思科-networkgateway区别在cisco16448中详细地讲解了这三条命令使用条件和

ipdefault-network、iproute、ipdefault-gatewaycisco16448ipdefault-gatewayiproutingipdefault-networkiprouteipdefault-networkiproute被路由选择协议出去。ipdefault-network产生的默认路由是可以被EIGRP和RIP的但不被OSPFRIPipdefault-network，debugipripiproute也可以被EIRGP，但是这条静态路由必须重分发到EIGRP协议中；在12.0T以后的IOS版本中，RIP将不默认路由，除非RIPRIP同样，在OSPF中也不能该命令产生的默认路由，（default-informationoriginate）ipdefault-network同时使用ipdefault-networkiproute方设定默认路由时，如果ipdefault-network设定的网络是直连（静态、且已知）的，那么它就成为默认路由；如果ipdefault-network指定的网络是由交换路由信iproute最后，如果使用多条iproute令，则流量会自动在多条链负载均衡。ipdefault-gateway，ipdefault-networkiproute默认路由的区别中遇到了也不犯错了。指定默认路由（lastresortgateway）31、ipdefault-iproutingipdefault-gateway2、ipdefault-networkiproute两者都用于iprouting有效的路由器上，区别主要在于路由协议是否这条路由信息。比如：IGRP无法识别，因此默认路由时必须用ipipdefault-networkadministrativedistance同时使用ipdefault-networkiproute双方设定默认路由iprouteiprouteiproutingmycisco(config)#noiproutingmycisco(config)#ipdefault-gatewayType sequencetoSending5,100-byteICMPEchoesto5,timeoutis2Successrateis100percent(5/5),round-tripmin/avg/max=60/60/60msmycisco#showiprouteDefaultgatewayisHostGatewayLastUseTotalUsesInterfaceICMPredirectcacheisemptyiprouteiprouteType sequencetoSending5,100-byteICMPEchoesto5,timeoutis2Successrateis100percent(5/5),round-tripmin/avg/max=56/56/60msmycisco#showiprouteCodes:C–connected,S–static,I–IGRP,R–RIP,M–mobile,–D–EIGRP,EX–EIGRPexternal,O–OSPF,IA–OSPFinterareaE1–OSPFexternaltype1,E2–OSPFexternaltype2,E–EGPi–IS-IS,L1–IS-ISlevel-1,L2–IS-ISlevel-2,*–candidatedefaultU–per-userstaticrouteGatewayoflastresortistonetworkC/8isdirectlyconnected,Loopback0C/24isdirectlyconnected,Ethernet0S*/0[1/0]viaipdefault-networkmycisco(config)#iproutemycisco#showipCodes:C–connected,S–static,I–IGRP,R–RIP,M–mobile,–D–EIGRP,EX–EIGRPexternal,O–OSPF,IA–OSPFinterareaE1–OSPFexternaltype1,E2–OSPFexternaltype2,E–EGPi–IS-IS,L1–IS-ISlevel-1,L2–IS-ISlevel-2,*–candidatedefaultU–per-userstaticrouteGatewayoflastresortisnotC/8isdirectlyconnected,Loopback0S/8[1/0]viaC/24isdirectlyconnected,接着执行mycisco(config)#ipdefault-networkmycisco#showipCodes:C–connected,S–static,I–IGRP,R–RIP,M–mobile,–D–EIGRP,EX–EIGRPexternal,O–OSPF,IA–OSPFinterareaE1–OSPFexternaltype1,E2–OSPFexternaltype2,E–EGPi–IS-IS,L1–IS-ISlevel-1,L2–IS-ISlevel-2,*–candidatedefaultU–per-userstaticrouteGatewayoflastresortistonetworkC/8isdirectlyconnected,Loopback0S*/8[1/0]viaC/24isdirectlyconnected,ipdefault-ipdefault-gatewaycommanddiffersfromtheothertwocommandsinthatitshouldonlybeusedwheniproutingisdisabledontheCiscorouter.Forinstance,iftherouterisahostintheIPworld,youcanusethiscommandtodefineadefaultgatewayforit.YoumightalsousethiscommandwhenyourlowendCiscorouterisinbootmodeinordertoTFTPaCiscoIOS®Softwareimagetotherouter.Inbootmode,therouterdoesnothaveiproutingenabled.ipdefault-Unliketheipdefault-gatewaycommand,youcanuseipdefault-networkwheniproutingisenabledontheCiscorouter.Whenyouconfigureipdefault-networktherouterconsidersroutestothatnetworkforinstallationasthegatewayoflastresortontherouter.Foreverynetworkconfiguredwithipdefault-network,ifarouterhasaroutetothatnetwork,thatrouteisflaggedasacandidatedefaultroute.LookatthefollowingroutingtabletakenfromaCiscorouter:2513#showipCodes:C-connected,S-static,I-IGRP,R-RIP,M-mobile,B-BGPD-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterareaE1-OSPFexternaltype1,E2-OSPFexternaltype2,E-EGPi-IS-IS,L1-IS-ISlevel-1,L2-IS-ISlevel-2,*-candidatedefaultGatewayoflastresortisnotsetissubnetted,1subnets isdirectlyconnected,Ethernet0S[1/0]viaissubnetted,1subnets isdirectlyconnected,Notethestaticroutetoviaandthatthegatewayoflastresortisnotset.Ifyouconfigureipdefault-network,theroutingtablechangestothefollowing:2513#showipCodes:C-connected,S-static,I-IGRP,R-RIP,M-mobile,B-BGPD-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterareaE1-OSPFexternaltype1,E2-OSPFexternaltype2,E-EGPi-IS-IS,L1-IS-ISlevel-1,L2-IS-ISlevel-2,*-candidatedefaultGatewayoflastresortistonetworkissubnetted,1subnets isdirectlyconnected,Ethernet0 [1/0]viaS*[1/0]viaissubnetted,1subnets isdirectlyconnected,TokenRing02513#showipprotocolsYoucanseethegatewayoflastresorthasnowbeensetas.Thisresultisindependentofanyroutingprotocol,asshownbytheshowipprotocolscommandatthebottomoftheoutput.YoucanaddanothercandidatedefaultroutesimplybyconfiguringanotherinstanceofipEnterconfigurationcommands,oneperline.EndwithCNTL/Z.2513(config)#ipdefault-network2513#showipCodes:C-connected,S-static,I-IGRP,R-RIP,M-mobile,B-BGPD-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterareaE1-OSPFexternaltype1,E2-OSPFexternaltype2,E-EGPi-IS-IS,L1-IS-ISlevel-1,L2-IS-ISlevel-2,*-candidatedefaultGatewayoflastresortistonetworkissubnetted,1subnets isdirectlyconnected,Ethernet0 [1/0]via [1/0]viaisvariablysubnetted,2subnets,2 [1/0]via [1/0]viaissubnetted,1subnets isdirectlyconnected,TokenRing0Noticethatafterenteringtheabovecommand,thenetworkwasnotflaggedasadefaultnetwork.Thefollowingsectionexplainswhy.FlaggingaDefaultNote:Theipdefault-networkcommandisclassful,whieansiftherouterhasaroutetothesubnetindicatedbythiscommand,itinstallstheroutetothemajornet.Atthispointneithernetworkhasbeenflaggedasthedefaultnetwork.Theipdefault-networkcommandmustbeissuedagain,usingthemajornet,inordertoflagthecandidatedefaultroute.Enterconfigurationcommands,oneperline.EndwithCNTL/Z.2513(config)#ipdefault-network2513#showipCodes:C-connected,S-static,I-IGRP,R-RIP,M-mobile,B-BGPD-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterareaE1-OSPFexternaltype1,E2-OSPFexternaltype2,E-EGPi-IS-IS,L1-IS-ISlevel-1,L2-IS-ISlevel-2,*-candidatedefaultGatewayoflastresortistonetworkissubnetted,1subnets isdirectlyconnected,Ethernet0 [1/0]via [1/0]viaisvariablysubnetted,2subnets,2 [1/0]via [1/0]viaissubnetted,1subnets isdirectlyconnected,TokenRing0Iftheoriginalstaticroutehadbeentothemajornetwork,theextrastepofconfiguringthedefaultnetworktwicewouldnothavebeennecessary.TherearestillnoIPprotocolsrunninghere.Withoutanydynamicprotocolsrunning,youcanconfigureyourroutertochoosefromanumberofcandidatedefaultroutesbasedonwhethertheroutingtablehasroutestonetworksotherthan/0.Thiscommandallowsyoutoconfigurerobustnessintotheselectionofagatewayoflastresort.Ratherthanconfiguringstaticroutestospecificnext-hops,youcanhavetherouterchooseadefaultroutetoaparticularnetworkbycheckingintheroutingtable.Ifyoulosetheroutetoaparticularnetwork,therouterselectsthesecondcandidatedefault,asspecifiedabove.Youcanremovethelostroutebyremovingthestaticrouteintheconfigurationasfollows:Enterconfigurationcommands,oneperline.EndwithCNTL/Z.2513(config)#noiproute%SYS-5-CONFIG_I:ConfiguredfromconsolebyAfterremovingthestaticroutetotheoriginaldefaultnetwork,theroutingtablelookslikethis:2513#showiprouteCodes:C-connected,S-static,I-IGRP,R-RIP,M-mobile,B-BGPD-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterareaE1-OSPFexternaltype1,E2-OSPFexternaltype2,E-EGPi-IS-IS,L1-IS-ISlevel-1,L2-IS-ISlevel-2,*-candidatedefaultGatewayoflastresortistonetworkissubnetted,1subnets isdirectlyconnected,Ethernet0 [1/0]via isvariablysubnetted,2subnets,2 [1/0]via [1/0]viaissubnetted,1subnets isdirectlyconnected,TokenRing0UsingDifferentRoutingGatewaysoflastresortselectedusingtheipdefault-networkcommandarepropagateddifferentlydependingonwhichroutingprotocolispropagatingthedefaultroute.ForIGRPandEIGRPtopropagatetheroute,thenetworkspecifiedbytheipdefault-networkcommandmustbeknowntoIGRPorEIGRP.ThismeansthenetworkmustbeanIGRP-orEIGRP-derivednetworkintheroutingtable,orthestaticrouteusedtogeneratetheroutetothenetworkmustberedistributedintoIGRPorEIGRP.RIPadvertisesarouteto.Forexample,notethatthegatewayoflastresortontherouterbelowwaslearnedusingthecombinationoftheiprouteandipdefault-networkcommands.IfyouenableRIPonthisrouter,RIPadvertisesarouteto(althoughnottotheTokenRingnetworkbecauseofsplit-horizon):%SYS-5-CONFIG_I:Configuredfromconsolebyconsole2513#debugipripRIPprotocoldebuggingisonRIP:sendingupdateto55viaEthernet0()default,metric1network,metricRIP:sendingupdateto55viaTokenRing0network,metricNote:InIOSrelease12.0Tandlater,RIPdoesnotadvertisethedefaultrouteriftherouteisnotlearnedviaRIP.Therefore,itmaybenecessarytoredistributetherouteintoRIP,orusethedefault-informationoriginatecommand.OSPF,likeRIP,advertisesaroutefor.However,withOSPF,therouteroriginatingthedefaultroutemustbeconfiguredwiththedefault-informationoriginatecommand.Formoredetailedinformation,seeHowDoesOSPFGenerateDefaultRoutes?.iprouteCreatingastaticroutetonetworkisanotherwaytosetthegatewayoflastresortonarouter.Aswiththeipdefault-networkcommand,usingthestaticroutetoisnotdependentonanyroutingprotocols.However,iproutingmustbeenabledontherouter.Note:IGRPdoesnotunderstandarouteto,thereforeitcannotpropagatedefaultroutescreatedusingtheiproutecommand.Usetheipdefault-networkcommandtohaveIGRPpropagateadefaultroute.EIGRPpropagatesaroutetonetwork,butthestaticroutemustberedistributedintoEIGRP.RIPandOSPFbehaveasdescribedwhenusingtheipdefault-networkcommand.Keepinmindthatthenoteabovestillapplies.LookatanexampleofconfiguringagatewayoflastresortusingtheiprouteEnterconfigurationcommands,oneperline.EndwithCNTL/Z.router-3(config)#iprouterouter-3#showipCodes:C-connected,S-static,I-IGRP,R-RIP,M-mobile,B-BGPD-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterareaN1-OSPFNSSAexternaltype1,N2-OSPFNSSAexternaltype2E1-OSPFexternaltype1,E2-OSPFexternaltype2,E-EGPi-IS-IS,L1-IS-ISlevel-1,L2-IS-ISlevel-2,*-candidatedefaultU-per-userstaticroute,o-ODRGatewayoflastresortistonetwork/24issubnetted,2subnetsCisdirectlyconnected,Cisdirectlyconnected,Ethernet0S*/0[1/0]viaNote:Ifyouconfiguremultiplenetworksascandidatedefaultroutesusingtheipdefault-networkcommand,thenetworkthathasthelowestadministrativedistanceischosenasthenetworkforthegatewayof