[c-nsp] 3560 cpu load question

Peter Rathlev peter at rathlev.dk
Thu May 21 19:09:48 EDT 2009


On Thu, 2009-05-21 at 15:18 -0700, Cord MacLeod wrote:
> My graphs show cpu spikes up to 20% every now and again, but the  
> following command shows 100% spikes.  Question being is this normal  
> behavior, how would I track the cause (assuming my traffic is  
> relatively stable throughout the day) and should I be worried this may  
> be impacting traffic?

Is it normal: Probably not. But that depends on what the device is
doing.

Will there be traffic impact: Probably not. Traffic forwarding is not
CPU bound. Traffic forwarding of course relies on the CPU executing
certain algorithms depending of protocols in use. (STP, IGP, BGP etc.)
which it might not be able to do in a timely fashion if busy doing
something else.

Tracking the cause: Start looking at "show proc cpu sorted" and see what
processes take up most CPU when the spike is occuring.

What is the device configured to do, apart from forwarding traffic?

Regards,
Peter




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