[AusNOG] GRE Tunnel MTU suggestions

[timothy b]

I'm fan of this article:

http://www.cisco.com/c/en/us/support/docs/ip/generic-routing-encapsulation-gre/25885-pmtud-ipfrag.html

It talks about MSS and MTU preferred settings for GRE and GRE+IPSec.

Timothy



> Date: Tue, 1 Jul 2014 16:56:28 +1000
> From: joe at apcs.com.au
> To: AusNOG at lists.ausnog.net
> Subject: [AusNOG] GRE Tunnel MTU suggestions
> 
> Hi List,
> 
>   Setting up a GRE tunnel for a customer and would appreciate a bit of 
> input.
> 
>   I can successfully push 1500byte packets with df-bit set between the 2 
> endpoints (1501 fails), so it is a full mtu of 1500.
> 
>   I'd like to set an ip mtu on the tunnel and an ip tcp adjust-mss. 
> Obviously I can't use 1500 as we have to account for GRE, so I'd like to 
> know the best suggestions for an MTU, and if its worth setting the MSS 
> at the same size as the MTU or if I should lower the MSS adjust and if 
> so by how much?
> 
>   Note: IPSec is not used on top, just GRE.
> 
> Thanks,
> Joe
> _______________________________________________
> AusNOG mailing list
> AusNOG at lists.ausnog.net
> http://lists.ausnog.net/mailman/listinfo/ausnog
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ausnog.net/pipermail/ausnog/attachments/20140701/8bececce/attachment.html>