show
Figure5.PFrame
Losses
Figure3.HFrame
Losses
Figure6.BFrameLosses
testalternateroutesandremovethemfromcacheifbro-keninaproactivemanner.Fig.[7]showstheimpactofourenhancementasthetransmissionrangeof802.11isin-creasedkeepingthenumberofnodes xedat100andspeedat15m/s.Atlowranges,ourenhancementbehavessimilartoregularDSRmainlyduetothelackofalternateroutes.Astherangeincreases,ourenhancementstartstoshowim-provementsovertheregularscheme.Fig.[8]showstheim-pactofspeedofthemobilenodes.Atlowspeeds,bothschemesarecomparablesinceroutebreakagesarenottoofrequent.Withincreasingspeeds,routesbreakmorefre-quentlywithneighborsgoingoutofrangewhereouren-hancementshowsmarkedimprovementoverregularDSR.
Figure4.IFrameLosses
theimprovementsinthelossesobservedforH,I,PandBFrameswhenregularDSRiscomparedagainstouren-hancedversion.Inthisexperiment,wemodi edthenumberofnodesinthenetworkwhilekeepingthespeedofnodes xedat15m/sand802.11rangeto250m.Foreachnodecount,thesimulationwasrun5timeswithdifferentrandommobilityscenariosandtheresultsaveraged.Inallcases,ourenhancedversionout-performsregularDSRwithverylittleoverhead(salvagingifthealternateroutechosenforvalidationisbroken).Whenaroutebreakoccursinregu-larDSR,acachedalternaterouteischosen.Inmanycases,thisroutealsoendsupbeingbrokenbutthesourcedoesnotknowthisuntilitreceivesaroutebreakerror.Ifavalu-ableframesuchasaIFramehadbeentransmittedoverthisbrokenroute,ingcontentinformation,ourenhancementisabletoidentifylowimpactcandidateframestouse
to
8
5Conclusion
Inthispaper,wepresentanarchitecturetoenableintel-ligentprocessingofdatastreamswithinthenetwork.Ourarchitecturereliesonsemantictagsprovidingcontentmeta-datathatcanbereasonedoverontheroutingelementstoenablespecializedhandlingfor ows.Ouraimistofacili-tateapplicationsanduserstocommunicatetheirpreferences
Today’s model of networking primarily concentrates intelligence at the end hosts with the network itself offering a simple“best-effort”,“data agnostic ” communication medium. However, this paradigm has proven to be insufficient to meet todays needs co
Figure7.FrameLossesvs.
Range
Figure8.FrameLossesvs.Speed
tothenetworkandletthenetworktrytoprovidetheneededlevelofservice.Policiesareusedtodriveadaptationsbothlocallyatanodeandcoordinatedacrossanetwork.Con-trolledcrosslayerinteractionsareusedtoprovidemoreef- cientprocessingwhilestillretainingtractability.Wehavealsopresentedtheresultsofoursimulationstudiesshowingthatcontentawarenessattheroutinglayeroffersbene tsovertraditionalcontentagnosticapproachestodatadistrib-utionoverawirelessnetwork.
References
[1]Application-OrientedNetworking(AON)
.
[2]RDFVocabularyDescriptionLanguage1.0:(RDFSchema)
/TR/rdf-schema/.[3]ResourceDescriptionFramework(RDF)
/RDF/.
[4]D.S.Alexander,W.A.Arbaugh,M.Hicks,P.Kakkar,
A.Keromytis,J.T.Moore,C.A.Gunter,tles,andJ.M.Smith.TheSwitchWareactivenetworkarchitecture.IEEENetworkMagazine,12(3):29–36,1998.SpecialissueonActiveandControllableNetworks.
9
[5]E.Amir,S.McCanne,andR.H.Katz.Anactiveser-viceframeworkanditsapplicationtoreal-timemultimediatranscoding.InSIGCOMM,pages178–189,1998.
[6]S.Ardon,P.Gunningberg,ndFeldt,M.P.Y.Ismailov,
andA.Seneviratne.March:adistributedcontentadaptationarchitecture.InternationalJournalofCommunicationSys-tems,SpecialIssue:WirelessAccesstotheGlobalInternet:MobileRadioNetworksandSatelliteSystems.,16(1),2003.[7]A.Barbir,R.Penno,R.Chen,M.Hofmann,andH.Orman.
RFC3835:AnArchitectureforOpenPluggableEdgeSer-vices(OPES),August2004.
[8]A.BeckandM.Hofmann.IRML:ARuleSpeci cation
LanguageforIntermediaryServices:draft-beck-opes-irml-00.txt,Febuary2001.
[9]H.Bharadvaj,A.Joshi,andS.Auephanwiriyakul.AnAc-tiveTranscodingProxytoSupportMobileWebAccess.In17thIEEESymposiumonReliableDistributedSystems,Oc-tober1998.
[10]S.Bhattacharjee,K.L.Calvert,andE.W.Zegura.Onactive
networkingandcongestion.TechnicalReportGIT-CC-96-02.
[11]R.Braden,D.Clark,andS.Shenker.RFC1633:Inte-gratedServicesintheInternetArchitecture:anOverview,June1994.
[12]R.Braden,Ed.,L.Zhang,S.Berson,S.Herzog,and
S.Jamin.RFC2205:ResourceReSerVationProtocol(RSVP)—version1functionalspeci cation,Sept.1997.[13]B.Branden,B.Lindell,S.Berson,andT.Faber.TheASP
EE:AnActiveNetworkExecutionEnvironment.InDARPAActiveNetworksConferenceandExposition(DANCE2002),pages238–254,June2002.
[14]S.Chandra,C.S.Ellis,andA.Vahdat.Application-LevelDifferentiatedMultimediaWebServicesUsingQual-ityAwareTranscoding.InIEEEJournalonSelectedAreasinCommunications,volume18,December2000.
[15]L.-U.Choi,M.T.Ivrlac,E.Steinbach,andJ.A.Nossek.
Bottom-upapproachtocross-layerdesignforvideotrans-missionoverwirelesschannels.In62ndIEEEVehicularTechnologyConference(tobepublished),September2005.[16]A.Fox,S.D.Gribble,Y.Chawathe,andE.A.Brewer.
AdaptingtoNetworkandClientVariationUsingActiveProxies:LessonsandPerspectives.InIEEEPersonalCom-munications,September1998.
[17]M.Gerla,L.-J.Chen,T.Sun,andG.Yang.Ubiquitousvideo