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

[ckuriyar74]

There is some proble while attaching the file. Again attached the file.

[jackyoung]

Please try to remove the "ip accounting" commands. It use lots of CPU resources. Only enable the ip accounting if there is a need, e.g. verify packet flow in interface.

If the CPU still high, it means the QoS commands may spend the router loading too. Try to remove the service policy command at the interface one by one to test. However, I believe the QoS commands are required, so if the ip accounting commands are removed but still high router loading, you may require to upgrade the router.

Hope this helps.

[akhan2004]

Pls read the following URL link:

http://cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2ae4.shtml

AK

[ckuriyar74]

Probably multilink configuration causing high CPU load?

Any suggestions to configure instead of MLPPP.

IP Cef per destination or per packet?

[jackyoung]

Could you check my reponse on 27 Dec ? IP accounting is a CPU intensive feature. More packet pass through, more cpu loading is used.

Please try to remove this command and check again.

Hope this helps.

[ckuriyar74]

I have already removed IP accounting but still CPU high.

[jackyoung]

Thanks for the update. It is quite strangth, could you post the updated config. ?

The MLPPP should not be the factor. I suspect there is bug or hardware limitation.

[ckuriyar74]

I have other 2801 router with

IOS c2801-ipbase-mz.124-1c.bin and have the same configuration in both 2801 & 2811

The output in 2801 is on ethernet not on serial and this is my backup router.

If the traffic is on 2801 router the CPU load does not go more than 20% but when the same amount of traffic on 2811 router with MLPPP goes upto 50%.

I have attached the config.

[royalblues]

When you do MLPPP, all packets are processed by CPU.

If you can spare a few IPs and configure each link wth a different one, try loadbalancing on CEF instead and check

HTH

Narayan

[jackyoung]

In addition to Naranya;s suggestion. If you tried to disable MLPPP and the CPU loading still high, you can try to remove those QoS and filtering command one-by-one to determine the root of cause.

However, 2811 do have higher processing power than 3640. Let me check the figure and return to you tomorrow.

[jackyoung]

In addition to my last post, please check below link that the 2811 perform 120,000PPS and 3640 perform 50,000 - 70,000PPS under CEF. Therefore, the process power of 3640 is much lower than 2811.

I suggest to make the 2811 as primary router w/ MLPPP and 3640 as the backup router to provide better service.

http://www.cisco.com/warp/public/765/tools/quickreference/routerperformance.pdf

Hope this helps.

[rabeder]

hi,

i did some testing with llq and 3640, 3825, 28xx routers.

!

the 3640 is not able to handle more than 4mb/s with llq.

it depends a little bit which encapsulation on layer 2 you are using.

i testet with frf16 (two e1 fr interfaces) - as i said, the router was overloaded.

if you use ethernet as layer 2 - you can say that a 3640 can the double of traffic than frame-relay

[royalblues]

I Agree with Kurt.

I have seen similar symptoms in a 2621 routers where the CPU would become a problem when you pump about 4 MB traffic on FR along with IPSec

The router just works fine when 10Mbps link is terminated on ethernet with the same features.

Narayan

[jackyoung]

I agreed too, this is why I ask to remove the function one-by-one to determine which one consume the CPU loading the most.

However, if the 2811 (high cpu power) can be the primary then it will solve the problem.

In IPSEC case, we have to consider the hardware-based encryption module to speed up the process and load-share the on-board CPU loading.

Just my 2 cents.