IPv6 主机和软件路由器转换机制(11)

IPv4-compatibleaddressformatwithdescriptionofautomatic
tunneling.
-Changedtheterm"IPv6-onlyaddress"to"IPv6-nativeaddress"per
currentusage.
-UpdatedtoalgorithmfordeterminingtunnelMTUtoreflectthe
changeintheIPv6minimumMTUfrom576to1280bytes[4].
-Deletedthedefinitionfortheterm"IPv6-in-IPv4encapsulation."
Ithasnotbeenwidelyused.
-RevisedIPv4-compatibleaddressconfigurationsection(5.2)to
recognizemultipleinterfaces.
AddeddiscussionofsourceaddressselectionwhenusingIPv4-
compatibleaddresses.
-Addedsectiononthecombinationofthedefaultconfigured
tunnelingtechniquewithhostsusingautomatictunneling.
-AddedprohibitionagainstautomatictunnelingtoIPv4broadcastor
multicastdestinations.
-Clarifiedthatconfiguredtunnelscanbeunidirectionalor
bidirectional.
-Addeddescriptionofbidirectionalvirtuallinksasanothertype
oftunnels.NodesMUSTrespondtoNUDprobesonsuchlinksand
SHOULDsendNUDprobes.
-Addedreferenceto[16]specificationasanalternativefor
tunnelingoveramulticastcapableIPv4cloud.
-ClarifiedthatIPv4-compatibleaddressesareassignedexclusively
tonodesthatsupportautomatictunnelsi.e.nodesthatcan
receivesuchpackets.
-Addedtextaboutformationoflink-localaddressesanduseof
NeighborDiscoveryontunnels.
-Addedrestrictionthatdecapsulatedpacketsnotbeforwarded
unlessthesourceaddressisacceptabletothedecapsulating
router.
-ClarifiedthatdecapsulatingnodesMUSTbecapableofreassembling
anIPv4packetthatis1300bytes(1280bytesplusIPv4header).
-ClarifiedthatwhenusingadefaulttunneltoanIPv4"anycast
address"thenetworkmusteitherhaveanIPv4MTUofleast1300
bytes(toavoidfragmentationofminimumsizeIPv6packets)orbe
configuredtoavoidfrequentchangestoIPv4routingtothe
"anycastaddress"(toavoiddifferentIPv4fragmentsarrivingat
differenttunnelendpoints).
-UsingA6/AAAAinsteadofAAAAtoreferenceIPv6addressrecordsin
theDNS.
-SpecifiedwhentoputIPv6addressesintheDNS.
-AddedreferencetothetunnelmibforTTLspecificationforthe
tunnels.
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