005ccnp课程以应用方式讲解加强版1spoto ccnp20课件101introducing spanning tree

Atransparentbridgehasthese1、Itmustnotmodifytheframesthatareforwarded.2、Itlearnsaddressby“listening”onaportforthesourceaddressofadevice.A3、Itmustforwardallbroadcastsoutofallports,exceptfortheportthatinitiallyreceivedthebridge,itforwardstheframeoutallportsexceptfortheportthatinitiallyreceivedAswitchhasthesamecharacteristicsasatransparentWhatIsaBridge冗余会产生的问题2、多帧复用:StationB同时收到2个相同的帧3、MAC地址不稳定:2/2覆盖2/1的mac地址Bridgeloopscanoccuranytimethereisaredundantpathorloopinthebridgenetwork.PreventingBridgeBridgeloopscanbepreventedbydisablingtheredundantD802.1D提供一种机制来防止环路的产生 BridgeProtocolDataBPDUsprovidefortheexchangeofinformationbetweenSpanningTreeOnerootbridgepernetworkOnerootportpernonrootbridgeOnedesignatedportpersegmentportsareblockingRootBridgeBPDU(default=sentevery2Rootbridge=bridgewiththelowestbridgeBridgeIDConfiguringtheRootSwitch(config)#spanning-treeSwitch(config)#spanning-treevlan1rootThis sthisswitchtobetheSwitch(config)#spanning-treeSwitch(config)#spanning-treevlan1rootThiscommandconfiguresthisswitchtobethesecondarySwitch(config)#spanning-treeSwitch(config)#spanning-treevlan1Thiscommandstaticallyconfiguresthepriority(inincrementsof4096).ExtendedSystemIDinBridgeIDBridgeIDSystemIDBridgeIDwiththeSystemIDPVST+ExtendedBridgeOnlyfourhigh-orderbitsofthe16-bitBridgePriorityfieldcarryactualpriority.Therefore,priority

VLANVLAN

4 12 beincrementedonlyinstepsof4096,ontowhichwillbeaddedtheVLANnumber.ForVLAN11:Ifpriorityisleftatdefault,the16-bitPriorityfieldwillhold32768+11=

PriorityValues PriorityValues 8 RootBridgeSelectionRootPortSpanningTreePathLinkCost(RevisedIEEECost(PreviousIEEE102114110010RootPortSelectionSWXistherootSWYneedstoelectarootWhichportistherootportonSWFastEthernettotalcost=0+Ethernettotalcost=0+DesignatedPortSwitchXistherootAllportsontherootbridgearedesignatedportsbecausetheyhaveapathcostof0.BecausetheEthernetsegmenthasapathcostof100,switchYwillblockonthatport.DoallsegmentshaveadesignatedSpanningtreetransitionseachportthroughseveraldifferentstates.SpanningTreePortaddressesaddressesarelearnedfromanytrafficthatisseen.learningstatelastsfor15secondsandisalsocalledtheforwarddelay；InforwardingstateuserdataisforwardedandMACaddressescontinuetobelearned.BPDUsarestillprocessed；PVST+STPDSTPTopologyEnhancementstoPortFast---相对于802.1D来说,Portfast是CISCO增加的属性.加速网络的收PerVLANSpanningTree+RapidSpanningTreeProtocolMultipleSpanningTreeProtocolMSTPisalsoknownasMulti-InstanceSpanningTreeProtocol(MISTP)onCiscoCatalyst6500switchesandabovePerVLANRapidSpanningTree交换机端⼝的5种状学习“活动”拓阻塞只接收禁用(BPDU的2个类确定根桥（rootBPDU的2个类确定根桥（rootbridge到根桥最小路径开销(path最小发送方BID（sender确定最小发送方的端口ID（port

STP收敛的3⼤步根桥（rootbridge端口(path指定端口（DesignatedooMaxBPDU的时健康网络中的配置BPDU（主要TCN不健康，即拓扑变化通知RapidSpanningTreeRSTPPortRSTPPortWhatAreEdgeWillneverhaveaswitchconnectedto ytransitionstoFunctionssimilarlytoPortFast（思科Configuredbyissuingthespanning-treeportfastcommand（思科WhenaedgeportreceivesaBPDU,itgeneratesaRSTPLink*通过接⼝命令修改其默认的链路类型spanning-treelink-typeRSTPBPDUFlagByteRSTPProposalandAgreementDownstreamRSTPProposalandRootandswitchAPortsonAcomeoutofProposaloragreementtakescebetweenAandB.RSTPTopologyChange导致相应的网桥产生TCBPDU.PVRSTImplementationspanning-treemoderapid-showspanning-treevlandebugspanning-HowtoImplementRapidVerifyingSwitch#showspanning-treevlan30SpanningtreeenabledprotocolRootIDPriority24606Address00d0.047b.2800ThisbridgeistherootTime2secMaxAge20secForwardDelay15secBridgeIDPriority24606(priority24576sys-id-extAddressTime2secMaxAge20secForwardDelay15secAgingTime300InterfaceRoleStsCostPrio.Nbr444 yspanningtreemodeissettoMultipleSpanningTreeInstance1mapstoVLANsInstance2mapstoVLANsMSTMSTconfigurationoneachVLANassociationExtendedSystemIDinBridgeIDConfiguringSwitch(config)#spanning-treeSwitch(config)#spanning-treemstEntersMSTconfigurationSwitch(config-mst)#nameSwitch(config-mst)#nameSetstheMSTregionSwitch(config-mst)#revisionSwitch(config-mst)#revisionSetstheMSTconfigurationrevisionSwitch(config-mst)#instanceSwitch(config-mst)#instanceinstvlanMapstheVLANstoanMSTSwitch(config)#spanning-treeSwitch(config)#spanning-treemstinstance_numberrootEstablishesprimaryandsecondaryrootsforMST RevisionInstanceVlans0111-1-Switch#showSwitch#showspanning-treemst ysMSTPconfigurationVerifyingMSTPSwitch#showSwitch#showspanning-treemst ysconfigurationinformationforaspecificMSTPSwitch#showspanning-treemst###