Specifications

Quality of Service Overview
May 09, 2011 Page 4 of 38
CoS Settings
UsetheCoSsettingsconfigurationwhenmappingthepriorityoftheingressingpackettoa
hardwareresourcereference,floodcontrolstate,dropprecedencebehavior,or802.1priorityor
ToSremarking.
CoS Hardware Resource Reference
TheCoShardwareresourcereferencecanbe:
•Areferencetoatransmitqueue.OntheSSeries,validvaluesare0‐10.
•Aninboundratelimiterreference.OntheSSeries,validvaluesare0‐31.
•Anoutboundratelimiterreference.OntheSSeries,validvaluesare0‐3.
CoS Flood Control State
CoSfloodcontrolstateenablesordisablesfloodcontrolfortheCoSsetting.
CoS Priority and ToS Rewrite
ThetwoparametersconfigurableforCoSpriorityare 802.1pandTypeofService(ToS).EachCoS
canbemappedtoan802.1ppriorityandaToSrewritevalue.802.1pandToSarespecifiedinthe
CoSsettingsconfigurationlayer.
The802.1pparameteris:
•AsubsetofToSwithvalues0–7(upper
3bitsofthe8bitToSfield)
Supportedinbothlayer2andlayer3
TheToSparameteris:
•An8bitfieldwithvalues0–255
Supportedinlayer3only
•AlsoreferredtoastheDifferentiatedServicesCodePoint(DSCP)whenlimitedtothelower5
bitsofthefield
Figure 1
displaystherelationshipbetweenyourapplication,prioritylevel,802.1p,andToS
assignments(shownhereusingDSCPterminology).
QoSpriority/ToSconfiguration:
Derivesitscharacteristicrequirementsfromtheendsystemapplication.
•Isconfiguredontheedgedevicetheapplicationisconnectedto
•Ispropagatedthroughthenetworkintheprotocolpacketheader
CoS Port Resource Specifies the transmit queue rate shaping or IRL, ORL, or flood control rate
limiter threshold value that the CoS reference is mapped to.
CoS Port Configuration Specifies the ports to which CoS resource configuration should be applied,
and provides for TxQ scheduling.
Table 1 CoS Configuration Terminology (continued)
Term Description