NAT64/464XLAT exists and it works. It can't really be "part of the protocol" because it depends on stateful IPv4 devices in the middle of the network. Ultimat

NAT64/464XLAT exists and it works. It can't really be "part of the protocol" because it depends on stateful IPv4 devices in the middle of the network. Ultimately it's up to the ISPs which IPv4-as-a-service mechanism they want to deploy.