MPLS流量工程

1©2001,CiscoSystems,[e-mail]2Presentation_ID©2001,CiscoSystems,Inc.Agenda•HowMPLSTEworks•WhatCodeIsMPLSTEIn?•PlatformIssuesinImplementation•LabDemo-config3Presentation_ID©2001,CiscoSystems,Inc.HowMPLSTEWorks•Prerequisites•HowMPLS-TEWorks•BasicConfiguration•Knobs!Knobs!Knobs!•DeployingandDesigning4Presentation_ID©2001,CiscoSystems,Inc.PrerequisitesYoushouldalreadyunderstand…•HowtoconfigureaCiscorouter•BasicMPLSconceptslikepush/pop/swap,EXP,andLFIB•Howalink-stateroutingprotocolworks•BasicQoSmechanismslikeMDRRandLLQ5Presentation_ID©2001,CiscoSystems,Inc.Agenda•Prerequisites•HowMPLS-TEWorks•BasicConfiguration•Knobs!Knobs!Knobs!•DeployingandDesiginig6Presentation_ID©2001,CiscoSystems,Inc.HowMPLS-TEWorks•HowMPLS-TEWorks-WhatgoodisMPLS-TE?-InformationDistribution-PathCalculation-PathSetup-ForwardingTrafficDownATunnel7Presentation_ID©2001,CiscoSystems,Inc.WhatGoodIsMPLS-TE?•Therearetwokindsofnetworks1.Thosethathaveplentyofbandwidtheverywhere2.Thosewithcongestioninsomeplaces,butnotinothers•Thefirstkindalwaysevolveintothesecondkind!8Presentation_ID©2001,CiscoSystems,Inc.WhatGoodIsMPLS-TE?•MPLS-TEintroducesa3rdkind:1.Thosethathaveplentyofbandwidtheverywhere2.Thosewithcongestioninsomeplaces,butnotinothers3.Thosethatusealloftheirbandwidthtoitsmaximumefficiency,regardlessofshortest-pathrouting!9Presentation_ID©2001,CiscoSystems,Inc.WhatGoodIsMPLS-TE?MultiProtocolLabelSwitching-TrafficEngineeringMagicProblem-solvingLaborSubstitutewhichisTotallyEffortlessThisstufftakeswork,butit’sworthit!!!WhatisMPLS-TE?Whatisitnot?10Presentation_ID©2001,CiscoSystems,Inc.InformationDistribution•Youneedalink-stateprotocolasyourIGPIS-ISorOSPF•Link-staterequirementisonlyforMPLS-TE!NotarequirementforVPNs,etc!11Presentation_ID©2001,CiscoSystems,Inc.NeedforaLink-StateProtocol•WhydoIneedalink-stateprotocol?1.Tomakesureinfogetsflooded2.Tobuildapictureoftheentirenetwork12Presentation_ID©2001,CiscoSystems,Inc.NeedforaLink-StateProtocolConsiderthefollowingnetwork:-Alllinkshaveacostof10-RtrA’spathtoRtrEisA-B-E,cost20-AlltrafficfromAto{E,F,G}goesA-B-ERtrARtrBRtrCRtrERtrDRtrFRtrG13Presentation_ID©2001,CiscoSystems,Inc.WhataDVProtocolSeesNodeNext-HopCostBB10CC10DC20EB20FB30GB30•RtrAdoesn’tseeallthelinks•RtrAonlyknowsabouttheshortestpath•ThisisbydesignRtrARtrBRtrCRtrERtrDRtrFRtrG14Presentation_ID©2001,CiscoSystems,Inc.WhataLSProtocolSeesNodeNext-HopCostBB10CC10DC20EB20FB30GB30•RtrAseesalllinks•RtrAonlycomputestheshortestpath•Routingtabledoesn’tchangeRtrARtrBRtrCRtrERtrDRtrFRtrG15Presentation_ID©2001,CiscoSystems,Inc.TheProblemWithShortest-PathNodeNext-HopCostBB10CC10DC20EB20FB30GB30•SomelinksareDS3,someareOC3RtrARtrBRtrCRtrERtrDRtrFRtrGOC3OC3DS3DS3DS3OC3OC3•RtrAhas40MboftrafficforRtrF,40MboftrafficforRtrG•Massive(44%)packetlossatRtrB-RtrE!•ChangingtoA-C-D-Ewon’thelp16Presentation_ID©2001,CiscoSystems,Inc.WhatMPLS-TEAddrsNodeNext-HopCostBB10CC10DC20EB20FTunnel030GTunnel130RtrARtrBRtrCRtrERtrDRtrFRtrGOC3OC3DS3DS3DS3OC3OC3•RtrAseesalllinks•RtrAcomputespathsonpropertiesotherthanjustshortestcost•Nocongestion!17Presentation_ID©2001,CiscoSystems,Inc.HowMPLS-TEWorks•HowMPLS-TEWorks-WhatgoodisMPLS-TE?-InformationDistribution-PathCalculation-PathSetup-ForwardingTrafficDownATunnel18Presentation_ID©2001,CiscoSystems,Inc.InformationDistribution•OSPF-UsesType10(OpaqueArea-Local)LSAs-Seedraft-katz-yeung-ospf-traffic19Presentation_ID©2001,CiscoSystems,Inc.InformationDistribution•IS-IS-UsesType22TLVs-Seedraft-ietf-isis-traffic20Presentation_ID©2001,CiscoSystems,Inc.InformationDistribution•IS-ISandOSPFpropagatethesameinformation!-Linkidentification-TEMetric-Bandwidthinfo(maxphysical,maxreservable,availableper-class)-Attributeflags21Presentation_ID©2001,CiscoSystems,Inc.InformationDistribution•TEfloodingislocaltoasingle{area|level}•Inter-{area|level}TEharder,butpossible(thinkPNNI)22Presentation_ID©2001,CiscoSystems,Inc.HowMPLS-TEWorks•HowMPLS-TEWorks-WhatgoodisMPLS-TE?-InformationDistribution-PathCalculation-PathSetup-ForwardingTrafficDownATunnel23Presentation_ID©2001,CiscoSystems,Inc.PathCalculation•ModifiedDijkstraattunnelhead-end•OftenreferredtoasCSPFConstrainedSPF•…orPCALC(pathcalculation)24Presentation_ID©2001,CiscoSystems,Inc.PathCalculation•NormalSPF–findshortestpathacrossalllinks•SeePerlman(2nded),Moy,etc.forexplanationofSPFRtrARtrBRtrCRtrERtrDRtrFRtrG“what’stheshortestpathtoallrouters?”25Presentation_ID©2001,CiscoSystems,Inc.PathCalculation•NormalSPF–findshortestpathacrossalllinks•SeePerlman(2nded),Moy,etc.forexplanationofSPFRtrA“what’stheshortestpathtoallrouters?”26Presentation_ID©2001,CiscoSystems,Inc.PathCalculation•NormalSPF–findshortestpathacrossalllinks•SeePerlman(2nded),Moy,etc.forexplanationofSPFRtrARtrBRtrC“what’stheshortestpathtoallrouters?”27Presentation_ID©2001,CiscoSystems,Inc.PathCalculation•NormalSPF–findshortestpathacrossalllinks•SeePerlman(2nded),Moy,etc.forexplanationofSPFRtrARtrBRtrCRtrD“what’stheshortestpathtoallrouters?”28Presentation_ID©2001,CiscoSystems,Inc.PathCalculation•NormalSPF–fi