路由交換基礎(chǔ)-OSPF協(xié)議與路由重分發(fā)

OSPF的原理與配置方法目錄鏈路狀態(tài)協(xié)議的特點(diǎn)單域OSPF的工作過(guò)程單域OSPF的基本配置OSPF驗(yàn)證的配置方法OSPF配置的核查與排錯(cuò)鏈路狀態(tài)協(xié)議的特點(diǎn)鏈路狀態(tài)協(xié)議的工作過(guò)程1–泛洪(Flooding)鏈路狀態(tài)信息2–構(gòu)建拓?fù)鋷?kù)3–執(zhí)行SPF算法4–構(gòu)建SPF樹(shù)5–計(jì)算路由表鏈路狀態(tài)協(xié)議的特點(diǎn)收斂迅速:一旦發(fā)生變化受影響的源端立即發(fā)送更新信息強(qiáng)有力的防止環(huán)路措施：路由器了解整體的拓?fù)湫畔㈡溌窢顟B(tài)數(shù)據(jù)包是有序且?guī)Т_認(rèn)機(jī)制的SPF算法保證無(wú)環(huán)路鏈路狀態(tài)協(xié)議支持VLSM和CIDR對(duì)路由器的資源(CPU和內(nèi)存)要求較高需要對(duì)網(wǎng)絡(luò)進(jìn)行嚴(yán)格的規(guī)劃和(層次化)設(shè)計(jì)初始化過(guò)程中會(huì)產(chǎn)生過(guò)量的泛洪信息單域OSPF的工作過(guò)程O(píng)SPF術(shù)語(yǔ)InterfacesLink:對(duì)應(yīng)路由器的接口Linkstate:描述路由器的接口與它鄰居工作狀態(tài)的信息：

接口的IP地址和掩碼，接口連接的網(wǎng)絡(luò)類(lèi)型

鏈路的度量(cost)OSPF屬于鏈路狀態(tài)路由協(xié)議全部鏈路狀態(tài)信息組成一個(gè)鏈路狀態(tài)庫(kù)(LSDB)。NeighborsInterfaces構(gòu)建鄰居關(guān)系有嚴(yán)格的規(guī)則!

OSPF術(shù)語(yǔ)NeighborsInterfacesCost=10Cost=6Cost=48CiscoOSPFCost的計(jì)算方法:

108/接口帶寬(bps)路由的度量值是路由器的某個(gè)接口到目的網(wǎng)絡(luò)之間所有出方向接口Cost之和。

E1(2.048-Mbps串行鏈接)=48Ethernet=10

16-MbpsTokenRing=6

FastEthernet=1問(wèn)題：GigabitEthernet及更高速率=1OSPF術(shù)語(yǔ)AutonomousSystem(自治系統(tǒng))NeighborsInterfacesArea1Area0Cost=10Cost=6Cost=48OSPF術(shù)語(yǔ)RoutingTableListsBestRoutesTopologyDatabaseListsAllRoutesNeighborshipTableListsNeighborsCost=10Cost=6NeighborsInterfacesArea1Area0Cost=48AutonomousSystem(自治系統(tǒng))OSPF術(shù)語(yǔ)OSPF數(shù)據(jù)包類(lèi)型Hello數(shù)據(jù)包數(shù)據(jù)報(bào)頭Hello數(shù)據(jù)包Helloafadjfjorqpoeru39547439070713RouterIDHello/deadintervalsNeighborsArea-IDRouterpriorityDRIPaddressBDRIPaddressAuthenticationpasswordStubareaflag**

*標(biāo)記*的內(nèi)容在鄰居之間必須一致HelloADECB建立鄰居關(guān)系*RouterID–在OSPF網(wǎng)絡(luò)中標(biāo)識(shí)路由器OSPF中選擇router-id的規(guī)則：

Highestloopbackaddress

HighestactiveIPaddressLoopback接口永遠(yuǎn)不會(huì)被動(dòng)關(guān)閉。RouterIDHello/Dead間隔路由器在每個(gè)啟用OSPF的接口上發(fā)送Hello包:在多路訪問(wèn)和點(diǎn)到點(diǎn)鏈路上缺省Hello間隔為10秒在NBMA網(wǎng)絡(luò)中缺省Hello間隔為30秒OSPF的Hello包的目的地址通常為組播地址224.0.0.5Cisco路由器上缺省的Dead間隔為Hello間隔的4倍。注意:

相鄰的路由器的Hello和Dead間隔必須一致才能建立鄰居關(guān)系，否則Hello包被丟棄。Helloafadjfjorqpoeru39547439070713RouterIDHello/deadintervalsNeighborsArea-IDRouterpriorityDRIPaddressBDRIPaddressAuthenticationpasswordStubareaflag

*

***HelloADECB建立鄰居關(guān)系標(biāo)記*的內(nèi)容在鄰居之間必須一致Helloafadjfjorqpoeru39547439070713相鄰兩個(gè)接口IP地址在同一子網(wǎng)Hello/dead間隔相同Area-ID相同如果配置驗(yàn)證要求口令和驗(yàn)證類(lèi)型相同HelloADECB建立鄰居關(guān)系的必要條件OSPF的工作過(guò)程172.16.5.1/24E0172.16.5.2/24E1ABDownStateHelloDownState

–OSPF已啟動(dòng)并且發(fā)送了Hello包，但沒(méi)有收到對(duì)端的Hello包。172.16.5.1/24E0172.16.5.2/24E1RouterBNeighborsList172.16.5.1/24,intE1IamrouterID172.16.5.1andIseenoone.DownStateInitStateABHelloOSPF的Hello數(shù)據(jù)包的目的地址通常為

224.0.0.5，其中包含RouterID信息InitState

–收到了Hello包，但其中不包含該路由器的RouterIDOSPF的工作過(guò)程172.16.5.1/24E0IamrouterID172.16.5.2,andIsee172.16.5.1.172.16.5.2/24E1RouterBNeighborsList172.16.5.1/24,intE1IamrouterID172.16.5.1andIseenoone.DownStateInitStateABHelloOSPF的工作過(guò)程172.16.5.1/24E0IamrouterID172.16.5.2,andIsee172.16.5.1.RouterANeighborsList172.16.5.2/24,intE0172.16.5.2/24E1RouterBNeighborsList172.16.5.1/24,intE1IamrouterID172.16.5.1andIseenoone.DownStateInitStateTwo-WayStateABHelloTwo-wayState–

收到Hello包，而且包含該路由器的RouterID。OSPF的工作過(guò)程O(píng)SPF的工作過(guò)程O(píng)SPF的工作過(guò)程O(píng)SPF的工作過(guò)程拓?fù)鋷?kù)的內(nèi)容一致OSPF拓?fù)?/p>

(網(wǎng)絡(luò)類(lèi)型)Point-to-PointNBMABroadcast

MultiaccessX.25

FrameRelay廣播型多路訪問(wèn)網(wǎng)DRBDR達(dá)到Two-Way狀態(tài)后選舉DR(DesignatedRouter)和BDR(BackupDesignatedRouter)代表某個(gè)廣播域每個(gè)路由器與DR和BDR的拓?fù)鋷?kù)保持一致

(FullState)FullState:所有路由器應(yīng)保持一致的拓?fù)鋷?kù)信息注意：每個(gè)子網(wǎng)一對(duì)DR/BDR。P=1P=0P=1選舉DR和BDRP=3P=2DRBDRHello接口優(yōu)先級(jí)最高的路由器被選為DR，若優(yōu)先級(jí)相同RouterID最大的當(dāng)選?？梢栽诮涌谏显O(shè)置優(yōu)先級(jí)，缺省為1，設(shè)置范圍是0至255，0表示不能被選為DR或BDR。向DR/BDR發(fā)送的OSPF數(shù)據(jù)包的目的地址為224.0.0.6DR向其它路由器發(fā)送的OSPF數(shù)據(jù)包的目的地址為224.0.0.5DRotherDRotherDRother一旦DR選舉完畢，一臺(tái)擁有更高優(yōu)先級(jí)的路由器加入后不會(huì)成為新的DR。如果DR失敗，BDR會(huì)成為新的DR并選舉新的BDR。P=1P=0P=1P=3P=2DRBDRHelloDRotherDRotherDRotherP=255DRother新加入的路由器對(duì)DR/BDR選舉的影響P=1P=0P=1DR的工作過(guò)程(每個(gè)子網(wǎng)一個(gè)DR/BDR)P=3P=2DRBDRHelloP=2P=1DRBDR2LSULSU1x4LSULSU33LSULSU---224.0.0.6LSU---224.0.0.5P=1DRotherDRotherDRotherP=1Point-to-Point鏈接通常是采用PPP或HDLC封裝的串行接口

或幀中繼/ATM中的點(diǎn)到點(diǎn)子接口

不需要選舉DR/BDROSPF自動(dòng)探測(cè)這種接口類(lèi)型OSPF數(shù)據(jù)包在這種網(wǎng)絡(luò)類(lèi)型中使用目的IP地址224.0.0.5在NBMA拓?fù)渲羞x舉DR/BDROSPF將NBMA看做廣播型媒介。在全網(wǎng)狀拓?fù)渲幸x舉DR/BDR，但NBMA網(wǎng)絡(luò)并不總是全網(wǎng)狀的。是否選舉DR/BDR取決于NBMA的拓?fù)洌缭O(shè)置了點(diǎn)到點(diǎn)子接口的幀中繼網(wǎng)絡(luò)不選舉DR/BDR。X.25

FrameRelay計(jì)算路由表

TopologyTableNetCostOutInterface10.2.2.07To010.3.3.017To010.3.3.020E0Cost=10Cost=6Cost=1ABC這是去往10.3.3.0/24子網(wǎng)的最優(yōu)路由。10.1.1.0/2410.2.2.0/2410.3.3.0/2410.4.4.0/24Cost=10E0To0單域OSPF的基本配置單域OSPF的基本配置命令Process-id是本地有效的，不需要與其它路由器上OSPF的進(jìn)程號(hào)相同。配置路由器的RouterID[H3C]router-idrouter-id

啟動(dòng)OSPF協(xié)議[H3C]ospf[process-id]配置OSPF區(qū)域[H3C-ospf-1]areaarea-id在指定網(wǎng)段使能ospf[H3C-ospf-1-area-0.0.0.0]networkip-addresswildcard-maskOSPF配置實(shí)例路由器A:InterfaceEthernet0/0ipaddress1.1.1.1255.255.255.0InterfaceSerial0/0ipaddress2.2.2.1255.255.255.0Ospf1area0.0.0.0

network2.2.2.00.0.0.255area0.0.0.1

network1.1.1.00.0.0.255區(qū)域2區(qū)域0區(qū)域1S0/0E0/0路由器AS0/01.1.1.1/243.3.3.1/24E0/02.2.2.2/242.2.2.1/24路由器B路由器B:InterfaceEthernet0/0ipaddress3.3.3.1255.255.255.0InterfaceSerial0/0ipaddress2.2.2.2255.255.255.0Ospf1area0.0.0.0

network2.2.2.00.0.0.255area0.0.0.2

network3.3.3.00.0.0.255配置環(huán)回地址[h3c]interfaceloopback0[H3C-loopback0]ipaddress172.16.17.5255.255.255.255如果配置新的環(huán)回接口地址時(shí)，OSPF進(jìn)程已經(jīng)啟動(dòng)，則該環(huán)回接口地址不參與RouterID的選舉，除非重新啟動(dòng)路由器或關(guān)掉OSPF進(jìn)程后重啟。router-idip-address

后面可跟任意的32比特IP地址(點(diǎn)分十進(jìn)制形式)。如果執(zhí)行該命令時(shí)，OSPF進(jìn)程已經(jīng)啟動(dòng)，需要重新啟動(dòng)路由器或執(zhí)行下列命令后新的RouterID才生效:OSPFrouter-id命令[H3C][H3C]ospf1[H3C]router-id172.16.1.1[H3C]resetospf1

processresetospfprocess-id

process

[H3C]配置OSPF接口的路由器優(yōu)先級(jí)接口的DR優(yōu)先級(jí)決定了該接口在選舉DR/BDR時(shí)所具有的資格，優(yōu)先級(jí)的設(shè)置范圍是0至255,數(shù)值越大，優(yōu)先級(jí)越高。

設(shè)置為0意味著該接口所在的子網(wǎng)中此路由器不能被選為DR或BDR。缺省的接口優(yōu)先級(jí)是1,設(shè)備不支持在Null接口、Loopback接口上配置DR優(yōu)先級(jí)。<H3C>system-view[H3C]interfaceinterface-typeinterface-number[H3C-Ethernet1/0]ospfdr-prioritypriority設(shè)置OSPF的計(jì)時(shí)器[H3C-Ethernet1/0]ospftimerhelloseconds[H3C-Ethernet1/0]ospftimerdeadseconds如果網(wǎng)絡(luò)中有多個(gè)廠商的設(shè)備，可能需要調(diào)整這些間隔值。缺省情況下：在多路訪問(wèn)和點(diǎn)到點(diǎn)鏈路上缺省Hello間隔為10秒，Dead間隔40秒在NBMA網(wǎng)絡(luò)中缺省Hello間隔為30秒，Dead間隔120秒。注意：修改Hello間隔時(shí)，Dead間隔會(huì)自動(dòng)調(diào)整為Hello間隔的4倍。禁止接口發(fā)送OSPF報(bào)文缺省情況下，允許接口發(fā)送OSPF報(bào)文。禁止接口發(fā)送OSPF報(bào)文后，它將成為被動(dòng)接口（Passiveinterface），不再發(fā)送Hello報(bào)文。如果要使OSPF路由信息不被某一網(wǎng)絡(luò)中的路由器獲得，可使用本命令禁止在此接口上發(fā)送OSPF報(bào)文。<H3C>system-view[H3C]ospf[process-id|router-idrouter-id][H3C-ospf-1]silent-interface{all|interface-typeinterface-number}default-route-advertise[always|costcost|typetype][H3C]不帶always參數(shù)時(shí)，僅當(dāng)本路由器的路由表中含有缺省路由時(shí)才會(huì)向鄰居傳播0.0.0.0的缺省路由帶always參數(shù)時(shí)，

無(wú)論本路由器的路由表中是否含有缺省路由都會(huì)向鄰居傳播0.0.0.0的缺省路由在OSPF域中傳播缺省路由在OSPF域中配置缺省路由的實(shí)例CompanyXH3CAospf20area0network10.0.0.00.255.255.255

default-route-advertisealwaysiproute-static

0.0.0.00.0.0.0s0

S0PublicNetworkOSPF驗(yàn)證的配置方法配置OSPF區(qū)域驗(yàn)證<OutputOmitted>interfaceEthernet0ipaddress10.64.0.2255.255.255.0

ospfauthentication-modesimplecipher1234!interfaceSerial0ipaddress10.2.1.2255.255.255.0routerospf50area0network10.2.1.20.0.0.0network10.64.0.20.0.0.0

authentication-modesimpleBroadcastNetworkPoint-to-PointNetwork

E010.64.0.110.64.0.2E0

S010.2.1.210.2.1.1S1ABC<OutputOmitted>interfaceEthernet0ipaddress10.64.0.1255.255.255.0ospfauthentication-modesimplecipher1234!routerospf1area0network10.0.0.00.255.255.255

authentication-modesimple明文口令<OutputOmitted>interfaceEthernet0ipaddress10.64.0.2255.255.255.0

ospfauthentication-modemd515cipher1234!interfaceSerial0ipaddress10.2.1.2255.255.255.0<OutputOmitted>routerospf50area0network10.2.1.20.0.0.0network10.64.0.20.0.0.0

authentication-modemd5BroadcastNetworkPoint-to-PointNetwork

E010.64.0.110.64.0.2E0

S010.2.1.210.2.1.1S1ABCinterfaceEthernet0ipaddress10.64.0.1255.255.255.0

ospfauthentication-modemd515cipher1234!<OutputOmitted>routerospf1area0network10.0.0.00.255.255.255

authentication-modemd5加密口令配置OSPF區(qū)域驗(yàn)證key-id

配置范圍1至255<OutputOmitted>interfaceEthernet0ipaddress10.64.0.2255.255.255.0

ospfauthentication-modesimplecipher1234!interfaceSerial0ipaddress10.2.1.2255.255.255.0<OutputOmitted>routerospf50area0network10.2.1.20.0.0.0network10.64.0.20.0.0.0BroadcastNetworkPoint-to-PointNetwork

E010.64.0.110.64.0.2E0

S010.2.1.210.2.1.1S1ABC<OutputOmitted>interfaceEthernet0ipaddress10.64.0.1255.255.255.0

ospfauthentication-modesimplecipher1234!<OutputOmitted>routerospf1area0network10.0.0.00.255.255.255配置OSPF接口驗(yàn)證(簡(jiǎn)單模式)<OutputOmitted>interfaceEthernet0ipaddress10.64.0.2255.255.255.0

ospfauthentication-modemd515cipher1234!interfaceSerial0ipaddress10.2.1.2255.255.255.0<OutputOmitted>routerospf50area0network10.2.1.20.0.0.0network10.64.0.20.0.0.0BroadcastNetworkPoint-to-PointNetwork

E010.64.0.110.64.0.2E0

S010.2.1.210.2.1.1S1ABC<OutputOmitted>interfaceEthernet0ipaddress10.64.0.1255.255.255.0

ospfauthentication-modemd515cipher1234!<OutputOmitted>routerospf1area0network10.0.0.00.255.255.255加密口令key-id

配置范圍1至255配置OSPF接口驗(yàn)證一個(gè)區(qū)域中所有的路由器的驗(yàn)證類(lèi)型必須一致，一個(gè)網(wǎng)段中所有路由器的驗(yàn)證字口令也必須一致。OSPF配置的核查與排錯(cuò)displayiprouting-table<Sysname>displayiprouting-tableRoutingTables:PublicDestinations:6Routes:6Destination/MaskProtoPreCostNextHopInterface2.2.2.0/24Direct002.2.2.1Eth0/12.2.2.1/32Direct00127.0.0.1InLoop0127.0.0.0/8Direct00127.0.0.1InLoop0127.0.0.1/32Direct00127.0.0.1InLoop0192.168.80.0/24Direct00192.168.80.10Eth1/1192.168.80.10/32Direct00127.0.0.1InLoop0displayospfrouting<Sysname>displayospfroutingOSPFProcess1withRouterID192.168.1.2RoutingTablesRoutingforNetworkDestinationCostTypeNextHopAdvRouterArea192.168.1.0/241562Stub192.168.1.2192.168.1.20.0.0.0172.16.0.0/161563Inter192.168.1.1192.168.1.10.0.0.0TotalNets:2IntraArea:1InterArea:1ASE:0NSSA:0displayospfinterface<Sysname>displayospfinterfaceOSPFProcess1withRouterID192.168.1.1InterfacesArea:0.0.0.0IPAddressTypeStateCostPriDRBDR192.168.1.1PTPP-2-P156210.0.0.00.0.0.0Area:0.0.0.1IPAddressTypeStateCostPriDRBDR172.16.0.1BroadcastDR11172.16.0.10.0.0.0displayospfpeer<Sysname>displayospfpeerOSPFProcess1withRouterID1.1.1.1NeighborBriefInformationArea:0.0.0.0RouterIDAddressPriDead-TimeInterfaceState1.1.1.21.1.1.2140Eth0/1/0Full/DROSPF的拓?fù)鋷?kù)displayospflsdb<Sysname>displayospflsdbOSPFProcess1withRouterID192.168.0.1LinkStateDatabaseArea:0.0.0.0TypeLinkStateIDAdvRouterAgeLenSequenceMetricRouter192.168.0.2192.168.0.247436800000040Network192.168.0.1192.168.0.132132800000030Sum-Net192.168.1.0192.168.0.132128800000021LinkStateID:產(chǎn)生該routerLSA的RouterID。ADVRouter:通告該routerLSA的OSPF路由器的RouterID。Age：LSA的老化時(shí)間Len：LSA的長(zhǎng)度Sequence：LSA序列號(hào)Metric：度量值displayospfbrief顯示OSPF的概要信息。<Sysname>displayospfbriefOSPFProcess1withRouterID192.168.1.2OSPFProtocolInformationRouterID:192.168.1.2BorderRouter:NSSARouteTag:0Multi-VPN-InstanceisnotenabledApplicationsSupported:MPLSTraffic-EngineeringSPF-schedule-interval:505000LSAgenerationinterval:505000LSAarrivalinterval:1000DefaultASEparameters:Metric:1Tag:1Type:2RoutePreference:10ASERoutePreference:150SPFComputationCount:22RFC1583CompatibleAreaCount:1NssaAreaCount:1ExChange/LoadingNeighbors:0路由重分發(fā)在不同的協(xié)議轉(zhuǎn)換過(guò)渡期間特定的應(yīng)用需求一種協(xié)議不能滿足所有的要求不同的行政區(qū)劃不同的域之間采用不同的路由協(xié)議設(shè)備之間不兼容不同廠商的設(shè)備互操作問(wèn)題為什么需要使用多種路由協(xié)議?不同的協(xié)議采用不同的度量類(lèi)型不同的度量類(lèi)型之間沒(méi)有可比性需要對(duì)不同類(lèi)型的度量進(jìn)行轉(zhuǎn)換(Redistribution)同一臺(tái)路由設(shè)備上運(yùn)行多種路由協(xié)議時(shí)選擇最優(yōu)路由的規(guī)則：

1.

首先比較雙方的管理距離(AdministrativeDistance)2.管理距離相同再比較度量172.16RIP172.16OSPFRIP172.16.0.0OSPF172.16RIP172.16OSPF不同的路由協(xié)議之間如何銜接？SeedMetric最初的度量值(seedmetric)是根據(jù)路由的直連接口確定的。不同的協(xié)議之間做路由重分發(fā)時(shí)度量的處理方式：根據(jù)初始的度量值按照該路由協(xié)議的規(guī)則繼續(xù)計(jì)算度量新設(shè)置的度量值應(yīng)比該路由域中最大的度量值大RIPOSPF協(xié)議之間重分發(fā)(轉(zhuǎn)換)的命令[H3C-rip-1]import-route?bgpBorderGatewayProtocol(BGP)directConnectedegpExteriorGatewayProtocol(EGP)eigrpEnhancedInteriorGatewayRoutingProtocol(EIGRP)igrpInteriorGatewayRoutingProtocol(IGRP)isisISOIS-ISiso-igrpIGRPforOSInetworksodrOnDemandstubRoutesospfOpenShortestPathFirst(OSPF)ripRoutingInformationProtocol(RIP)staticStaticroutes缺省的SeedMetrics協(xié)議缺省的初始度量值(SeedMetrics)RIPInfinityIGRP/EIGRPInfinityOSPF20forallexceptBGP,whichis1IS-IS0BGPBGPmetricissettoIGPmetricvalue示例：重分發(fā)之前示例：重分發(fā)之前H3C配置重分發(fā)import-routerip40type2tag33cost50import-routeospfcost3示例：配置重分發(fā)之后的路由表OSPF典型案例（一）故障現(xiàn)象：兩臺(tái)路由器上的以太網(wǎng)段無(wú)法互相ping通；兩臺(tái)路由器都無(wú)法學(xué)習(xí)到對(duì)方的OSPF路由。E0/0:111.111.111.0/24FRS1/0:100.1.0.1/16S0/0:100.1.0.2/16RouterID:197.7.1.1RouterID:197.7.1.2E0/0:222.222.222.0/24RTARTBOSPF典型案例（一）RTA上的配置：

RTB上的配置：routerid197.7.1.1sysnameRTA#interfaceEthernet0/0ipaddress111.111.111.1255.255.255.0#interfaceSerial1/0link-protocolfripaddress100.1.0.1255.255.0.0ospfnetwork-typenbmafrinterface-typeDCEfrmapip100.1.0.216#ospf1peer100.1.0.2area0.0.0.0network100.1.0.00.0.255.255network197.7.1.10.0.0.0network111.111.111.00.0.0.255routerid197.7.1.2sysnameRTB#interfaceEthernet0ipaddress222.222.222.1255.255.255.0#interfaceSerial0/0clockDTECLK1link-protocolfripaddress100.1.0.2255.255.0.0ospfnetwork-typebroadcastfrmapip100.1.0.116#ospf1peer100.1.0.1area0.0.0.0network100.1.0.00.0.255.255network197.7.1.20.0.0.0network222.222.222.00.0.0.255解決問(wèn)題從查看的路由器配置和相應(yīng)的接口狀態(tài)信息看來(lái)，RTA和RTB相連接口的OSPF網(wǎng)絡(luò)類(lèi)型配置得并不一致，因此導(dǎo)致路由計(jì)算錯(cuò)誤，無(wú)法得到OSPF路由。在RTA和RTB的相應(yīng)接口把網(wǎng)絡(luò)類(lèi)型改為一致，則可以正常學(xué)習(xí)OSPF路由。改變RTB的s0/0接口的OSPF網(wǎng)絡(luò)類(lèi)型：

[RTB-Serial0/0]ospfnetwork-typenbmaOSPF典型案例（二）故障現(xiàn)象：RTB和RTC之間的虛連接總是處于down狀態(tài)RTA無(wú)法訪問(wèn)RTB和RTC上的Loopback網(wǎng)段

S1/0:55.2.1.2/24

area1

RTCarea0area1[RTB]displayospfvlinkOSPFProcess1withRouterID2.2.2.2VirtualLinksVirtual-linkNeighbor-id->3.3.3.3,State:DownCost:0State:DownType:VirtualTransitArea:0.0.0.1Timers:Hello10,Dead40,Poll0,Retransmit5,

S1/0:55.0.1.1/2455.0.1.1/24

S1/0:

S1/1:57.1.1.1/24

S1/1:55.2.1.1/24

57.1.1.2/24S1/1:

Loopback2:133.1.1.1/24

Loopback2:56.0.1.1/24

area0

area1

RTA

RTB[RTC]displayospfvlinkOSPFProcess1withRouterID3.3.3.3VirtualLinksVirtual-linkNeighbor-id->2.2.2.2,State:DownCost:0State:DownType:VirtualTransitArea:0.0.0.1Timers:Hello10,Dead40,Poll0,Retransmit5,

OSPF典型案例（二）查看路由器上的相關(guān)配置：[RTB]displaycurrent-configuration#routerid2.2.2.2sysnameRTB#……

ospf1area0.0.0.1vlink-peer3.3.3.3#[RTC]displaycurrent-configuration#routerid3.3.3.3sysnameRTC#……ospf1area0.0.0.1vlink-peer2.2.2.2#OSPF典型案例（二）查看兩臺(tái)路由器上的鄰居列表和鄰居狀態(tài)：<RTB>displayospfpeerOSPFProcess1withRouterID2.2.2.2NeighborsArea0.0.0.0interface57.1.1.1(Serial1/1)'sneighbor(s)RouterID:55.2.1.2Address:57.1.1.2State:FullMode:NbrisMasterPriority:1DR:NoneBDR:NoneDeadtimerexpiresin35sNeighborhasbeenupfor00:00:50Area0.0.0.1interface55.0.1.2(Serial1/0)'sneighbor(s)RouterID:1.1.1.1Address:55.0.1.1State:FullMode:NbrisSlavePriority:1DR:NoneBDR:NoneDeadtimerexpiresin39sNeighborhasbeenupfor00:04:57Virtuallinkwithinterface(null)'sneighborRouterID:3.3.3.3Address:(null)State:DownMode:None