option 212 for 6RD

[Jean-Francois.TremblayING at videotron.com]

> I would like to know other peoples experiences with "just turning on" 
IPv6 
> by means of 6RD via DHCP option 212.

By "turning on", do you mean 
a) send it to all clients or 
b) send it to all clients who request it (option 212 in request)?

We've been doing b) at Videotron since June 2011. The option content is 
different per-user since we use multi-domain 6RD (one domain per ARIN 
prefix). 

So far we've seen very few issues with this deployment, with a number of 
users in the five digits. A few complaints from Linux and OpenWRT users 
asking us to publish our domains (we don't), but someone managed 
to put together a 6rd dhcp script that works 
(http://www.beloin.net/doc/videotron_6rd.html). 

The only recent issue we hit what with a specific brand of home routers
that auto-detects native IPv6 vs 6RD. In some cases, they forget to lower 
the IPv6 MTU in RAs to 1480. This issue will be fixed in their future 
release. Leaving the LAN MTU at 1500 with 6RD causes PMTUD problems 
with many content providers, especially YouTube, who doesn't seem to 
process ICMP too bigs properly. 

> Any insights and thougts appreciated!

I'd say you're safe enabling it, but be aware that you may get a few
support call from people having "YouTube problems" on the short term. 

/JF