[c-nsp] 6509 w/SUP720-3BXL and high CPU load

[Lee Starnes]

Hello Nathan,

So what I find interesting is that a process that shows 13% CPU is actually
using 60% CPU. Using a "show proc cpu sorted 5sec" I was able to see that
SNMP was coming up with 13 and 15% CPU on the process when this is going on
(all the time), but on the other switches, that would only appear once for
about 5 seconds and then go away. Leaving a brief. spike and then drop to
normal on the CPU load. So started to investigate and the machine that was
hitting it with 25K packets each time was our machine that runs MRTG. A
little research into that and found that the config for this switch was old
and had some interfaces that were not in the chassis anymore and missing
some that were new in the chassis. Rebuilt that and the issue resolved.
Packets went from 25K to 746 and completed its poll of the interfaces
within 5-7 seconds.

Thanks for the response.

-Lee


On Thu, Mar 19, 2020 at 11:39 AM Nathan Lannine <nathan.lannine at gmail.com>
wrote:

>
>> First thing I'd try is to capture punted packets.
>>
>> Per the document the you linked, I've found netdr or cpu span to be
> helpful in this regard.  That community post pretty much mirrors an
> official doc on the same topic.  I think the last time I saw something like
> this it was some kind of link local IPv6 stuff.  Either way, it would be
> nice to know what you find the problem to be.
>
> Thank you,
> Nathan
>