Change MTU for just one Site-to-Site VPN between ASAs?

Posted on 2012-09-18
Medium Priority
Last Modified: 2012-10-03
Hi -
I'm setting up a Site-to-Site Cisco VPN between ASA 5510s. I'm being told by the remote site engineer to set the maximum MTU at 1362.
Is it possible to set the MTU for one specific site-to-site VPN on my ASA 5510 Security Plus to MTU 1362? I see my interfeces are all set at 1500.

I came across sysopt connection tcpmss "MTU size" but this appears to be for all traffic going through the ASA.
If not, would you recommend I setup a subinterface on my inside network router and a subinterface on the ASA with an MTU of 1362 to get around this issue? Then use this subinterface for traffic from my inside network to transverse through prior to hitting the VPN.
Thank you.
Question by:First Last
LVL 35

Accepted Solution

Ernie Beek earned 2000 total points
ID: 38410909
Afaik you can only set the MTU on a physical interface. You might want to try setting it anyway. Chances are that the rest will still work.
LVL 15

Expert Comment

by:Robert Sutton Jr
ID: 38421961
Ernie is correct. MTU can only be set on the physical intf's and not sub's. A subinterface will always take the MTU from the physical one.

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