cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
1765
Views
0
Helpful
2
Replies

What caused 100% CPU usage after seeing "show process cpu history"?

axa-wongjeff
Level 1
Level 1

I received an alert from one of my routers for high CPU utilization. The router responded to ping, so it was still active. I tried to telnet to the router, but the attempt timed out. After about 10-20 minutes, I managed to access the router. I did a 'show process memory' and 'show process cpu'. I did not notice any process high compared to my baseline.  The 'show process cpu history' did vouch that the router experienced high CPU.

Anyone suggest how I go about trying to find out what caused the spike? Monitoring tools, other commands, etc.?

Thanks.

High CPU History.jpg

2 Replies 2

Reza Sharifi
Hall of Fame
Hall of Fame

Reasons for CPUs spike include traffic that normally is handled via CEF switching all of a sudden gets process switched, bad TTL values which result in the traffic reaching the CPU of the device, an ACL which starts filtering WAY too much traffic, IGP instability resulting in lots of CPU cycles spent on recalculations/convergence. Also, IPSec can cause CPU issues, especially if you're doing software encryption

I would also check your current IOS version running on the box for any kinds of bugIDs, specifically memory issues and buggy processes.

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a00800a70f2.shtml

HTH

Reza

catalindominte
Level 1
Level 1

Hi,

Another thing you can do is to setup a SPAN session, which can be configured to mirror all the packets that are sent to the RP, instead of being CEF switched. A guide on how to do that can be found here:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008015c612.shtml

It includes different switch models, etc.

Hope it helps

Catalin

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: