high cpu utilization on cisco 7206vxr npe-g2, ios 12.4(4)XD10

Unanswered Question
Jun 9th, 2008

Good day, dear experts,

we have a problem with a router from subject. CPU usage grows proportionally ip traffic. ip route-cache is enabled on all interfaces, but with

traffic about 200kpps there is 40% cpu load on the router. Output interpreter found two errors from result of command show tech-support:

1) ERROR: This router has dropped 994 packet(s) (12.52994%) due to a shortage of

'Huge buffers'.

2) ERROR: No Processes were found having a CPU utilization greater than 10%.

there is no any debug enabled.

please, give advice for resolving this issue.

thanks in advance!

p.s. listing of "show interfaces switching" is in the attache.

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Paolo Bevilacqua Mon, 06/09/2008 - 07:05

1. please make sure "ip cef" is enabled and no "ip route-cache" commands of any sort are configured under interface. Thats is, default configuration.

2. configure "buffers tune automatic".

Hope this helps, please rate post if it does!

servicedesk.nl@... Mon, 06/09/2008 - 07:31

Thanks for answer, Paolo.

I've configured buffers tune automatic and remove from all interfaces "ip route-cache flow". ip cef was enabled.

Now there is 26% cpu load on router vs 33% with route-cache flow. Still too much for traffic 140kpps :(

Paolo Bevilacqua Mon, 06/09/2008 - 07:46

Hi, don't worry too much as long CPU doesn't go over 85%. It doesn't scale linearly.

You can re-enable flow if you need this info.

Send some more "show int" and "show proc" if you want, but as long there are no drops, you should be okay.

ashish_gupta Mon, 06/09/2008 - 09:24


I have processes problem in other IOS version as well. like 12.4(15)T1. Here we had to upgrade the router to T5 and it went stable.

Also see that processes can go high if lots of fragmentation happening on the interfaces.

Which protocol you are running. Check for the calculations in the database,


Ashish Gupta


This Discussion