option 212 for 6RD

Trevor Warwick (twarwick) twarwick at cisco.com
Thu Jan 24 15:58:31 CET 2013

In IOS 15.2(4)M and later, the "ip tcp adjust-mss" command will also cause the same configured value to be used for adjusting IPv6 TCP connections. 

There's currently no modification applied to take account of the different IPv4/IPv6 network layer header sizes.

-----Original Message-----
From: ipv6-ops-bounces+twarwick=cisco.com at lists.cluenet.de [mailto:ipv6-ops-bounces+twarwick=cisco.com at lists.cluenet.de] On Behalf Of Ivan Pepelnjak
Sent: 19 January 2013 15:16
To: 'Tore Anderson'
Cc: 'Daniel Roesen'; ipv6-ops at lists.cluenet.de
Subject: RE: option 212 for 6RD

Oh, BTW, there's no "ipv6 tcp adjust-mss" command in Cisco IOS. Problem "solved" ;)

> That said, if you read between the lines of the original question, it
> suggests:  I have no control over my subscribers' CPEs . Which makes 
> the LAN MTU solution extremely impractical to deploy. In that 
> situation, the solution that is the most likely to yield the best 
> effect, would be to enable TCP MSS clamping for 6RD traffic on the BR 
> (or somewhere else in the ISP's core network). IMHO.
> --
> Tore Anderson

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