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Community Member

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

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.

6 REPLIES
Hall of Fame Super Silver

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

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

Giuseppe

Super Bronze

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

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.

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

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.

HTH

Sam

Community Member

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

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.

Super Bronze

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

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.

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

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.

HTH

Sam

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