And generating stinkin' ICMPv6 too big messages ends up being perhaps the most 
significant scaling factor of a 6rd BR deployment...

- Mark

On Jan 7, 2014, at 3:59 PM, Simon Perreault wrote:

> Le 2014-01-07 08:46, [email protected] a écrit :
>> In the list of "tricks", you might want to add:
>> * Slightly raise the ICMPv6 rate-limit values for your 6RD BR (we do 50/20)
> 
> Yeah, this is really problematic. When IPv6 packets arrive at the BR from the 
> Internet, the BR needs to send too bigs so that the remote node can do PMTUD 
> correctly and figure out the 1480 MTU. If you rate-limit those too bigs, you 
> create black holes. You need to expect a lot of too bigs to be generated by 
> the BR in regular operation, even if the CPE uses tricks such as TCP MSS 
> adjustment or advertising 1480 in RA, because we still need to live with 
> non-TCP traffic and nodes that don't understand the MTU param in RAs.
> 
> Simon
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