I have just received high interface overrrun errors on one of the routers I manage at work. On checking the cisco site, I find that these errors could occur because the interface's capability has been exceeded and it cannot process the oncoming traffic, therefore it drops the packet.
However on checking the router I see that there is no interface load at all, nor is there any high cpu utilization on the router. (Its off business hours right now, so there is no one at the office).
#sh processes cpu
CPU utilization for five seconds: 0%/0%; one minute: 2%; five minutes: 4%.
reliability 135/255, txload 1/255, rxload 1/255
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
3639 input errors, 0 CRC, 0 frame, 3639 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
It says 3639 errors and 3639 overrun.. However there is no packets input at all! Does that mean that the overrun counter is incrementing even though there is no packets arriving at the interface?? Is this a software bug or is there a real issue at hand?
You may have to check the CPU history, with "sh proce cpu hist".
Do you have a spare interface to terminate the link ?
Wonder why the link is not 100% reliable (reliability 135/255) though
Also can you clear and check if this is frequent ?
This question has been answered in other threads.
From the evidence, I suspect a layer 1 problem.