[c-nsp] 7206VXR Big CPU Increase After 12.4 Upgrade

[Mark Taylor]

Hi,

We upgraded one of our 7206VXR NPE-G1's from 12.3(12a) to 12.4(12) this 
morning to cover the recent security releases. We decided to make the major 
revision jump as we were reloading.

After the reload the box jumped from 20 percent cpu to 35 percent on the new 
12.4(12) image and at the time there was around 75Mbps in each direction of 
traffic running through the box - so an immediate increase of 15 percent.

Now there is about 185Mbps each way and cpu is at 65 percent. This would 
have been about 45 percent before the change of image, so an increase of 20 
percent.

This is looking very much like cpu could potentially increase more quickly 
than traffic. The jump in cpu between images is beginning to concern me a 
little. Has anybody else experienced this? Is it normal?

The box is a peering router running IPv4 and OSPF, a full BGP table from one 
upstream and about 20 other direct peers at a small IX and a few ACLs. CEF 
is still running.

I was hoping to get around 350Mbps through the box before running out of cpu 
and it was looking that way based on 12.3(12a). I guess I could go back to 
12.3(22) which is fixed, assuming that the increase in cpu comes with 12.4. 
I just wanted to find out if this big jump in cpu between releases was 
normal/expected.

Any help/experience appreciated.
Thanks,
Mark.