CCIP-v2 2 pptISP 运营商系列QOS22S09L02

QoSBestPractices,DeployingEnd-to-EndQoS,QoSServiceLevelAgreements,QoSSLAsprovidecontractualassuranceformeetingthedifferenttrafficQoSrequirements.QoSSLAstypicallyprovidecontractualassuranceforparameterssuchas:Delay(fixedandvariable)JitterPacketlossThroughputAvailabilityQoSSLAsareakeydifferentiatorforserviceproviders.,EnterpriseNetworkwithTraditionalLayer2Service,ProvidersellsthecustomeraLayer2servicePoint-to-pointSLAfromtheproviderEnterpriseWANlikelytogetcongestedQoSrequiredforvoice,video,dataintegrationServiceproviderisnotinvolvedinQoS,EnterpriseNetworkwithIPService,CustomerbuysLayer3servicefromtheproviderPoint-to-cloudSLAfromproviderforconformingtrafficEnterpriseWANlikelytogetcongestedServiceproviderisinvolvedinQoS,KnowtheSLAOfferedbyYourSP,SLAtypicallyincludesthreetofiveclasses.Real-timetrafficgetsfixedbandwidthallocation.Datatrafficgetsvariablebandwidthallocationwithminimumguarantee.Additionalclassesnotvisibletocustomermayexistattheedge.,TypicalSLARequirementsforVoice,ServiceProviderSLAExample,Thisisjustanexample.TheactualSLAofferedbyserviceprovidersmayvary.,BranchQoSissimilartoCampusQoS,DeployingEnd-to-EndQoS,DeployingEnd-to-EndQoS(Cont.),Arobust,modernswitchingdesignisarequirement.Buffermanagementismoreofaconcernthanbandwidthmanagement.MultiplequeuesarerequiredonallinterfacestopreventTxqueuecongestionanddrops.Voicetrafficshouldalwaysgointothehighestpriorityqueue.TrustCiscoIPPhoneCoSsettingbutnotthePCCoSsetting.Classifyandmarktrafficasclosetothesourceaspossible.Useclass-basedpolicingtorate-limitcertainunwantedexcesstraffic.,CampusQoSGeneralGuidelines:,CampusQoSImplementation,CampusAccessandDistributionLayerQoSImplementation,Catalyst3550AccessSwitch,1P3Q2T(recommended)or4Q2TWRRdefaultEachqueueisgivenarelativeweightwithonepriorityqueueDefaultvaluesareasfollows:CoSValueCoSPriorityQueues0,112,324,536,74(priorityqueue)MoveCoS5traffictoqueue4TrustCiscoIPPhoneonaccesslinksTrustDSCPorCoSonuplinksCoS-to-DSCPmappingsClassifyandmarkmission-criticaltrafficusingACLs,Catalyst3550AccessSwitchConfiguration,mlsqos!mlsqosmapcos-dscp08162634464856!class-mapmatch-allvoice-bearermatchaccess-group101class-mapmatch-allvoice-controlmatchaccess-group102class-mapmatch-allmission-criticalmatchaccess-group103!policy-mapmarkclassvoice-bearersetipdscpefclassvoice-controlsetipdscp26classmission-criticalsetipdscpaf31!access-list101permitudpanyanyrange1638432767access-list102permittcpanyanyrange20002002access-list102permittcpanyanyeq1720access-list102permittcpanyanyrange1100011999access-list102permitudpanyanyeq2427access-list103permit,!interfaceGigabitEthernet0/12descriptionUplinktoDistributionnoipaddressmlsqostrustdscppriority-queueoutwrr-queuecos-map45!interfaceFastEthernet0/1descriptiontoIPPhonecdpenablenoipaddressservice-policyinputmarkmlsqostrustcosmlsqostrustdevicecisco-phoneswitchportpriorityextendcos0switchportvoicevlan111switchportaccessvlan11priority-queueoutwrr-queuecos-map45,QoSinCatalyst4000:Distribution(SUPIII),4queues(1P3Q2T)ConfigurablePQforqueue3CoSvalue4,5selectsqueue3TrustDSCPorCoSDefaultmappingfromCoStoDSCPandDSCPtoCoSClass-basedpolicingtorate-limittraffic,Catalyst4000DistributionSwitchConfiguration,class-mapcitrix-servermatchaccess-group1!policy-mappolice-citrixclasscitrix-serverpolice480008000exceed-actiondrop!interfaceGigabitEthernet4/1descriptiontoaccessswitchservice-policyinpolice-citrixqostrustdscptx-queue3priorityhigh!interfaceGigabitEthernet4/2descriptiontocoreqostrustdscptx-queue3priorityhigh!access-list1permithost,WANEdge(CE-PE)QoSImplementation,TrafficLeavingEnterpriseNetwork,OutputQoSpolicyonCEcontrolledbyserviceproviderServiceproviderenforcesSLAusingtheoutputQoSpolicyonCEOutputpolicyusesqueuing,dropping,andpossiblyshapingElaboratetrafficclassificationormappingofexistingmarkingsMayrequireLFIorcRTP,OutputQoSpolicyonCEnotcontrolledbyserviceproviderServiceproviderenforcesSLAusinginputQoSpolicyonPEInputpolicyusespolicingandmarkingElaboratetrafficclassificationormappingofexistingmarkingsonPE,TrafficLeavingEnterpriseNetwork(Cont.),CEOutputPolicyClassification/Marking/MappingLLQWREDShapingLFIorcRTP,PEInputPolicy,CEOutputPolicy,PEInputPolicyClassification/Marking/MappingPolicing,TrafficLeavingServiceProviderNetwork,ServiceproviderenforcesSLAusingtheoutputQoSpolicyonPE.Outputpolicyusesqueuing,dropping,and,optionally,shaping.MayrequireLFIorcRTP.NoinputQoSpolicyonCEneeded.,ServiceproviderenforcesSLAusingtheoutputQoSpolicyonPE.Outputpolicyusesqueuing,dropping,and,optionally,shaping.MayrequireLFIorcRTP.InputQoSpolicyonCEirrelevant.,TrafficLeavingServiceProviderNetwork(Cont.),CEInputPolicy,PEOutputPolicyLLQWREDShapingLFIorcRTP,CEInputPolicy,PEOutputPolicyLLQWREDShapingLFIorcRTP,ManagedCEwithThreeServiceClassesExample,Theserviceproviderinthiscasestudyoffersmanagedcustomeredgeservicewiththreeserviceclasses:Premium(VoIP):Maximumbandwidthguarantee,lowlatency,nolossBusiness:Minimumbandwidthguarantee,lowlossClass-Default:Noguarantees(besteffort)MostDiffServdeploymentsuseaproportionaldifferentiationmodel:Ratherthanallocateabsolutebandwidthstoeachclass,serviceprovideradjustsrelativebandwidthratiosbetweenclassestoachieveSLAdifferentiation:VoIPservicedwithpriorityuptoamax.percentageofbandwidth,forexample,25%Businessclassgetsmajorityofremainingbandwidth,forexample,75%Besteffortgetswhateverisleft,forexample,25%ofremainingbandwidth,WANEdgeDesign,VoIPPacketmarkedEFclassandsenttoLLQMaxbandwidth=25%ofCIRPolicedExcessdroppedVoIPsignalingsharestheLLQwithVoIPtrafficBusinessdataPacketsmarkedAF31classandsenttoCBWFQAllocated75%ofremainingbandwidthonceLLQhasbeenservicedPolicedExceedingorviolatingtrafficre-markedWREDconfiguredtooptimizeTCPthroughputBestEffortBest-effortclasssenttoCBWFQWhateverisleft=25%ofremainingbandwidthafterLLQhasbeenservicedWREDconfiguredtooptimizeTCPthroughput,CE-to-PEQoSforFrameRelayAccessCEOutbound,class-mapmatch-allPREMIUMmatchipaccess-group101class-mapmatch-allBUSINESSmatchipaccess-group102!policy-mapOUT-POLICYclassPREMIUMprioritypercent25setipdscpefclassBUISNESSbandwidthremainingpercent75setipdscpaf31random-detectdscp-basedclassclass-defaultbandwidthremainingpercent25setipdscp0random-detectdscp-based,CE-to-PEQoSforFrameRelayAccessCEOutbound(Cont.),CE-to-PEQoSforFrameRelayAccessPEInbound,CE-to-PEQoSforFrameRelayAccessPEInbound(Cont.),Marking,policing,andshapingshouldbedoneattheedgesofthenetwork.Queuinganddroppingaredoneinthecorebasedonpacketmarkingdoneattheedge.,ServiceProviderBackboneQoSImplementation,ServiceProviderBackbone,Overprovisioningbest-effortbackboneisanalternative,buthasthesedrawbacks:ExpensiveFatesharingPlanningmistakesFailureconditionsUnexpectedtrafficdemandDiffServbackboneisbetter,WhatAretheBenefitsofUsingaDiffServBackbone?,DiffServallowssupportofmultipleclassesoftrafficwithdifferentunderprovisioningandoverprovisioningratiosperclassofservice.MaximumpotentialeconomicbenefitofDiffServiswhentrafficrequiringthehighestSLArepresentsaminorproportionoftheoverallcapacity.,PE-to-PQoSPEOutbound,P-to-PQoSPOutbound,P-to-PEQoSPOutbound,PE-to-CEQoSforFrameRelayAccessPEOutbound,PE-to-CEQoSforFrameRelayAccessPEOutbound(Cont.),Summary,AnSLAstipulatesthedeliveryandpricingofnumerousservicelevels.SLAscoveranassortmentofdataservicessuchasFrameRelay,leasedlines,Internetaccess,webhosting,etc.Thereare