Chapter 11Data CommunicationsData Communications

MANAGEMENT INFORMATION SYSTEMS 8/E

Raymond McLeod, Jr. and George Schell

Copyright 2004 Prentice-Hall, Inc.

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Communication BasicsCommunication Basics

�� Computer communications is at Computer communications is at

three levelsthree levels

–– Application level Application level

–– Computer levelComputer level

–– Communication channelCommunication channel

�� Protocol Protocol

–– Set of rules for communicationsSet of rules for communications

–– OSI StandardOSI Standard

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OSI (Open System Interconnection) OSI (Open System Interconnection)

ReferenceReference ModelModel

Layer Name Purpose

7 Application Layer Application-to-application communication

6 Presentation Layer Manage data representation conversions

5 Session Layer Establish and maintain communication channel

4 Transport Layer Guarantee end-to-end integrity of transmission

3 Network Layer Route data between network addresses

2 Data Link Layer Move data from one network address to another

1 Physical Layer Put data onto and off of the network media

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11-4

Andrew S. Tannebaum,

1996, “Computer

Network”, Third

Edition, Prentice Hall

Inc., A. Simon &

Schuster Company,

Upper Saddle River,

New Jersey 07458

11-5

Andrew S. Tannebaum, 1996, “Computer Network”, Third Edition, Prentice Hall Inc., A.

Simon & Schuster Company, Upper Saddle River, New Jersey 07458

11-6

Andrew S. Tannebaum, 1996,

“Computer Network”, Third

Edition, Prentice Hall Inc., A.

Simon & Schuster Company,

Upper Saddle River, New

Jersey 07458

ISO WebsiteISO Website

11-7

Protocols for Computer Protocols for Computer

CommunicationCommunication

�� Early computersEarly computers

–– TerminalsTerminals

–– Sneaker netSneaker net

�� System Network Architecture (SNA)System Network Architecture (SNA)

–– Established by IBM in 1974Established by IBM in 1974

–– ProprietaryProprietary

�� TokenToken--RingRing

–– Host computer controlledHost computer controlled

–– peerpeer--toto--peerpeer 11-8

Protocols for Computer Protocols for Computer

CommunicationCommunication

�� EthernetEthernet

–– Xerox working with Intel and Digital Xerox working with Intel and Digital

Equipment Corporation developed this protocolEquipment Corporation developed this protocol

–– NonNon--proprietaryproprietary

–– Defined by IEEEDefined by IEEE

–– Works on a single transmission lineWorks on a single transmission line

–– No token is passedNo token is passed

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PacketsPackets

�� Piece of the total data to be communicated, Piece of the total data to be communicated,

combined with the address of the destination combined with the address of the destination

computer for the data and other control computer for the data and other control

information.information.

Transmission Control Protocol/Internet

Protocol (TCP/IP) is one of the more

important packet switching protocols

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Analogi Analogi PacketPacket pada pipapada pipa

Analogi Analogi PacketPacket pada pada JJalan Raalan Rayyaa

Network AddressesNetwork Addresses

�� Address Address

–– FourFour--part set of numbers part set of numbers

–– Each from 0 to 255Each from 0 to 255

�� Internet Service Providers (ISPs)Internet Service Providers (ISPs)

–– User connects through common carrierUser connects through common carrier

�� Serial Line Internet Protocol (SLIP) and Serial Line Internet Protocol (SLIP) and

PointPoint--toto--Point Protocol (PPP)Point Protocol (PPP)

–– Protocols for users at homeProtocols for users at home

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Protocols for Public Phone Protocols for Public Phone

SystemsSystems

�� X.25X.25

–– analoganalog

–– older protocololder protocol

�� Integrated Services Digital Network (ISDN)Integrated Services Digital Network (ISDN)

–– Digital Digital

–– Can carry voice, data, and videoCan carry voice, data, and video

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Protocols for Public Phone Protocols for Public Phone

Systems (cont.)Systems (cont.)

�� Frame RelaysFrame Relays

–– Move to fiber opticsMove to fiber optics

�� Asynchronous Transfer Mode (ATM)Asynchronous Transfer Mode (ATM)

–– Smaller packet sizeSmaller packet size

–– Faster transmission speedsFaster transmission speeds

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Data Communications Links theData Communications Links the

General Systems Model ElementsGeneral Systems Model Elements

Standards

ManagementInformation

processor Environment

Input Transformation Output

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