高級(jí)路由管理OSPF路由協(xié)議應(yīng)用配置幻燈片資料

高級(jí)路由管理

—OSPF路由協(xié)議應(yīng)用配置提綱OSPF技術(shù)要點(diǎn)回顧OSPF的基本配置選項(xiàng)OSPF的附加配置OSPFfloodingReductionOSPFRedistributionandFilteringOSPFSummarizationOSPFDefaultRoutingOSPFAuthenticationOSPFVirtualLinks確認(rèn)OSPF的運(yùn)行狀態(tài)ShowdebugOSPFv3的新特點(diǎn)OSPF技術(shù)要點(diǎn)回顧OSPF基本工作過(guò)程初始化，通過(guò)組播地址發(fā)送hello包到所有外連接口。在NBMA和multipoint類型接口則采用單點(diǎn)地址。通過(guò)交互，路由維護(hù)各自鄰居信息。鄰居關(guān)系獨(dú)立于物理連接關(guān)系，相當(dāng)于為交流路由信息而在路由之間選擇建立的專用虛擬鏈路。路由器各自向其新加入的neighbour發(fā)送LSA信息.路由器將收到的LSA記錄下來(lái)，并繼續(xù)轉(zhuǎn)發(fā)到其他新加入的neighbour。所有路由器根據(jù)收集到的LSA集合，建立Link-statedatabases。當(dāng)databases構(gòu)建完成，運(yùn)用SPF算法計(jì)算出從本節(jié)點(diǎn)出發(fā)到達(dá)其他路由節(jié)點(diǎn)的loop-free的路徑，并組成SPF的tree結(jié)構(gòu)。從SPF的tree結(jié)構(gòu)提取信息，對(duì)應(yīng)加入到路由表中，作為優(yōu)選的最佳路徑。OSPF的Hello協(xié)議用于Neighbourdiscovery（Hello包中包含的信息）RouterIDAreaIDOriginatingrouterinterface的addressmaskAuthencationType和AuthencationinformationHelloIntervalHellodeadintervalRouterpriorityDR/BDRSomeflagsRouterIDsoforiginatingrouter’sneighbour鄰居關(guān)系的確認(rèn)及維護(hù)使用Hellointerval、Deadinterval、areaIDs、authencationtypeandpassword驗(yàn)證鄰居關(guān)系的建立鄰居keeplive算法Deadinterval被設(shè)置為4倍的Hellointerval，如果在deadinterval之內(nèi)未收到hello信息，則鄰居關(guān)系解除在broadcast和NBMA類型網(wǎng)絡(luò)中DR/BDRs的選擇

RouterID、現(xiàn)有DR/BDR、routerpriority用于新的DR/BDR選擇及狀態(tài)判定OSPF的相鄰網(wǎng)絡(luò)類型Point-to-Pointnetworks不必選舉DR/BDRs，但采用組播地址在路由之間傳送hello和LSA數(shù)據(jù)。Broadcastnetworks通過(guò)組播/在普通節(jié)點(diǎn)和DR/BDRs之間傳送數(shù)據(jù)。NBMAnetworks不能使用組播地址傳送數(shù)據(jù)，鄰居關(guān)系需要手工指定，DR/BDR選舉出后，所有的數(shù)據(jù)均為單播地址傳送。一般而言，DR/BDR應(yīng)該為與其他路由器均有鏈路相連的節(jié)點(diǎn)。Point-to-multipoint必須被靜態(tài)指定，被作為多個(gè)點(diǎn)對(duì)點(diǎn)網(wǎng)絡(luò)對(duì)待VirtualLinks專用于連接Area0的特殊網(wǎng)絡(luò)在NBMA網(wǎng)絡(luò)中運(yùn)行OSPFOSPF的DR/BDRs選舉優(yōu)勢(shì)減少LSA數(shù)據(jù)的傳送量新加入的節(jié)點(diǎn)只需和已選出的DR/BDR建立鄰居關(guān)系選舉過(guò)程路由器各自發(fā)送及接收hello信息Hello信息中的priority將被檢測(cè)，最高優(yōu)先級(jí)被選為DR，默認(rèn)優(yōu)先級(jí)為1，可更改。優(yōu)先級(jí)為0的鄰居不參加選舉如果DR沒(méi)有選出或者不響應(yīng)，則BDR轉(zhuǎn)為DR角色，而后選舉新的BDR。如果出現(xiàn)一個(gè)以上相同優(yōu)先級(jí)的設(shè)備節(jié)點(diǎn)，則從RouterID最高的中選出BDR運(yùn)行過(guò)程中有新的更高優(yōu)先級(jí)的設(shè)備加入，DR/BDR仍舊保持不變，只在失效時(shí)才重起選舉進(jìn)程鄰居之間周期性發(fā)送hello信息，在deadinterval內(nèi)沒(méi)有信息傳送，則鄰居關(guān)系解除OSPF的RIDUniquerouterID可以帶來(lái)以下優(yōu)勢(shì)可以識(shí)別出重復(fù)的LSA唯一確認(rèn)virtuallink的端點(diǎn)在DR/BDR競(jìng)選中起關(guān)鍵作用RID（routerID）的選擇路由設(shè)備所有有效接口的IP地址均參與RID的選擇，最高值被選為相應(yīng)鏈路上該設(shè)備的RID如果loopback接口存在，該接口地址被選用，如果有多個(gè)loopback接口，最高值的接口地址被選用需要控制RID的值，選擇配置loopback接口，定制地址。此地址不需要被外界其他用戶所訪問(wèn)OSPFLoopbackAddressForOSPFtofunctiontheremustalwaysbeanactiveinterfacePhysicalinterfacese.g.serial/Ethernetmaynotalwaysbeactive–routingwouldfailConfigurevirtual“l(fā)oopback”interfaceassolutionSubnetmaskwillalwaysbe55

Router(config)#interfaceloopbacknumberRouter(config-if)#ipaddress

ip-addresssubnet-maskSPF及OSPF鏈路的評(píng)估SPF基于網(wǎng)絡(luò)拓?fù)涞挠袡?quán)無(wú)向圖進(jìn)行計(jì)算各個(gè)鏈路的權(quán)值主要以來(lái)BW計(jì)算FDDI,ATM,GigabitEthernetcost=1HSSI45M cost=216-MbpsTokenRing cost=610-MbpsEthernet cost=10T1（1.544Mbps） cost=6456kbps cost=1785各個(gè)鏈路的權(quán)值可以人工指定OSPFCost計(jì)算CostistheOSPFmetricusedinpathselectionCostisbasedonbandwidthDefaultbandwidthis1.544Mbps–costis64Costis108

÷bandwidthRouter(config)#interfaceserial0/0Router(config-if)#bandwidth64

Router(config-if)#ipospfcost

number

Cost=100,000,000/BandwidthFastEthernet100MbpsCost=100,000,000/100MCost=1SerialLink64kbpsCost=100,000,000/64kCost=1562OSPF的Router、Areas、LSAsTypesAreaTypesBackbonearea（area0/）Nonbackbone,nonstubareaStubareaTotallystubbyareaNot-so-stubbyarea（NSSAs）RouterTypesInternalroutersAreaBorderRouters（ABRs）BackboneroutersAutonomousSystemBoundaryRouters（ASBRs）LSAstypesRouterLSANetworkLSASummaryLSAsforABRsSummaryLSAsforASBRsAutonomoussystemexternalLSAsNSSAexternalLSAOSPF的PATHtype（o）Intra-areapaths/routers（oIA）Interareapaths/routers（oE1）ExternalType1paths/routers（oE2）ExternalType2paths/routers（oN1）OSPFNSSAtype1（oN2）OSPFNSSAtype2OSPF基本配置選項(xiàng)準(zhǔn)備參數(shù)Area0的設(shè)定所有路由器的RID路由器的priority及RID用于DR/BDR選舉在單域內(nèi)盡量保持地址連續(xù)，利于地址聚合收斂選擇合適的stub網(wǎng)絡(luò)類型盡量避免virtuallinks的使用STUB區(qū)域、路由聚合和虛連接OSPF基本配置步驟將網(wǎng)絡(luò)劃分為若干邏輯區(qū)域area，明確backbonearea0。在需要選擇DR/BDR的區(qū)域，選擇最佳選擇。通過(guò)loopbackinterface或者直接設(shè)定routerID的方式為每一臺(tái)路由指定RID在路由器上啟用OSPF，并配置RID配置路由的各個(gè)接口地址參數(shù)需要時(shí)指定OSPF的鄰居節(jié)點(diǎn)需要時(shí)設(shè)置特殊area類型設(shè)置其他OSPF運(yùn)行參數(shù)選項(xiàng)，如hellointerval/deadinterval，routesummarization，authencation等配置OSPF協(xié)議——?jiǎng)澐謪^(qū)域劃分區(qū)域的基本原則按照自然的地區(qū)或者行政單位劃分按照網(wǎng)絡(luò)中的高端路由器來(lái)劃分按照IP地址的規(guī)律一些制約條件區(qū)域的規(guī)模與骨干區(qū)域連通ABR的處理能力啟動(dòng)OSPF協(xié)議的基本配置EnablinganOSPFprocessusingtherouterospf<process-id>command.Assigningareastotheinterfacesusingthenetwork<networkorIPaddress><mask><area-id>command.Process-idcanbeavaluebetween0and65,535WildcardmaskNOTsubnetmaskusedwithnetworkcommand啟動(dòng)OSPF協(xié)議的基本配置配置路由器的RouterID[Quidway]routeridA.B.C.D啟動(dòng)OSPF協(xié)議[Quidway]ospfenable配置OSPF區(qū)域[Quidway-Serial0]ospfenableareaarea_idOSPF基本配置樣例一routerospf63network.area1network55area0networkarea1Area0Area1

E1T0

E0

E2OSPF基本配置樣例二Router5#configureterminalEnterconfigurationcommands,oneperline.EndwithCNTL/Z.Router5(config)#routerospf87Router5(config-router)#network55area0Router5(config-router)#exitRouter5(config)#endRouter5#OSPF基本配置樣例三Router9#configureterminalEnterconfigurationcommands,oneperline.EndwithCNTL/Z.Router9(config)#routerospf87Router9(config-router)#exitRouter9(config)#interfaceFastEthernet0/0Router9(config-if)#ipaddressRouter9(config-if)#ipospf87area10Router9(config-if)#exitRouter9(config)#endRouter9#OSPF的附加配置OSPFfloodingReduction/TuningOSPFRouter(config-if)#ipospfflood-reduction默認(rèn)LSAflooding每3600秒（1小時(shí)）進(jìn)行一次，此命令可禁止floodingRouter(config-if)#ospfdatabase-filterallout禁止在指定接口向外傳送LSARouter(config-router)#neighbourip_addressdatabase-filterallout禁止向特定的neighbour傳送LSARouter(config-if)#ipospfhello-intervalinteral_in_secondsRouter(config-if)#ipospfdead-intervaldead_interval_in_secondsRouter(config-if)#ipospfretransmit-intervalAllowsrouting-informationexchangebetweenOSPFandotherroutingprotocolsOSPFRouteRedistributionOSPFRIPIGRPEnhancedIGRPIS-ISBGPEGPRouter(config-router)#redistributeprotocol[process-id][metricvalue]

[metric-typevalue][subnets]OSPFRedistributionCommandRedistributesroutesfromOSPFintootherroutingprotocols(andviceversa)OSPFRedistributionExample1RedistributionbetweenRIPandOSPFRIPOSPFArea0S0S1R1OSPFRedistributionExample1routerospf109network55area0network55area0redistributeripsubnetsmetric-type1metric20routerripnetworkpassive-interfaceserial0passive-interfaceserial1default-metric10redistributeospf109matchinternalexternal1external2OSPFRedistributionExample2"Backdoor"creates

potentialloopRIPRIPOSPFArea0RIPAvoidingLoopsR2R3R2R1RedistributionExample2controuterospf109network55area0network55area0redistributeripsubnetsmetric-type1metric20distribute-list11outripaccess-list11permit55

MinimizesroutingtableentriesLocalizesimpactofatopologychangeOSPFRouteSummarizationArea0BackboneABRsArea1SummarizationxxO

O

O

O

O

O

O

RoutingTableforBRoutingTableforCIAInter-area(IA)summarylinkcarriesmaskOneentrycanrepresentseveralsubnetsRouteSummarization(cont.)Area1Area0ABRSummarizationBACSummaryRouteMask=240

Address=12ExistingSubnetMask=252

Address=121111 11 00

0000 11 001111 0000

0000 1100Valid

3rdSubnetInvalidSubnet

ZeroSomeaddressesmayneedreallocatingRouteSummarizationIssueRouter(config-router)#areaarea-idrangeaddressmaskRouteSummarizationCommandsConsolidatesIAroutesonanABRRouter(config-router)#summary-addressaddressmaskConsolidatesexternalroutesonanASBRRouteSummarizationExampleR2R2#routerospf100

network 55area2

network 55area0area0range

area2rangeR1#routerospf100

network 55area1

network 55area0area0range

area1range-

Area2-

-

Area1InterfaceAddresses

(mask)InterfaceAddresses

(mask)R1R2Area0DefaultroutetoroutersoutsidetheareaAddadefaultroutetotheOSPFrouterconnectedtotheoutsidenetwork.Thisroutecanberedistributedtoeachrouterin

theAreathroughnormalOSPFupdates

Router(config)#iproute[interface|next-hopaddress]ThefollowingconfigurationstatementwillpropagatethisroutetoalltheroutersinanormalOSPFarea:Router(config-router)#

default-informationoriginateAllroutersintheOSPFareawilllearnadefaultrouteprovidedthattheinterfaceoftheborderroutertothedefaultgatewayisactive.OSPFrouteauthencationEnableareaauthencationonallroutersinthatareaRouter(config-router)#areaarea_idauthencationRouter(config-router)#ipospfauthencation-keypasswordMD5cyrptographicauthencationRouter(config-router)#areaarea_idauthencationmessage-digestRouter(config-router)#ipospfmessage-digest-keykey_valuemd5passwordOSPFvirtuallinksIt’sthelastoption,andthebetterchoiceistoavoidvirtuallinkRouter(config-router)#areatransit_area_idvirtual-linkrouter_id_of_remoteRouter#showipospfvirtual-links確認(rèn)OSPF配置及運(yùn)行狀態(tài)VerifiesinterfacesareincorrectareasRouter#showipospfinterfacee0

Ethernet0isup,lineprotocolisup

InternetAddress,Area

ProcessID10,RouterID1,NetworkTypeBROADCAST,

Cost:10

TransmitDelayis1sec,StateBDR,Priority1

DesignatedRouter(ID),Interfaceaddress

BackupDesignatedrouter(ID)1,Interfaceaddress

Timerintervalsconfigured,Hello10,Dead40,Wait40,Retransmit5

Helloduein0:00:02

NeighborCountis3,Adjacentneighborcountis3

Adjacentwithneighbor(DesignatedRouter)

Loopback0isup,lineprotocolisup

InternetAddress155,Area1

ProcessID10,RouterID1,NetworkTypeLOOPBACK,Cost:1

LoopbackinterfaceistreatedasastubHost

showipospfinterfaceCommandShowIPospfinterfaceInthisexample,weuseloopbackinterfaceinsteadofEthernetinterfaceDisplaysgeneralinformationaboutthe

OSPFroutingprocessRouter#showipospf

RoutingProcess"ospf1"withID

SupportsonlysingleTOS(TOS0)routes

SPFscheduledelay5secs,HoldtimebetweentwoSPFs10secs

Numberofareasinthisrouteris1

Area23

Numberofinterfacesinthisareais3

Areahasnoauthentication

SPFalgorithmexecuted19times

Arearangesare

LinkStateUpdateIntervalis0:30:00andduein0:04:55

LinkStateAgeIntervalis0:20:00andduein0:04:55

showipospfCommandRouter#showipospfdatabaseOSPFRouterwithID()(ProcessID1)RouterLinkStates(Area23)LinkIDADV

RouterAgeSeq#780x8000003216910x8000002B116930x80000030Checksum0x80B60xE11C0xE35ELink

count5516960x800000260x80A11NetLinkStates(Area23)LinkIDADVRouterAgeSeq#Checksum16910x800000300x2FCE16930x800000240xFB29showipospfdatabaseCommandRouter>showipprotocolRoutingProtocolis“ospf300”Sendingupdatesevery0secondsInvalidafter0seconds,holddown0,flushedafter0OutgoingupdatefilterlistforallinterfacesisnotsetIncomingupdatefilterlistforallinterfacesisnotsetRedistributing:ospf300RoutingforNetworks:/55/55RoutingInformationSources:GatewayDistanceLastUpdate1106d2121100:17:32921100:17:33941100:17:331106d211100:17:331100:17:33301106d19281100:17:331100:17:331100:17:33Distance:(defaultis110)--More--showipprotocolCommandRouter#showipospfvirtual-linksOtherOSPFshowCommandsDisplaysparametersaboutOSPFvirtuallinks

Router#showipospfneighbordetailDisplaysneighborinformationperinterfaceRouter#showipospfborder-routersDisplaysroutestotheABRandASBROSPF的debug命令Debugipospfadj查看OSPF的hello協(xié)議Debugipospfevents查看OSPF的LSA信息傳送將hello協(xié)議的運(yùn)做記入日志Router(config)#routerospf7Router(config-router)#log-adjacency-changesRouter#showlogOSPFv3的新特點(diǎn)OSPFv3特點(diǎn)OSPFforIPv6BasedonOSPFv2,withenhancementsDistributesIPv6prefixesRunsdirectlyoverIPv6Ships-in-the-nightwithOSPFv2OSPFv3/OSPFv2相似性BasicpackettypesHello,DBD,LSR,LSU,LSAMechanismsforneighbordiscoveryandadjacencyformationInterfacetypesP2P,P2MP,Broadcast,NBMA,VirtualLSAfloodingandagingNearlyidenticalLSAtypesOSPFv3/OSPFv2不同點(diǎn)OSPFv3runsoveralink,ratherthanasubnetMultipleinstancesperlinkOSPFv2topologynotIPv6-specificRouterIDLinkIDStandardauthenticationmechanismsUseslink-localaddressesGeneralizedfloodingscopeTwonewLSAtypesConfiguringOSPFv3inCiscoIOS?SoftwareSimilartoOSPFv2PrefixingexistingInterfaceandExecmodecommandswith“ipv6”InterfacesconfigureddirectlyReplacesnetworkcommand“Native”IPv6routermodeNotasub-modeofrouterospfConfigurationModesinOSPFv3

Enteringroutermode[no]ipv6routerospf<processID>

Entering

interfacemode[no]ipv6ospf<processID>area<areaID>

Execmode[no]showipv6ospf[<processID>]clearipv6ospf[<processID>]CiscoIOSOSPFv3SpecificAttributesConfiguringarearange[no]area<areaID>range<prefix>/<prefixlength>ShowingnewLSAshowipv6ospf[<processID>]databaselinkshowipv6ospf[<processID>]databaseprefixOSPFv3DebugCommandsAdjacencyisnotappearing [no]debugipv6ospfadj [no]debugipv6ospfhelloSPFisrunningconstantly [no]debugipv6ospfspf [no]debugipv6ospfflooding [no]debugipv6ospfevents [no]debugipv6ospflsa-generation [no]debugipv6ospfdatabase-timerGeneralpurpose [no]debugipv6ospfpackets [no]debugipv6ospfretransmission [no]debugipv6ospftreeOSPFv3configurationexampleLAN1:2001:1:1:1::/64LAN2:2001:2:2:2::/64Eth0Eth1Router1Router1#interfaceEthernet0ipv6address2001:1:1:1::1/64ipv6ospf1area0interfaceEthernet1ipv6address2001:2:2:2::2/64ipv6ospf1area1

ipv6routerospf1router-idarea1range2001:2:2::/48

Area0Area1Router2CiscoIOSOSPFv3DisplayRouter2#showipv6routeospfIPv6RoutingTable-9entriesCodes:C-Connected,L-Local,S-Static,R-RIP,B-BGPU-Per-userStaticrouteI1-ISISL1,I2-ISISL2,IA-ISISinterareaO-OSPFintra,OI-OSPFinter,OE1-OSPFext1,OE2-OSPFext2O2001:1:1:2::1/128[110/1]viaFE80::205:5FFF:FEAF:2C38,Ethernet0OI2001:2:2::/48[110/2]viaFE80::205:5FFF:FEAF:2C38,Ethernet0Area0Area1Router2CiscoIOSOSPFv3DatabaseDisplayRouter2#showipv6ospfdatabase

OSPFRouterwithID()(ProcessID1)RouterLinkStates(Area0)LinkIDADVRouterAgeSeq#ChecksumLinkcount020090x8000000A0x2DB1105010x800000070xF3E61NetLinkStates(Area0)LinkIDADVRouterAgeSeq#Checksum74800x800000060x3BADInterAreaPrefixLinkStates(Area0)ADVRouterAgeSeq#Prefix17610x800000052001:2:2:2::/649820x800000052001:2:2:4::2/128Link(Type-8)LinkStates(Area0)LinkIDADVRouterAgeSeq#ChecksumInterface112450x800000060xF3DCLo072360x800000080x68FFa2/075010x800000080xE7BCFa2/0IntraAreaPrefixLinkStates(Area0)LinkIDADVRouterAgeSeq#ChecksumReflstype04800x800000080xD6700x20011072360x800000080xC05F0x200202450x800000060x3FF70x2001CiscoIOSOSPFv3DetailedLSADisplayshowipv6os