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OSPF协议及配置,链路状态协议(Link-StateProtocols),OSPF概述(OSPFOverview),分层设计(HierarchicalDesign),1.大的OSPF网络采用分层设计,所有区域连接到主干区域。LargeOSPFnetworksuseahierarchicaldesign.Multipleareasconnecttoadistributionarea,area0,alsocalledthebackbone.2.好处(benefit):(1)减少路由更新(reducesroutingoverhead)(2)加速收敛(speedsupconvergence)(3)限制不稳定到一个区域(confinesnetworkinstabilitytoanarea)(4)提高网络性能(improvesperformance),OSPF术语(OSPFTerminology),OSPF数据包类型(OSPFPacketTypes),OSPF数据包头格式(OSPFPacketHeaderFormat),OSPF操作(OSPFOperation),1.建立邻接关系Establishrouteradjacencies2.必要的进行DR选举ElecttheDR/BDR(ifnecessary)3.发现路由Discoverroutes4.选择相应的路由Selectappropriateroutes5.维护路由信息Maintainroutinginformation,邻居关系(Neighborship),*标记的在邻居路由器上必须匹配,建立双向通信(EstablishingBidirectionalCommunication),建立双向通信(EstablishingBidirectionalCommunication),建立双向通信(EstablishingBidirectionalCommunication),建立双向通信(EstablishingBidirectionalCommunication),查找网络路由(DiscoveringtheNetworkRoutes),查找网络路由(DiscoveringtheNetworkRoutes),增加链路状态条目(AddingtheLink-StateEntries),增加链路状态条目(AddingtheLink-StateEntries),增加链路状态条目(AddingtheLink-StateEntries),维护路由信息(MaintainingRoutingInformation),路由器用224.0.0.6通知DRRouterAnotifiesallOSPFDRson224.0.0.6,维护路由信息(MaintainingRoutingInformation),DR利用组播地址224.0.0.5通知其它路由器DRnotifiesotherson224.0.0.5,维护路由信息(MaintainingRoutingInformation),维护路由信息(MaintainingRoutingInformation),维护路由信息(MaintainingRoutingInformation),OSPF网络类型(OSPFNetworkTypes),FrameRelayX.25,广播BroadcastMultiaccess,非广播NonbroadcastMultiaccess,点到点Point-to-Point,点到多点Point-to-Multipoint,点到点链路(Point-to-PointLinks),1.不进行DR选举NoDRorBDRelectionrequired2.OSPF自动检测这种接口类型OSPFautodetectsthisinterfacetype,广播型多路访问网络(MultiaccessBroadcastNetwork),1.进行DR选举DRandBDRselectionrequired2.邻居只与DR和DBR形成邻接关系AllneighborroutersformfulladjacencieswiththeDRandBDRonly,选举DR和BDR(ElectingtheDRandBDR),1.最高接口优先级的路由器被选成DRTherouterwiththehighestOSPFpriorityisselectedastheDR.2.最高路由器ID的路由器被选举成DRUsetheOSPFrouterIDasthetiebreaker.3.DR选举不具有抢占性TheDRelectionisnonpreemptive.,设置接口优先级(SettingInterfacePriority),ipospfprioritynumber,1.不同的接口可以指定不同的值Differentinterfacesonaroutermaybeassigneddifferentvalues.2.接口优先级默认为1,取值范围是0-255Thedefaultpriorityis1.Therangeisfrom0to255.3.接口优先级为0表示不参加DR选举0meanstherouterisaDROTHER;itcantbetheDRorBDR.,Router(config-if)#,routerospfprocess-id,Router(config)#,启动路由进程TurnsononeormoreOSPFroutingprocesses,OSPF基本配置(ConfiguringBasicOSPF),networkaddressinverse-maskareaarea-id,Router(config-router)#,用network命令ospf运行的接口,并将网络指定到特定的区域RouterOSPFsubordinatecommandthatdefinestheinterfaces(bynetworknumber)thatOSPFwillrunon.Eachnetworknumbermustbedefinedtoaspecificarea.,OSPF配置实例(ConfiguringOSPFExample),验证ospf配置(VerifyingOSPFOperation),showipprotocolsShowipospfneighborShowipospfdatabaseShowiprouteShowipospfShowipospfinterfaceDebugipospfadjDebugipospfevent,确定OSPF路由器ID(OSPFRouterID),1.通过router-id命令指定的最为优先AnOSPFrouter-idcommandcanoverrideOSPFrouterID.2.最高的环回接口地址次之AloopbackinterfacecanoverrideOSPFrouterID.ItisthehighestIPaddressofanyactiveloopbackinterface.3.最后是最高活动的物理接口的IP地址therouterIDisthehighestIPaddressonanactiveinterfaceatthemomentofOSPFprocessstartup.为了稳定,命令或环回接口被推荐Theloopbackorrouter-idcommandisrecommendedforstability.,环回接口(LoopbackInterfaces),interfaceloopback0,ipaddress172.16.17.5255.255.255.255,如果ospf路由进程已经启动,必须重新清除ospf进程,新的路由器ID才生效。IftheOSPFprocessisalreadyrunning,theOSPFprocessmustbeclearedbeforethenewrouter-idcommandwilltakeeffect.,Router(config)#,Router(config-if)#,router-idip-address,这是路由进程下的子命令Thiscommandissubordinatetotherouter-idospfcommand.用clearipospfprocess命令可以使得配置生效。IfthiscommandisusedonanOSPFprocessthatisalreadyactive,thenthenewrouterIDisusedatthenextreloadoratamanualOSPFprocessrestartusingtheclearipospfprocesscommand.,OSPFrouter-id命令(OSPFrouter-idcommand),routerospf1,router-id172.16.1.1,Router(config-router)#,Router(config-if)#,Router(config-router)#,显示路由器ID(OSPFRouterIDVerification),RouterA#showipospfRoutingProcessospf1withID1.1.3.1SupportsonlysingleTOS(TOS0)routesSPFscheduledelay5secs,HoldtimebetweentwoSPFs10secsNumberofDCbitlessexternalLSA0NumberofDoNotAgeexternalLSA0Numberofareasinthisrouteris1.1normal0stub0nssaAreaBACKBONE(0)(Active)Numberofinterfacesinthisareais2AreahasnoauthenticationSPFalgorithmexecuted10timesArearangesareLinkStateUpdateIntervalis00:30:00andduein0:07:16LinkStateAgeIntervalis00:20:00andduein00:07:15NumberofDCbitlessLSA0NumberofindicationLSA0NumberofDoNotAgeLSA0,配置OSPF计时器(ConfiguringOSPFTimers),OSPF计时器在接口下配置,配置OSPF认证(ConfiguringOSPFAuthentication),维护大的OSPF网络的问题(IssueswithMaintainingaLargeOSPFNetwork),解决方案:OSPF分层路由(TheSolution:OSPFHierarchicalRouting),OSPF路由器类型(TypesofOSPFRouters),OSPF路由器类型(TypesofOSPFRouters),OSPF路由器类型(TypesofOSPFRouters),OSPF路由器类型(TypesofOSPFRouters),OSPF路由器类型(TypesofOSPFRouters),OSPF路由的类型(TypesofRoutes),E1和E2路由cost计算(CalculatingCostsforE1andE2Routes),E1和E2路由cost计算(CalculatingCostsforE1andE2Routes),areaarea-idrangeaddressmask,Router(config-router)#,Consolidatesinter-area(IA)routesonanABR,配置路由汇总(ConfiguringRouteSummarization),summary-addressaddressmasknot-advertisetagtag,Router(config-router)#,Consolidatesexternalroutes,usuallyonanASBR,在ABR配置路由汇总实例(RouteSummarizationConfigurationExampleatABR),在ASBR配置路由汇总实例(RouteSummarizationConfigurationExampleatABSR),RIPv2必须重分布进OSPFRIPv2mustberedistributedintoOSPF,OSPF中默认路由(DefaultRoutesinOSPF),default-informationoriginatealways,Router(config-router)#,默认路由配置实例(DefaultRouteConfigurationExample),CaseStudy,思考题(Questions),1.OSPF是一种典型的_路由协议。2.OSPF路由协议的管理距离是_。3.OSPF路由协议采用_作为度量标准。4.OSPF路由器利用_算法,独立地计算出到达任意目的地的路由。5.默认情况下,快速以太网的开销是_。6.OSPF将网络划分为四种类型:_、_、_、_。7.Ethernet的HelloInterval为_秒,DeadInterval为_秒。8.NBMA网络的HelloInterval_秒,DeadInterval为_秒。9.OSPF路由器可以周期性发送_包来建立和维持邻居关系。10.当DR和BDR需要发送一个LSU时,它会将更新发送给组播地址_。11.OSPF接口优先级的范围是_。12.OSPF路由进程process-id必须指定范围在_。13.当络区域ID为_的区域称为主干区域。14._命令用来查看邻居及其状态。15.OSPF通过_两种方法启用认证功能。16.OSPF路由器的类型为_、_、_、_。17.OSPF区域类型包括_、_、_、_。18._区域负责把LSAType7转换成LSAType5。19.OSPF路由汇总的两种类型包括_。20.如何确定RouterID?21.OSPF的特性包括哪些?,
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