MPLS原理简介

1ASBroadband99©1999,CiscoSystems,Inc.IntroductionMPLS–Technology&[e-mail]2©1999,CiscoSystems,Inc.Agenda•Backgroundandbusinesscase•Technologybasics–WhatisMPLS?Whereisitused?•LabelDistributioninMPLSNetworks–LDP,RSVP,BGP•BuildingMPLSbasedServices–IP+ATMIntegration–VPNs–TrafficEngineering(FRR&Protection)•Conclusions3©1999,CiscoSystems,Inc.EvolutionofMPLS•FromTagSwitching•ProposedinIETF–LatercombinedwithotherproposalsfromIBM(ARIS),Toshiba(CSR)199619971998199920002001TimeCiscoCallsaBOFatIETFtoStandardizeTagSwitchingTrafficEngineeringDeployedMPLSVPNDeployedLargeScaleDeploymentCiscoShipsMPLS(TagSwitching)CiscoShipsMPLSTEMPLSCroupFormallyCharteredbyIETF4ASBroadband99©1999,CiscoSystems,Inc.MPLS-KeyDrivers4Presentation_ID©1999,CiscoSystems,Inc.5©1999,CiscoSystems,Inc.MPLSasaFoundationforValueAddedServicesProviderProvisionedVPNsMPLSTrafficEngineeringIP+ATMNetworkInfrastructureIP+OpticalGMPLSAnyTransportOverMPLS6©1999,CiscoSystems,Inc.USVPNSpending0200400600800100012001400160018002000199719981999200020012002YankeeGroupPredictionsforVPNSpending($USmillions)InfoneticsVPNSpendProjectionsin($USmillions05000100001500020000250003000019992000200120022003VPNProductsVPNServices7©1999,CiscoSystems,Inc.NewApplicationsforVPN73%64%27%0%20%40%60%80%IndividualRemoteAccessSite-to-siteExtranetsVPNTypesImplementedby2002Source:InfoneticsApril20008©1999,CiscoSystems,Inc.TheServiceProviderChallenge•GenerateNewservices•ProtectExistingInfrastructure–ATM/FR•CombinePrivateDataServiceswithInternetServices•Moveintorapiddeployment9ASBroadband99©1999,CiscoSystems,Inc.TechnologySpecifics10©1999,CiscoSystems,Inc.EncapsulationsLabelHeaderPPPHeaderLayer3HeaderPPPHeader(PacketoverSONET/SDH)ATMCellHeaderHECLabelDATACLPPTIVCIGFCVPILabelHeaderMACHeaderLayer3HeaderLANMACLabelHeader11©1999,CiscoSystems,Inc.MPLSOperation–Re-Cap1a.Existingroutingprotocols(e.g.OSPF,IS-IS)establishreachabilitytodestinationnetworks1b.LabelDistributionProtocol(LDP)establisheslabeltodestinationnetworkmappings.2.IngressEdgeLSRreceivespacket,performsLayer3value-addedservices,and“labels”packets3.LSRswitchespacketsusinglabelswapping4.EdgeLSRategressremoveslabelanddeliverspacket12ASBroadband99©1999,CiscoSystems,Inc.LabelDistributioninMPLSNetworks13©1999,CiscoSystems,Inc.LabelDistributionProtocol•DefinedinRFC3035and3036•UsedtodistributeLabelsinaMPLSnetwork•ForwardingEquivalenceClass»HowpacketsaremappedtoLSPs(LabelSwitchedPaths)•AdvertiseLabelsperFEC»Reachdestinationa.b.c.dwithlabelx•Neighbordiscovery»BasicandExtendedDiscovery14©1999,CiscoSystems,Inc.LabelDistributionProtocol•LabelMerge»Donebydefaultforpacketnetworks–uniquelabeladvertisedperFEC»RequiresVCmergeforATMnetworks15©1999,CiscoSystems,Inc.TDP&LDP•TagDistributionProtocol»Pre-cursortoLDP»UsedforCiscoTagSwitching•TDPandLDPsupportedonthesamebox»Perneighbor/linkbasis»Pertargetbasis16©1999,CiscoSystems,Inc.RSVP&LabelDistribution•UsedinMPLSTrafficEngineering•AdditionstoRSVPsignalingprotocol•LeveragetheadmissioncontrolmechanismofRSVP•LabelrequestsaresentinPATHmessagesandbindingisdonewithRESVmessages•EXPLICT-ROUTEobjectdefinesthepathoverwhichsetupmessagesshouldberouted•UsingRSVPhasseveraladvantages»TrafficEngineering,SharedExplicit,FRR17©1999,CiscoSystems,Inc.MPLSExample:ForwardingPackets128.89171.69101Inlabel--...AddressPrefix128.89171.69...OutI’face11...Outlabel45...Inlabel45...AddressPrefix128.89171.69...OutI’face01...Outlabel97...128.89.25.4Data4128.89.25.4Data128.89.25.4Data128.89.25.4Data9Inlabel9...AddressPrefix128.89...OutI’face0...Outlabel-...0LabelSwitchforwardsbasedonlabel18©1999,CiscoSystems,Inc.LabelStacking•IGPLabels–Usedforroutingpackets•BGPLabels–Usedforassigningendusers/communities•RSVPLabels–UsedforTEtunnels•Ifmorethanoneserviceisused–Thenmultiplelabelsarerequired–TEandFRR–Insomecasesasingleservicerequirestheuseofmultiplelabels-VPNs19©1999,CiscoSystems,Inc.LabelStacking–how?•ArrangeLabelsinastack•Innerlabelscanbeusedtodesignateservices/FECsetc»E.gVPNs,FastRe-route•Outerlabelusedtoroute/switchtheMPLSpacketsinthenetwork•Allowsbuildingservicessuchas»MPLSVPNs–Basic&Advanced-CSC»TrafficEngineeringandFastRe-route»VPNsoverTrafficEngineeredcore»AnyTransportoverMPLSTELabelIGPLabelVPNLabelInnerLabelOuterLabelIPHeader20ASBroadband99©1999,CiscoSystems,Inc.MPLSbasedservices21ASBroadband99©1999,CiscoSystems,Inc.ProviderProvisionedVPNs22©1999,CiscoSystems,Inc.Categories•BGPMPLSVPNs–RFC2547–SupportedbyCisco•VirtualRouters––Alternativeproposal–reliesonlogicalpartitioningofthephysicalbox–RequirestheuseofMulticast/broadcastforbetterconvergence23©1999,CiscoSystems,Inc.MPLSBasedIP-VPNArchitecture•ScalableVPNs•IPQoSandtrafficengineering•EasytomanageandNoVCprovisioningrequired•ProvidesalevelofSecurityequivalenttoFrame-relayandATM•Supportsthedeploymentofnewvalue-addedapplications•CustomerIPaddressfreedomMPLSNetworkTrafficSeparationatLayer3EachVPNhasUniqueRDMPLSVPNRenaultMPLSVPNBankcorpVPNASite2VPNASite3CorpASite1CorpBSite2CorpBSite1CorpBSite3VPNMembership-BasedonLogicalPort24©1999,CiscoSystems,Inc.•Thenetworkdistribu