MTU is 9196 (9170 is available to IP)

[kuriakose1]

When I did this command  on a ASR 9904 , p#sh ipv4 interface bundle-ether 11, got below output

MTU is 9196 (9170 is available to IP)

trying to figure out , how come this is possible to work. I believe  there has to be min (40 ) difference between IP MPTU and MTU . IP header =20, TCP header 20 =40 .

second question is:  When one of the interface from this ASR  get connect to a switch , what should be the MTU setting on the other end device ? 9196 9170 or some thing else,  will there be   performance issue i use different setting on th eother end device . if then why ?

[rais]

9170 available to IP means that full IP packet [including its overhead etc.] could be 9170 octets. The rest 9196-9170=26 is to be used by layers below. Ethernet uses 18 octets and the remaining 8 are preamble bits for a total of 26.

HTH.

[MHM Cisco World]

how the router calculate the 9170 is hard since even small tag can effect bytes calculation. 
but for other side what you must config sure it 9196  not 9170.