Catalyst 6500 High CPU with "show run" or "wr mem" command.

Unanswered Question
Jun 1st, 2009

I have problem with Catalyst 6500 switch. When I give the command "show running-config" or "wr mem" CPU utilization increases to 80% and then back to 1%.

I appreciate any help.

I have this problem too.
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Giuseppe Larosa Mon, 06/01/2009 - 10:14

Hello Jose,

you may be hitting a SW bug.

To get better help you should provide more details:

supervisor model

number of supervisors in chassis (the issue could be in communication betweeen sups)

Native IOS/ Hybrid mode

IOS image name for native

Catos image name and msfc ios image name if Hybrid

you can attach a file with your sh ver

Hope to help


Joseph W. Doherty Mon, 06/01/2009 - 11:22

If the config rather large? It might be normal. Just tried a show run on a 6500 with sup720, and saw CPU jump from 1% to about 45% for a few seconds. See CPU history text file attachment.

cisco_lad2004 Mon, 06/01/2009 - 12:57

It is normal to see a spike when saving or viewing running config (starting config should not increase CPU).

I will clarify that it is only normal if it is a short spike and no traffic is dropped. if packets are dropping or device reloads then you are hitting a bug as Giuseppe mentioned.



jrmalmeida Tue, 06/02/2009 - 07:21

Hi all!

Considering that this is normal, which occurs in the IOS to have such high cpu at the command "show running-config" and "wr mem"?

I put a setting similar to the 6500 in a 7200, I gave the command "show running-config", and rose only 20% use of cpu. Unlike the 6500 which went up 60, 70%. Here attachd file "show_proc_his".

Thank you.

Joseph W. Doherty Tue, 06/02/2009 - 09:17

At first glance, that seems surprising, but while doing some "lab" network testing, discovered 2801s seem to have a more powerful CPU than 3750.

I think what the deal is, L3 switches rely on their ASICs to accelerate "normal" features. "Unusual" things, as perhaps parsing a config file, require main CPU intervention and the main CPU on many L3 switches might be weak in comparison to some software based routers.

cisco_lad2004 Tue, 06/02/2009 - 09:30

I have same issue with 4510 SUP V-10G, after a long debate with Cisco I had a confirmation that CPU spikes when saving or viewing running configs are normal.

I validate the above on a totally different platform 7609 and I saw same thing.




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