[c-nsp] 3550 High CPU - nothing in proc cpu

[Harald Firing Karlsen]

Hector Herrera wrote:
> During a high network usage event, the cpu load increased to 90%
> sustained, while a 'show processes cpu' did not reveal any culprits.
> I suspected IP Input may be consuming a high amount of cpu, but it was
> only at 2.7%
>
> The 3550 is working as a L3 router with two static entries for the
> default gw (for load balancing on our uplink).
>
> Traffic levels at the time of the high cpu usage were ~120Mbps.
>
> I also examined broadcast packet counts and traffic destined for the
> router itself.  They also did not reveal anything out of the ordinary.
>
> Do you have any suggestions on what I should be looking at to
> determine the source of the high cpu usage?
>   
What did the topmost line in the "show processes cpu" say? At the five 
second average you got two values; one is for interrupts and the other 
is for process cpu usage. My guess is you was seing a lot of interrupts 
which means traffic was punted to the CPU. Take a look at some of the 
other threads on c-nsp to find out what kind of traffic was being punted 
("show cef not-cef-switched" is a good start).

Hope this was helpfull

-- 
Harald Firing Karlsen