简介：UnderstandinghowtheInternetisusedbyHEPiscriticaltooptimizingtheperformanceoftheinter-labcomputingenvironment.Typicallyuserequirementshavebeendefinedbydiscussionsbetweencollaborators.However,lateranalysisoftheactualtraffichasshownthisisoftenmisunderstoodandactualuseissignificantlydifferenttothatpredicted.Passivemonitoringoftherealtrafficprovidesinsightintothetruecommunicationsrequirementsandtheperformanceofalargenumberofalargenumberofinter-communicatingnodes.ItmaybeusefulinidentifyingperformanceproblemsthatareduetofactorsotherthanInternetcongestionespeciallywhencomparedtoothermethodssuchasactivemonitoringwheretrafficisgeneratedspecificallytomeasureitsperformance.Controlledactivemonitoringbetweendedicatedserversoftengivesanindicationofwhatcanbeachievedonanetwork,Passivemonitoringoftherealtrafficgivesapictureofthetrueperformance.ThispaperwilldiscussthemethodandresultsofcollectingandanalyzingflowsofdataobtainedfromtheSLACInternetborder,TheuniquenatureofHEPtrafficandtheneedsoftheHEPcommunitywillbehighlighted.Theinsightsthishasbroughttounderstandingthenetworkwillbereviewedandthebenefitiscanbringtoengineeringnetworkswillbediscussed.

简介：Real-timevideotransportoverwirelessInternetfacesmanychallengesduetotheheterogeneousenvironmentincludingwirelineandwirelessnetworks.Arobustnetworkconditionclassificationalgorithmusingmultipleend-to-endmetricsandSupportVectorMachine(SVM)isproposedtoclassifydifferentnetworkeventsandmodelthetransitionpatternofnetworkconditions.End-to-endQuality-of-Service(QoS)mechanismslikecongestioncontrol,errorcontrol,andpowercontrolcanbenefitfromthenetworkconditioninformationandreacttodifferentnetworksituationsappropriately.TheproposednetworkconditionclassificationalgorithmusesSVMasaclassifiertoclusterdifferentend-to-endmetricssuchasend-to-enddelay,delayjitter,throughputandpacketloss-ratefortheUDPtrafficwithTCP-friendlyRateControl(TFRC),whichisusedforvideotransport.Thealgorithmisalsoflexibleforclassifyingdifferentnumbersofstatesrepresentingdifferentlevelsofnetworkeventssuchaswirelinecongestionandwirelesschannelloss.Simulationresultsusingnetworksimulator2(ns2)showedtheeffectivenessoftheproposedscheme.