CCIP-v2 2 pptQOS22S05L05-del不用看

CongestionManagement,ConfiguringLANCongestionManagement,Multiplequeuesprotectthequeuecontainingimportanttraffic(voice)fromdrops.Thenumberofqueuesavailabledependsupontheswitchmodelandporttype.Onsomeswitches,“dropthresholds”canbeassignedtoeachqueue.Onsomeswitches,queuescanhavenormaltaildroporWREDdropping.Dropshappenindata-onlyqueue(s).,QueuingonCatalystSwitches,Keyqueuingfeaturesdependupontheswitchhardware:ThenumberofqueuesperportThetypeofqueues(priorityorstandard)ThecapabilitytohavedropthresholdsforaqueueThenumberofdropthresholdsperqueueThetypeofdropthresholds(taildroporWRED)Switchqueuingcapabilitiesareshownas:2Q2T:TwoqueuesTwodropthresholdsforeachqueue1P2Q2T:OnepriorityqueueTwoadditionalqueuesTwodropthresholdsforeachqueue,QueuingonCatalystSwitches(Cont.),QueuingonCatalystSwitches(Cont.),QueuingonCatalystSwitches(Cont.),Catalyst2950Switches4transmitqueues(1P3Qor4Q)NeedtoconfigurePQandensurethatCoS5trafficisassignedtothePQConfigurablePQforqueue4ConfigurableCoStospecificqueueConfigurablequeueweight,WeightedRoundRobin,WRRovercomestheproblemofhavingPQstarvingoutthelowerpriorityqueues.WRRschedulingpreventsqueueswithalowerweightfrombeingcompletelystarvedduringperiodsofheavyhigh-prioritytraffic.Differentweightsareassignedtoeachqueue.Forexample,inoneschedulinground,theWRRschedulerwilltransmit:Threeframesfromaqueueassignedweight3Fourframesfromaqueueassignedweight4WRRwithanexpeditequeue:WhenWRRisconfiguredonaCatalyst2950,theoptionexiststoconfigurequeue4asapriorityqueuean“expeditequeue.”,ConfiguringPQonCatalyst2950Switches,wrr-queuecos-mapquidcos1.cosn,Switch(config)#,AssignsCoSvaluestoCoSpriorityqueuesquid:SpecifiesthequeueIDoftheCoSpriorityqueue.(Rangesare1to4where1isthelowestCoSpriorityqueue.)cos1.cosn:SpecifiestheCoSvaluesthataremappedtothequeueID.DefaultIDvaluesare:QueueIDCoSValues10,122,334,546,7,ConfiguringWRRonCatalyst2950Switches,wrr-queuebandwidthweight1.weight4,Switch(config-if)#,AssignsWRRweightstothefouregressqueuesRangesfortheWRRvalues:Forweight1,weight2,andweight3,therangeis1to255.Forweight4,therangeis0to255(whenweight4issetto0,queue4isconfiguredastheexpeditequeue).,!interfaceGigabitEthernet0/12wrr-queuebandwidth201800nowrr-queuecos-mapwrr-queuecos-map10124wrr-queuecos-map3367wrr-queuecos-map45,MonitoringQueuingonCatalyst2950Switches,showmlsqosmapscos-dscp|dscp-cos,Switch,DisplaysQoSmappinginformation.Thiscommandisavailablewithenhancedsoftwareimageswitches.,SwitchshowmlsqosmapsDscp-cosmap:dscp:081016182426323440424856-cos:0112233445567Cos-dscpmap:cos:01234567-dscp:08162432404856,MonitoringQueuingonCatalyst2950Switches(Cont.),showwrr-queuecos-map,Switch,DisplaysthemappingoftheCoSpriorityqueues,showwrr-queuebandwidth,Switch,DisplaystheWRRbandwidthallocationfortheCoSpriorityqueues,Switchshowwrr-queuebandwidthWRRQueue:1234Bandwidth:10203040,Switchshowwrr-queuecos-mapCoSValue:01234567PriorityQueue:11223344,showmlsqosinterfaceinterface-idpolicers,Switch,DisplaysQoSinformationattheinterfacelevel,Switchshowmlsqosinterfacefastethernet0/1FastEthernet0/1truststate:trustcostrustmode:trustcosCOSoverride:disdefaultCOS:0pass-through:nonetrustdevice:cisco-phone,MonitoringQueuingonCatalyst2950Switches(Cont.),Summary,ThenumberandcapabilitiesofqueuesonCatalystswitchesdependuponthemodeloftheswitch,supervisor,andlinecards.PQandWRRarethetwoqueuingmethodsusedforCatalystswitches.TheuseofPQcanstarvelower-priorityqueues.WithWRR,differentweightsareassignedtoeachqueue.UseofWRRschedulingpreventsthelow-priorityqueuesfrombeingcompletelyneglectedduringperiodsofhigh-prioritytraffic.OnmostCatalystswitches,asinglepriorityqueuecanbeconfiguredwithWRRtoensureprioritydispatchofvoicetraffic.ToconfigureCoS-to-queuemappingsforPQontheCatalyst2950switch,specifythequeueIDoftheCoSpriorityqueue.(Rangesare1to4where1isthelowestCoSpriorityqueue.)Then,specifytheCoSvaluesthataremappedtothequeueID.Usethewrr-queuecos-mapquidcos1.cosncommand.,Summary(Cont.),Th