新一代互聯網網絡層協議IPv6徐恪清華大學計算機系1清華大學研究生課程新一代互聯網網絡層協議IPv6徐恪1清華大學研究生課程OutlineProtocolBackgroundTechnologyHighlightsEnhancedCapabilitiesTransitionIssuesNextSteps2清華大學研究生課程OutlineProtocolBackground2清華大WhyaNewIP?1991–ALEWGstudiedprojectionsaboutaddressconsumptionrateshowedexhaustionby2008.Bake-offinmid-1994selectedapproachofanewprotocolovermultiplelayersofencapsulation.3清華大學研究生課程WhyaNewIP?1991–ALEWGstuWhatEverHappenedtoIPv5?0 IPMarch1977version(deprecated)1 IPJanuary1978version(deprecated)2 IPFebruary1978versionA(deprecated)3 IPFebruary1978versionB(deprecated)4 IPv4September1981version(currentwidespread)5 STStreamTransport(notanewIP,littleuse)6 IPv6December1998version(formerlySIP,SIPP)7 CATNIPIPngevaluation(formerlyTP/IX;deprecated)8 PipIPngevaluation(deprecated)9 TUBAIPngevaluation(deprecated)10-15unassigned4清華大學研究生課程WhatEverHappenedtoIPv5?0 I1992年，IETF開始開發IPv6協議

1993年，IETF開始研究IPng領域，調查各種不同協議，并對進一步的研究過程提出簡介。

1994年，IETF的IPng項目管理者們在多倫多舉行的IETF會議上提出了創建IPv6的建議。

1994年11月17日，因特網工程指導小組(InternetEngineeringSteeringGroup,IESG)起草了IPv6提議標準

1995年12月在RFC1883中公布了建議標準（proposalstandard）

1996年7月，發布了版本2得草案標準（draftstandard）

1997年11月，發布了版本2.1的草案標準（draftstandard）

1998年8月10日，IPv6核心協議成為IETF草案標準。

1998年12月，發布了標準RFC2460

5清華大學研究生課程1992年，IETF開始開發IPv6協議

1993年，IET在IPv6的發展過程中，有過數種不同提議,主要的提議有以下幾種：

[1]TUBA：含有更多地址的TCP和UDP（TCPandUDPwithBiggerAddresses，TUBA，由RFC1347描述）建議采用ISO/OSI的CLNP協議來代替IPv4，這種解決方案允許用戶有20字節的NSAP地址，以及一個可以使用的OSI傳輸協議的平臺。[2]IPv7，TP/IX，CATNIP：IPv7是1992年由RobertUllmann提出的。1993年，RFC1475進行了更詳細的描述，其標題為“TP/IX：下一代的Internet”，TP/IX有64位地址。TP/IX后來演變成了RFC1707中定義的另一個協議CATNIP（CommonArchitecturefortheInternet）。該方案包含了諸如快速信息包處理和新的RAP路由協議等觀點，試圖為IP、CLNP和IPX等信息包定義一個統一的格式，為眾多的傳輸協議如OSI/TP4、TCP、UDP和SPX等提供支持。[3]IPinIP，IPAE：IPinIP是1992年提出的建議，計劃采用兩個IPv4層來解決互聯網地址的匱乏：一層用于全球骨干網絡，另一層用于某些特定的范圍。到了1993年，這個建議得到了進一步的發展，名稱也改為了IPAE（IPAddressEncapsulation），并且被采納為SIP的過渡方案。

6清華大學研究生課程在IPv6的發展過程中，有過數種不同提議,主要的提議有以下幾

[4]SIP：SIP（SimpleIP）是由SteveDeering在1992年11月提出的，他的想法是把IP地址改為64位，并且去除IPv4中一些已經過時的字段。這個建議由于其簡單性立刻得到了許多公司的支持

[5]PIP：PIP（Paul‘sInternetProtocol）由PaulFrancis提出，PIP是一個基于新的結構的IP。PIP支持以16位為單位的變長地址，地址間通過標識符進行區分，它允許高效的策略路由并實現了可移動性。1994年9月，PIP和SIP合并，稱為SIPP。

[6]SIPP：SIPP（SimpleIPPlus，由RFC1710描述）試圖結合SIP的簡單性和PIP路由的靈活性。SIPP設計為高性能的網絡上運作，比如ATM，同時也可以在低帶寬的網絡上運行，如無線網絡。SIPP去掉了IPv4包頭的一些字段，使得包頭很小，并且采用64位地址。與IPv4將選項作為IP頭的基本組成部分不同，SIPP中把IP選項與包頭進行了隔離。該選項如果有的話，將被放在包頭后的數據報中并位于傳輸層協議頭之前。使用這種方法后，路由器只有在必要的時候才會對選項頭進行處理，這樣一來就提高了對于所有數據進行處理的性能。7清華大學研究生課程7清華大學研究生課程Technologies&effortstoslowtheconsumptionrateDial-access/PPP/DHCPProvidestemporaryallocationalignedwithactualendpointuse.StrictallocationpoliciesReducedallocationratesbypolicyof“current-need”vs.previouspolicybasedon“projected-maximum-size”.

CIDRAlignsroutingtablesizewithneeds-basedaddressallocationpolicy.Additionalenforcedaggregationactuallyloweredroutingtablegrowthratetolinearforafewyears.

NATHidesmanynodesbehindlimitedsetofpublicaddresses.8清華大學研究生課程Technologies&effortstoslowWouldincreaseduseof

NATsbeadequate?NO!NATenforcesa“client-server”applicationmodelwheretheserverhastopologicalconstraints.Theywon’tworkforpeer-to-peerordevicesthatare“called”byothers(e.g.,IPphones)Theyinhibitdeploymentofnewapplicationsandservices,becauseallNATsinthepathhavetobeupgradedBEFOREtheapplicationcanbedeployed.9清華大學研究生課程Wouldincreaseduseof

NATsbReturntoanEnd-to-EndArchitectureGlobalAddressingRealmAlways-onDevicesNeedanAddressWhenYouCallThemNewTechnologies/ApplicationsforHomeUsers‘Always-on’—Cable,DSL,Ethernet@home,Wireless,…10清華大學研究生課程ReturntoanEnd-to-EndArchitWhyisalargeraddressspaceneeded?OverallInternetisstillgrowingitsuserbase~320millionusersin2000 ~550millionusersby200511清華大學研究生課程WhyisalargeraddressspaceWhyisalargeraddressspaceneeded?Usersexpandingtheirconnecteddevicecount405millionmobilephonesin2000,over1billionby2005~1billioncarsin201015%likelytouseGPSandlocalitybasedYellowPageservicesBillionsofnewInternetappliancesforHomeusers12清華大學研究生課程WhyisalargeraddressspaceWhyWas128BitsChosen

astheIPv6AddressSize?Proposalsforfixed-length,64-bitaddressesAccommodates1012sites,1015nodes,at.0001allocationefficiencyMinimizesgrowthofper-packetheaderoverheadEfficientforsoftwareprocessingoncurrentCPUhardware13清華大學研究生課程WhyWas128BitsChosen

astheWhyWas128BitsChosen

astheIPv6AddressSize?Proposalsforvariable-length,upto160bitsCompatiblewithdeployedOSINSAPaddressingplansAccommodatesauto-configurationusingIEEE802addressesSufficientstructureforprojectednumberofserviceproviders14清華大學研究生課程WhyWas128BitsChosen

astheWhyWas128BitsChosen

astheIPv6AddressSize?Settledonfixed-length,128-bitaddresses(340,282,366,920,938,463,463,374,607,431,768,211,456inall!)15清華大學研究生課程WhyWas128BitsChosen

astheBenefitsof

128bitAddressesRoomformanylevelsofstructuredhierarchyandroutingaggregationEasyaddressauto-configurationEasieraddressmanagementanddelegationthanIPv4Abilitytodeployend-to-endIPsec16清華大學研究生課程Benefitsof

128bitAddressesRIncidentalBenefitsof

NewDeploymentChancetoeliminatesomecomplexityinIPheaderimproveper-hopprocessingChancetoupgradefunctionalitymulticast,QoS,mobilityChancetoincludenewfeaturesbindingupdates17清華大學研究生課程IncidentalBenefitsof

NewDepSummaryofMainIPv6BenefitsExpandedaddressingcapabilitiesStructuredhierarchytomanageroutingtablegrowthServerlessautoconfigurationandreconfigurationStreamlinedheaderformatandflowidentificationImprovedsupportforoptions/extensions18清華大學研究生課程SummaryofMainIPv6BenefitsEIPv6AdvancedFeaturesSourceaddressselectionMobility-MoreefficientandrobustmechanismsSecurity-Built-in,strongIP-layerencryptionandauthenticationQualityofServicePrivacyExtensionsforStatelessAddressAutoconfiguration(RFC3041)19清華大學研究生課程IPv6AdvancedFeaturesSourceaIPv6MarketsHomeNetworkingSet-topbox/Cable/xDSL/Ether@HomeResidentialVoiceoverIPgatewayGaming(10B$market)Sony,Sega,Nintendo,MicrosoftMobiledevicesConsumerPCConsumerDevicesSony(Mar/01-…energeticallyintroducingIPv6technologyintohardwareproducts…)EnterprisePCServiceProvidersRegionalISP,Carriers,MobileISP,andGreenfieldISP’s20清華大學研究生課程IPv6MarketsHomeNetworking20清OutlineProtocolBackgroundTechnologyHighlightsEnhancedCapabilitiesTransitionIssuesNextSteps21清華大學研究生課程OutlineProtocolBackground21清華031VersionClassFlowLabelPayloadLengthNextHeaderHopLimit128bitSourceAddress128bitDestinationAddress4122416TheIPv6Header

40octets,8fields22清華大學研究生課程031VersionClassFlowLabelPayl031VerIHLTotalLength Identifier FlagsFragmentOffset32bitSourceAddress32bitDestinationAddress482416ServiceType OptionsandPadding TimetoLiveHeaderChecksumProtocolTheIPv4Header

20octets+options:13fields,including3flagbitsshadedfieldsareabsentfromIPv6header23清華大學研究生課程031VerIHLTotalLength IdentifSummaryofHeaderChanges

betweenIPv4&IPv6StreamlinedFragmentationfieldsmovedoutofbaseheaderIPoptionsmovedoutofbaseheaderHeaderChecksumeliminatedHeaderLengthfieldeliminatedLengthfieldexcludesIPv6headerAlignmentchangedfrom32to64bits24清華大學研究生課程SummaryofHeaderChanges

betwSummaryofHeaderChanges

betweenIPv4&IPv6RevisedTimetoLive’HopLimitProtocol’NextHeaderPrecedence&TOS’TrafficClassAddressesincreased32bits’128bitsExtendedFlowLabelfieldadded25清華大學研究生課程SummaryofHeaderChanges

betwExtensionHeadersnextheader=TCPTCPheader+dataIPv6headernextheader=RoutingTCPheader+dataRoutingheadernextheader=TCPIPv6headernextheader=RoutingfragmentofTCPheader+dataRoutingheadernextheader=FragmentFragmentheadernextheader=TCPIPv6header26清華大學研究生課程ExtensionHeadersnextheader=ExtensionHeadersGenerallyprocessedonlybynodeidentifiedinIPv6DestinationAddressfield=>muchloweroverheadthanIPv4optionsprocessingexception:Hop-by-HopOptionsheaderEliminatedIPv4’s40-bytelimitonoptionsinIPv6,limitistotalpacketsize,

orPathMTUinsomecasesCurrentlydefinedextensionheaders:Hop-by-HopOptions,Routing,Fragment,Authentication,Encryption,DestinationOptions,Mobility27清華大學研究生課程ExtensionHeadersGenerallyproFragmentHeaderthoughdiscouraged,canuseIPv6Fragmentheadertosupportupperlayersthatdonot(yet)dopathMTUdiscoveryIPv6frag.&reasm.isanend-to-endfunction;routersdonotfragmentpacketsen-routeiftoobig—theysendICMP“packettoobig”insteadNextHeaderOriginalPacketIdentifierReservedFragmentOffset00M28清華大學研究生課程FragmentHeaderthoughdiscouraRoutingSame“longest-prefixmatch”routingasIPv4CIDRStraightforwardchangestoexistingIPv4routingprotocolstohandlebiggeraddressesunicast:OSPFv3,RIPng,IS-IS,BGP4+,…multicast:PIM,MOSPF,…UseofRoutingheaderwithanycastaddressesallowsroutingpacketsthroughparticularregionse.g.,forproviderselection,policy,performance,etc.29清華大學研究生課程RoutingSame“longest-prefixmaRoutingHeaderAddress[1]ReservedAddress[0]NextHeaderHdrExtLenRoutingTypeSegmentsLeft???30清華大學研究生課程RoutingHeaderAddress[1]ReservSABDExampleofUsingtheRoutingHeader31清華大學研究生課程SABDExampleofUsingtheRoutiSABDExampleofUsingtheRoutingHeader32清華大學研究生課程SABDExampleofUsingtheRoutiSABDExampleofUsingtheRoutingHeader33清華大學研究生課程SABDExampleofUsingtheRoutiSABDExampleofUsingtheRoutingHeader34清華大學研究生課程SABDExampleofUsingtheRoutiSomeTerminologynode aprotocolmodulethatimplementsIPv6router anodethatforwardsIPv6packetsnotexplicitly

addressedtoitselfhost anynodethatisnotarouterlink acommunicationfacilityormediumoverwhich

nodescancommunicateatthelinklayer,

i.e.,thelayerimmediatelybelowIPv6neighbors nodesattachedtothesamelinkinterface anode’sattachmenttoalinkaddress anIPv6-layeridentifierforaninterfaceoraset

ofinterfaces35清華大學研究生課程SomeTerminologynode aprotocTextRepresentationofAddresses“Preferred”form: 1080:0:FF:0:8:800:200C:417ACompressedform: FF01:0:0:0:0:0:0:43 becomesFF01::43IPv4-compatible: 0:0:0:0:0:0: or::36清華大學研究生課程TextRepresentationofAddressIPv6-AddressingModelLink-LocalSite-LocalGlobal

AddressesareassignedtointerfacesNochangefromIPv4ModelInterface‘expected’tohavemultipleaddressesAddresseshavescopeLinkLocalSiteLocalGlobalAddresseshavelifetimeValidandPreferredlifetime37清華大學研究生課程IPv6-AddressingModelLink-LoTypesofIPv6AddressesUnicastAddressofasingleinterfaceDeliverytosingleinterfaceMulticastAddressofasetofinterfacesDeliverytoallinterfacesinthesetAnycastAddressofasetofinterfacesDeliverytoasingleinterfaceinthesetNomorebroadcastaddresses38清華大學研究生課程TypesofIPv6AddressesUnicastAddressTypePrefixes

Addresstype

BinaryprefixIPv4-compatible 0000...0(96zerobits)globalunicast 001link-localunicast 1111111010site-localunicast 1111111011multicast 11111111allotherprefixesreserved(approx.7/8thsoftotal)anycastaddressesallocatedfromunicastprefixes39清華大學研究生課程AddressTypePrefixesAddresssitetopology(16bits)interfaceidentifier(64bits)publictopology(45bits)interfaceIDSLA*NLA*TLA001GlobalUnicastAddressesTLA=Top-LevelAggregator

NLA*=Next-LevelAggregator(s)

SLA*=Site-LevelAggregator(s)allsubfieldsvariable-length,non-self-encoding(likeCIDR)TLAsmaybeassignedtoprovidersorexchanges40清華大學研究生課程siteinterfacepublicinterfaceILink-localaddressesforuseduringauto-configurationandwhennoroutersarepresentSite-localaddressesforindependencefromchangesofTLA/NLALink-Local&Site-LocalUnicastAddresses11111110100interfaceID11111110110interfaceIDSLA*41清華大學研究生課程Link-localaddressesforusedInterfaceIDsLowest-order64-bitfieldofunicastaddressmaybeassignedinseveraldifferentways:auto-configuredfroma64-bitEUI-64,orexpandedfroma48-bitMACaddress(e.g.,Ethernetaddress)auto-generatedpseudo-randomnumber

(toaddressprivacyconcerns)assignedviaDHCPmanuallyconfiguredpossiblyothermethodsinthefuture42清華大學研究生課程InterfaceIDsLowest-order64-bSomeSpecial-PurposeUnicastAddressesTheunspecifiedaddress,usedasaplaceholderwhennoaddressisavailable:

0:0:0:0:0:0:0:0Theloopbackaddress,forsendingpacketstoself:

0:0:0:0:0:0:0:143清華大學研究生課程SomeSpecial-PurposeUnicastAMulticastAddressFormatflagfieldlow-orderbitindicatespermanent/transientgroup(threeotherflagsreserved)scopefield: 1-nodelocal 8-organization-local2-link-local B-community-local5-site-local E-global(allothervaluesreserved)mapIPv6multicastaddressesdirectlyintoloworder32bitsoftheIEEE802MACFP

(8bits)Flags(4bits)Scope(4bits)GroupID(32bits)11111111000TLcl/Sit/GblLocallyadministeredRESERVED(80bits)MUSTbe044清華大學研究生課程MulticastAddressFormatflagfOutlineProtocolBackgroundTechnologyHighlightsEnhancedCapabilitiesTransitionIssuesNextSteps45清華大學研究生課程OutlineProtocolBackground45清華IPv6Security46清華大學研究生課程IPv6Security46清華大學研究生課程IPv6SecurityAllimplementationsrequiredtosupportauthenticationandencryptionheaders(“IPsec”)AuthenticationseparatefromencryptionforuseinsituationswhereencryptionisprohibitedorprohibitivelyexpensiveKeydistributionprotocolsareunderdevelopment(independentofIPv4/v6)Supportformanualkeyconfigurationrequired47清華大學研究生課程IPv6SecurityAllimplementatioAuthenticationHeaderDestinationAddress+SPIidentifiessecurityassociationstate(key,lifetime,algorithm,etc.)ProvidesauthenticationanddataintegrityforallfieldsofIPv6packetthatdonotchangeen-routeDefaultalgorithmisKeyedMD5NextHeaderHdrExtLenSecurityParametersIndex(SPI)ReservedSequenceNumberAuthenticationData48清華大學研究生課程AuthenticationHeaderDestinatiEncapsulatingSecurityPayload(ESP)PayloadNextHeaderSecurityParametersIndex(SPI)SequenceNumberAuthenticationDataPaddingLengthPadding49清華大學研究生課程EncapsulatingSecurityPayloadIPv6QualityofService50清華大學研究生課程IPv6QualityofService50清華大學IPQualityofServiceApproachesTwobasicapproachesdevelopedbyIETF:“IntegratedService”(Intserv)fine-grain(per-flow),quantitativepromises(e.g.,xbitspersecond),usesRSVPsignaling“DifferentiatedService”(Diffserv)coarse-grain(per-class),qualitativepromises(e.g.,higherpriority),noexplicitsignaling51清華大學研究生課程IPQualityofServiceApproachIPv6SupportforIntServ20-bitFlowLabelfieldtoidentifyspecificflowsneedingspecialQoSeachsourcechoosesitsownFlowLabelvalues;routersuseSourceAddr+FlowLabeltoidentifydistinctflowsFlowLabelvalueof0usedwhennospecialQoSrequested(thecommoncasetoday)thispartofIPv6isnotstandardizedyet,andmaywellchangesemanticsinthefuture52清華大學研究生課程IPv6SupportforIntServ20-bitIPv6SupportforDiffServ8-bitTrafficClassfieldtoidentifyspecificclassesofpacketsneedingspecialQoSsameasnewdefinitionofIPv4Type-of-Servicebytemaybeinitializedbysourceorbyrouterenroute;mayberewrittenbyroutersenroutetrafficClassvalueof0usedwhennospecialQoSrequested(thecommoncasetoday)53清華大學研究生課程IPv6SupportforDiffServ8-bitCompromiseSignaledDiffServ(RFC2998)usesRSVPforsignalingwithcourse-grainedqualitativeaggregatemarkingsallowsforpolicycontrolwithoutrequiringper-routerstateoverhead54清華大學研究生課程CompromiseSignaledDiffServ(RIPv6Mobility55清華大學研究生課程IPv6Mobility55清華大學研究生課程IPv4Mobility:Vocabularyhomenetwork:permanent“home”ofmobile(e.g.,128.119.40/24)permanentaddress:addressinhomenetwork,canalwaysbeusedtoreachmobilee.g.,86homeagent:

entitythatwillperformmobilityfunctionsonbehalfofmobile,whenmobileisremotewideareanetwork56清華大學研究生課程IPv4Mobility:VocabularyhomeIPv4Mobility:morevocabularycare-of-address:addressinvisitednetwork.(e.g.,79,129.13.2)wideareanetworkvisitednetwork:networkinwhichmobilecurrentlyresides(e.g.,79.129.13/24)permanentaddress:remainsconstant(e.g.,86)foreignagent:

entityinvisitednetworkthatperformsmobilityfunctionsonbehalfofmobile.

correspondent:

wantstocommunicatewithmobile57清華大學研究生課程IPv4Mobility:morevocabularyIPv4Mobility:registrationEndresult:foreignagentknowsaboutmobilehomeagentknowslocationofmobilewideareanetworkhomenetworkvisitednetwork1mobilecontactsforeignagentonenteringvisitednetwork2foreignagentcontactshomeagenthome:“thismobileisresidentinmynetwork”58清華大學研究生課程IPv4Mobility:registrationEndIPv4Mobilitywideareanetworkhomenetworkvisitednetwork3241correspondentaddressespacketsusinghomeaddressofmobilehomeagentinterceptspackets,forwardstoforeignagentforeignagentreceivespackets,forwardstomobilemobilerepliesdirectlytocorrespondent59清華大學研究生課程IPv4MobilitywideareanetworkIPv6MobilityMobilehostshaveoneormorehomeaddressrelativelystable;associatedwithhostnameinDNSAHostwillacquireaforeignaddresswhenitdiscoversitisinaforeignsubnet(i.e.,notitshomesubnet)usesauto-configurationtogettheaddressregisterstheforeignaddresswithahomeagent,

i.e,arouteronitshomesubnetPacketssenttothemobile’shomeaddress(es)areinterceptedbyhomeagentandforwardedtotheforeignaddress,usingencapsulationMobileIPv6hostswillsendbinding-updatestocorrespondenttoremovehomeagentfromflow60清華大學研究生課程IPv6MobilityMobilehostshaveHomeAgentBindingMaintenancewideareanetworkhomenetworkvisitednetworkIntheIPv6header,thesourceaddressisthemobilenode'scare-ofaddressandthedestinationaddressisthehomeagent'saddress.TheDestinationOptionsextensionheadercontainstheHomeAddressoption.ESPheader.TheMobilityheadercontainstheBindingUpdatemessagewiththeHomeRegistration(H)flagandtheAck(A)flagisalsosetto1.161清華大學研究生課程HomeAgentBindingMaintenanceHomeAgentBindingMaintenancewideareanetworkhomenetworkvisitednetwork2IntheIPv6header,thesourceaddressisthehomeagent'saddressandthedestinationaddressisthemobilenode'scare-ofaddress.TheType2Routingheadercontainsthemobilenode'shomeaddress.ESPheaderTheMobilityheadercontainseitheraBindingAcknowledgementmessage(sentinresponsetoabindingupdate)oraBindingRefreshRequestmessage162清華大學研究生課程HomeAgentBindingMaintenanceIPv6Mobilitywideareanetworkhomenetworkvisitednetwork21correspondentaddressespacketsusinghomeaddressofmobilehomeagentinterceptspackets,forwardstomobilewithtunnelIntheinnerIPv6header,thesourceaddressisthecorrespondentnode'saddressandthedestinationaddressisthemobilenode'shomeaddress63清華大學研究生課程IPv6MobilitywideareanetworkIPv6Mobilitywideareanetworkhomenetworkvisitednetwork21IntheinnerIPv6header,thesourceaddressisthemobilenode'shomeaddressandthedestinationaddressisthecorrespondentnode'saddress.3464清華大學研究生課程IPv6MobilitywideareanetworkDirectDeliveryWhenthemobilenodeisawayfromhome,itcanchoosetosenddatafromitscare-ofaddresswithoutusingMobileIPv6ForTransportlayerconnectiondatathatislong-termandbeingsenttoacorrespondentnodewithwhichithascompletedcorrespondentregistration,themobilenodesendsthedatafromitscare-ofaddress.Forshort-termcommunicationthatdoesnotrequirealogicalconnection,themobilenodecansenddatafromitscare-ofaddress.65清華大學研究生課程DirectDeliveryWhenthemobileCorrespondentNodeBindingMaintenanceReturnRoutabilityprocedureBindingUpdateandBindingAcknowledgementmessageexchangeResults:Onthemobilenode,thereisanentryinitsbindingupdatelistforthecorrespondentnode.Onthecorrespondentnode,thereisanentryinitsbindingcacheforthemobilenode66清華大學研究生課程CorrespondentNodeBindingMaiReturnRoutabilityProcedure67清華大學研究生課程ReturnRoutabilityProcedure67BindingUpdatewideareanetworkhomenetworkvisitednetworkIntheIPv6header,thesourceaddressisthemobilenode'scare-ofaddressandthedestinationaddressisthecorrespondentnode'saddress.TheDestinationOptionsextensionheadercontainstheHomeAddressoption.TheMobilityheadercontainstheBindingUpdatemessage,whichcontainsthecryptographicproof.168清華大學研究生課程BindingUpdatewideareanetworBindingAcknowledgementwideareanetworkhomenetworkvisitednetwork2IntheIPv6header,thesourceaddressisthecorrespondentnode'saddressandthedestinationaddressisthemobilenode'scare-ofaddress.IntheType2Routingheader,theHomeAddressfieldissettothemobilenode'shomeaddress.TheMobilityheadercontainseitheraBindingAcknowledgementmessage.169清華大學研究生課程BindingAcknowledgementwidearDirectDeliverywideareanetworkhomenetworkvisitednetworkIntheIPv6header,thesourceaddressisthemobilenode'scare-ofaddressandthedestinationaddressisthecorrespondentnode'saddress.InDestinationOptionsheader,theHomeAddressoptioncontainsthehomeaddressofthemobilenode.170清華大學研究生課程DirectDeliverywideareanetwoDirectDeliverywideareanetworkhomenetworkvisitednetwork2IntheIPv6header,thesourceaddressisthecorrespondentnode’saddressandthedestinationaddressisthemobilenode'scare-ofaddress.IntheType2Routingheader,theHomeAddressfieldissettothemobilenode'shomeaddress.171清華大學研究生課程DirectDeliverywideareanetwoComparisonwithMobileIPv4Thereisno"foreignagents“inMobileIPv6.Supportforrouteoptimizationisafundamentalpartoftheprotocol.MobileIPv6routeoptimizationcanoperatesecurelyevenwithoutpre-arrangedsecurityassociations.72清華大學研究生課程ComparisonwithMobileIPv4TheComparisonwithMobileIPv4SupportisalsointegratedintoMobileIPv6forallowingrouteoptimizationtocoexistefficientlywithroutersthatperform"ingressfiltering".MostpacketssenttoamobilenodewhileawayfromhomeinMobileIPv6aresentusinganIPv6routingheader.MobileIPv6isdecoupledfromanyparticularlinklayer,asitusesIPv6NeighborDiscoveryinsteadofARP.73清華大學研究生課程ComparisonwithMobileIPv4SupICMPandND74清華大學研究生課程ICMPandND74清華大學研究生課程ICMPErrorMessagescommonformatAsmuchoftheinvokingpacketaswillfitwithouttheICMPpacketexceeding1280octets(codeandparameteraretype-specific)TypeCodeChecksumParameter75清華大學研究生課程ICMPErrorMessagescommonformICMPErrorMessageTypesdestinationunreachablenorouteadministrativelyprohibitedaddressunreachableportunreachablepackettoobigtimeexceededparameterproblemerroneousheaderfieldunrecognizednextheadertypeunrecognizedoption76清華大學研究生課程ICMPErrorMessageTypesdestinICMPInformationalMessagesEchorequest&reply(sameasIPv4)Multicastlistenerdiscoverymessages:

query,report,done(likeIGMPforIPv4):TypeCodeChecksumMaximumResponseDelayReservedMulticastAddress77清華大學研究生課程ICMPInformationalMessagesEchNeighborDiscoveryICMPmessagetypes: routersolicitationrouteradvertisementneighborsolicitationneighboradvertisementredirectFunctionsperformed:routerdiscoveryprefixdiscoveryautoconfigurationofaddress&otherparametersduplicateaddressdetection(DAD)neighborunreachabilitydetection(NUD)Link-layeraddressresolutionfirst-hopredirect78清華大學研究生課程NeighborDiscoveryICMPmessageRouterAdvertisementsPeriodicallymulticastbyroutertoall-nodesmulticastaddress(linkscope)Contents:“Iamarouter”(implied) listof:lifetimeasdefault(1sec–18hr) ?prefix“getaddressesfromDHCP”flag ?prefixlength“getotherstufffromDHCP”flag ?validlifetimerouter’slink-layeraddress ?preferredlifetimelinkMTU ?on-linkflagsuggestedhoplimit ?autoconfigOKflagNotsentfrequentlyenoughforunreachabilitydetection79清華大學研究生課程RouterAdvertisementsPeriodicaOtherNeighborDiscoveryMessagesRoutersolicitationssentonlyathoststart-up,tosolicitimmediaterouteradvert.senttoall-routersmulticastaddress(linkscope)Neighborsolicitationsforaddressresolution:sentto“solicitednode”multicastaddr.forunreachabilitydetection:senttoneighbor’sunicastaddr.Neighboradvertisementsforaddressresolution:senttounicastaddressofsolicitorforlink-layeraddresschange:senttoall-nodesmulticastaddr.includesrouter/hostflag80清華大學研究生課程OtherNeighborDiscoveryMessaServerlessAutoconfigurationHostscanconstructtheirownaddresses:subnetprefix(es)learnedfromperiodicmulticastadvertisementsfromneighboringrouter(s)interfaceIDsgeneratedlocallyOtherIP-layerparametersalsolearnedfromrouteradverts(e.g.,routeraddresses,recommendedhoplimit,etc.)Higher-layerinfo(e.g.,DNSserverandNTPserveraddresses)discoveredbymulticast/anycast-basedservice-locationprotocolDHCPalsoavailableforthosewhowantmorecontrol81清華大學研究生課程ServerlessAutoconfigurationHoAuto-Reconfiguration

(“Renumbering”)Newaddressprefixescanbeintroduced,andoldoneswithdrawnweassumesomeoverlapperiodbetweenoldandnew,i.e.,no“flashcut-over”hostslearnprefixlifetimesandpreferenceorderfromrouteradvertisementsoldTCPconnectionscansurviveuntilendofoverlap;newTCPconnectionscansurvivebeyondoverlapRouterrenumberingprotocol,toallowdomain-interiorrouterstolearnofprefixintroduction/withdrawalNewDNSstructuretofacilitateprefixchanges82清華大學研究生課程Auto-Reconfiguration

(“RenumbeMinimumMTUDefinitions:linkMTU alink’smaximumtransmissionunit,

i.e.,themaxIPpacketsizethatcan

betransmittedoverthelink