ignored and overrun counter differences

smcclenaghan

I've looked online and I can't find a clear difference between these two counters as show via a 'sho interface fa0/1' command:

Received 7066 broadcasts (4246 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 4246 multicast, 0 pause input
0 input packets with dribble condition detected
50969 packets output, 3804110 bytes, 0 underruns

Does someone have a good answer as to what would cause one of these counters to increment but not the other? As best as I can tell, both seem to be incremented whenever the hardware buffer is full, however there are examples online of the ignored counter increasing when the overrun doesn't (just, no clear explanation as to why).

Thanks.

NetworkVeteran

Cisco explains the "show interface" output here:

Troubleshooting Switch Port and Interface Problems - Cisco Systems

Be wary of getting lost in minutae. If you have the right book (Odom or Lammle), and it doesn't explain something, it's probably because it's relatively unimportant for you to know at this point. You will never know everything.

smcclenaghan

Thanks NetworkVeteran. I was looking at that also (very good link by the way) but it still doesn't really clarify the difference between overrun and ignored, attributing both to the inability to use a hardware buffer.

And you're right about the minutae and that's good advice. This was really just a curiosity. Thanks for the response.