Should I set MSS on ALL network devices?

[MicJameson1]

Hello.

Because this enterprise extensively utilizes DMVPN encapsulation, I am concluding that it is best to set every network device (including layer 2 switches) to tcp mss= 1360 and MTU to 1400 (1400 ma not be exactly correct, but I am providing for extra room for options).

QUESTIONS:

1. Do you agree with changing every enterprise network device to MTU=1400?

2. If I set MTU to 1400, is it still helpful, or is it unnecessary, to set tcp mss to 1360?

Thank you.

[MHM Cisco World]

Can you share doc. About using 9000 frame in dmvpn.

I would like to see which router can hardware or software encrypt decrypt this huge packet.

[Joseph W. Doherty]

The underlying physical network was supporting jumbo 9k.  DMVPN packets didn't exceed 1500.

With 1500 on top of 9k, no fragmentation issues.  I.e. tunnel interface 1500, physical interface 9k.

Haven't ever tried DMVPN using 9k frames, but would expect it to work, but fragmentation issues possible.

[MHM Cisco World]

this other Cisco recommendation for set tcp mss and value need. 

for the SP as I know SP use Juniper or Cisco ASR9k, both as I know only use 1500 for WAN