ITUTG8032 ERPS协议介绍PPT课件

G 8032EthernetRingProtectionOverviewMarch 2008ITU TQ9 SG15 2 Agenda G 8032RecommendationIntroductionG 8032ObjectivesandPrinciplesG 8032ConceptsG 8032ProtectionSwitchingG 8032R APSMessagesG 8032ItemsUnderStudy 3 ITU TSG15 Q9G 8032Recommendation G 8032RecommendationconsentedFebruary2008ThisRecommendationdefinestheAPSprotocolandprotectionswitchingmechanismsforETHlayerringtopologies Includedaredetailspertainingtobridgedringprotectioncharacteristics architecturesandtheringAPSprotocol G 8032ProposalsandContributions G 8032ConvergedProposals G 8032ERPWorkItemApprovedinITU T G 8032Objective Principles andRequirementsSetting G 8032RecommendationConsent 4 G 8032ObjectivesandPrinciples Useofstandard802MACandOAMframesaroundthering Usesstandard802 1Q andamendedQbridges butwithxSTPdisabled RingnodessupportsstandardFDBMAClearning forwarding flushbehaviourandportblocking unblockingmechanisms Preventsloopswithintheringbyblockingoneofthelinks eitherapre determinedlinkorafailedlink MonitoringoftheETHlayerfordiscoveryandidentificationofSignalFailure SF conditions Protectionandrecoveryswitchingwithin50msfortypicalrings Totalcommunicationfortheprotectionmechanismshouldconsumeaverysmallpercentageoftotalavailablebandwidth 5 G 8032TermsandConcepts RingProtectionLink RPL LinkdesignatedbymechanismthatisblockedduringIdlestatetopreventlooponBridgedringRPLOwner NodeconnectedtoRPLthatblockstrafficonRPLduringIdlestateandunblocksduringProtectedstateLinkMonitoring LinksofringaremonitoredusingstandardETHCCOAMmessages CFM SignalFail SF SignalFailisdeclaredwhenETHtrailsignalfailconditionisdetectedNoRequest NR NoRequestisdeclaredwhentherearenooutstandingconditions e g SF etc onthenodeRingAPS R APS Messages ProtocolmessagesdefinedinY 1731andG 8032AutomaticProtectionSwitching APS Channel Ring wideVLANusedexclusivelyfortransmissionofOAMmessagesincludingR APSmessages 6 G 8032Timers G 8032specifiestheuseofdifferenttimerstoavoidraceconditionsandunnecessaryswitchingoperationsWTR WaittoRestore Timer UsedbytheRPLOwnertoverifythattheringhasstabilizedbeforeblockingtheRPLafterSFRecoveryHold offTimers UsedbyunderlyingETHlayertofilteroutintermittentlinkfaultsFaultswillonlybereportedtotheringprotectionmechanismifthistimerexpires 7 ControllingtheProtectionMechanism ProtectionswitchingtriggeredbyDetection clearingofSignalFailure SF byETHCCOAMRemoterequestsoverR APSchannel Y 1731 ExpirationofG 8032timersR APSrequestscontrolthecommunicationandstatesoftheringnodesTwobasicR APSmessagesspecified R APS SF andR APS NR RPLOwnermaymodifytheR APS NR indicatingtheRPLisblocked R APS NR RB RingnodesmaybeinoneoftwostatesIdle normaloperation nolink nodefaultsdetectedinringProtecting Protectionswitchingineffectafteridentifyingasignalfault 8 PhysicaltopologyhasallnodesconnectedinaringERPguaranteeslackofloopbyblockingtheRPL linkbetween6 1infigure Logicaltopologyhasallnodesconnectedwithoutaloop EachlinkismonitoredbyitstwoadjacentnodesusingETHCCOAMmessagesSignalFailureasdefinedinY 1731 istriggertoringprotectionLossofContinuityServerlayerfailure e g PhyLinkDown RPLOwner RPL ETH CC ETH CC ETH CC ETH CC ETH CC ETH CC Physicaltopology Logicaltopology RingIdleState 9 ProtectionSwitching LinkFailure Link nodefailureisdetectedbythenodesadjacenttothefailure Thenodesadjacenttothefailure blockthefailedlinkandreportthisfailuretotheringusingR APS SF messageR APS SF messagetriggersRPLOwnerunblockstheRPLAllnodesperformFDBflushingRingisinprotectionstateAllnodesremainconnectedinthelogicaltopology Physicaltopology Logicaltopology RPLOwner RPL 10 ProtectionSwitching FailureRecovery Whenthefailedlinkrecovers thetrafficiskeptblockedonthenodesadjacenttotherecoveredlinkThenodesadjacenttotherecoveredlinktransmitR APS NR messageindicatingtheyhavenolocalrequestpresentWhentheRPLOwnerreceivesR APS NR messageitStartsWTRtimerOnceWTRtimerexpires RPLOwnerblocksRPLandtransmitsR APS NR RB messageNodesreceivingthemessage performaFDBFlushandunblocktheirpreviouslyblockedportsRingisnowreturnedtoIdlestate RPLOwner RPL Physicaltopology Logicaltopology 1 2 6 4 3 5 11 SignalingChannelInformation ERPusesR APSmessagestomanageandcoordinatetheprotectionswitchingR APSdefinedinY 1731 OAMcommonfieldsaredefinedinY 1731 Version 00000 forthisversionofRecommendationOpCode definedtobe40inY 1731Flags 00000000 shouldbeignoredbyERP 12 R APSSpecificInformation Specificinformation 32octets definedbyG 8032Request Status 4bits 1011 SF 0000 NR Other FutureStatus RB 1bit SetwhenRPLisblocked usedbyRPLOwnerinNR Status DNF 1bit SetwhenFDBFlushisnotnecessary Future NodeID 6octets MACaddressofmessagesourcenode Informational Reserved1 4bits StatusReserved 6bits Reserved2 24octets Futuredevelopment 13 ItemsUnderStudy G 8032iscurrentlyaninitialrecommendationthatwillcontinuetobeenhanced Thefollowingtopicsareunderstudyforfutureversionsoftherecommendation Interconnectedringsscenarios sharednode sharedlinksRPLblockedatbothends configurationoftheringwherebothnodesconnectedtotheRPLcontroltheprotectionmechanismSupportforManualSwitch administrativedecisiontoclosedownalinkandforcea recovery situationarenecessaryfornetworkmaintenanceSupportforSignalDegradescenarios SDsituationsneedspecialconsiderationforanyprotectionmechanismNon revertivemode Allowsthenetworktoremainin recovery configurationeitheruntilanewsignalfailureoradministrativeswitchingRPLDisplacement DisplacementoftheroleoftheRPLtoanotherringlinkflexiblyinthenormal idle conditionIn depthanalysisofdifferentoptimizations e g FDBflushing Etc 14 ThankYou 15 Backup 16 G 8032BasicFunctions 17 ERPFunctionalityDecomposition Inputs Localnoderequests ETHsignals R APSmessages WTRTimer Filters LocalPriorityLogic ValidityCheck GuardTimer PriorityLogic guaranteethathighestprioritymessagearrivesforprocessing ERPProcessing R APSRequestProcessing processesfilteredmessageaccordingtoStateMachinewithknowledgeofcurrentstateandRPL OwnerindicationOutputs Nodefunctions FDBFlushing Block Unblockport sending orstopping R APSmessages 18 StateMachine Threenodestates Initialization whenfirstdefiningtheringA Idle the normal stateoftheringnodeswithRPLblockedandallnodes portsworkingB Protecting whenprotectionswitchingisineffect RPLunblocked other usuallyfault linkisblocked DifferentinputmessagesassignedpriorityasappearsintheStateMachinedescription PrioritymechanismtoallowproperreactiontofaultsStateMachinedescribestheactionstobetakenbythenodedependentoncurrentstateandinputmessage Onlymessagewithhighestprioritywillpassthroughthefiltering Differentactionsinclude transmissionofR APSmessage blocking unblockingaport flushingtheFDB switchingcurrentstateofnode andstarting stoppingtimers 19 StateMachine FDBflushingwillclearallofthelearnedfilteringruleswithinthenode CurrentRecommendationincludesbasicoptimization onlyflushingonceonfaultdiscoveryandonceonrecovery DNFstatusflagisforfuturedefinition 20 SwitchingTriggers Detection ClearingofSF SignalFail SF LossofCCM SFsignalpassedupfromunderlying sub layerSwitchingisperformedwhenhold offtimerexpiresafterdetectionofSF Operator srequest Lockout Forcedswitch Manualswitch Clear forfuturespecification Remoterequest SwitchingrequestindicatedinreceivedR APSinformationfromtheothernode Protectionswitchingalgorithmisbasedonprioritiesassignedtoalltriggers 21 EthernetRingsandtheRPL Ethernetnodesconnectedinaringtopology Eachnodeconnectedtotwoneighborsvialinks E Wports Deterministicnetworktopology Avoidloopswithinringbyblockingadesignatedlink RPL NoderesponsibletocontroltheblockingstateofRPLisRPLownerRPLisunblockedduringprotectionstateandmayreverttoblockedduringrecovery RPL 22 RPLOwnerreceivesSFmessageandunblocksitsendofRPLlink row3 StableState SFmessagesontheringFurtherSFmessagestriggernofurtheraction row10 B C D E F G A SF Normal Protectionstate failure SF SF A ScenarioA NormaltoProtection NormalStateFailureOccursNodesCandDdetectlocalSignalFailureconditionandafterrespectinghold offtimeandBlockfailedport row1 NodeCandDperiodicallysendSFmessage onbothringports whileSFconditionpersists EachnodeperformsaFDBFlushwhenreceivingtheSFmessage RPLOwner B SF SF C D E SF SF SF SF SF SF F 50ms G Flush Flush Flush Flush Flush Flush Flush 23 WhennodeCandDexpireth