ip路由协议配置手册

CHAPTERConfiguringIPRoutingProtocols19-1ConfiguringIPRoutingProtocols19ThischapterdescribeshowtoconfigurethevariousInternetProtocol(IP)routingprotocols.Foracompletedescriptionofthecommandslistedinthischapter,refertothe“IPRoutingProtocolsCommands”chapteroftheRouterProductsCommandReferencepublication.ForinformationonconfiguringtheIPprotocol,refertothe“ConfiguringIP”chapterofthismanual.Cisco’sImplementationofIPRoutingProtocolsCisco’simplementationofeachoftheIProutingprotocolsisdiscussedindetailatthebeginningoftheindividualprotocolsectionsthroughoutthischapter.IProutingprotocolsaredividedintotwoclasses:InteriorGatewayProtocols(IGPs)andExteriorGatewayProtocols(EGPs).TheIGPsandEGPsthatCiscosupportsarelistedinthefollowingsections.NoteManyroutingprotocolspecificationsrefertoroutersasgateways,sothewordgatewayoftenappearsaspartofroutingprotocolnames.However,arouterusuallyisdefinedasaLayer3internetworkingdevice,whereasaprotocoltranslationgatewayusuallyisdefinedasaLayer7internetworkingdevice.Thereadershouldunderstandthatwhetheraroutingprotocolnamecontainstheword“gateway”ornot,routingprotocolactivitiesoccuratLayer3oftheOSIreferencemodel.InteriorGatewayProtocolsInteriorprotocolsareusedforroutingnetworksthatareunderacommonnetworkadministration.AllIPinteriorgatewayprotocolsmustbespecifiedwithalistofassociatednetworksbeforeroutingactivitiescanbegin.Aroutingprocesslistenstoupdatesfromotherroutersonthesenetworksandbroadcastsitsownroutinginformationonthosesamenetworks.Theinteriorroutingprotocolssupportedareasfollows:�InternetGatewayRoutingProtocol(IGRP)�EnhancedInternetGatewayRoutingProtocol(EnhancedIGRP)�OpenShortestPathFirst(OSPF)�RoutingInformationProtocol(RIP)�IntermediateSystem-to-IntermediateSystem(IS-IS)19-2RouterProductsConfigurationGuideCisco’sImplementationofIPRoutingProtocolsExteriorGatewayProtocolsExteriorprotocolsareusedtoexchangeroutinginformationbetweennetworksthatdonotshareacommonadministration.IPexteriorgatewayprotocolsrequirethreesetsofinformationbeforeroutingcanbegin:�Alistofneighbor(orpeer)routerswithwhichtoexchangeroutinginformation�Alistofnetworkstoadvertiseasdirectlyreachable�TheautonomoussystemnumberofthelocalrouterThesupportedexteriorgatewayprotocolsareasfollows:�BorderGatewayProtocol(BGP)�ExteriorGatewayProtocol(EGP)RouterDiscoveryProtocolsOurroutersalsosupporttworouterdiscoveryprotocols,GatewayDiscoveryProtocol(GDP)andICMPRouterDiscoveryProtocol(IRDP),whichallowhoststolocaterouters.GDPwasdevelopedbyCiscoandisnotanindustrystandard.UnsupportedexampleGDPclientscanbeobtaineduponrequestfromCisco.OurIRDPimplementationfullyconformstotherouterdiscoveryprotocoloutlinedinRFC1256.MultipleRoutingProtocolsYoucanconfiguremultipleroutingprotocolsinasingleroutertoconnectnetworksthatusedifferentroutingprotocols.Youcan,forexample,runRIPononesubnettednetwork,IGRPonanothersubnettednetwork,andexchangeroutinginformationbetweentheminacontrolledfashion.Theavailableroutingprotocolswerenotdesignedtointeroperatewithoneanother,soeachprotocolcollectsdifferenttypesofinformationandreactstotopologychangesinitsownway.Forexample,RIPusesahop-countmetricandIGRPusesafive-elementvectorofmetricinformation.Inthecasewhereroutinginformationisbeingexchangedbetweendifferentnetworksthatusedifferentroutingprotocols,therearemanyconfigurationoptionsthatallowyoutofiltertheexchangeofroutinginformation.Ourrouterscanhandlesimultaneousoperationofupto30dynamicIProutingprocesses.Thecombinationofroutingprocessesonaroutercanconsistofthefollowingprotocols(withthelimitsnoted):�Upto30IGRProutingprocesses�Upto30OSPFroutingprocesses�OneRIProutingprocess�OneIS-ISprocess�OneBGProutingprocess�Upto30EGProutingprocessesConfiguringIPRoutingProtocols19-3IPRoutingProtocolsTaskListIPRoutingProtocolsTaskListWithanyoftheIProutingprotocols,youneedtocreatetheroutingprocess,associatenetworkswiththeroutingprocess,andcustomizetheroutingprotocolforyourparticularnetwork.YouwillneedtoperformsomecombinationofthetasksinthefollowingsectionstoconfigureIProutingprotocols:�DetermineaRoutingProcess�ConfigureIGRP�ConfigureEnhancedIGRP�ConfigureOSPF�ConfigureRIP�ConfigureIS-IS�ConfigureBGP�ConfigureEGP�ConfigureGDP�ConfigureIRDP�ConfigureIPMulticastRouting�ConfigureRoutingProtocol-IndependentFeatures�MonitorandMaintaintheIPNetworkSeetheendofthischapterforIProutingprotocolconfigurationexamples.DetermineaRoutingProcessChoosingaroutingprotocolisacomplextask.Whenchoosingaroutingprotocol,consider(atleast)thefollowing:�Internetworksizeandcomplexity�Supportforvariable-lengthsubnetmasks(VLSM);IS-IS,staticroutes,andOSPFsupportVLSM.�Internetworktrafficlevels�Securityneeds�Reliabilityneeds�Internetworkdelaycharacteristics�Organizationalpolicies�OrganizationalacceptanceofchangeThefollowingsectionsdescribetheconfigurationtasksassociatedwitheachsupportedroutingprotocol.Thispublicationdoesnotprovidein-depthinformationonhowtochooseroutingprotocols;youmustchooseroutingprotocolsthatbestsuityourneeds.19-4RouterProductsConfigurationGuideConfigureIGRPConfigureIGRPTheInteriorGatewayRoutingProtocol(IGRP)isadyna