高级路由OSPF协议详解.ppt

OSPF路由协议 OSPF路由综述 OSPF协议概述数据包类型网络类型邻居关系状态链路状态通告 LSA 类型路由器类型区域类型 单区域 多区域 Stub NSSAOSPF和RIP重分布 OSPF是链路状态路由协议 可适应大规模网络路由变化收敛速度快无路由自环支持VLSM支持等值路由支持区域划分提供路由分级管理支持验证支持以组播地址发送协议报文 OSPF分层的路由 由区域和自治系统组成路由更新流量很少 ShortestPathFirst算法 将路由器放在树根 基于累加的值计算到达每个网络的最短路径 Cost 108 bandwidth bps 选择路由 TopologyTableNetCostOutInterface10 2 2 06To010 3 3 07To010 3 3 010E0 Cost 10 Cost 6 Cost 1 A B C Thisisthebestrouteto10 3 3 0 10 1 1 0 24 10 2 2 0 24 10 3 3 0 24 10 4 4 0 24 OSPF数据包类型 OSPF包头 OSPF数据包在hello头标中载有的信息 邻居关系 Hello afadjfjorqpoeru39547439070713 RouterIDHello deadintervalsNeighborsArea IDRouterpriorityDRIPaddressBDRIPaddressAuthenticationpasswordStubareaflag Entrymustmatchonneighboringrouters 邻居关系 cont Hello afadjfjorqpoeru39547439070713 RouterIDHello deadintervalsNeighborsArea IDRouterpriorityDRIPaddressBDRIPaddressAuthenticationpasswordStubareaflag Entrymustmatchonneighboringrouters OSPF网络类型 Point to PointNeighborship RouterdynamicallydetectsitsneighboringrouterusingtheHelloprotocolNoelection 选举 AdjacencyisautomaticassoonasthetworouterscancommunicateOSPFpacketsarealwayssentasmulticast224 0 0 5 NBMATopology X 25FrameRelayATM Singleinterfaceinterconnects 相互连接 multiplesitesNBMAtopologiessupportmultipleroutersbutwithoutbroadcastingcapabilities 能力 FrameRelayTopologies Star HubandSpoke FullMesh PartialMesh DRSelectioninNBMATopology OSPFconsiders 认为 NBMAtobelikeotherbroadcastmediaDRandBDRneedtohavefullphysicalconnectivity 连通性 withallotherroutersDRandBDRneedalistofneighbors Subinterfaces TypicallyusedinNBMAtopologiesAphysicalinterfacecanbesplitintomultiplelogicalinterfaces calledsubinterfacesCanbepoint to pointormultipoint NBMAModeNeighborship Usuallyafully meshednetworkDR BDRelectedNeighborsmustbestaticallyconfiguredOneIPsubnetStabilityofthenetworkmaybeanissueReplicate 复制 LSApacketsRFC2328compliant Point to MultipointModeNeighborship Fully meshedorpartially meshedtopologyNoDR BDRelectionNeighborsdonotneedtobestaticallyconfiguredOneIPsubnetReplicateLSApacketsRFC2328compliant NBMA拓扑上的OSPF小结 RFCorCisco 首选网络结构 子网地址 邻居关系 NBMA OSPF模式 Cisco Cisco RFC Point to point Fullymeshed Partialmeshorstar usingsubinterface Same Same Differentforeachsubint Same 手工配置DR BDRelected 自动配置NoDR BDR Same RFC Cisco Broadcast 自动配置DR BDRelected Point to multipoint Partialmeshorstar 自动配置NoDR BDR Point to multipointnonbroadcast 手工配置NoDR BDR Partialmeshorstar Fullymeshed Debugipcostadj Point to pointinterfacescomingup Noelection LINK 3 UPDOWN InterfaceSerial1 changedstatetoupOSPF InterfaceSerial1goingUpOSPF Rcvhellofrom192 168 0 11area0fromSerial110 1 1 2OSPF EndofhelloprocessingOSPF BuildrouterLSAforarea0 routerID192 168 0 10OSPF RcvDBDfrom192 168 0 11onSerial1seq0 x20C4opt0 x2flag0 x7len32stateINITOSPF 2WayCommunicationto192 168 0 11onSerial1 state2WAYOSPF SendDBDto192 168 0 11onSerial1seq0 x167Fopt0 x2flag0 x7len32OSPF NBRNegotiationDone WearetheSLAVEOSPF SendDBDto192 168 0 11onSerial1seq0 x20C4opt0 x2flag0 x2len72Ethernetinterfacecomingup ElectionOSPF 2WayCommunicationto192 168 0 10onEthernet0 state2WAYOSPF endofWaitoninterfaceEthernet0OSPF DR BDRelectiononEthernet0OSPF ElectBDR192 168 0 12OSPF ElectDR192 168 0 12DR 192 168 0 12 Id BDR 192 168 0 12 Id OSPF SendDBDto192 168 0 12onEthernet0seq0 x546opt0 x2flag0 x7len32OSPF DR BDRelectiononEthernet0OSPF ElectBDR192 168 0 11OSPF ElectDR192 168 0 12DR 192 168 0 12 Id BDR 192 168 0 11 Id DRandBDR DR BDR HelloselectDRandBDRtorepresentsegmentEachrouterthenformsadjacencywithDRandBDR HellopacketsexchangedviaIPmulticastElectingDRandBDR1 highestOSPFpriority2 highestRouterID P 1 P 0 P 1 ElectingtheDRandBDR P 3 P 2 DR BDR OSPF状态 DOWNINIT 初始 TWO WAY 双向 EXSTART 准启动 EXCHANGE 交换 LOADING 加载 FULLadjacency 全毗邻 邻居关系建立状态 172 16 5 1 24E0 172 16 5 2 24E1 A B DownState 邻居关系建立状态 续 172 16 5 1 24E0 172 16 5 2 24E1 RouterBNeighborsList172 16 5 1 24 intE1 IamrouterID172 16 5 1andIseenoone DownState InitState A B 邻居关系建立状态 续 172 16 5 1 24E0 IamrouterID172 16 5 2 andIsee172 16 5 1 172 16 5 2 24E1 RouterBNeighborsList172 16 5 1 24 intE1 IamrouterID172 16 5 1andIseenoone DownState InitState A B 邻居关系建立状态 续 172 16 5 1 24E0 IamrouterID172 16 5 2 andIsee172 16 5 1 RouterANeighborsList172 16 5 2 24 intE0 172 16 5 2 24E1 RouterBNeighborsList172 16 5 1 24 intE1 IamrouterID172 16 5 1andIseenoone DownState InitState Two WayState A B 邻居关系建立状态 续 E0172 16 5 1 DR E0172 16 5 3 No IwillstartexchangebecauseIhaveahigherrouterID IwillstartexchangebecauseIhaverouterID172 16 5 1 Hello afadjfjorqpoeru39547439070713 Hello afadjfjorqpoeru39547439070713 ExstartState 邻居关系建立状态 续 发现路由 Hereisasummaryofmylink statedatabase DBD afadjfjorqpoeru39547439070713 ExchangeState Hereisasummaryofmylink statedatabase E0172 16 5 1 DR E0172 16 5 3 No IwillstartexchangebecauseIhaveahigherrouterID IwillstartexchangebecauseIhaverouterID172 16 5 1 Hello afadjfjorqpoeru39547439070713 Hello afadjfjorqpoeru39547439070713 ExstartState 邻居关系建立状态 续 发现路由 E0172 16 5 1 E0172 16 5 3 Thanksfortheinformation LSAck afadjfjorqpoeru39547439070713 LSAck afadjfjorqpoeru39547439070713 DR 邻居关系建立状态 续 发现路由 Ineedthecompleteentryfornetwork172 16 6 0 24 Hereistheentryfornetwork172 16 6 0 24 Thanksfortheinformation LSR afadjfjorqpoeru39547439070713 LSAck afadjfjorqpoeru39547439070713 LSU afadjfjorqpoeru39547439070713 LoadingState E0172 16 5 1 E0172 16 5 3 Thanksfortheinformation LSAck afadjfjorqpoeru39547439070713 LSAck afadjfjorqpoeru39547439070713 DR 邻居关系建立状态 续 发现路由 FullState Ineedthecompleteentryfornetwork172 16 6 0 24 Hereistheentryfornetwork172 16 6 0 24 Thanksfortheinformation LSR afadjfjorqpoeru39547439070713 LSAck afadjfjorqpoeru39547439070713 LSU afadjfjorqpoeru39547439070713 LoadingState E0172 16 5 1 E0172 16 5 3 Thanksfortheinformation LSAck afadjfjorqpoeru39547439070713 LSAck afadjfjorqpoeru39547439070713 DR 维护路由信息 RouterAtellsallOSPFDRson224 0 0 6 Link StateChange LSU DR A B 维护路由信息 续 LSU RouterAtellsallOSPFDRson224 0 0 6DRtellsotherson224 0 0 5 Link StateChange LSU DR A B LSU 维护路由信息 续 LSU Link StateChange LSU DR A B RouterAtellsallOSPFDRson224 0 0 6DRtellsotherson224 0 0 5 维护路由信息 续 Ineedtoupdatemyroutingtable 4 LSU LSU Link StateChange LSU DR A B RouterAtellsallOSPFDRson224 0 0 6DRtellsotherson224 0 0 5 维护路由信息 续 Isentryinlink statedatabase No RunSPFtocalculatenewroutingtable Addtodatabase FloodLSA End SendLSAcktoDR 维护路由信息 续 Yes Isseq thesame Yes IgnoreLSA Isentryinlink statedatabase No RunSPFtocalculatenewroutingtable Addtodatabase FloodLSA SendLSAcktoDR End 维护路由信息 续 Yes A No SendLSUwithnewerinformationtosource Isseq higher No Yes Isseq thesame Yes IgnoreLSA Isentryinlink statedatabase No RunSPFtocalculatenewroutingtable Addtodatabase FloodLSA SendLSAcktoDR End End End End OSPF单区域 链路状态通告 LSA 类型 LSA类型1 路由器链路条目 O OSPF 链路状态和成本开销LSA类型2 网络链路条目 O OSPF 由DR产生描述区域内的路由信息LSA类型3 汇总链路条目 IA OSPF内部区域间 由ABR产生LSA类型4 汇总链路条目 IA OSPF外部区域间 由ABR产生LSA类型5 自治系统外部链路条目 E1 OSPF外部类型1 E2 OSPF外部类型2 由ASBR产生LSA类型6 多目组播OSPF MOSPF LSA类型7 自治系统外部链路条目 N1 OSPFNSSA外部类型1 N2 OSPF外部类型2 配置OSPF在内部的路由器上 CanAssignNetworkorInterfaceAddress BroadcastNetwork Point to PointNetwork E0133 1 1 2 133 1 1 1E0 S110 1 1 1 10 1 1 3S0 DCE R2 R1 R3 interfaceEthernet0ipaddress133 1 1 2255 255 255 0 routerospf20network133 1 1 00 0 0 255area0 interfaceEthernet0ipaddress133 1 1 1255 255 255 0 interfaceSerial1ipaddress10 1 1 2255 255 255 0routerospf10network10 1 1 10 0 0 0area0network133 1 1 10 0 0 0area0 RouterID 通常将路由器ID设置为最大的物理接口IP地址 接口无须参加OSPF进程 但必须是活跃的 如果配置了环回接口 那环回接口将优先于物理接口地址成为路由器ID可以使用命令router id来手工设置路由器ID 这样设置的路由器ID将优先于其他两种方式选择的路由器ID AdvertisedLoopbackAddressEx 172 16 17 5 InOSPFtable Usesaddressspace Canuseping UnadvertisedLoopbackAddressEx 192 168 255 254 NotinOSPFtable Savesaddressspace Cannotuseping Network172 16 0 0 配置可选的命令 给一个接口指派一个成本该成本指明在两个路由器之间的链路成本使用缺省的成本在两个路由器之间 Cisco Non Cisco Traffic 配置可选的命令 续 在NBMA中配置OSPF NBMAmode Point to multipointmode 在NBMA中配置OSPF 续 Router config if ipospfnetworkpoint to point Point to pointmode Broadcastmode 在NBMA中配置OSPF 续 Router config router neighborip address prioritynumber poll intervalsec costnumber R1 config interfaceSerial0R1 config if ipaddress10 1 1 1255 255 255 0R1 config if encapsulationframe relayR1 config if ipospfnetworknon broadcastR1 config routerospf1R1 config router network10 1 1 00 0 0 255area0R1 config router neighbor10 1 1 2R1 config router neighbor10 1 1 3R1 config router neighbor10 1 1 4 如果缺省是非广播型网络 那么不需要使用命令ipospfnetwork指明邻居必须显示声明和配置 配置OSPF在点到多点模式 不选举DR BDR不需要手动配置指定邻居OSPF交换链路状态更新信息通常运行在部分互连网络 R1 config interfaceSerial0R1 config if ipaddress10 1 1 1255 255 255 0R1 config if encapsulationframe relayR1 config if ipospfnetworkpoint to multipointR1 config routerospf1R1 config router network10 1 1 00 0 0 255area0 R1 config interfaceSerial0R1 config if ipaddress10 1 1 1255 255 255 0R1 config if encapsulationframe relayR1 config if ipospfnetworkbroadcastR1 config routerospf1R1 config router network10 1 1 00 0 0 255area0 配置OSPF在广播模式 选举DR BDR不需要指定邻居适用于全网状拓扑或部分网状拓扑 配置OSPF在点到点模式 R1 config interfaceSerial0R1 config if noipaddressR1 config if encapsulationframe relayR1 config interfaceSerial0 1point to pointR1 config subif ipaddress10 1 1 1255 255 255 0R1 config subif frame relayinterface dlci51R1 config interfaceSerial0 2point to pointR1 config subif ipaddress10 1 2 1255 255 255 0R1 config subif frame relayinterface dlci52R1 config routerospf1R1 config router network10 1 0 00 0 255 255area0 OSPF认为每个子接口连接在一个物理的点到点的网络邻居关系是自动建立的 检验OSPF运行 VerifyingOSPFOperation 显示区域ID和邻居信息 校验OSPF的配置信息 显示所有OSPF路由信息 显示关于DR BDR和邻居的信息显示链路状态数据库 检验OSPF运行 续 显示OSPF时间信息和统计信息 该命令允许你清除IP路由表 显示路由器交换hello数据包的信息 检验OSPF运行 续 showipospfinterface R2 showipospfinterfaceEthernet0Ethernet0isup lineprotocolisupInternetAddress192 168 0 12 24 Area0ProcessID1 RouterID192 168 0 12 NetworkTypeBROADCAST Cost 10TransmitDelayis1sec StateDROTHER Priority1DesignatedRouter ID 192 168 0 11 Interfaceaddress192 168 0 11BackupDesignatedrouter ID 192 168 0 13 Interfaceaddress192 168 0 13Timerintervalsconfigured Hello10 Dead40 Wait40 Retransmit5Helloduein00 00 04NeighborCountis3 Adjacentneighborcountis2Adjacentwithneighbor192 168 0 13 BackupDesignatedRouter Adjacentwithneighbor192 168 0 11 DesignatedRouter Suppresshellofor0neighbor s showipospfneighbor MultiaccessandPoint to Point NeighborIDPriStateDeadTimeAddressInterface192 168 0 1312WAY DROTHER00 00 31192 168 0 13Ethernet0192 168 0 141FULL BDR00 00 38192 168 0 14Ethernet0192 168 0 1112WAY DROTHER00 00 36192 168 0 11Ethernet0192 168 0 121FULL DR00 00 38192 168 0 12Ethernet0 OSPFoverEthernet 多路访问网络 NeighborIDPriStateDeadTimeAddressInterface192 168 0 111FULL 00 00 3910 1 1 2Serial1 OSPFoverHDLC 点到点网络 showipospfneighbor NBMATopologyNBMAMode NeighborIDPriStateDeadTimeAddressInterface192 168 0 121FULL DROTHER0 01 5610 1 1 2Serial0192 168 0 130FULL DROTHER0 01 3410 1 1 3Serial0192 168 0 111FULL BDR0 01 5610 1 1 1Serial0 OSPFoverFrameRelay NBMAModeUsingtheneighborCommand NeighborIDPriStateDeadTimeAddressInterface192 168 0 141FULL DR00 00 3010 1 1 4Serial0192 168 0 131FULL DROTHER00 00 3610 1 1 3Serial0192 168 0 121FULL DROTHER00 00 3910 1 1 2Serial0 OSPFoverFrameRelay BroadcastMode showipospfneighbor NBMATopologyNBMAMode R2 showipospfdatabaseOSPFRouterwithID 192 168 0 12 ProcessID1 RouterLinkStates Area0 LinkIDADVRouterAgeSeq ChecksumLinkcount192 168 0 10192 168 0 108170 x800000030 xFF561192 168 0 11192 168 0 118170 x800000030 xFD551192 168 0 12192 168 0 128160 x800000030 xFB541192 168 0 13192 168 0 138160 x800000030 xF9531192 168 0 14192 168 0 148170 x800000030 xD9901NetLinkStates Area0 LinkIDADVRouterAgeSeq Checksum192 168 0 14192 168 0 148120 x800000020 x4AC8 showipospfdatabase debugipospfadj 192 168 0 14onEthernet0 state2WAYOSPF endofWaitoninterfaceEthernet0OSPF DR BDRelectiononEthernet0OSPF ElectBDR192 168 0 14OSPF ElectDR192 168 0 14DR 192 168 0 14 Id BDR 192 168 0 14 Id OSPF SendDBDto192 168 0 14onEthernet0seq0 x11DBopt0 x2flag0 x7len32OSPF BuildrouterLSAforarea0 routerID192 168 0 11OSPF NeighborchangeEventoninterfaceEthernet0OSPF RcvDBDfrom192 168 0 14onEthernet0seq0 x1598opt0 x2flag0 x7len32stateEXSTARTOSPF NBRNegotiationDone WearetheSLAVEOSPF SendDBDto192 168 0 14onEthernet0seq0 x1598opt0 x2flag0 x2len52OSPF RcvDBDfrom192 168 0 14onEthernet0seq0 x1599opt0 x2flag0 x3len92stateEXCHANGEOSPF ExchangeDonewith192 168 0 14onEthernet0OSPF SendDBDto192 168 0 14onEthernet0seq0 x159Aopt0 x2flag0 x0len32OSPF Synchronizedwith192 168 0 14onEthernet0 stateFULLOSPF BuildrouterLSAforarea0 routerID192 168 0 11OSPF NeighborchangeEventoninterfaceEthernet0OSPF DR BDRelectiononEthernet0OSPF ElectBDR192 168 0 13OSPF ElectDR192 168 0 14DR 192 168 0 14 Id BDR 192 168 0 13 Id 修改链路成本 CISCOIOS用公式108 带宽来自动确认链路成本 修改链路成本 在一个接口上配置OSPF链路成本值Router config ints0Router config if ipospfcost1000 在一个串行接口上设置带宽Router config ints1Router config if bandwidth56 配置认证 路由器的每个OSPF接口都可以有一个不同的认证密钥 起功能是作为同一区域中OSPF路由器之间的口令 Router config if ipospfauthentication keypassword 为整个区域启动认证功能 Router config if areanumberauthentication key message digest 在OSPF路由器的接口上配置一个消息摘要密钥 Router config if ipospfmessage digest keykey idmd5 encryption type password 配置认证 RTB config ints0RTB config if ipospfmessage digest key1md57cisco123RTB config if inte0RTB config if ipospfmessage digest key1md57cisco789RTB config if routerospf1RTB config router area0authenticationmessage digest 配置OSPF记时器 配置hello间隔和DOWN机判定间隔时间的命令如下 Router config if ipospfhello intervalsecondsRouter config if ipospfdead intervalseconds 配置事例 Router config inte0Router config if ipospfhello interval5Router config if ipospfdead interval20 OSPF多区域 在一个大型网络运行OSPF Myroutingtableistoobig Iamrunninglowonmemory TheSPFisrunningtoooftenformetoroute IamonlyreceivingLSAs nodata OSPF OSPF OSPF OSPF OSPF Area0 Area1 Area2 AutonomousSystem ConsistsofareasandautonomoussystemsMinimizesroutingupdatetraffic 解决方案 OSPF分级的路由模式 创建多个OSPF区域 OSPF将一个大型互连网络分解为多个小区域的能力称为体系化路由 体系化路由的优点是 汇总路由信息避免路由颠簸造成的路由更新SPF计算频率降低路由表变小链路状态更新额外开销降低 OSPF区域类型 标准区域主干区域末节区域完全末节区域次末节区域 NOT SO STUBBYAREA NSSA OSPF路由器类型 内部路由器主干路由器区域边界路由器 ABR 自治系统边界路由器 ASBR 链路状态通告 LSA 类型 LSA类型1 路由器链路条目 O OSPF 链路状态和成本开销LSA类型2 网络链路条目 O OSPF 由DR产生描述区域内的路由信息LSA类型3 汇总链路条目 IA OSPF内部区域间 由ABR产生LSA类型4 汇总链路条目 IA OSPF外部区域间 由ABR产生LSA类型5 自治系统外部链路条目 E1 OSPF外部类型1 E2 OSPF外部类型2 由ASBR产生LSA类型6 多目组播OSPF MOSPF LSA类型7 自治系统外部链路条目 N1 OSPFNSSA外部类型1 N2 OSPF外部类型2 OSPFMulti Area组成 Routers LSAs Internal ABR ASBR Backbone Type1 Type2 Type3 4 Type5 Area0Iamabackbone Area2Iamastub Area1Iamstandard Areas OSPF路由类型 Area1 Area2 BackboneArea0 ExternalAS 链路状态通告类型 Type1 路由链路条目Type2 网络链路条目Type3and4 汇聚链路条目Type5 AS外部链路条目 LSAsinOSPFDatabase Router Area1 Area0 Network Summary External ABR DR p1r3 showipospfdatabaseOSPFRouterwithID 10 64 0 1 ProcessID1 RouterLinkStates Area1 LinkIDADVRouterAgeSeq ChecksumLinkcount10 1 2 110 1 2 16510 x800000050 xD4824NetLinkStates Area1 LinkIDADVRouterAgeSeq Checksum10 64 0 110 64 0 15380 x800000020 xAD9ASummaryNetLinkStates Area1 LinkIDADVRouterAgeSeq Checksum10 2 1 010 2 1 24390 x800000020 xE6F8 ASBR ExternalAS Area0 10 R4 R3 sCostto AS1 E1 viaR1 1795AS1 E1 viaR3 1785 10 1785 1785 R1 R3 AS1 汇聚后的成本计算和外部路由的成本计算 Area1 10 R5 R3 sCostto AS1 E1 viaR1 1795AS1 E1 viaR3 1785 R5 sCostto AS1 E1 viaR1 1815AS1 E1 viaR3 1805 Area0 10 R4 10 1785 1785 R1 R3 AS1 汇聚后的成本计算和外部路由的成本计算 续 区域类型 互连区域 允许所有的LSAs BackboneArea0 区域类型 续 StubArea 不接受外部的LSAs 互连的区域 允许所有的LSAs BackboneArea0 区域类型 续 TotallyStubbyArea 不允许外部的或汇聚的LSAs StubArea 不允许外部的LSAs BackboneArea0 互连区域 允许所有的LSAs 区域类型 续 实施OSPF多区域环境中 在多区域网络中数据包的转发 BBone Internal Internal ABR2 ABR1 Area50 Data ToABR1 ToBackbone ToABR2 ToDestinationNetwork Area1 Area0 BBone Internal ABR2 ABR1 Internal Type1 Area1 Area0 Area50Stub 泛洪LSUs到多区域 BBone Internal ABR2 ABR1 Internal Type3 Type1 Type3 Area1 Area0 Area50Stub 泛洪LSUs到多区域 续 Type5 afadjfjorqpoeru39547439070713 Type5 Default Area1 Area0 BBone Internal ABR2 ABR1 Area50Stub Internal RIP Type3 Type3 Type1 泛洪LSUs到多区域 续 RoutingTable Inter AreaRoutes Intra AreaRoutes External Non OSPFRoutes Area1 Area1 Area0 Area1 RIP 泛洪LSUs到多区域 续 VirtualLinks的应用 所有通信在主干区域交互Virtuallinks提供到主干区域的通道 在主干区域汇聚信息 Area3 Area1 VirtualLink TransitArea Area3 用虚连接连接不连续的网络新加入的网络冗余 在主干区域汇聚信息 Area3 Area0 Area0 TransitArea Area1 Area2 2000 CiscoSystems Inc 5 93 使用和配置OSPF多区域 配置OSPFABRs E0133 1 1 2 133 1 1 1E0 S010 1 1 1 10 1 1 3S1 DCE R2 R1 R3 ABR interfaceEthernet0ipaddress133 1 1 2255 255 255 0 routerospf20network133 1 1 00 0 0 255area0 Area1 Area0 interfaceEthernet0ipaddress133 1 1 1255 255 255 0 interfaceSerial0ipaddress10 1 1 1255 255 255 0routerospf10network133 1 1 10 0 0 0area0network10 1 1 10 0 0 0area1 Default Default Summary Default 使用末节和完全末节区域 Area1 TotallyStubby Area0 Internal ABR2 ABR1 Area50 Stub Summary External External InternalNon CiscoRouter BBone Summary RIP ASBR Typicallyasingleexitpointintoarea ifmultipleexitpoints suboptimalpathsmaybeselectedAnASBRcannotbeinternaltostubAreaisnotthebackboneArea0Virtuallinksarenotallowed 末节和完全末节区域的条件 SingleExitPoint Area2 0 0 0 0 R3 R4 ExternalAS Createsastubarea Router config router areaarea idstub no summary Router config router areaarea iddefault costcost 配置末节和完全末节区域 Specifiescostfordefaultroutesentintostubarea OSPF末节区域配置例子 192 168 15 2 Area0 StubArea2 192 168 14 1 192 168 15 1 S0 S0 E0 R3 interfaceEthernet0ipaddress192 168 14 1255 255 255 0interfaceSerial0ipaddress192 168 15 1255 255 255 252routerospf100network192 168 14 00 0 0 255area0network192 168 15 00 0 0 255area2area2stub R4 interfaceSerial0ipaddress192 168 15 2255 255 255 252routerospf15network192 168 15 00 0 0 255area2area2stub ExternalAS R4 R3 R4 routerospf15network192 168 15 00 0 0 255area2area2stub OSPF完全末节配置示例 R3 routerospf100network192 168 14 00 0 0 255area0network192 168 15 00 0 0 255area2area2stubno summary 192 168 15 2 Area0 192 168 14 1 192 168 15 1 S0 S0 E0 ExternalAS R4 R3 TotallyStubbyArea2 多区域NBMA环境 Area0 Area1 StubArea R1 FrameRelay 多区域NBMA环境 Area0 Area2 Area3 Area4 FrameRelay Area0 R1 MinimizesnumberofroutingtableentriesLocalizesimpactofatopologychangeReducesLSAsandsavesCPU 支持路由汇聚 Area0Backbone ABRs Area1 Summarization 支持VLSM OSPF路由更新信息中包含子网掩码信息使用分级的结构设计 使用路由汇聚 O172 16 8 0255 255 252 0O172 16 12 0255 255 252 0O172 16 16 0255 255 252 0O172 16 20 0255 255 252 0O172 16 24 0255 255 252 0O172 16 28 0255 255 2