On 28 jan 2008, at 4:54, Brian E Carpenter wrote:
I think there are two other options for the relay.
3) Forward the packet to your local friendly NAT-PT box. This is really a version of #2 - in fact it's the only case I can think of where #2 would be useful. Of course, most people don't have a local friendly NAT-PT.
Also, the use cases for NAT-PT and 6to4 are highly orthogonal: one supports reaching IPv4 for hosts with only IPv6 connectivity, the other supports reaching IPv6 for hosts with only IPv6 connectivity. So I guess NAT-PT and 6to4 together would be useful for hosts without _any_ connectivity?
A point about Windows XP: the IPv4 and IPv6 stacks are separate. So XP can't generate IPv4 packets when applications use the IPv6 socket calls. This is of course highly suboptimal but this means that "simply generate IPv4 packets for ::ffff:x.x.x.x AAAA records" is not a natural choice.
I would suggest that implementations ignore AAAA records with IPv4- mapped addresses. There are probably some other address ranges that shouldn't show up in the DNS too (multicast?).