MTU handling in 6RD deployments

Mark Townsley mark at
Fri Jan 17 18:07:37 CET 2014

On Jan 17, 2014, at 5:14 PM, Mikael Abrahamsson wrote:

> On Fri, 17 Jan 2014, Templin, Fred L wrote:
>> Sorry, I was looking at the wrong section. I see now that Section 8 is talking about a method for a CE to send an ordinary data packet that loops back via the BR. That method is fine, but it is no more immune to someone abusing the mechanism than would be sending a ping (or some other NUD message). By using a ping, the BR can impose rate-limiting on its ping responses whereas with a looped-back data packet the BR really can't do rate limiting.
> You don't ping the BR, you ping yourself via the BR. The BR only forwards the packet.

Precisely. The whole idea is to stay on the data plane. 

- Mark

>> Also, Section 8 of RFC5969 only talks about the CE testing the forward
>> path to the BR. Unless the BR also tests the reverse path to the CE it
>> has no way of knowing whether the CE can accept large packets.
> You misread the text.
> -- 
> Mikael Abrahamsson    email: swmike at

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