[AusNOG] GRE Tunnel MTU suggestions

[Joseph Goldman]

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