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Pinning down cause of high CPU on core switch.

swaize
Frequent Advisor

Pinning down cause of high CPU on core switch.

We have a 5412 that is regularly hitting high CPU levels. Have seen it go to 100% before.

There is nothing in the switch event log that seems to coincide with the times that this happening.

Does anyone have any tips or methods to try and pin down the cause?

Thanks.
6 REPLIES
cenk sasmaztin
Honored Contributor

Re: Pinning down cause of high CPU on core switch.

enable spanning tree on your core switch

config)#spanning-tree

your switch between have many active connection

enable spanning-tree after

show spanning-tree command

you can see blocked state port
cenk

swaize
Frequent Advisor

Re: Pinning down cause of high CPU on core switch.

Thanks for the reply, Cenk.

I did as you said, as we already have STP enabled.

I can't see that any ports have been blocked. I have attached the output from 'sh spanning-tree'

However, looking at the switch log, I can see one port is repeatably being blocked by STP:

=
I 02/22/11 09:41:02 00077 ports: port H18 is now off-line
I 02/22/11 09:41:04 00435 ports: port H18 is Blocked by STP
I 02/22/11 09:41:04 00076 ports: port H18 is now on-line

Do you think this is the cause?

Thanks.
cenk sasmaztin
Honored Contributor

Re: Pinning down cause of high CPU on core switch.

can you send me sh tech print
cenk

swaize
Frequent Advisor

Re: Pinning down cause of high CPU on core switch.

Show Tech attached
cenk sasmaztin
Honored Contributor

Re: Pinning down cause of high CPU on core switch.

I can't see any unusual data your show tech


may be software bug

can you upgrade switch K15020005
cenk

swaize
Frequent Advisor

Re: Pinning down cause of high CPU on core switch.

I checked the release notes. There is a fix for high cpu under certain circumstances, when the switch receives multicasts.

Hopefully this will fix it for us!

Will update here once we've done the upgrade.