6to4 connectivity test

[james woodyatt <jhw@apple.com>]

On Feb 1, 2008, at 10:35, Christian Huitema wrote:
> OK. So, what would we changed in 6to4 if we optimized for host- 
> based or CPE-based deployment? Do we trust that we will get enough  
> 6to4 gateways deployed to sustain growth, or do we need to add a  
> "gateway discovery service" similar to the Teredo spec?

A standard method of discovering whether the 6to4 relay at the  
anycast address is functioning properly would be a fine idea.

At the moment, some very large ISP's are now hindering transition to  
IPv6 by forwarding 6to4 packets to relays that are black-holing them  
rather than forwarding them.  (This was not the case when AirPort  
Extreme shipped.)  These ISP's have no plans to deploy 6to4 relays in  
their own IPv6-capable networks, nor do they have any plan to forward  
6to4 traffic to relays that will carry it for them.  This is making  
some large content providers *remove* their AAAA records when they  
discover that customers behind 6to4 routers, e.g. AirPort Extreme,  
are unable to receive service because their applications do not fall  
back to IPv4 when IPv6 connectivity is broken.

Search the Apple discussion boards for IPv6, and you will see that a  
lot of people are turning off IPv6 entirely on their computers to  
work around the connectivity issues involved here.


--
james woodyatt <jhw@apple.com>
member of technical staff, communications engineering