You may be able to capture the broken frames on the ASR9k, which
should help you narrow down where the problem happens.

https://gist.github.com/ytti/436fe3b602a963acf21e

On Sat, 23 Mar 2019 at 20:26, Curtis Piehler <[email protected]> wrote:
>
> The rate at which these CRCs come in so quick that it is difficult to clear 
> both the router and switch counters at the same time to get an exact match.  
> However, bear in mind the human delay is 1-2 seconds between hitting "enter" 
> to clear the counters on the devices, yes they do appear to match on both 
> sides.  The frequency of these Input MIB CRC is quite literally 5 every 
> second. It is a consistent increase every second.  Over a couple minute time 
> frame I already have 500+ CRC errors accrued.
>
> On Sat, Mar 23, 2019 at 1:29 PM Saku Ytti <[email protected]> wrote:
>>
>> Hey Curtis,
>>
>> > One of the Bundle members appears to be accruing active Input MIB CRC which
>> > then reflects on standard Input CRC errors.  These accruing errors do not
>> > seem to be service impacting as there is 500M-1G of traffic on the physical
>> >     Input error CRC             = 2635490
>> >     Input MIB CRC               = 2635490
>> > The Nexus 5k side just indicates accruing "Output Errors" under the
>> > interface with no further details.  The actual counter error output of the
>> > interface sees nothing.
>>
>> Do the counts match? ASR9k CRC input and Nexus 5k output errors?
>>
>> I believe 5596 supports cut-through switching so CRC is detected after
>> frame has been sent. So possibly:
>>
>> A => 5596 => ASR9k
>>
>> A>5596 transit is breaking your frames or broken memory in 5596 and
>> ASR9k is dropping them on ingress due to FCS/CRC check.
>>
>> And I'd be surprised if it is not service affecting, what ever frames
>> those are, they are not delivered. Voice with modern codecs is very
>> insensitive to quality, tolerates massive packet losses and jitter.
>> Couple CRC errors here and there wouldn't matter at all.
>>
>> --
>>   ++ytti



-- 
  ++ytti
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