[c-nsp] cisco 6500 sup2 high load

Adam KOSA adamk at sch.bme.hu
Sat Oct 2 18:52:07 EDT 2004

Hi everyone

I'm asking for your help since i have no experience in finding out the
cause of high loads.

a cisco 6506 with sup2 is handling a giga ethernet line, and also about 50
smaller switches (all cisco).

None of the lines are used above 70%, especially the gbit ethernet is
never used over 40-50%.

Today i recognised that normal ping times (<1.5 ms) are grown even to 8000
ms or above - only for a couple of minutes.  The ping time suddenly clibs
to 6000 ms, slowly increases to around 7000 ms, than crawling back to
700-900 ms.  After this, it jumps again up to 5000-7000 ms.  This whole
process takes about 4-5 minutes.  Than, like everything is normal, it
falls back to 0.5-1 ms.

the 6500 show proc cpu is normal (4%), i never reach its interface.  the
msfc2 is routing, the outside interface gives the pings above, i never
reach the inside.  the msfc's show proc cpu is the following:

Akiron#sh processes cpu
CPU utilization for five seconds: 5%/4%; one minute: 46%; five minutes:

That 75% bothers me, but i don't know the reason.  This never happened
before.  The only process which has >1% cpu usage is:

PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
41     1018884   5980897        170  2.12%  4.78%  6.92%   0 IP Input

which makes sense.  I still don't know what to do not to let this happen
again.  This incident occured several times during the past 48 hours (3-4
times).  During this mrtg shoved minimal traffic on the gbit link.

Sorry for this long description, i just wanted to make sure i describe the
problem clearly, and english is not my native.

thanks for any help

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