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Copyright 2003 Prentice Hall, Inc Slides created by Bob Koziel

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Copyright 2003 Prentice Hall, Inc 2

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NEXTSLIDE

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Copyright 2003 Prentice Hall, Inc

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Chapter 7

Networks: Communicating and Sharing Resources

COMPUTERS IN YOUR FUTURE 2004by Bryan Pfaffenberger and Bill Daley

Chapter 7

Networks: Communicating and Sharing

ResourcesWhat You Will Learn

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Major types of computer networks

How computer connections increase the value of anorganizations information technology investment

The importance of protocols in a computer network

Contrast between circuit switching and packet switching,

as well as their strengths and weaknesses

Differences between peer-to-peer and client/server LANs

The most popular LAN protocol and its benefits

Business applications of WANs

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Copyright 2003 Prentice Hall, Inc 6NEXT

SLIDE

Reduced hardwarecosts

Users share

equipment

Connected people People can work

together without being

at the same location

Groupware enables

sharing of schedulesand communications

Networking Synergies in a Nutshell

Shared applications Users share software

File server enables all

users to work with the

same application

program

Building information

resources

Users create common

pools of data that can

be accessed by

employees

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SLIDE

Network Fundamentals

Physical media used in networks:

CablesTelephone lines, coaxial cable,microwave, satellites, wireless, and fiber opticcables connect computers.

RoutersDevices that examine the data

transmitted and send it to its destination.

SwitchesHigh speed electronic switchesmaintain connections between computers.

ProtocolsStandards that specify how networkcomponents communicate with each other.

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SLIDE

Circuit switching Network creates an end-

to-end circuit between thesending and receiving

computers

Same as voice networks

Suited to voice and real-

time videoconferencing

Switching and Routing Techniques

Packet switching

Outgoing message is

divided into fixed-size

data units called packets Packets are numbered and

addressed to receiving

computer

Routers examine the

packets and send them to

their destination

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Advantages Disadvantages

Circuit switching

Voice and real-timetransmission

No delivery delays

Costly

Need to have directelectrical connection

between computers tocommunicate

Packet switching

Efficient, lessexpensive, reliable

Will function if part ofthe network is down

Delays in receivingpackets

Not ideal for real-timevoice communication

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SLIDE

Advantages and Disadvantages of Circuit

and Packet Switching

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SLIDE

Protocols

Protocolsare fixed, formalized exchanges that

specify how two dissimilar network components canestablish communication.

Proprietary protocolsAre standards developed andprotected by hardware manufacturers. All hardware

is bought from same manufacturer for the network tofunction.

Open protocolsAre nonproprietary protocols. Theyare established by independent organizations. Any

hardware supporting the protocols will operate onthe network.

Protocol suiteThe total package of protocols thatspecify how a network functions.

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SLIDE

Network Architecture

Network architectureis the overall design of a

network.

The network design is divided into layers, each of

which has a function separate from that of the other

layers. Protocol stackThe vertical (top to bottom)

arrangement of the layers. Each layer is governed by

its own set of protocols.

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SLIDE

Peer-to-Peer Networks

All computers on the network are treated as equal. There are no file servers.

Users decide which files and peripherals to share.

They arent suited for networks with many

computers. They are easy to set up. Example: Home networks

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SLIDE

Client-Server Networks

Typical corporate networks are client-server.

They use various topologiesor physical layouts.

The network requires file servers, networked computers(clients), and a network operating system (NOS).

Clients send requests to servers for programs and data,

and to access peripherals.

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Network Media

NEXT

SLIDE

LANs use a variety of media to carry network signals.

Twisted pairTwo insulated wires twisted around eachother. The same type of wire as that used for telephones.

Coaxial cableConsists of an insulated center wire

surrounded by a layer of braided wire. The same type of

wire as that used for cable TV. Fiber-optic cableA type of fiber glass cable that transmits

data in the form of light impulses. It can carry more data for

longer distances than other wire.

InfraredA wireless system that includes a transmitter and

receiver for sending and receiving signals.

RadioA wireless system that uses radio signals to send

and receive data.

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LAN Topologies The physical layout of a LAN is called its topology.

Topologies resolve the problem of contention,whichoccurs when multiple users try to access the LAN at thesame time.

Collisionsor corrupt data occur when differentcomputers use the network at the same time.

Bus topology

Called daisy chain

Every workstation connected

to a single bus cable

Resolves collisions through

contention management

Difficult to add workstations

Star topology

Contains a hub or central

wiring concentrator

Easy to add workstations

Resolves collisions through

contention management

Ring topology

All workstations attached in a

circular arrangement

A special unit of data called a

token travels around the ring

Workstations can only

transmit data when they

possess a token

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SLIDE

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SLIDE

LAN Technologies

LAN protocols are standards that govern the layers of

the protocol stack. Lower-layer protocols deal with contentionbetween

computers.

Lower-layer protocols:

Ethernet LocalTalk

Token ring

Higher-layer protocols handle the network functions.

Higher-layer protocols: AppleTalk IPX/SPX

NetBeui

TCP/IP

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SLIDE

Wide Area Networks (WANs)

WANsare similar to long-distance telephone systems.

They have a local access number called a point ofpresence(POP).

They contain long-distance trunk lines called backbones.

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SLIDE

Point of Presence (POP)

A point of presenceis a WAN network connectionpoint that enables customers to access the WAN by

making a local telephone call.

Media used to create a connection from an

organization to a POP include: 56 Kbpsleased line

ISDN

ADSL

T1 line

Permanent virtual circuit (PVC)

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Private Data Network

Used by corporations, banks and

governments

Not open to the public

Most secure type of WAN

Virtual private networkLines are leased

to a single company

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SLIDE

WAN Organization

Internet

Backbone providers charge

fees to Internet Service

Providers(ISPs).

ISPs sell subscriptions to

users.

Not secure

Not ideal for businesses

Public Data Network (PDN)

A for-profit data

communications network

Fees paid on a per-byte-

transferred basis

Good security

High bandwidth

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SLIDE

WAN Protocols

X.25Oldest packet switching protocol. It is used by

automated teller machines and credit cardauthorization devices.

Switched Multimegabit Data Service (SMDS)

Designed for digital phone lines. Faster data transferrates than X.25.

Asynchronous Transfer Mode (ATM)Newer type of

protocol. It is designed for digital lines.

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Electronic Data Interchange (EDI)

Standards that specify how companies set upbusiness-to-business transactions

Speeds ordering, invoicing, and payments

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SLIDE

WAN Applications

LAN-to-LAN WANs used to connect

LANs at two or more

geographic locations

Used to connect branches of

a company into one networksystem

Transaction Acquisition Information about

transaction instantly relayed

to corporate headquarters

Uses point-of-sale (POS)

terminal as cash register

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Copyright 2003 Prentice Hall, Inc 25NEXTSLIDE

Chapter 7 Summary

1. Computer networks link two or more computers to

exchange data and share resources.

2. Three types of computer networks:

A. Local area network (LAN)

B. Metropolitan area network (MAN)

C. Wide area network (WAN)

3. Computer networks:A. Reduce hardware costs

B. Enable users to share applications

C. Provide a means to pool an organizations data

D. Foster teamwork

4. Computer networks require physical media such astelephone wire, coaxial cable, infrared, and radio

signals to connect the computers.

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Copyright 2003 Prentice Hall, Inc 26NEXTSLIDE

Chapter 7 Summary cont.

5. Network protocols enable the network to function

smoothly.

6. Data is sent through the network by switching and

routing techniques.

7. LAN topologies include:

A. Bus topologyB. Star topology

C. Ring topology

8. Wide area networks are used to link computers

throughout the world.

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