option 212 for 6RD

Mikael Abrahamsson swmike at swm.pp.se
Mon Jan 14 21:34:35 CET 2013

On Mon, 14 Jan 2013, Jean-Francois.TremblayING at videotron.com wrote:

> 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)?

Well, I was under the impression that one did a), but I would imagine 
doing b) would cause far less problems.

> 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.

It would really help if you could share more specifics on this.

> 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.

If I knew the ethernet address prefix of this vendor we could perhaps 
blacklist that one from getting the option 212 response?

Mikael Abrahamsson    email: swmike at swm.pp.se

More information about the ipv6-ops mailing list