Sabahattin Gucukoglu wrote:
If the application is going to use the AA record it has to have
an IPv4.1 stack. This causes it to emit IPv4 packets where the
first four bytes are sent in the IPv4 header and the remaining
four bytes are sent as a header option.
I think this should be possible, today, with 6to4 and NAT64/46 in
combination without any changes for the IPv4 host at all.
That's overkill.
Port restricted IP with the current TCP and UDP already achieved
"remaining *TWO* bytes are sent as a *PAYLOAD*".
Moreover, URLs can specify port numbers, which is why new DNS
records are not necessary.
6to4 has
the nice property that it is instantly compatible with every other
6to4 user, without any kind intermediate choke points
There is no room for 6.
(assuming that
the non-tunneled IPv4 Internet remains reasonably flat and NAT-free,
of course).
which means you *MUST* deploy port restricted IPv4, which means
there is no room for 6.
Sooner or later you're going to need IPv6 on the wire, though,
because your IPv4-only hosts aren't capable of encoding more bits
into their packets than they know how (address and port).
Sooner, port restricted IP with 2B port gives a lot more than enough
application address space.
Later, as a natural extension, we will use IPv4 with more than 2B
for port (I call it TUPLE (TCP and UDP with Port Length Enhancement)),
which means there is no room for 6.
Besides
that, quite a few apps do not fair well with NAT64,
That's partly why there is no room for 6.
Masataka Ohta
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