Lenovo ThinkSystem NE2552E - Priority Groups; Pgid

© Copyright Lenovo 2018 Chapter 15: Fibre Channel over Ethernet 261
IntheassignmentmodelshowninFigure 26onpage 260,priorityvalues0through
2areassignedforregularEthernettraffic,whichhas“besteffort”transport
characteristics.
Priority3istypicall yusedtoidentifyFCoE(SAN)traffic.
Priorities4‐7aretypicallyusedforlatencysensitivetrafficandotherimportant
businessapplications.
Forexample,priority4and5areoftenusedforvideoand
voiceapplicationssuchasIPTV,VideoonDemand(VoD),andVoiceoverIP
(VoIP).Priority6and7areoftenusedfortrafficcharacterizedwitha“mustget
there”requirement,withpriority7usedfornetworkcontrolwhichis
requires
guaranteeddeliverytosupportconfigurationandmaintenanceofthenetwork
infrastructure.
Note: Thedefaultassignmentof802.1ppriorityvaluesontheNE2552Echanges
dependingonwhetherCEEisonoroff.See“TurningCEEOnorOff”onpage 246
fordetails.
Priority Groups
ForETSuse,each801.2ppriorityvalueisassignedtoaprioritygroupwhichcan
thenbeallocatedaspecificportionofavailablelinkbandwidth.Toconfigurea
prioritygroup,thefollowingisrequired:
 CEEmustbeturnedon(“TurningCEEOnorOff”onpage 246)fortheETS
featuretofunction.
 AprioritygroupmustbeassignedaprioritygroupID(PGID),oneormore
802.1ppriorityvalues,andallocatedlinkbandwidthgreaterthan0%.
PGID
Eachprioritygroupisidentifiedwithnumber(0through7,and15)knownasthe
PGID.
PGID0through7mayeachbeassignedaportionoftheswitch’savailable
bandwidth.
PGID8through14arereservedasperthe802.1QazETSstandard.
PGID15isastrictprioritygroup.Itis
generallyusedforcriticaltraffic,suchas
networkmanagement.AnytrafficwithpriorityvaluesassignedtoPGID15is
permittedasmuchbandwidthasrequired,uptothemaximumavailableonthe
switch.AfterservingPGID15,anyremaininglinkbandwidthissharedamongthe
othergroups,dividedaccordingtothe
configuredbandwidthallocationsettings.
All802.1ppriorityvaluesassignedtoaparticularPGIDshouldhavesimilartraffic
handlingrequirements.Forexample,PFC‐enabledtrafficshouldnotbegrouped
withnon‐PFCtraffic.Also,trafficofthesamegeneraltypeshouldbeassignedto
thesamePGID.Splittingonetypeoftraffic
intomultiple802.1ppriorities,andthen
assigningthoseprioritiestodifferentPGIDsmayresultinunexpectednetwork
behavior.
Each802.1ppriorityvaluemaybeassignedtoonlyonePGID.However,each
PGIDmayincludemultiplepriorityvalues.UptoeightPGIDsmaybeconfigured
atanygiventime.