High Cpu utilization on Cisco 3640 router 1

[khaldi]

Hi
I 've a 3640 router running Cisco IOS 12.1(5)T with 8 Mb flash Ram and 32 Mb Ram.
I use it as a nas with 2 Cisco Modems module (16 Modems for each module).
I added an NM-4T card (4 serial connections).
In each serial port there is a 2 Mbps PPP connexion with an ISP.
The CPU is always at 96 % of use .
Any help please.

 

[fynx]

Hi,
In enable mode enter:-
show proc cpu

And note which processes are using the most of your CPU. and post back please.

Regards,
Phil.

 

[wybnormal]

THere are many reasons for this. Do the command

show proc cpu

This gives a list of processes along with a percent of utilization for 1 minute, 5 minute and one more that I forget right now. FOr example, I have a 2500 that averages 20% but spikes as high of 80%. The show proc cpu showed that IPX SAP IN took over 28% of the processor and IPX EIGRP was taking another 10%. THis gives the clue that there are way too many route updates and SAPs for this router..

DLSW can cause havoc if not properly configured, bridging causes pain. If you turned off ip route caching, you have just destroyed your performance and this also includes complicated access-lists which force the router to examine each and every packet.

Cisco has a good paper on this. Using the following link

http://www.cisco.com/warp/public/63/highcpu.html

Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[state]

As mentioned earlier, there are several reasons why CPU utilizations can be high. Both of the above replys are a good start. Another area you can check is debugging. Often when we troubleshoot we turn on debugging (very process intensive) and forget to turn it off. Do a show debug, if its on turn it off by typing u all. Hope this helps.

 

[state]

As mentioned earlier, there are several reasons why CPU utilizations can be high. Both of the above replys are a good start. Another area you can check is debugging. Often when we troubleshoot we turn on debugging (very process intensive) and forget to turn it off. Do a show debug, if its on turn it off by typing u all. Hope this helps.

 

[munsonbrown]

12.1.5T has been deferred. The current release is 12.1.5T7. If the version yuo have is anything other than "IP" , like "IP Plus", you'll need to upgrade the memory.

 

[khaldi]

Hi Wybnormal

I found the cisco paper referenced on your response but my problem is wich average is considered as a limit .
The show proc cpu gave me :

5Sec 1Min 5 Min TTY Process
0.16% 0.01% 0.00% 0 PPP Auth
0.08% 0.10% 0.08% 0 IP Input
0.08% 0.04% 0.01% 0 Exec

You've here what I noticed , but I don't think that the pb is here.
I checked for throttles on interfaces , nothing.
I also checked memoru alignment corrections , no spuriuos memory.

We are thinking about upgrading memory.

Thanks

 

[khaldi]

Hi munsonbrown

We have a Cisco IOS 12.1(5)T IP version .
Do we need to upgrade the memory.
We are thinking about it.

 

[wybnormal]

How do you know the CPU utilization is too high? Get a demo copy of solarwinds.net and use the utilization gauge for real time stats. Also, use the traffic monitor to see if there is a burst of traffic when the CPU goes high. Not always but something to look at.

You showed only 3 lines but there should have been about 2 pages worth of stats.

If you think you need memory, do a router# show proc mem and look at the very top line which gives the amount of RAM, amount used and amount left. The rest tells you what is using what of the RAM. For example, if you have 16 meg of RAM, using 8meg and have 8 left, you are fine. I have many routers with 1-2 meg left from 16 and they run fine. It will dicy for anymore route table updates but they do work.

Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin