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IPv6IPv4

IPv6/IPv4CoexistenceandMigration

MicrosoftCorporation

Published:

August2002

Abstract

ThemigrationofIPv4toIPv6willnothappenovernight.Rather,therewillbeaperiodoftransitionwhenbothprotocolsareinuseoverthesameinfrastructure.Toaddressthis,thedesignersofIPv6havecreatedtechnologiesandtypesofaddressessothatnodescancommunicatewitheachotherinamixedenvironment,eveniftheyareseparatedbyanIPv4infrastructure.ThisarticledescribesIPv4andIPv6coexistenceandmigrationtechnologiesandhowthesetechnologiesaresupportedbytheIPv6protocolfortheWindows.NETServer2003family.Thisarticleisintendedfornetworkengineersandsupportprofessionalswhoarealreadyfamiliarwithbasicnetworkingconcepts,TCP/IP,andIPv6.

Thisisapreliminarydocumentandmaybechangedsubstantiallypriortofinalcommercialreleaseofthesoftwaredescribedherein.TheinformationcontainedinthisdocumentrepresentsthecurrentviewofMicrosoftCorporationontheissuesdiscussedasofthedateofpublication.BecauseMicrosoftmustrespondtochangingmarketconditions,itshouldnotbeinterpretedtobeacommitmentonthepartofMicrosoft,andMicrosoftcannotguaranteetheaccuracyofanyinformationpresentedafterthedateofpublication.

Thisdocumentisforinformationalpurposesonly.MICROSOFTMAKESNOWARRANTIES,EXPRESSORIMPLIED,ASTOTHEINFORMATIONINTHISDOCUMENT.

Complyingwithallapplicablecopyrightlawsistheresponsibilityoftheuser.Withoutlimitingtherightsundercopyright,nopartofthisdocumentmaybereproduced,storedinorintroducedintoaretrievalsystem,ortransmittedinanyformorbyanymeans（electronic,mechanical,photocopying,recording,orotherwise）,orforanypurpose,withouttheexpresswrittenpermissionofMicrosoftCorporation.

Microsoftmayhavepatents,patentapplications,trademarks,copyrights,orotherintellectualpropertyrightscoveringsubjectmatterinthisdocument.ExceptasexpresslyprovidedinanywrittenlicenseagreementfromMicrosoft,thefurnishingofthisdocumentdoesnotgiveyouanylicensetothesepatents,trademarks,copyrights,orotherintellectualproperty.

©2002MicrosoftCorporation.Allrightsreserved.

MicrosoftandWindowsareeitherregisteredtrademarksortrademarksofMicrosoftCorporationintheUnitedStatesand/orothercountries.

Thenamesofactualcompaniesandproductsmentionedhereinmaybethetrademarksoftheirrespectiveowners.

Contents

Introduction1

NodeTypes1

CompatibilityAddresses2

CoexistenceMechanisms4

DualIPLayer4

IPv6overIPv4Tunneling5

DNSInfrastructure6

AddressRecords6

PointerRecords6

AddressSelectionRules6

TunnelingConfigurations7

Router-to-Router7

Host-to-RouterandRouter-to-Host8

Host-to-Host8

TypesofTunnels9

ConfiguredTunnels9

AutomaticTunnels9

6to411

6to4SupportintheWindows.NETServer2003Family13

ISATAP16

UsinganISATAPRouter17

ResolvingtheISATAPName18

Resolvingthe_ISATAPNameforWindowsXP19

Usingthenetshinterfaceipv6isatapsetrouterCommand20

SettingupanISATAPRouter20

ISATAPand6to4Example21

Part1:

FromISATAPHostAto6to4RouterA23

Part2:

From6to4RouterAto6to4RouterB23

Part3:

From6to4RouterBtoISATAPHostB24

PortProxy25

MigratingtoIPv627

AppendixA:

IPv6AutomaticTunneling28

AppendixB:

6over429

Summary32

RelatedLinks33

Introduction

ProtocoltransitionsarenoteasyandthetransitionfromIPv4toIPv6isnoexception.Protocoltransitionsaretypicallydeployedbyinstallingandconfiguringthenewprotocolonallnodeswithinthenetworkandverifyingthatallnodeandrouteroperationsworksuccessfully.Althoughthismightbepossibleinasmallormediumsizedorganization,thechallengeofmakingarapidprotocoltransitioninalargeorganizationisverydifficult.Additionally,giventhescopeoftheInternet,rapidprotocoltransitionbecomesanimpossibletask.

ThedesignersofIPv6recognizethatthetransitionfromIPv4toIPv6willtakeyearsandthattheremightbeorganizationsorhostswithinorganizationsthatwillcontinuetouseIPv4indefinitely.Therefore,whilemigrationisthelong-termgoal,equalconsiderationmustbegiventotheinterimcoexistenceofIPv4andIPv6nodes.

ThedesignersofIPv6intheoriginal“TheRecommendationfortheIPNextGenerationProtocol”specification（RFC1752）definedthefollowingtransitioncriteria:

∙ExistingIPv4hostscanbeupgradedatanytime,independentoftheupgradeofotherhostsorrouters.

∙Newhosts,usingonlyIPv6,canbeaddedatanytime,withoutdependenciesonotherhostsorroutinginfrastructure.

∙ExistingIPv4hosts,withIPv6installed,cancontinuetousetheirIPv4addressesanddonotneedadditionaladdresses.

∙LittlepreparationisrequiredtoeitherupgradeexistingIPv4nodestoIPv6ordeploynewIPv6nodes.

TheinherentlackofdependenciesbetweenIPv4andIPv6hosts,IPv4routinginfrastructure,andIPv6routinginfrastructurerequiresanumberofmechanismsthatallowseamlesscoexistence.

Note

Exceptwherenoted,thesupportforcoexistenceandmigrationisthesamefortheIPv6protocolfortheWindows.NETServer2003familyandtheIPv6protocolforWindowsXPorWindowsXPwithServicePack1（SP1）.

NodeTypes

RFC2893definesthefollowingnodetypes:

∙IPv4-onlynode

AnodethatimplementsonlyIPv4（andhasonlyIPv4addresses）.ThisnodedoesnotsupportIPv6.MosthostsandroutersinstalledtodayareIPv4-onlynodes.

∙IPv6-onlynode

AnodethatimplementsonlyIPv6（andhasonlyIPv6addresses）.ThisnodeisonlyabletocommunicatewithIPv6nodesandapplications.Thistypeofnodeisnotcommontoday,butmaybecomemoreprevalentassmallerdevicessuchascellularphonesandhandheldcomputingdevicesincludeIPv6stacks.

∙IPv6/IPv4node

AnodethathasbothIPv4andIPv6implemented.ThisnodeisIPv6-enabledifithasanIPv6interfaceconfigured.

∙IPv4node

AnodethatimplementsIPv4（itcansendandreceiveIPv4packets）.AnIPv4nodecanbeanIPv4-onlynodeoranIPv6/IPv4node.

∙IPv6node

AnodethatimplementsIPv6（itcansendandreceiveIPv6packets）.AnIPv6nodecanbeanIPv6-onlynodeoranIPv6/IPv4node.

Forcoexistencetooccur,thelargestnumberofnodes（IPv4orIPv6nodes）cancommunicateusinganIPv4infrastructure,anIPv6infrastructure,oraninfrastructurethatisacombinationofIPv4andIPv6.TruemigrationisachievedwhenallIPv4nodesareconvertedtoIPv6-onlynodes.However,fortheforeseeablefuture,practicalmigrationisachievedwhenasmanyIPv4-onlynodesaspossibleareconvertedtoIPv6/IPv4nodes.IPv4-onlynodescancommunicatewithIPv6-onlynodesonlywhenusinganIPv4-to-IPv6proxyortranslationgateway.

CompatibilityAddresses

ThefollowingaddressesaredefinedtoaidinthecoexistenceofIPv4andIPv6nodes:

∙IPv4-compatibleaddresses

TheIPv4-compatibleaddress,0:

0:

0:

0:

0:

0:

w.x.y.zor:

:

w.x.y.z（wherew.x.y.zisthedotteddecimalrepresentationofapublicIPv4address）,isusedbyIPv6/IPv4nodesthatarecommunicatingwithIPv6overanIPv4infrastructure.WhentheIPv4-compatibleaddressisusedasanIPv6destination,theIPv6trafficisautomaticallyencapsulatedwithanIPv4headerandsenttothedestinationusingtheIPv4infrastructure.

∙IPv4-mappedaddresses

TheIPv4-mappedaddress,0:

0:

0:

0:

0:

FFFF:

w.x.y.zor:

:

FFFF:

w.x.y.z,isusedtorepresentanIPv4-onlynodetoanIPv6node.Itisusedonlyforinternalrepresentation.TheIPv4-mappedaddressisneverusedasasourceordestinationaddressofanIPv6packet.TheIPv6protocolfortheWindows.NETServer2003familydoesnotsupporttheuseofIPv4-mappedaddresses.TheIPv4-mappedaddressisusedbysomeIPv6implementationswhenactingasatranslatorbetweenIPv4-onlyandIPv6-onlynodes.

∙6over4addresses

6over4addressesarecomprisedofavalid64-bitunicastaddressprefixandtheinterfaceidentifier:

:

WWXX:

YYZZ（whereWWXX:

YYZZisthecolon-hexadecimalrepresentationofw.x.y.z,aunicastIPv4addressassignedtoaninterface）.Anexampleofalink-local6over4addressbasedontheIPv4addressof131.107.4.92isFE80:

:

836B:

45C.6over4addressesareusedtorepresentahostwhenusingtheautomatictunnelingmechanismdefinedinRFC2529.Formoreinformation,seeAppendixBinthisarticle.

∙6to4addresses

6to4addressesarebasedontheprefix2002:

WWXX:

YYZZ:

:

/48（whereWWXX:

YYZZisthecolon-hexadecimalrepresentationofw.x.y.z,apublicIPv4addressassignedtoaninterface）.6to4addressesareusedtorepresentasitewhenusingtheautomatictunnelingmechanismdefinedinRFC3056,alsoknownas6to4.Formoreinformation,see“6to4”inthisarticle.

∙ISATAPaddresses

Intra-siteAutomaticTunnelAddressingProtocol（ISATAP）addressesarecomposedofavalid64-bitunicastaddressprefixandtheinterfaceidentifier:

:

0:

5EFE:

w.x.y.z（wherew.x.y.zisaunicastIPv4addressassignedtoaninterface）.Anexampleofalink-localISATAPaddressisFE80:

:

5EFE:

131.107.4.92.ISATAPaddressesareusedtorepresentahostwhenusingtheautomatictunnelingmechanismdefinedintheInternetdrafttitled"Intra-SiteAutomaticTunnelAddressingProtocol（ISATAP）"（draft-ietf-ngtrans-isatap-0x.txt）.Formoreinformation,see“ISATAP”inthisarticle.

CoexistenceMechanisms

TocoexistwithanIPv4infrastructureandtoprovideeventualmigrationtoanIPv6-onlyinfrastructure,thefollowingmechanismsareused:

∙DualIPlayer

∙IPv6overIPv4tunneling

∙DNSinfrastructure

DualIPLayer

ThedualIPlayerisanimplementationoftheTCP/IPsuiteofprotocolsthatincludesbothanIPv4InternetlayerandanIPv6Internetlayer.ThisisthemechanismusedbyIPv6/IPv4nodessotha