computers: Information Technology in Perspective, 11e
Larry Long and Nancy Long
Chapter 7
Networks and Networking
Copyright Prentice Hall, Inc. 2
Objectives
Once you have read and studied this chapter, you will have learned: 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
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
Everything is becoming digitally compatible: DVDs Telephones Televisions Computers Newspapers College courses Textbooks on CD-ROM Banking/Finance
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Connectivity
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
Internally (for company resources) via Intracompany networking Intranets
Externally (for world competition) via Intercompany networking Business-to-business (B2B) E-commerce (electronic
commerce) Extranets VPS Tunneling
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The Data Communications Channel
A communications channel is the medium through which digital information must pass 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
Twisted-pair wire contains two insulated copper wires twisted around each other
One twisted-pair line provides POTS 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
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
Carries data via microwave or radio signals
Transmission is line-of-sight
Use transceivers/repeater stations
Satellites Eliminates line-of-sight
limitation Geosynchronous orbit set
at 22,300 miles above earth
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Transmission Media: Without Wires
Wireless transceivers between PCs
Alternative to running twisted-pair, 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
Multichannel Multiport Distribution Service (MMDS)
Local Multiport Distribution Service (LMDS)
Wireless at fiber optic-level speeds
Will provide Internet service at 1 G bps
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Transmission Media: Fiber Optic Cable
Carries data as laser-generated 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
Asynchronous Transmission Low speed Modem needed Transmitted as needed Start/stop bits used
Synchronous Transmission High speed Source and destination in
“synch” No start/stop bits needed
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Data Communications Hardware
Data communication hardware is used to transmit digital information
There are many devices that enable data communication Concentrators Hubs Bridges Routers Brouters NIC Modems And more…
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The Standard Telephone-Link Modem
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 fiber-optic cable
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Network Interface Cards
Allows exchange of data via a LAN
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Routers
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
Enables both input and output from a remote computer system
Dumb and smart terminals
Examples: VDT (hospitals and
airports) Windows terminals Telephone terminals Special function (ATMs)
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Networks
Networks are about sharing and communicating
Networks allow printers, data, Internet access, and more to be shared
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Network Topologies
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 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
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 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
Local Area Network (LAN) Small network Usually confined to a building
or an office floor Wide Area Network (WAN)
Two or more LANs connected together
The Internet is an example Metropolitan Area Network
(MAN) Covers a large area, such as a
city
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LAN Overview
One node at a time can send Token access method Ethernet
Transmission media Twisted-pair, coax, and
fiber optic LAN Servers
File server Print server Communications Server
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LAN Software
Operating Systems Peer-to-Peer LANs LANs with dedicated
servers Client/Server
Applications Software Shared software Groupware
Networks on the Fly Portable networks
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Home Network
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
Our Wired World The Data
Communications Channel
Data Communications Hardware
Networks
© 2006 Pearson Prentice Hall Lecture Outlines PowerPoint Chapter 8 Earth Science 11e Tarbuck/Lutgens
© 2006 Pearson Prentice Hall Lecture Outlines PowerPoint Chapter 1 Earth Science 11e Tarbuck/Lutgens