Has anything changed since MTU Behavior on Cisco IOS XR and Cisco IOS Routers was written?
# no subinterfaces
RP/0/RP0/CPU0:A9K#show interfaces Te0/2/0/3/0 | i MTU
MTU 1514 bytes, BW 10000000 Kbit (Max: 10000000 Kbit)
RP/0/RP0/CPU0:A9K#show controllers Te0/2/0/3/0 | i M.U
MTU: 1514
MRU: 1514
# subinterface with 1 dot1q tag
RP/0/RP0/CPU0:A9K#show interfaces Te0/1/0/3/6 | i MTU
MTU 1514 bytes, BW 10000000 Kbit (Max: 10000000 Kbit)
RP/0/RP0/CPU0:A9K#show controllers Te0/1/0/3/6 | i M.U
MTU: 1518
MRU: 1518
On 5.3.4 it doesn't look like `show controller` MTU/MRU accounts for CRC.