chapter 10 data communications management information systems 8/e raymond mcleod, jr. and george...
TRANSCRIPT
Chapter 10Data CommunicationsData Communications
MANAGEMENT INFORMATION SYSTEMS 8/ERaymond McLeod, Jr. and George Schell
Copyright 2001 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 Reference ModelOSI Reference Model
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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ISO WebsiteISO Website
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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
Token-RingToken-Ring– Host computer controlledHost computer controlled– peer-to-peerpeer-to-peer
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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– Non-proprietaryNon-proprietary– 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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Network AddressesNetwork Addresses
Address Address – Four-part set of numbers Four-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 Point-to-Point Protocol (PPP)Point-to-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 theGeneral Systems Model ElementsGeneral Systems Model Elements
Standards
Management Informationprocessor
Environment
Input Transformation Output
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NetworksNetworks
Each device must be connected to the Each device must be connected to the communications medium via a network communications medium via a network interface card (NIC)interface card (NIC)
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Types of NetworksTypes of Networks
LAN (local area network)LAN (local area network)– Limited area but could include 100 or so microsLimited area but could include 100 or so micros– Facilitates office automationFacilitates office automation
MAN (metropolitan area networks)MAN (metropolitan area networks)– spans one city/metropolitan areaspans one city/metropolitan area
WAN (wide area network)WAN (wide area network)– Covers a large geographic areaCovers a large geographic area– Includes a wide variety of circuits Includes a wide variety of circuits – Usually includes host computersUsually includes host computers
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UsersUsers
Manager 1Manager 1
Secretary 1Secretary 1
Secretary 2Secretary 2
WorkstationWorkstation11
WorkstationWorkstation22
WorkstationWorkstation33
WorkstationWorkstation44
Manager 2Manager 2
NetworkNetworkServerServer
HardHardDiskDisk
Letter QualityLetter QualityPrinterPrinter
PlotterPlotter
A Local Area NetworkA Local Area Network 10-14
Common LAN TopologiesCommon LAN TopologiesStarStar
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Common LAN TopologiesCommon LAN TopologiesRingRing
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Common LAN TopologiesCommon LAN TopologiesBusBus
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SatelliteSatellite
EarthEarthstationstation
EarthEarthstationstation
TelephoneTelephonecompanycompanycentral officecentral office
TelephoneTelephonecompanycompanycentral officecentral office
TelephoneTelephonecompanycompanycentral officecentral office
TelephoneTelephonecompanycompanycentral officecentral office
LocalLocallooploop
User’sUser’smodemmodem
MicrowaveMicrowave towertower
MicrowaveMicrowave towertower
IXC circuitIXC circuit(interexchange(interexchange
channel)channel)
IXC circuit
(interexchange channel)
LocalLocallooploop
Wide Area Wide Area NetworkNetwork
User’sUser’smodemmodem
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Types of Networks (cont.)Types of Networks (cont.)
InternetInternet– Collection of networksCollection of networks– PublicPublic
IntranetIntranet– Uses Internet network protocolsUses Internet network protocols– Limits accessibilityLimits accessibility– FirewallFirewall
ExtranetExtranet– For trusted business partners and customersFor trusted business partners and customers
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Control of Data Control of Data Communications NetworksCommunications Networks CentralizedCentralized
– Point-of-sale terminalsPoint-of-sale terminals– Data collection terminalsData collection terminals
Distributed processingDistributed processing– Receiving computer runs programs that use dataReceiving computer runs programs that use data
Client/server processingClient/server processing– Mixes centralized and decentralized processing Mixes centralized and decentralized processing
strategiesstrategies
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Legend:
Computer Terminal
A Network of TerminalsA Network of Terminals
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Legend:
CentralComputer
DistributedComputer
A Distributed Processing A Distributed Processing NetworkNetwork
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Communications HardwareCommunications Hardware
ModemModem– Converts digital to analog and vice versaConverts digital to analog and vice versa– Bits per second determines transmission speedBits per second determines transmission speed– Local loopLocal loop
Hub Hub – Receives a data packet from a computer at one end Receives a data packet from a computer at one end
of one spoke of the star topography and copies its of one spoke of the star topography and copies its contents to all other computerscontents to all other computers
– Manageable hubsManageable hubs
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Data Communications with a Data Communications with a ModemModem
ComputerComputerModemModem ChannelChannel ModemModemComputerComputer
A modem is always required between a telephone and a digital computer
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Communications Hardware Communications Hardware (cont.)(cont.)
RouterRouter– Device that connects many LANsDevice that connects many LANs– More sophisticated than a bridgeMore sophisticated than a bridge– Process header information of a packetProcess header information of a packet
SwitchSwitch– Filters data not intended for a computer on a Filters data not intended for a computer on a
particular networkparticular network
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Communications Communications ConnectionsConnections
Private LinesPrivate Lines– Circuit that is always open to communications Circuit that is always open to communications
traffictraffic– Also called leased line or dedicated lineAlso called leased line or dedicated line– Two typesTwo types
» T-1 - Maximum speed just over 1.5 MbpsT-1 - Maximum speed just over 1.5 Mbps
» T-3 - Maximum speed 43 MbpsT-3 - Maximum speed 43 Mbps
» Collections of 64 Kbps connectionsCollections of 64 Kbps connections
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Communications Communications Connections (cont.)Connections (cont.)
Virtual Private Networks (VPNs)Virtual Private Networks (VPNs)– Tunneling software makes Internet connections Tunneling software makes Internet connections
more securemore secure– Privacy through authenticationPrivacy through authentication– More cost effective than private linesMore cost effective than private lines
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Network ManagementNetwork Management
Digital nervous systems of an organizationDigital nervous systems of an organization Network planningNetwork planning
– Anticipates firm’s network needsAnticipates firm’s network needs– Monitor’s performanceMonitor’s performance
Network ControlNetwork Control– Determines faultsDetermines faults
» Errors in data communicationErrors in data communication
» Alerts to potential faultsAlerts to potential faults
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Network Management Network Management (cont.)(cont.)
Network managerNetwork manager– Planning, implementing, operating, and controlling a Planning, implementing, operating, and controlling a
firm’s data communications network(s)firm’s data communications network(s) StaffStaff
– Network analysts (a type of systems analyst)Network analysts (a type of systems analyst)– Software analysts Software analysts – Data Communication Technicians (specialize in Data Communication Technicians (specialize in
hardware)hardware)– LAN managersLAN managers
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Wireless NetworksWireless Networks
Cellular networksCellular networks– Hand held telephonesHand held telephones– Primarily for voicePrimarily for voice
Wireless LANs Wireless LANs – Extensions of regular LANsExtensions of regular LANs
Wide-area wireless networksWide-area wireless networks– NationwideNationwide
10-30Highlights in MIS
Wireless Networks (cont.)Wireless Networks (cont.)
Paging networksPaging networks– Receive only capabilityReceive only capability
Personal Communications Network (PCN) is the networking infrastructure for wireless.
It is not yet in place!
10-31Highlights in MIS
A Network with Mobility A Network with Mobility CapabilityCapability
MSS = mobile support station MU = mobile units
MU MU MU
MU MU MU MU MU MU
MU MU MU
MSS
MSS MSS
MSS
Fixed host
Fixed host
Fixed host
Fixed host
Fixed network
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SummarySummary
Data communications enable computers to Data communications enable computers to share information and applicationsshare information and applications
NetworksNetworks– LANsLANs– MANsMANs– WANsWANs
Communication standardsCommunication standards
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Summary [cont.]Summary [cont.]
Basic HardwareBasic Hardware– HubsHubs– RoutersRouters– BridgesBridges– SwitchesSwitches
Planned growthPlanned growth
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