setting MTU on IPsec to enable video calls

[angelito_mas]

Hi guys!

I configured a simple L2L IPSec tunnel between 2 Cisco 8300.

I'd like to make a video call (using webex) between 2 hosts over the tunnel. Should I change the MTU settings on the tunnel interface? Idk, maybe setting mtu 1400 and tcp-mss adjust 1366?

Thanks for your help!

[MHM Cisco World]

why you want to do that, 
the Video or VoIP use small frame size.
and MTU 1400 as I see it OK (small but it OK).
so you dont need to change anything
MHM

[angelito_mas]

What do you suggest?
My customer told me that he tried to make a videocall via webex but with no success. He wants to "crypt" the call......

[Ruben Cocheno]

@angelito_mas 

I'm assuming that you have webex on-premises but without having more details becomes a bit difficult to give you more direction. Having lower MTU 1400 on the egress and using tcp-mss shouldn't break it.

[angelito_mas · Accepted solution]

Guys, I found the solution.. MTU 1406 and TCP MSS Adjust 1338

the problem most affecting was on the data transfer not on voip communication...

[Ruben Cocheno]

@angelito_mas 

Glad that you were able to find the sweet spot