延迟容忍网络及其应用西藏民院讲座课件

延迟容忍网络及其应用

DTNandItsApplication

张钢教授2009-71RelatedConcept相关概念互联网Internet无线局域网WLAN(WirelessLAN)无线自组织网络MANET(mobileadhocnetwork)延迟容忍网络DTN(delaytolerantnetwork)机会网络Oppnets(OpportunisticNetworks)2SomeNetworks几种网络FundamentallydifferentwayoflookingatnetworksInternetWiredLANWirelessLANCelltowerInfrastructure=Celltower,LAN,Accesspoint3Internet互联网TheusabilityoftheInternetdependsonsomeimportantassumptions几个重要假设Continuous,bidirectionalend-to-endpath连续、双向端到端通路Shortround-trips往返时间短Symmetricdatarates对称数据传输率Lowerrorrates低错误率5SomeSpecialCases

互联网中的特殊情况Intermittentconnectivity间歇连接Longorvariabledelay长延迟/不定延迟Asymmetricdatarates非对称数据传输率Higherrorrates高出错率如果互联网出现这些特殊情况会怎样？67MANET无线自组织网络MobileAdhocNetworking(MANET)9MANET无线自组织网络MobileAdhocNetworking(MANET)Rapidlydeployable,selfconfiguring快速部署，自配置Noneedforexistinginfrastructure不需要基础设施Wirelesslinks无线链路Nodesaremobile,topologycanbeverydynamic结点移动、拓扑动态Nodesmustbeabletorelaytrafficsincecommunicatingnodesmightbeoutofrange结点必须能转发消息AMANETcanbeastandalonenetworkoritcanbeconnectedtoexternalnetworks(Internet)可以是独立的网络/可以连接到外部网络10MANET无线自组织网络MobileAdhocNetworking(MANET)Tosupportrobustandefficientoperationinmobilewirelessnetworksbyincorporatingroutingfunctionalityintomobilenodes

路由功能合并到每个移动节点中Suchnetworksareenvisionedtohavedynamic,sometimesrapidly-changing,random,multihoptopologieswhicharelikelycomposedbyrelativelybandwidth-constrainedwirelesslinks

带宽受限的无线链路11MANET无线自组织网络Characteristics特点Dynamictopologies动态拓扑Bandwidth-constrainedvariablecapacitylinks带宽受限Energy-constrainedoperations能量受限Limitedphysicalsecurity物理安全有限Theneedforscalability可扩展13MANET无线自组织网络MANET要求任一节点对之间存在至少一条完整的端到端通信路径可能导致网络不能连通问题节点移动节点稀疏射频关闭障碍物obstruction14DTN延迟容忍网络Disruption/Delay-TolerantNetworking(DTN)介绍最初是为星际网络IPN(interplanetarynetwork)通信提出来的其主要目标是支持具有间歇性连通、延迟大、错误率高的不同网络的互联和互操作如互联Internet和传感器网络、移动自组织网络等15171819AnInterplanetaryInternetExample21WhatDoesIPDo?End-to-Endprotocolsfailandclosetheconnectionduringextendeddisruptions

在长时间的中断期间，端到端协议失败并关闭链接Theydonothandledisruptiongracefully22WhatIsDTN?ConnectsHop-by-Hop,NotEnd-to-End（点到点）ForwardsOverOutgoingLinks（流出链路）OpportunisticallyHoldsDatainPersistentStorage（持久存储器）WhenOutgoingLinksareDownNetworkProtocolsthatProvideReliableMessageDeliveryacrossintermittent/disrupted/dynamicnetworks提供跨越间歇/中断/动态网络的可靠消息传递的网络协议23TheBundleLayer–BundledData&ControlMinimizeNetworkTraversals

捆绑的数据和控制使网络往返移动最小化•AvoidsProtocolChattiness–MinimalDependenceonRemoteInformation

最小依赖于远程信息25TheBundleLayer26Step2:TransmissionbySource29Step3:First-HopBundleProcessingandForwarding30Step4:Second-HopBundleProcessingandForwarding31Step5:BundleReceptionbyDestination32OpportunisticNetworks

机会网络Inopportunisticnetworkingnoassumptionismadewithregardtotheexistenceofacompletepathbetweentwonodeswishingtocommunicate.

在机会网络中并不假设在希望通信的两个结点之间存在完整的通路Nevertheless,opportunisticnetworkingtechniquesallowsuchnodestoexchangemessagesbetweenthem.

然而，机会网络技术允许这样的结点之间交换信息33OpportunisticNetworks

机会网络DifferentlyfromDTNs,inopportunisticnetworkseachsinglenodeactsasagateway.

与DTN网络不同的是，在机会网络中每个结点都是网关34OpportunisticNetworks

机会网络Anetworkconnectionbetweenthetwowomenneverexistsbut,byopportunisticallyexploitingcontactsamongheterogeneousdevices,themessageisdeliveredhop-by-hopclosertothedestination,andeventuallytothedestinationitself.35OpportunisticNetworks

机会网络Anoppnetgrowsfromitsseed—theoriginalsetofnodesemployedtogetheratthetimeoftheinitialoppnetdeployment.Theseedgrowsintoalargernetworkbyextendinginvitationstojointheoppnettoforeigndevices,nodeclusters,ornetworksthatitisabletocontact.36OpportunisticNetworks

机会网络Themainfocusofresearchonopportunisticnetworkshasbeenonroutingandforwardingissues路由和向前推进问题Becausefindingroutestowardsthedesireddestinationinsuchdisconnectedenvironmentsisregardedasthemostcompellingissue.最引人注目的问题37OpportunisticNetworks

机会网络机会网络可以看成是具有一般DTN网络特征的无线自组网方法1：源节点必须缓存数据直到进入目标节点通信范围内才允许传输数据38OpportunisticNetworks

机会网络方法2：源节点将消息传输给邻居中继节点,该节点缓存消息再将消息转发给目标节点或遇到的其他中继节点39OpportunisticNetworks

机会网络40OpportunisticNetworks

机会网络41WhynotdeployInfrastructure?为什么不部署基础设施？

InfrastructureexpensivetodeployProvidingInternetconnectivitytodevelopingregionsKioskNetinWaterloo,DigitalGangeticProjectinIndia42DTN/OppnetApplications

DTN/机会网络应用Inter-PlanetaryNetwork(IPN)星际网络Terrestrialandinterplanetarylinks.LONGdelaysandepisodicconnectivity

陆地和星际链路，长延迟和断续连通性ZebraNet斑马网络Collectsinformationaboutdispersedzebrapopulations

收集分散的斑马数量信息4343DTN/OppnetApplications

DTN/机会网络应用DataMules数据骡子Randomlymoveandcollectdatafromlow-powersensors

随意移动并从低能量传感器收集数据VillageNetworks村庄网络Usingbusservice(couriers)toprovideconnectivitytoisolatedareas

对孤立区域使用巴士提供连接性服务（信使）4444DTN/OppnetApplications

DTN/机会网络应用野生动物追踪ZebraNet斑马网络--追踪非洲草原斑马Intelligenttrackingcollarsplacedonsampledsetofzebras安装在斑马脖子上的低功耗传感器项圈车载移动基站ZebraNetproject,PrincetonDeployedinMpala,Kenya45DTN/OppnetApplications

DTN/机会网络应用NodescollectlogsofGPSpositionandotherinformation结点收集GPS位置日志和其它信息Peer-to-peercommunicationaggregatesdatabacktoresearcherbasestation

点到点通信聚集数据到研究者基站Researchstationisnotfixed.Rather,itmovesandisonlyintermittentlyavailable研究者基站不固定、移动，而且仅仅是间歇可使用46Drive-byMobileBaseStation

车载移动基站Vandalismisaproblemfordeployinganarrayoffixedantennasorbasestations

设置固定的天线或基站阵列有破坏自然环境的问题47PeertoPeerSystemDesign

点到点系统设计zebraA1010111101100011000110000zebraB1001011111100011000048PeertoPeerSystemDesign

点到点系统设计zebraA1010111101100011000110000zebraB10010111111000110000zebraA1010111101100011000110000zebraB1001011111100011000049PeertoPeerSystemDesign

点到点系统设计zebraB10010111111000110000zebraA1010111101100011000110000zebraB10010111111000110000zebraA101011110110001100011000050PeertoPeerSystemDesign

点到点系统设计zebraB10010111111000110000zebraA101011110110001100011000051ClassicMobileNetworks

经典移动网络52Solution:CollaborativelyReturnData

解决方案：合作地返回数据53DTN/OppnetApplications

DTN/机会网络应用野生动物追踪NetworkonWhales(SWIM监视海洋鲸鱼)“WherethereisaWhalethereisaWay”.鲸鱼身上的特殊Tag水面浮标基站海鸟携带基站54DataMule数据骡子Three-tierarchitecture:三层结构AccessPointsDataMuleswithlargestoragecapacityandrenewablepowerSensorsLargepowersavingsbysensors55DTN/OppnetApplications

DTN/机会网络应用AdHocCity自组织城市fixedandmobilenodesfixednodesshouldactasbasestationssparselydeployedonthecityterritoryNetworkmobilenodesshouldbeimplementedonfleetssuchascitybuses,taxicabs,anddeliveryvehiclesthatnaturallycoverthecityareasinbothspaceandtimepersonalmobilenodes,suchasPDAsandlaptops,heldbyusersmovingaroundinthecity例如,电子邮件服务，当发送节点和接收节点位于相互通信范围内时，PSN节点不需要接入Internet通过传统的SMTP和POP3等技术实现，而是直接利用本地连接转发数据56DTN/OppnetApplications

DTN/机会网络应用VehicleAdHocNetworks(VANETs)车载网络FleetNetVehicle-to-vehiclecommunicationsvehicle-to-roadsidecommunicationsGPSCarTel基于车辆传感器的信息收集和发布系统嵌入式CarTel节点Wi-Fi、BlueTooth、路边的无线接入点能够用于环境监测、路况收集、车辆诊断和路线导航等57DTN/OppnetApplications

DTN/机会网络应用58DTN/OppnetApplications

DTN/机会网络应用59ApplyingDTNtoMobileInternetAccess60ApplyingDTNtoMobileInternetAccess61DTN/OppnetApplications

DTN/机会网络应用偏远地区网络传输.DakNet部署在印度偏远地区村民的PDA、

村庄的Kiosk设备、

公交车辆上的MAP(mobileaccesspoints)设备、

城镇的互联网AP设备Wi-FiSaamiNetworkCon