[namibj]

They are, though? It's how dual stack sockets work, they just map IPv4 into the part of IPv6 where they belong.

[paperplatter]

But then you're still using ipv4.

[namibj]

You can; but I'd not be surprised if there are commercial setups that use IPv6 packets for everything, including situations with IPv4 addresses. I think it would allow getting rid of most of the ethernet header overhead, by basically just talking bare IPv6 packets.