2851 high CPU

Unanswered Question
Dec 31st, 2008

Further to the below mail, another thing that was observed is as follows:

The ACLXX is used for dynamic nat. This includes only some IP's. Any ip that does not match this acl will not get natted. When u inlcude a permit any statement in the acl, all hosts get natted and the cpu came down from 90% to 28% drastically. But this is not intended as some applications dont work well with nat.

So this other traffic which goes without natting is getting process switched or something.

I have this problem too.
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mchin345 Tue, 01/06/2009 - 08:40

Common symptoms of high CPU utilization

* High percentages in the show processes cpu command output.

* Slow performance

* Services on the router fail to respond, for instance:

- Slow response in Telnet or unable to Telnet to the router

- Slow response on the console

- Slow or no response to ping

- Router does not send routing updates to other routers

Check for a possible security issue. Commonly, high CPU utilization is caused by a security issue, such as a worm or virus operating in your network. This is especially likely to be the cause if there have not been recent changes to the network. Usually, a configuration change, such as adding additional lines to your access lists can mitigate the effects of this problem.

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a00800a70f2.shtml

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