網(wǎng)絡(luò)與通信(chap7-Location Mibility Management(Mobile IP))課件

WirelessCommunicationandNetworkChapter7Location/MibilityManagement1WirelessCommunicationandNetWhydoweneedlocation/mobilitymanagement?Whatislocation/mobilitymanagement?Typesofmobilitymanagement

HandoffmanagementLocationmanagementLocationManagementinGSMConceptofLocationareaLocationupdateprocedureCalldeliveryprocedureOtherlocationmanagementstrategiesLocationupdatePagingDatabasemanagementMobileIPmanagementWhatwewilllearninthischapter:2Whydoweneedlocation/mobiliWhymobilitymanagement?Inwirelinenetworks,thereisafixedrelationshipbetweenaterminalanditsphysicallocationsIncontrast,mobileterminals(MT’s)arefreetotravelandthusitsnetworkaccesspointchangesasitmovesaroundthenetworkcoverageareaTheIDofanMTnolongerprovidesthecurrentlocationinformationoftheMT.Howtokeeptrackofmobileterminals?3Whymobilitymanagement?InwirWhymobilitymanagement?Anexample:cellularnetworkCaller’stelephonetunestothestrongestsignal.Caller’srequestincludesbothherandCallee’stelephonenumbers.BSrelaystherequesttotheswitch.TheswitchcommandsseveralBS’stotransitpagingmessagescontainingCallee’snumber.Callee’sphonerespondstothepagingmessagebyinformingthesystemofitslocation.TheswitchcommandsCaller’sphonetotunetochannelXandCallee’sphonetochannelY.Thecellularphoneconversationstarts.Duringtheconversation,Calleemovestoanewcell.Thesystemrearrangesitselftomaintaintheconversation.WhereiSendbroadcastmessagesfromeverybasestation?4Whymobilitymanagement?AnexaWhatismobilitymanagement?MobilitymanagementisoneofthemostimportantandchallengingproblemsThe

objectiveisforthenetworktodeterminethelocationoftheMTatanytimeforbothmessagedeliveryandmaintainingconnectionsastheMTismovingintoanewareaMaintainlocationinformationasMTs

power-on,move,orpower-offAfunctionatnetworklayerandabove5Whatismobilitymanagement?MoTypesofmobilitymanagementHandoffmanagement(keeptheconnection)Maintainauser’sconnectionastheMTcontinuestomoveandchangeitsaccesspointtothenetwork.Triggeredbyusermobility/roaming,signalstrengthdeterioration(弱化),trafficloadmanagement,etcLocationmanagement(establishthecommunication)Trackingthe

changesoflocationsofMTs.DiscoveringthecurrentlocationoftheMTforcall/messagedelivery.6TypesofmobilitymanagementHaHandoffmanagementThreestagesInitiation

Eithertheuser,anetworkagent,orchangingnetworkconditionsidentifytheneedforhandoffNewconnectiongenerationThenetworkfindresourcesforthehandoffconnectionandperformanyadditionalroutingoperationsData-flowcontrolThenetworkmustmaintainthedeliveryofthedatafromtheoldconnectionpathtothenewconnectionpathaccordingtoagreed-upon(意見一致)

serviceguarantees7HandoffmanagementThreestagesLocationmanagementEverymobilenetworkmanageslocationinformationdifferentlydependingonseveralfactors:typeofofferedservice(calls,messages,etc..)subscriberdensitytrafficofmobileterminalcalls/messagesTwomainmethodsusedformobilitymanagement:methodswithoutlocationupdatingmethodsusinglocationareas8LocationmanagementEverymobilWithoutlocationupdatingNetworkdoesnotknowwheretheMTislocatedWheneveranincomingmessageorcallarrives,sendssearchingmessagesalloverthecoveredareas.TheadvantageissimplicityDisadvantages:LimitedcapacityforincomingcallsLimitedsubscriberdensitypopulation9WithoutlocationupdatingNetwoUsinglocationareasLocationarea(LA)consistsofacertainnumberofcellsorsubnets.MTreportsitscurrentlocationareafromtimetotime-locationupdateNetworkalwaysknowsinwhichlocationareatheMTislocated(vialocationupdating),butitdoesnotknowpreciselywhatcell.Uponthearrivalofanincomingmessage,theMTissearchedonlyinsidethelocationarea.Limitsthecostofresourceutilizationduetolimitingthesearchingtothelocationarea.GSMusesthismethod.10UsinglocationareasLocationaLocationmanagementTwostagesLocationupdate(registration)MTnotifiesthenetworkofitsnewaccesspoint(e.g.,whenitispoweredon,ormovingintonewarea)NetworkauthenticatestheMTandrevisestheMT’slocation.Needlocationinformationstorage.MessagedeliveryNetworkisqueriedfortheMT’slocationprofileandthecurrentpositionoftheMTisfound.Message/callisdeliveredtothefoundlocation.11LocationmanagementTwostages1TwoMajorComponentsLocationUpdateThemobileterminalinformsthesystemitscurrentlocation.PagingThesystemsendsmessages(fromoneormorebasestations)tofindaparticularuser.12TwoMajorComponentsLocationUTwoExtremeCasesLocationneverupdate(nocost).Needtopageeverycells(highcost).Locationupdatesforeverycellcrossing(highcost).Needtopageonlyonecell(lowcost).Locationupdate13TwoExtremeCasesLocationnevePartitiontheregionintodifferentlocationareas.LocationArea14PartitiontheregionintodiffLocationUpdateLA-1LA-2LocationupdateNolocationupdateLocationupdateisperformedwhenthereisaboundarycrossing.HowtodeterminethesizeofaLA?15LocationUpdateLA-1LA-2LocatioLocationDatabasesHomeDatabaseEveryMSispermanentlyassociatedwithahomedatabaseKeeptrackoftheprofileoftheMSMobileID,authenticationkeys,location,etc.VisitingDatabaseKeepstrackoftheMSsinitsservicearea.ThesetwodatabasescommunicatewitheachothertoauthenticateandupdateeachotheraboutthelocationofanMS.GSMTerminology:HomeLocationRegister(HLR)VisitorLocationRegister(VLR)16LocationDatabasesHomeDatabasMSCMSCVLRVLRHLR(1)(2)(3)(4)(6)(5)GSMExample:LocationUpdateMobileSwitchingCenter17MSCMSCVLRVLRHLR(1)(2)(3)(4)(6)LocationUpdateProceduresMStransmitsaLUtothenewBSTheBSforwardstheLUtotheMSCMSCsendsLUtotheHLRandupdatesVLRHLRdoesthefollowing:authenticatetheMSrecordtheIDofthenewVLRsendanACKtothenewVLRHLRsendsaregistrationcancellationmessagetotheoldVLRTheoldVLRremovestherecordoftheMSandreturnsanACKtoHLR18LocationUpdateProceduresMStGSMExample:CallDeliveryMSCMSCVLRVLRHLR(1)(6)(4)(3)(2)(5)MobileSwitchingCenterCallingMSCalledMS(7)19GSMExample:CallDeliveryMSCMCallDeliveryProcedureCallingMSsendsacallinitiationsignaltoMSCthroughBS.MSCsendsalocationrequesttoHLRofthecalledMSHLRdeterminesservingVLRofcalledMSandsendsarouterequestmessagetoit.MSCallocatesatemporaryIDtoMSandsendsthisIDtoHLRHLRforwardstheIDtoMSCofthecallingMSCallingMSCrequestsacallsetuptothecalledMSCPagingmessagesaresenttocellswithintheLA.20CallDeliveryProcedureCallingOtherLocationManagementStrategies21OtherLocationManagementStraPing-PongEffectLA-1AlotoflocationupdatesmaybegeneratedifausercrossesLAboundaryfrequently.22Ping-PongEffectLA-1AlotoflOtherLocationUpdateAlgorithmsTimeBasedEachuserperiodicallyupdateshislocation(e.g.everyhour)MovementBasedEachusercountsthenumberofboundarycrossingsbetweencells.Updateshislocationwhenthisnumberreachesapredefinedvalue,N.DistanceBasedEachusertracksthedistancehehasmoved(innumberofcells)sincethelastupdate.Updateshislocationwhenthedistancereachesapredefinedvalue,N.23OtherLocationUpdateAlgorithMovementBased(N=2)LocationupdateSupposelocationupdateisperformedwhenenteringthiscell.24MovementBased(N=2)LocationDistanceBased(N=2)LocationupdateSupposelocationupdateisperformedwhenenteringthiscell.25DistanceBased(N=2)LocationPageeverycellswithintheLA.Blanket(地毯)Paging26PageeverycellswithintheLAPagethecellssequentiallyuntiltheuserisfound.SequentialPaging1234876591027PagethecellssequentiallyunHowtodeterminepagingorder?Method1:ShortestDistanceFirstPagestheuserstartingfromthecellwherehelastupdatedhislocation.Moveoutwardinashortest-distance-firstorder.Tiesarebrokenarbitrarily.Example:(inahighway)LastLocationUpdate1234528Howtodeterminepagingorder?Howtodeterminepagingorder?Method2:BasedonLocationProbabilityEstimatetheprobabilitythatauserislocatedineachcellwithinthecurrentLA.Pagethecellsindecreasingorderofprobability.Example:(inahighway)LastLocationUpdateABCDESupposeProb.Distributionis:{0.05,0.2,0.4,0.25,0.1}Pagingorder:C,D,B,E,A29Howtodeterminepagingorder?PagingDelayInourpreviousexample,theexpecteddelayisE

[D

]=0.4×1+0.25×2+0.2×3+0.1×4+0.05×1=1.95(pagingcycles)Worst-casedelayis5pagingcycles.Theexpectednumberofcellstobepagedisalso1.95.Worst-case:5cells.30PagingDelayInourpreviousexBlanketPagingvs.SequentialPagingBlanketSequentialPagingcostLargeSmallPagingdelaySmallLargeSequentialgrouppagingmaybeusedifthereisaconstraintonpagingdelay31BlanketPagingvs.SequentialPagegroupsofcellssequentiallyuntiltheuserisfound.SequentialGroupPaging1222333344Worstcasedelayis4cycles.32PagegroupsofcellssequentiaDatabaseManagementLocationUpdateInvolvestheupdatingoflocationdatabasesCallDeliveryInvolvesthequeryingoflocationdatabasesThecostisveryhighiftheMSislocatedfarawayfromitsHLR.e.g.iftheMSisroaminginUSAanditsHLRisinBeijing.33DatabaseManagementLocationUpDatabaseManagementThreeEnhancementMethods:PerUserLocationCachingUserProfileReplicationForwardingPointers34DatabaseManagementThreeEnhanPer-UserLocationCachingEverytimeuserxiscalled,x’slocatoniscachedattheVLRinthecaller’sLA.AnysubsequentcalltoxoriginatedfromthatLAcanreusethisinformation.Noneedtocontactuserx’sHLR.35Per-UserLocationCachingEveryCacheInvalidationEagerCachingWheneverausermovestoanewLA,allcacheentriesforthisuser’slocationareupdated.Locationupdatecostincreasesifausermovesfrequently.LazyCachingCacheupdateisnotperformed.Twocasescanoccur:ahitoramissIncaseofamiss,contacttheHLRthereisanadditionalcost,sincethecachedVLRmustbevisitedfirst.36CacheInvalidationEagerCachinUserProfileReplicationObservation:Eachuserusuallycommunicatesfrequentlywithasmallnumberofsources.Howcanwemakeuseofthisobservation?UserprofilesarereplicatedatselecteddatabasestoreducethecostofqueryingtheHLR.37UserProfileReplicationObservUserProfileReplicationWhenacallisinitiatedfromacertainLA,thecorrespondingMSCdeterminesifareplicationofthecalledMS’suserprofileisavailablelocally.Ifavailable,noHLRqueryisneeded.WhentheMSmovestoanotherlocation,thenetworkupdatesallreplications.38UserProfileReplicationWhenaPointerForwardingEachtimeausermovestoanewLA,aforwardingpointerissetuptoitsperviousVLRtopointtothenewVLR.CallstotheuserwillfirstquerytheHLRtodeterminethefirstVLRandthenfollowthechaintoreachthecurrentVLR.ThelengthofthepointerchainislimitedtoamaximumvalueN.ThismethodcanreducethecostofupdatingtheHLR.39PointerForwardingEachtimeaMobileIP40MobileIP40OutlineHowtosupportInternetmobility?byMobileIP.OurdiscussionwillbebasedonIPv4(thecurrentversion).41OutlineHowtosupportInternetIPAddressIPaddressisa32-bitnumberassignedtoeachnetworkinterfaceofanode.Nodes(suchasrouters)withmultiplenetworkinterfaceshavemultipleIPaddresses.IPAddressinDotted-DecimalNotation42IPAddressIPaddressisa32-bNetworkPrefix;HostPortionAnIPaddresshastwocomponentsNetworkprefixIdentifyingalinkIdenticalforallnodesattachedtothesamelinkHostportionIdentifyingaspecifichostorrouterconnectedtothatlinkExample:6,prefixlength=24Networkprefix=129.61.18Hostportion=2643NetworkPrefix;HostPortionAnMotivations:Withoutspecificsupport,messagedeliveryisnotpossibleformobilehosts(MHs)awayfromitshomeIPsubnet:IProutingisbasedonthenetworkprefixanddestinationIPaddress:Example:6,prefixlength=24Networkprefix=129.61.18Hostportion=26MTcannotchangeIPaddressonmovingtonewIP-subnet–otherwisenotabletodeliverymessages.44Motivations:WithoutspecificsRoutingTableaRouterARouterBRouterCHost1Target/Prefix-LengthNextHopInterface9/32router1a/24router2a/0router3aHost1’sroutingtableHost1wantstoforwardapackettoRulesforRouting:1.Comparetheleft-mostPrefix-LengthbitsofeachTargetwiththeIPdestinationaddress.2.ChoosethematchingroutewiththelargestPrefix-Length.Defaultroute45RoutingTableaRouterARouterB5454aaac5352cc53b52bbbbHost1Host2Host3Host4Host5RouterARouterBRouterCARoutingExample:

Target/Prefix-LengthNextHopInterface/24“direct”a/054aHost1’sroutingtableEthernetANetworkPrefix=1.0.0High-SpeedFiberBackboneNetworkPrefix=3.0.0EthernetBNetworkPrefix=2.0.0EthernetCNetworkPrefix=4.0.04655454aaac5352cc53b52bbbbHost1Host2Host3Host4Host5RouterARouterBRouterCARoutingExample:

Target/Prefix-LengthNextHopInterface/24“direct”a/24“direct”c/2453c/2452cRouterA’sroutingtableEthernetANetworkPrefix=1.0.0High-SpeedFiberBackboneNetworkPrefix=3.0.0EthernetBNetworkPrefix=2.0.0EthernetCNetworkPrefix=4.0.04755454aaac5352cc53b52bbbbHost1Host2Host3Host4Host5RouterARouterBRouterCARoutingExample:

Target/Prefix-LengthNextHopInterface/2454c/24“direct”b/24“direct”cRouterB’sroutingtableEthernetANetworkPrefix=1.0.0High-SpeedFiberBackboneNetworkPrefix=3.0.0EthernetBNetworkPrefix=2.0.0EthernetCNetworkPrefix=4.0.04855454aaac5352cc53b52bbbbHost1Host2Host3Host4Host5RouterARouterBRouterCARoutingExample:

Target/Prefix-LengthNextHopInterface/2454c/24“direct”b/24“direct”cRouterB’sroutingtableEthernetANetworkPrefix=1.0.0High-SpeedFiberBackboneNetworkPrefix=3.0.0EthernetBNetworkPrefix=2.0.0EthernetCNetworkPrefix=4.0.0?495ProblemThepacketisundeliverableHost4isnotconnectedtoEthernetB.RouterBwillthensendaHostUnreachableerrormessagebacktoHost1.Q:Howtosolveit?50ProblemThepacketisundeliverSolution1:Host-SpecificRoutePlacehost-specificroutesintheroutingtablesofRouterA,B,andCasfollows:Target/Prefix-LengthNextHopInterface/3252cTarget/Prefix-LengthNextHopInterface/3252cTarget/Prefix-LengthNextHopInterface/32“direct”bRouterARouterBRouterCQ:Isthisagoodsolution?51Solution1:Host-SpecificRouSolution2:ChangeIPAddressSimplychangetheIPaddressofhost4,asitmovesfromEthernetBtoEthernetC.Forexample,DynamicHostConfigurationProtocol(DHCP)canbeusedtoacquireanewIPaddress.這是我們通常使用的方式！Q:Isthisagoodsolution?52Solution2:ChangeIPAddressSSolution3:MobileIPAstandardproposedtosolvetheproblemofInternetmobility.ItallowsthemobilenodetousetwoIPaddresses:afixedhomeaddressacare-ofaddressthatchangesateachnewpointofattachment53Solution3:MobileIPAstandar引入移動(dòng)IP的原因主機(jī)移動(dòng)接入位置的變化IP變化無(wú)法路由到原來(lái)的主機(jī)地址上連接中斷54引入移動(dòng)IP的原因主機(jī)移動(dòng)54移動(dòng)IP的設(shè)計(jì)目標(biāo)移動(dòng)節(jié)點(diǎn)在改變數(shù)據(jù)鏈路層接入點(diǎn)后，應(yīng)能夠保持與Internet上其它節(jié)點(diǎn)的連續(xù)通信移動(dòng)節(jié)點(diǎn)無(wú)論連接到任何接入點(diǎn)，應(yīng)該能夠用原來(lái)的IP地址進(jìn)行通信移動(dòng)節(jié)點(diǎn)應(yīng)該能夠與不具有移動(dòng)IP的其它節(jié)點(diǎn)進(jìn)行通信，并且不需要修改這些節(jié)點(diǎn)的協(xié)議移動(dòng)節(jié)點(diǎn)不應(yīng)該比Internet上的其它節(jié)點(diǎn)面臨更多的安全危險(xiǎn)55移動(dòng)IP的設(shè)計(jì)目標(biāo)移動(dòng)節(jié)點(diǎn)在改變數(shù)據(jù)鏈路層接入點(diǎn)后，應(yīng)能夠移動(dòng)IP的功能實(shí)體移動(dòng)節(jié)點(diǎn)（MobileNode）家鄉(xiāng)代理（HomeAgent）外地代理（ForeignAgent）56移動(dòng)IP的功能實(shí)體移動(dòng)節(jié)點(diǎn)（MobileNode）56Mobile

IPTerminology&Func.MNHAFACNInternetMN,MobileNodeAnIPhostthatmaintainsnetworkconnectivityusingits“home”IPaddress,regardlessofwhichsubnet(ornetwork)itisconnectedtoFA,ForeignAgentProvidesanaddressablepointofattachmenttotheMNcalledCareOfAddress(COA)MaintainsanawarenessforallvisitingMNsActsasa‘relay’betweentheMNanditsHomeAgentReceivesallpacketsfortheMNfromtheMN’sHomeAgentHA,HomeAgentMaintainsanassociationbetweentheMN’s“home”IPaddressanditscareofaddress(loanedaddress)ontheforeignnetworkRedirectsandtunnelspacketstothecareofaddressontheforeignnetworkCN,CorrespondentNodeDestinationIPhostinsessionwithaMobileNodeCOAMN57Mobile

IPTerminology&Func.M常用術(shù)語(yǔ)家鄉(xiāng)地址轉(zhuǎn)交地址外地代理轉(zhuǎn)交地址(ForeignAgentCare-of-Address)配置轉(zhuǎn)交地址(CollocatedCare-of-Address)家鄉(xiāng)網(wǎng)絡(luò)、家鄉(xiāng)鏈路外地網(wǎng)絡(luò)、外地鏈路通信對(duì)端節(jié)點(diǎn)移動(dòng)綁定58常用術(shù)語(yǔ)家鄉(xiāng)地址58隧道(Tunnel)當(dāng)一個(gè)數(shù)據(jù)包被封裝在另一個(gè)數(shù)據(jù)包的凈荷中進(jìn)行傳送時(shí)，所經(jīng)過(guò)的路徑稱為隧道。圖中還給出了一個(gè)例子，表明家鄉(xiāng)代理為將數(shù)據(jù)包傳送給移動(dòng)節(jié)點(diǎn)，把數(shù)據(jù)包通過(guò)隧道先送給外地代理。59隧道(Tunnel)當(dāng)一個(gè)數(shù)據(jù)包被封裝在另一個(gè)數(shù)據(jù)包的凈荷中移動(dòng)IP的工作機(jī)制1.通過(guò)周期地組播或廣播一個(gè)稱為代理廣播（AgentAdvertisements）的消息，家鄉(xiāng)代理和外地代理宣告它們與鏈路的連接關(guān)系。60移動(dòng)IP的工作機(jī)制1.通過(guò)周期地組播或廣播一個(gè)稱為代理廣播（移動(dòng)IP的工作機(jī)制2.移動(dòng)節(jié)點(diǎn)收到這些代理廣播消息后，檢查其中的內(nèi)容以確定自己是連在家鄉(xiāng)鏈路還是外地鏈路上。當(dāng)它連在家鄉(xiāng)鏈路上時(shí)，移動(dòng)節(jié)點(diǎn)就可像固定節(jié)點(diǎn)一樣工作，即它不再利用移動(dòng)IP的其他功能。61移動(dòng)IP的工作機(jī)制2.移動(dòng)節(jié)點(diǎn)收到這些代理廣播消息后，檢查其移動(dòng)IP的工作機(jī)制下面的步驟假設(shè)移動(dòng)節(jié)點(diǎn)連接在一條外地鏈路上。3.連在外地鏈路上的移動(dòng)節(jié)點(diǎn)需要一個(gè)轉(zhuǎn)交地址。它可以從外地代理廣播的代理廣播消息中找到外地代理轉(zhuǎn)交地址，配置轉(zhuǎn)交地址必須通過(guò)一個(gè)配置規(guī)程得到，比如用DHCP（DynamicHostConfigurationProtocol）、PPP的IPCP或手工配置。62移動(dòng)IP的工作機(jī)制下面的步驟假設(shè)移動(dòng)節(jié)點(diǎn)連接在一條外地鏈路上移動(dòng)IP的工作機(jī)制4.移動(dòng)節(jié)點(diǎn)向家鄉(xiāng)代理注冊(cè)從第3步中得到的轉(zhuǎn)交地址，可以通過(guò)移動(dòng)IP中定義的消息交換來(lái)完成。在注冊(cè)過(guò)程中，如果鏈路上有一個(gè)外地代理，移動(dòng)節(jié)點(diǎn)就向它請(qǐng)求服務(wù)。為阻止拒絕服務(wù)攻擊，注冊(cè)消息要求進(jìn)行認(rèn)證。63移動(dòng)IP的工作機(jī)制4.移動(dòng)節(jié)點(diǎn)向家鄉(xiāng)代理注冊(cè)從第3步中得到移動(dòng)IP的工作機(jī)制5.家鄉(xiāng)代理或者是在家鄉(xiāng)鏈路上的其他一些路由器廣播對(duì)移動(dòng)節(jié)點(diǎn)家鄉(xiāng)地址的網(wǎng)絡(luò)前綴的可達(dá)性，從而吸引發(fā)往移動(dòng)節(jié)點(diǎn)家鄉(xiāng)地址的數(shù)據(jù)包，家鄉(xiāng)代理截取這個(gè)包（可能用代理ARP），并根據(jù)移動(dòng)節(jié)點(diǎn)在第4步中注冊(cè)的轉(zhuǎn)交地址，通過(guò)隧道將數(shù)據(jù)包傳送給移動(dòng)節(jié)點(diǎn)。6.在轉(zhuǎn)交地址處——可能是外地代理或移動(dòng)節(jié)點(diǎn)的一個(gè)端口，原始數(shù)據(jù)包被從隧道中提取出來(lái)送給移動(dòng)節(jié)點(diǎn)64移動(dòng)IP的工作機(jī)制5.家鄉(xiāng)代理或者是在家鄉(xiāng)鏈路上的其他一些移動(dòng)IP的工作機(jī)制65移動(dòng)IP的工作機(jī)制65MobileIPPacketForwardingTrafficissentasusualtothehomesubnetThehomeagentintercepts(ProxyARP)thetrafficwhilethemobilenodeisregisteredasawayTrafficistunneledtoitscurrentlocationTrafficfromthemobilenodecangodirectlytothecorrespondenthostMobileNodeHomeAgentForeignAgentCorrespondentHostMobileIPPacketForwardingTra代理搜索代理搜索由兩條簡(jiǎn)單的消息構(gòu)成代理廣播消息（AgentAdvertisement）代理請(qǐng)求消息（AgentSolicitation）通過(guò)ICMP協(xié)議改進(jìn)實(shí)現(xiàn)的67代理搜索代理搜索由兩條簡(jiǎn)單的消息構(gòu)成67移動(dòng)檢測(cè)移動(dòng)檢測(cè)：移動(dòng)節(jié)點(diǎn)確定自己從一條鏈路移到了另一條鏈路上用生存時(shí)間域作移動(dòng)檢測(cè)用網(wǎng)絡(luò)前綴作移動(dòng)檢測(cè)68移動(dòng)檢測(cè)移動(dòng)檢測(cè)：移動(dòng)節(jié)點(diǎn)確定自己從一條鏈路移到了另一條鏈路移動(dòng)注冊(cè)注冊(cè)消息

1.注冊(cè)請(qǐng)求（RegistrationRequest）

2.注冊(cè)應(yīng)答（RegistrationReply）注冊(cè)種類

1.移動(dòng)節(jié)點(diǎn)用外地代理轉(zhuǎn)交地址注冊(cè)在一條外地鏈路上

2.移動(dòng)節(jié)點(diǎn)用配置轉(zhuǎn)交地址注冊(cè)在一條外地鏈路上

3.移動(dòng)節(jié)點(diǎn)在回到家鄉(xiāng)鏈路后進(jìn)行注銷69移動(dòng)注冊(cè)注冊(cè)消息69注冊(cè)的種類70注冊(cè)的種類70路由71路由71路由優(yōu)化是否可行？72路由優(yōu)化是否可行？72移動(dòng)IP廣播接收廣播

1.用配置轉(zhuǎn)交地址接收廣播

2.用外地代理轉(zhuǎn)交地址接收廣播家鄉(xiāng)代理必須用多重封裝(NestedEncapsulation)來(lái)向注冊(cè)了外地代理轉(zhuǎn)交地址的移動(dòng)節(jié)點(diǎn)發(fā)送廣播包。首先，家鄉(xiāng)代理將廣播包封裝進(jìn)第一層封裝中，源IP地址為家鄉(xiāng)代理的地址，目的IP地址為移動(dòng)節(jié)點(diǎn)的家鄉(xiāng)地址。然后，家鄉(xiāng)代理為經(jīng)過(guò)第一層封裝的包加上第二層封裝，這時(shí)的源IP地址為家鄉(xiāng)代理的地址，目的IP地址為移動(dòng)節(jié)點(diǎn)的轉(zhuǎn)交地址。73移動(dòng)IP廣播接收廣播73移動(dòng)IP廣播發(fā)送廣播

1.送往移動(dòng)節(jié)點(diǎn)外地鏈路的特定鏈路廣播

2.送往移動(dòng)節(jié)點(diǎn)家鄉(xiāng)鏈路的特定鏈路廣播

3.特定前綴廣播74移動(dòng)IP廣播發(fā)送廣播74EntitiesandRelationshipsHomeLink–thelinkhavingthesamenetworkprefixasthenode’sIPaddressMobileNode“athome”HomeAgent–arouteronthemobilenode’shomelink.ForeignAgentForeignAgentForeignLinkForeignLinkMobileNode“visiting”aforeignlink75EntitiesandRelationshipsHomeCare-ofAddressTwoconceptualtypesofcare-ofaddressesForeignagentcare-ofaddressCollocatedcare-ofaddress76Care-ofAddressTwoconceptualForeignAgentCare-ofAddressIPaddressofaforeignagentwhichhasaninterfaceontheforeignlink.TheforeignagentmayhavemorethanoneIPaddress;hence,thenetwork-prefixneednotequalthenetworkprefixoftheforeignlinkThesameaddresscanbesharedbymanymobilenodessimultaneously.77ForeignAgentCare-ofAddressICollocatedCare-ofAddressAnIPaddresstemporarilyassignedtoamobilenode.Itcanbeusedbyonlyonemobilenodeatatime.Thenetworkprefixmustequalthenetworkprefixoftheforeignlink.Itmightbeusedbyamobilenodeinsituationswherenoforeignagentsareavailable.78CollocatedCare-ofAddressAnIThreeMechanismsAgentDiscoveryRegistrationRouting79ThreeMechanismsAgentDiscover1.AgentDiscoveryHomeAgentsandForeignAgentsperiodicallybroadcastsAgentAdvertisements.e.g.onceeveryfewsecondsIfthemobilenodedoesnotwanttowaitfortheperiodicadvertisement,itcanbroadcastAgentSolicitationsthatwillbeansweredbyanyforeignagentthatreceivesit.Mobilenodesdeterminewhethertheyhavemovedfromonelinktoanother.(How?)801.AgentDiscoveryHomeAgentsMoveDetectionAgentAdvertisementhasaLifetimefield.specifyhowsoonamobilenodeshouldexpecttohearanotheradvertisementfromthatsameagent.IfthemobilenodefailstohearanadvertisementfromthatagentwithinthespecifiedLifetime,thenitassumesthatithasmovedtoadifferentlink.81MoveDetectionAgentAdvertisemCare-ofAddressAmobilenodeconnectedtoaforeignlinkacquireaforeignagentcare-of-addressfromtheAgentAdvertisements.Ifmultiplecare-of-addressesarelisted,anyoneofthemcanbeused.Ifaforeignagentisunavailable,themobilenodeobtainacollocatedcare-ofaddressbyDynamicHostConfigurationProtocol(DHCP).82Care-ofAddressAmobilenodecDHCPGoalallowhosttodynamicallyobtainitsIPaddressfromnetworkserverwhenitjoinsanetworkAclient-serverprotocolFour-wayhandshake83DHCPGoal83DHCPClient-ServerScenario7EDHCP

server

arrivingDHCPclientneedsaddressinthisnetworkDHCPrelayagent(typicallyarouter)for223.1.1and223.1.3.ItknowstheaddressofaDHCPserverforthesenetworks.84DHCPClient-ServerScenario223DHCPserver:arrivingclienttimeDHCPdiscoversrc:,68dest.:55,67yiaddr:transactionID:654DHCPoffersrc:,67dest:55,68yiaddrr:transactionID:654Lifetime:3600secsDHCPrequestsrc:,68dest::55,67yiaddrr:transactionID:655Lifetime:3600secsDHCPACKsrc:,67dest:55,68yiaddrr:transactionID:655Lifetime:3600secsChooseanofferifmorethanoneserverreplies.BroadcastAddress:55UDPport67Whatissourceaddress?AllocatesanIPaddressandsetthetimeforwhichtheaddresswillbevalid.85DHCPserver:arriving2.RegistrationRegistrationistheprocessbywhichamobilenoderequestsroutingservicesfromaforeignagent;informsitshomeagentofitscurrentcare-ofaddress;renewsaregistrationwhichisduetoexpire;deregisterswhenitreturnstoitshomelink.862.RegistrationRegistrationisScenario1:RegisteringForeignAgentCare-ofAddressForeignAgentHomeAgent1234Themobilenode,withtheassistanceofaforeignagent,sendsa

RegistrationRequest

withthecare-ofaddressinformation.Whenthehomeagentreceivesthisrequest,itaddsthenecessaryinformationtoitsroutingtable,andsendsaRegistrationReplybacktothemobilenode.MobileNode“visiting”aforeignlink87Scenario1:RegisteringForeigScenario2:RegisteringCollocatedCare-ofAddressHomeAgent1.RegistrationRequestMobileNode“visiting”aforeignlink2.RegistrationReply88Scenario2:RegisteringCollocScenario3:DeregistrationHomeAgent1.(de-)RegistrationRequestMobileNodereturnstoitshomelink2.(de-)RegistrationReply89Scenario3:DeregistrationHomAuthenticationThehomeagentmustbecertainthatregistrationwasoriginatedbythemobilenodeandnotbysomeothermaliciousnode.Registrationofthecare-ofaddressrequiresauthentication.Themobilenodeneedstoproveitsidentitytoitshomeagent.Itisdonebymakinguseofasecretkeyknownonlytothemobilenodeanditshomeagent.90AuthenticationThehomeagentm3.RoutingDifferentScenarios:MobileNode→CorrespondentNodeCorrespondentNode→MobileNodeWithaforeignagentWithoutaforeignagent913.RoutingDifferentScenarios:HowtoSendPacketstoaCorrespondentNode?ForeignAgentHomeAgentCorrespondentMobileNodeSimplyusetheCorrespondent’sIPaddressasthedestinationaddress.Howaboutthesourceaddress?OriginalIPaddress?Care-ofAddress?92HowtoSendPacketstoaCorrHowtoSendPacketstoaMobileNode?ForeignAgentHomeAgentCorrespondentMobileNodeSourceaddressCorrespondent’sIPaddressDestinationaddressMobile’sIPaddress93HowtoSendPacketstoaMobiTunnelingtotheCare-ofAddressForeignAgentHomeAgentMobileNode“visiting”aforeignlinkTunnelHomeAgentinterceptspacketsdestinedtothemobilenode’shomeaddressand

tunnels

themtothemobilenode’scare-ofaddress.ForeignAgentremovesoriginalpacketfromthetunnelanddeliverstheoriginalpackettothemobilenodeovertheforeignlink.94TunnelingtotheCare-ofAddreIPinIPEncapsulationHeaderPayloadOriginalIPpacketIpsrc=OriginalSender Ipdes=Destination’sHomeAddressOuterHeaderOuterPayloadIpsrc=HomeAgent Ipdes=Mobilenode’sCare-ofAddressEncapsulatingIPpacketHeaderPayloadThehomeagentinsertsanewIPheader,ortunnelheader,infrontoftheIPheaderofanydatagramaddressedtothemobilenode’shomeaddress.95IPinIPEncapsulationHeaderPaTriangleRouting移動(dòng)節(jié)點(diǎn)“訪問(wèn)”一條外部鏈路ForeignAgentHomeAgent通信對(duì)方Whydoesn’tthemobilenodeinformthecorrespondentofitscare-ofaddressandhaveittunneldirectlytothemobilenode?96TriangleRouting移動(dòng)節(jié)點(diǎn)“訪問(wèn)”一條外部OptimizedRoutingMobileNode“visiting”aforeignlinkForeignAgentHomeAgentCorrespondentThisispotentiallymoreefficientintermsofdelayandresourceconsumption.Whyisitnotused?97OptimizedRoutingMobileNode“MainObstacle:SecurityMobileNode“visiting”aforeignlinkForeignAgentHomeAgentCorrespondentAbadguysendsafakeregistrationtothecorrespondentItisimpracticaltodistributekeysbetweenamobilenodeandeveryothernodewithwhichitmightcorrespond.98MainObstacle:SecurityMobileEND!99END!99WirelessCommunicationandNetworkChapter7Location/MibilityManagement100WirelessCommunicationandNetWhydoweneedlocation/mobilitymanagement?Whatislocation/mobilitymanage