2811 CPU performance issue

Unanswered Question
Sep 3rd, 2010

Hi, All

We are running a cisco 2811 router in office with route and NAT.

Router#show processes cpu

CPU utilization for five seconds: 51%/46%; one minute: 50%; five minutes: 43%


I know the most of CPU time is used to process interrupt. I don't know what is these interrupts working for , route or nat?

We have about 40 desktops in our office, and there is only one defaut route for internet on the router. Also, We enable the NAT on the router.

What I want to know is what is usring the most of CPU. Can anyone give some advise?


I have this problem too.
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Nagaraja Thanthry Fri, 09/03/2010 - 10:11


How is your default route configured? Do you have something like "ip route fastethernet 0/0"? If that is the case, then the high CPU could be due to ARP as the router will ARP for every destination. If that is not the case, can you check and make sure that you have enabled hardware switching (you do not have "no ip route-cache" under interface configuration)?

Hope this helps.



ciscohywl51 Sun, 09/05/2010 - 23:39


My router's default route setting is "ip route 60.247.***.***".

Router#show ip interface | include route-cache
  IP route-cache flags are Fast, CEF
  IP route-cache flags are Fast, CEF
  IP route-cache flags are Fast, CEF

I am not sure if these settings are what you mentioned. If yes, how can I fixe it?



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