《HCNA-HNTDFastTraining》SpanningTreeProtocol課程團(tuán)隊(duì)：葉禮兵王蘇南張悅吳偉強(qiáng)Foreword Astheenterprisenetworkexpands,multi-switchednetworksareintroducedtoprovidelinklayercommunicationbetweenagrowingnumberofendsystems.Asnewinterconnectionsareformedbetweenmultipleenterpriseswitches,newopportunitiesforbuildingeverresilientnetworksaremadepossible,howeverthepotentialforswitchingfailureasaresultofloopsbecomesevermorelikely.Itisnecessarythatthespanningtreeprotocol(STP)thereforebeunderstoodintermsofbehaviorinpreventingswitchingloops,andhowitcanbemanipulatedtosuitenterprisenetworkdesignandperformance.Page2Objectives Uponcompletionofthissection,traineeswillbeableto:Describetheissuesfacedwhenusingamulti-switchednetwork.Explainthelooppreventionprocessofthespanningtreeprotocol.ConfigureparametersformanagingtheSTPnetworkdesign.Page3Layer2RedundancyPage4SwitchASwitchBSwitchDSwitchCSwitchERedundancyinaswitchingnetworkminimizesconnectionfailurebutgeneratespotentialswitchingloops.BroadcastStormsPage5Switchingloopsallowforbroadcaststormstooccurandduplicationofframestobereceivedbyendstations.00-01-02-03-04-AA00-01-02-03-04-BBSwitchASwitchBSwitchCHostAHostBG0/0/3G0/0/2G0/0/1MACInstabilityPage6MACInterface00-01-02-03-04-AAG0/0/300-01-02-03-04-AAG0/0/2ReceivingpreviouslyforwardedframesgeneratesfalseMACentries,andinstabilitywithintheMACaddresstable.00-01-02-03-04-AA00-01-02-03-04-BBSwitchASwitchBSwitchCHostAHostBG0/0/2G0/0/3ResolvingLayer2RedundancyIssuesPage7Loopsareeliminatedbyrestrictingtrafficflowoverredundantpaths.00-01-02-03-04-AA00-01-02-03-04-BBSwitchASwitchBSwitchCHostAHostBG0/0/2G0/0/3TheSpanningTreeRootBridgePage8RootNon-RootNon-RootNon-RootNon-RootNon-RootAninvertedtreearchitectureiscreatedasaresultofSTP.Therootbridgerepresentsthebaseofthespanningtree.BridgeIDPage9RootRoot409600-01-02-03-04-AA3276800-01-02-03-04-BB3276800-01-02-03-04-CC3276800-01-02-03-04-CC3276800-01-02-03-04-DD3276800-01-02-03-04-EEBridgeIdentifiersareusedtoelecttherootbridge.Thebridgeprioritycanbemanipulatedtoforcerootselection.BridgeProtocolDataUnitPage10PIDPVIBPDUTypeFlagsRootIDRPCBridgeIDPortIDMessageAgeMaxAgeHelloTimeFwdDelayConfiguration

TCNBPDUBPDURootPathCostPage11RootpathcostiscarriedintheBPDUandusedtodeterminetheshortestpathtotheroot.20000200002000020000200002000020000Root20000RPC20000RPC20000RPC0RPC0RPC20000RPC2000020000PathCostStandardsPage12PortSpeed802.1D802.1tPathCostLegacy10Mbps9919999991999100Mbps181999991991Gbps4200002010Gbps220002STPsupportsvariouspathcoststandardsThe802.1tisthedefaultstandardusedbyHuaweiswitchesSpanningTreePortRolesPage13Spanningtreesupportsdesignated,rootandalternateportroles.Therootpathcostenablesportrolestobedetermined.DDDDDDRRARootRootRRRRPC20000RPC20000RPC0RPC0RPC20000RPC20000PortIDPage14Wheretherootpathcostisequal,aportidentifierisusedtodeterminetheactiveandalternatepathstotheroot.RootRPC0RPC0409600-01-02-03-04-AA3276800-01-02-03-04-BB3276800-01-02-03-04-CCDDDADR128.1128.2128.3128.2128.1ARTimersPage15TheMAXAgerepresentstheagingtimerofaBPDU.BPDUarediscardedwhenMessageAgeexceedsMAXAgeBPDUInterval(2seconds)MSGAge:0MAXAge:20MSGAge:1MAXAge:20MSGAge:2MAXAge:20MSGAge:2MAXAge:20MSGAge:1MAXAge:20RootElectionProcessPage16SwitchA3276800-e0-fc-41-42-593276800-e0-fc-41-43-693276800-e0-fc-16-ee-43BPDUBPDUBPDUBPDUBPDUBPDUSwitchCSwitchBAllSTPswitchesadvertiseBDPUtopeerswithselfasroot.PortRoleEstablishmentProcessPage17RootG0/0/1G0/0/2G0/0/1G0/0/2G0/0/2G0/0/1ADRootPortRootPortDDSwitchASwitchCSwitchBRPC20000RPC20000RPC0RPC03276800-e0-fc-41-42-593276800-e0-fc-41-43-693276800-e0-fc-16-ee-43TheBridgeIDandRootPathCostareusedtoelectportroles.PortStateTransitionPage18DisabledForwardingListeningLearning①Blocking③③④③④⑤⑤⑤⑤②STPModesPage19[SWA]stpmode?

mstpMultipleSpanningTreeProtocol(MSTP)mode

rstpRapidSpanningTreeProtocol(RSTP)mode

stpSpanningTreeProtocol(STP)mode[SWA]stpmodestpSwitchBSwitchCSwitchAAssigningTheRootPage20[SWA]stppriority4096Apr15201316:15:33-08:00SWADS/4/DATASYNC_CFGCHANGE:OID1.3.6.1.4.1.2011.5.25.191.3.1configurationshavebeenchanged.Thecurrentchangenumberis4,thechangeloopcountis0,andthemaximumnumberofrecordsis4095.409600-01-02-03-04-AASwitchBSwitchCSwitchA3276800-01-02-03-04-BB3276800-01-02-03-04-CCRootcanbesetmanuallyorbydefiningtheswitchasprimaryAssigningPathCostPage21[SWC]stppathcost-standard?

dot1d-1998IEEE802.1D-1998

dot1tIEEE802.1T

legacyLegacy[SWC]interfaceGigabitEthernet0/0/1

[SWC-GigabitEthernet0/0/1]stpcost2000409600-01-02-03-04-AASwitchBSwitchCSwitchA3276800-01-02-03-04-BB3276800-01-02-03-04-CCG0/0/1RootProtectionPage22Rootprotectionpreventschangestothetopologyasaresultofrootbridgetransition,causedbyreceivinghigherpriorityBPDU.409600-01-02-03-04-AASwitchBSwitchCSwitchA3276800-01-02-03-04-BB3276800-01-02-03-04-CC[SWA]interfaceGigabitEthernet0/0/1[SWA-GigabitEthernet0/0/1]stproot-protectionG0/0/1ConfigurationValidationPage23[SWA]displaystp[CISTGlobalInfo][ModeSTP]CISTBridge:4096.00-01-02-03-04-BBBridgeTimes:Hello2sMaxAge20sFwDly15sMaxHop20CISTRoot/ERPC:4096.00-01-02-03-04-BB/0CISTRegRoot/IRPC:4096.00-01-02-03-04-BB/0CISTRootPortId:0.0BPDU-Protection:DisabledTCorTCNreceived:37TCcountperhello:0STPConvergeMode:NormalShareregion-configuration:EnabledTimesincelastTC:0days0h:1m:29s……ConfigurationValidationPage24[SWA]displaystp……[Port1(GigabitEthernet0/0/1)][FORWARDING]PortProtocol