survey of qos routing

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1、SurveyofQoSRouting1PragyansmitaPaulandSVRaghavan(pragyan@cs.iitm.ernet.in,svr@cs.iitm.ernet.in)DepartmentofComputerScienceandEngineeringIndianInstituteofTechnologyMadrasChennai600036INDIAAbstractVariousreal-timeservices,likewebcasting,audio/videoconferencin

2、gandtelemedicine,arebeingdeployedovertheInternet.Thisrequiresthenetworktoprovidetheguaranteeoftheservicebeingprovidedtothereceiver.TheneedsoftheapplicationisspecifiedintermsoftheQualityofService(QoS)metricslikedesiredbandwidth,responsetime,etc.End-to-endQoS

3、canbeprovidedmostefficientlywheneachlayeroftheprotocolstacktranslatestheapplicationprovidedrequirementintolayerspecificrequirementandsatisfiesthesame.NetworklayerhasacriticalroletoplayintheQoSprovisionprocess.ItprovidesthedesiredQoSbyconsideringtheQoSmetric

4、sinthepathselectionprocess.ThefocusofthispaperisontheQoSroutingalgorithmsandprotocolsforunicastandmulticastintheIPv4basedInternetthatconstrainsoroptimizesanindividualorcombinationofmetrics.ThedesiredfeaturesofaroutersupportingQoShavebeendiscussedindetail.Qo

5、Sroutingleadstoanincreaseincomputation(morecomplexpathselectionprocess)andcommunication(protocoloverheadduetoincreaseinstateinformation).However,theincreaseincostiscounterbalancedbytheincreaseinperformance.Astudyofworkrelatedtothecost/performancetradeoffofQ

6、oSroutingispresented.Beinganareaofactiveresearch,QoSroutinghasanumberofopenissuesthathasbeendiscussedaspartofthispaper.1.0IntroductionVariousreal-timeservices,likewebcasting,audio/videoconferencingandtelemedicine,arebeingdeployedovertheInternet.Thisrequires

7、thenetworktoprovidetheguaranteeofthequalityoftheservicetothereceiver.Thequalityoftheservicecanbeestimatedandspecifiedintermsofsomeparameters(calledmetrics)thatareofprimeimportancetotheapplicationunderconsideration.Theseparametersareusedtoexpresstheapplicati

8、onsrequirementsthatmustbeguaranteedbytheunderlyingnetwork.Themetric(s)canbedelay,bandwidth,variationinthedelayexperiencedbythereceiver(alsoknownasjitter),packetlossthatcanbetoleratedand/ornumberofhops,