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Policy-Map Commands

XSR CLI Reference Guide 12-93

random-detect (WRED)

ThiscommandconfiguresandenablesWeightedRandomEarlyDetect(WRED)fortheclass.

WREDisacongestionavoidancemechanismthatslowstrafficbyrandomlydroppingpackets

whencongestionexists.WREDisusefulwithprotocolslikeTCPthatrespondtodroppedpackets

bydecreasingthetransmissionrate.

TosetorchangeWRED

parameters,usetherandom-detect {dscp | precedence}command.

Ifnoparameterpassedtothecommand,thedefaultisprec‐basedWRED.

Syntax

random-detect {dscp-based | prec-based}

Syntax of the “no” Form

ThenoformofthiscommanddisablesWREDonaninterface:

no random-detect

Mode

Policy‐MapClassconfiguration:XSR(config-pmap-c-<xx>)#

Default

Prec‐based

Example

ThefollowingexampleenablesWREDasDSCP‐basedwiththedefaultvaluesforparameters:

XSR(config)#policy-map DSCP

XSR(config-pmap<DSCP>)#class A

XSR(config-pmap-c<a>)#random-detect dscp-based

random-detect dscp

ThiscommandchangestheWeightedRandomEarlyDetect(WRED)minimumandmaximum

thresholdandmaximumdropprobabilityforaDiffServCodePoint(DSCP)value.

ThiscommandspecifiestheDiffServCodePoint(DSCP)value.TheDSCPcanbeanumberfrom0

to63,oranyofthefollowingkeywords:af1,af12

,af13,af21,af22,af23 ,af31, af32,af33,af41, af42,

af43,cs1,cs2,cs3,cs4,cs5,cs6,cs7,efordefault.EachDSCPvaluehasinitialWREDparameters.

Table12‐1providesinitialparametersettingsforeachDSCPvalue.Thelastrowdetails

parametersforDSCPvaluesnotshowninthe

table.

dscp-based

WREDusesDSCPvalueswhencalculatingdropprobability.

prec-based

WREDusesIPprecedencevalueswhencalculatingdropprobability.

Note: This command must be used in conjunction with the random-detect (interface) command.

Also, random-detect dscp is available only if you specified the dscp-based argument when

using the random-detect (interface) command.

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