3640 High CPU load

[ckuriyar74]

I have 3640 router configured for MLPPP with 2 E1 links.

Currently the IOS used is c3640-i-mz.122-40.bin

When the bandwidth usage is high the CPU load reach 100%

Any suggestion to upgrade the IOS to resolve the CPU load issue.

3640 has Flash:8MB and RAM:96MB

[spremkumar]

Hi

Are you only running multilink or having any other routing protocol or any QOS config done in the box ?

Also can you post the output of show process cpu & show version here ?

The outputs will help to find out the process which hogs up the cpu as well as to check the ios code for any bugs..

Do make sure that you have cef enabled on your box which will also solve the high cpu utilisation problem..

you can enable the same using ip cef under global config mode..

regds

[ckuriyar74]

ip cef is already enabled and i have QOS configured and no routing protocols used.

[sourabhagarwal]

please find attachment which has possible causes and sloution of the high CPU utilization.

hoope it helps ... rate if it does ...

[ckuriyar74]

Fast switching enabled on all interfaces and still no luck & high CPU load.

[jackyoung]

Can you post the config ?

Are you hit this bug ?

***Quoted Start

CSCdv68743

Symptoms: The performance of a router may be lower than you would expect, and CPU utilization may be high during packet forwarding.

Conditions: These symptoms are observed on a nondistributed Cisco router that runs Cisco IOS Release 12.2, 12.2 S, 12.2 T, 12.3, or 12.3 T under the following circumstances:

?The router has a service policy attached to one or more interfaces.

?The policy map of the service policy contains one or more class maps that are configured with one or more match access-group name access-group-name class-map configuration commands.

?There is a large number of named extended IP access control list (ACLs) configured on the router, and the packets that are passing through the router match these ACLs.

Workaround: If this is an option, enter the match access-group access-group class-map configuration command in the class maps, that is, enter the access-group argument instead of the access-group-name argument.

*** Quoted End

I cannot suggest the IOS unless there is more info.

Any PBR, debug are running on the router ?

If there is maintenance window, it is fine to upgrade the IOS to test it but be backup all config. and original IOS before carry the upgrade. Also need to check the memory requirement for the new IOS.

Hope this helps.

[royalblues]

i agree with Jack.

I have seen similar symptoms when i had PBR configured on a 3640 router.

Try upgrading the IOS to the latest one but iam very doubtful that you would be able to load a new one with just 8 MB capacity

HTH

Narayan

[ckuriyar74]

I agree with Jack.

This router has a service policy attached to one or more interfaces and also the policy map of the service policy contains one or more class maps.

Also there is a large number of named extended IP access control list (ACLs) configured on the router.

The problem like i just have 8MB flash to upgrade the IOS.

We have ordered new 2811 router and probably replacing in day or two.

Thanks to every one for the suggestions.

[jackyoung]

If you have chance, try to remove those PBR command in interface then check the CPU loading.

Please advise the result if you took the test. :)

[ckuriyar74]

I have replaced the router with 2811.

The IOS I have uploaded is

c2800nm-advipservicesk9-mz.124-11.T.bin

and also attached the router config.

[royalblues]

Hi

I see NBAR configured on the routers. This process is CPU intensive and can definitely choke a 3640 router.

The 2811 should be able to take the load.

Are you still seeing high utilization BTW

HTH

Narayan

[ckuriyar74]

I still see 70% CPU load when the util reaches 100%.

[sachin]

Have you checked your router is not hit by any infected machines ??

[jackyoung]

I can't download the config file, can you reattach it. However, I agree w/ Narayan that any packet inspection feature will increase the router loading, so try to remove / disable those commands and test again.

Hopt this helps.

[ckuriyar74]

Again attached the config file.

I tried disabling those commands and 10% of CPU load reduced.