I put the 75% threshold for max average router CPU utilization into my Designing Cisco Networks Version 1.0 class without doing a formal study of any sort, and then it got emblazoned in stone for the CCDA test. ;-) I couldn't get a straight answer out of TAC or the software or hardware engineers at Cisco. But I did base the 75% number on discussions with senior Cisco SEs and instructors from training partners who dealt with network engineers from many of Cisco's larger customers on a regular basis.
Also, the theory behind it is sound. If you use about 75% then you'll be OK for most bursts of activity. Note that the 75% is for the 5-minute average. The 5-second and 1-minute could be somewhat higher. Of course, the real answer is that you should have a baseline of your router's performance under normal conditions when there are no problems. You should track not just an overall utilization, but also get an idea of which processes are the biggest CPU hogs. That way when you get attacked by Code Red or whatever, you will recognize when ARP or whatever suddenly starts using way more processor power than it used to. Thanks for telling me about the Web forum. Note that I am using it now and I did use the Quote button, which I think everyone should do. ;-) I will probably go back to doing Group Study via e-mail, though. Then I can spell check. I'm a horrible speller. ;-) Priscilla Michael L. Williams wrote: > > If memory serves, 75% is where Cisco likes to draw the line. > From an online > CCDA study guide "No Cisco router CPU utilization should exceed > 75 percent" > > You could do either one you choose (replace with better/faster > equipment or > simply shift some of the load to other equipment). I can't say > if one is > better than the other...... It depends on the router that's > loaded down and > what technologies are being used. If you're using a 5500 w/RSM > and you're > NOT using Multilayer Switching, then you can dramatically lower > the CPU > utilization on the RSM by using MLS. If you have an old 2500 > that the CPU > is getting high on, and you're using access-lists, see if you > can optimize > your access-list to reduce CPU usage, etc.... > > There are a million answers, many no more right that > others....... > > HTH, > Mike W. > > "Lupi, Guy" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > I was wondering if there was ever any kind of study done by > Cisco to > > determine the acceptable average level of processor > utilization on their > > equipment. How much is too much on, let's say, a 3524 > switch, or a 7513 > > router? I am sure it varies, but is there a list of some > sort that states > > that at a particular average usage you should think about > upgrading, or > > removing some of the load on a particular piece of gear? > Just curious. > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=42725&t=42712 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
