Getting POS interface Overuns that Match input errors.

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Nov 28th, 2007

We have a cisco 7206VXR (NPE-G1) processor (revision B) with 229376K/32768K bytes of memory. running Version 12.3(15.4) with POS1/0 interface and am seeing 249 input errors, 0 CRC, 0 frame, 249 overrun, 0 ignored, 0 abort

Has anyone seen this before. Speculate on what might be causing it.

I have this problem too.
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s-moriarty Wed, 11/28/2007 - 17:08

Do you have some small spikes in traffic or bursty traffic of some kind over this link? Can you clear counters and see how long it takes for it to increment again? I believe that the input errors will represent an aggregrate of the other error counters so you should expect that input errors will match overruns because the interface buffer is being flooded.



d.worthley Wed, 11/28/2007 - 17:32

We cleared the counters during the heavy load period and we were receiving 1000s of overruns with the input errors.

s-moriarty Wed, 11/28/2007 - 18:25

Essentially the input errors will increment anytime you see any one of the CRC, frame, overruns, etc. increment. This does not have to happen in lock-step fashion as a single packet can trigger more than one counter, but will only put one tick against the Input Errors.

e.g. 3839 input errors, 1088 CRC, 2084 frame, 0 overrun, 0 ignored, 667 abort

Input errors are not a separate type of error but an aggregate counter. The overruns you have are caused by the router's inability to process the traffic fast enough that is coming in on the link.

Not knowing where this link is going is there anyway you can manage the inbound traffic or what is being sent to this interface? Something else to consider is moving to the NPE-G2 if that is feasible. This problem you are seeing is essentially a resource problem at the receiving end and short of managing the traffic and adding additional horsepower with the G2 you would need to take other measures to add additional bandwidth.


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