延迟容忍网络的路由.ppt

《延迟容忍网络的路由.ppt》由会员上传分享，免费在线阅读，更多相关内容在PPT专区-天天文库。

1、RoutinginDelayTolerantNetworkQingYeEDIFYGroupofLehighUniversityOutlineIntroductionRoutingIssueandtheModelDTNRoutingApproachesGossiping-likeShortest-path-likeSummaryandOurviewIntroduction–ConceptDelayTolerantNetworks:networkssufferfromfrequent,longdurationpartitioningand

2、thelackofguaranteedend-to-endpathExamples:LowEarthOrbitingSatellitesInterplanetarynetworksbysatellites,spaceships,andbasestationsSpecialMilitaryNetworksGroupsofHandhelddevicesforsearchandrescueteamsIntroduction–CharacteristicsHeterogeneity:Ahybridofwiredandwirelesslinks

3、Bandwidth,delayandcapacityoflinksmayvaryDifferenttypesend-devicesNodemaymoveornotIsDTNaMobileAdhocNetworks??Largerend-to-enddelayNofixedstableend-to-endpathUpanddownoflinksmaybepredictable,periodic,oropportunisticRoutingIssueConventionalRouting:Internet:distancevectoran

4、dlinkstateWirelessAdhocnetworks:table-drivenandsource-initiatedon-demandFindandtakeadvantageofthebestcurrentavailableend-to-endpathbetweensourceanddestinationDTNRouting:whatifnoend-to-endpathexistinthenetworkSo-calledmessageferrybecomesimportantBuffersizeintheintermedia

5、tenodesbecomeaprecioussystemresourceReliability(eventualpacketdeliveryinlifetime)becomearesearchgoalHop-by-hopschemebecomesdominant,ratherthanend-to-endmethodsDTNRoutingModelDTNamultigraphG(E,N),multiplepathsmayexistaccordingtodifferenttypesoflinksContact:point-to-poin

6、topportunity,(src,dst,uptime,downtime,delay,capacity)Message:(src,dst,creationtime,lifetime,size)Storage:finitebufferinintermediatenodes,infinitebufferindestinationsRouting:hop-by-hopstore-and-forwardapproach,howtoselectthenexthopDTNRoutingApproaches–FirstContact(FC)Bas

7、icidea:amessageisforwardedalongacontactchosenrandomlyamongallcurrentavailablecontacts.OrthefirstavailablecontactisselectedSimilarapproach:GossipingRoutingProperties:Simple:routingisbasedonalocalviewSmallcontroloverheadNotaloop-freeapproachUnreliable:routingdecisionmaybe

8、incorrectDTNRoutingApproaches–MinimumExpectedDelay(MED)Assumptions:theupanddownschedulesaswellasthedelaysofove