what constitutes high CPU usage and how much can my router handle?

Unanswered Question
May 15th, 2007
User Badges:

We recently moved from a creaky 3640 up to a nice new 2811. It sits at the middle of our LAN, run two TI connections to two remote sites, a 16 line modem bank for dial in access (never actually used to anywhere near full capacity. Usually only 2 or 3 lines in usa) and routes all Internet traffic from all three sites to the gateway firewall router. We are a very small college so the traffic is not all that enormous.

Right now with a minimal setup and a couple of minimal access lists CPU usage is around 20%.

I would like to add vlans and comprehensive access lists to our network. But this would increase the routers workload.

How can I figure out how much it can take and decide when its had enough?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 4 (1 ratings)
spremkumar Tue, 05/15/2007 - 19:28
User Badges:
  • Red, 2250 points or more

Hi Johny

Cisco has clearly given the specs on how much each router model will be able to handle and also the processing speed of the boxes.

20% usage at this point of time may not be a concern but when it nears or tops over 50% always then you need to start verifying actual traffic.

you can refer the below guide to have a fair idea on how much load each device is capable of handling.


In some case you may have some worms/virus traffic which is being handled by the CPU and actually hogs up the performance of the device..

Martin Ermel Wed, 05/16/2007 - 03:39
User Badges:
  • Blue, 1500 points or more

the attached paper is really a good summery, but where did you get it? I cant find it on Ciscos website. Could you post a link?


This Discussion