Re: implications of 6to4 for v6coex - 6to4 and 6rd properties

[Rémi Denis-Courmont <rdenis@simphalempin.com>]

	Hello,

Le lundi 6 octobre 2008 17:08:01 Rémi Després, vous avez écrit :
> > On 3/10/2008, at 2:26 AM, Erik Kline wrote:
> >> Well it seems to be working well enough (or popular enough, anyway).
> >> What if I said that 69.8% of IPv6-enabled users who visit google.com
> >> have 6to4?
>
> As we discussed in Montreal, this proves that there is, for v6 packets
> that have the prefix of 6to4 (2002::/16), a path from ipv6.google.com
> servers to the IPv4 Internet.
>
> But it doesn't prove that clients of IPv6.Google, if they try to reach
> another IPv6 server, will always have a 6to4 return path for their
> packets. similarly, they may not be reachable, as servers, from any
> client having native IPv6 connectivity.

Last time I checked, Google used HTTP, HTTP ran on TCP, and TCP checked 
return-routability in the three-way handshake.

I don't disagree that the lack of built-in return-routability in 6to4 _is_ a 
problem in certain circumstances. Namely, when there is an IPv4 firewall on 
the proto-41 path. But lets not pretend it is worse than it really is.

-- 
Rémi Denis-Courmont
http://www.remlab.net/