Symptom
9800 would show up giants on interface increase at the same time as input error increase, showing the very exact number of input errors equals the giants, this is giants = input errors
Verified with a packet capture that the interface is not receiving packets bigger than 1500 MTU.
The counter on individual interface(s) might increase, but it does not increase on port channel
In this case po1 is built by tengig0/0/0 and tengig0/0/1 but only tengig0/0/0 counter is increasing. Reliability on interface would also be reduced on interface showing the error.
TenGigabitEthernet0/0/0 is up, line protocol is up
reliability 171/255, txload 1/255, rxload 2/255
0 runts, XXXXXX giants, 0 throttles
XXXXXX input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
TenGigabitEthernet0/0/1 is up, line protocol is up
reliability 255/255, txload 2/255, rxload 1/255
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
Port-channel1 is up, line protocol is up
reliability 255/255, txload 2/255, rxload 2/255
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
Conditions
Confirmed MTU matches on both sides WLC and neighbor switch
Confirmed with a packet capture that interface is not receiving jumbo frames bigger than MTU configured
Workaround
At this moment there is no workaround
