Zte ZXR10 ZSR V2 - Figure 16-5 Principles of a 4 In6 Tunnel

ZXR10ZSRV2CongurationGuide(IPv6)
oftwoIPv6networksthroughanIPv4networkandthuseliminatesthelimitationsof
automaticIPv4-compatibleIPv6tunnelsinpracticaluse.
The6to4tunnelinvolvesatunnelencapsulationanddecapsulationprocess.
lEncapsulation:IftheegressinterfaceofthesentIPv6packetisatunnelinterface,
thehostrstdeterminesthetunneltype.Ifthetunnelisa6to4tunnel,thehost
implementsIPv4headerencapsulation.Duringtheencapsulation,thesourceaddress
isuser-conguredwhereasthedestinationaddressisobtainedfromthedestination
addressofthepacket.TheencapsulatedpacketisthensentaccordingtotheIPv4
packetsendingprocess.
lDecapsulation:IftheprotocolnumberintheIPv4headerofthereceivedIPv4packetis
41,thehostproceedstothe6to4decapsulationprocessandsearchesforthematched
tunnelnumberaccordingtothesourceaddressofthepacket.Ifthetunnelnumber
isfound,thehostremovestheIPv4headeraddedduringtunnelencapsulationand
deliverstheremainingIPv6packettotheIPv6packetreceivingprocessforfurther
handling.
4in6Tunnel
Figure16-5showstheoperatingprinciplesofa4in6tunnel.
Figure16-5Principlesofa4in6Tunnel
The4in6tunnelinvolvesatunnelencapsulationanddecapsulationprocess.
lEncapsulation:Ifthepacketegressinterfaceisatunnelinterfacewhenahostor
routersendsanIPv4ow,thehostorrouterrstdeterminesthetunneltype.Ifthe
tunnelisa4in6tunnel,thehostorroutersendsthepackettotheIPv6protocolstack
forIPv6headerencapsulation.Duringtheencapsulation,thesourceanddestination
addressesoftheIPv6headeraremanuallyconguredbytheuser.Theencapsulated
packetisthensentaccordingtotheIPv6packetsendingprocess.
lDecapsulation:Theprocessisjustcontrarytotheencapsulationprocess.Ifthe
protocolnumberintheIPv6headerofthereceivedIPv6packetis4,thehostorrouter
proceedstothe4in6decapsulationprocess,andsearchesforthematchedtunnel
numberaccordingtothesourceanddestinationaddressesofthepacket.Ifthetunnel
numberisfound,thehostorrouterremovestheIPv6headeraddedduringtunnel
encapsulationanddeliverstheremainingIPv4packettotheIPv4packetreceiving
processforfurtherhandling.
16-4
SJ-20140504150128-018|2014-05-10(R1.0)ZTEProprietaryandCondential