Zte ZXR10 5900 Series - Traffic Shaping

Chapter8QoSConguration
Thefollowingtwomethodswillbedescribed:
1.SingleRateThreeColorMarker(SrTCM)
ThisalgorithmisusedinDiffservtrafcconditioner .SrTCM
measuresdataowandmarkspacketsaccordingtothreetraf-
cparameters(CommittedInformationRate,CIR;Committed
BurstSize,CBS;ExcessBurstSize,EBS).Wecallthethree
parametersasgreen,yellowandredmarkerrespectively.A
packetisgreenifitssizeislessthanCBS.Apacketisyellowif
itssizeisbetweenCBSandEBSandisredifitssizeexceeds
EBS.Bydefault,redpacketisdiscarded.
2.TwoRateThreeColorMarker(TrTCM)
ThisalgorithmisusedinDiffservtrafcconditioner .TrTCM
measuresIPdataowandmarkspacketswithgreen,yellow
andredbasedontwotypesofrates(PeakInformationRate,
PIRandCommittedInformationRate,CIR)andtheirrelated
committedburstsize(CBSandPBS).Apacketismarkedin
redifitssizeexceedsPIR.Apacketismarkedinyellowisits
sizeisbetweenPIRandCIRandismarkedingreenifitssize
islessthanCIR.
TrafficShaping
Trafcshapingisusedtocontroltherateofoutputpacketsthus
sendingpacketsatevenspeed.Trafcshapingisusedtomatch
packetratewithdownlinkequipmenttoavoidcongestionand
packetdiscarding.
Thedifferencebetweentrafcshapingandtrafcpolicingisthat
trafcshapingistocachepacketswhoserateexceedsthelimited
valueandsendpacketsatevenratewhereastrafcpolicingisto
discardpacketswhoserateexceedsthelimitedvalue.Moreover ,
trafcshapingmakesdelaylongerbuttrafcpolicingdoesnotin-
troduceanyextradelay.
QueueBandwidthLimit
Queuebandwidthlimitmeanslimitingthebandwidthofqueueon
interfacetoensuretheminimumbandwidthforqueue.Whentraf-
cisblocked,certainbandwidthcanbeensuredforthisqueue.
QueueSchedulingandDefault
802.1p
EachphysicalportoftheZXR105900/5200supportseightoutput
queues(queue0toqueue7)calledCoSqueues.Theswitchper-
formsincomingportoutputqueueoperationaccordingtotheCoS
queuecorrespondingto802.1pofpackets.Innetworkconges-
tion,thequeueschedulingisgenerallyusedtosolvetheproblem
CondentialandProprietaryInformationofZTECORPORATION71