C5500 show proc command

[n.titchener]

We all know that swicthing is done in hardware. So the question is, when the 'Show proc cpu' command is entered does displayed result reflect the amount of switching taking place or is it showing how busy the background (non switching) processes are?

The reason for my question is this. We have a c5500 switch and a c6000 series switch performing similar tasks. The c5500s cpu is frequently running at 24-48% and the c6000 series switch runs at about 7%. Both switches perform similar functions and have similar traffic throughput.

So, why the big difference in cpu usage?

Any suggestions would be appreciated.

Just a note. When the 'show system' command in enetered the cpu untilization values are much lower.

[jbayuka]

The statistics reported is only for the control processes that run on the CPU. With regard to your question on why cat5K consumes more cpu than cat6K can probably only be answered by Cisco as this could be due to some architectural differences. My guess is that Cat5K uses ROSM (Route Once Switch Many) technique, which might be consuming CPU resource for every first packet in a flow. Whereas Cat6K employs CEF to switch all including the first packet. May be this is the reason you see less utility of CPU in Cat6K.

[Frederic Vanderbecq]

Normally, if you look to the output of show proc cpu, you should see which processes are using the more resources.

If you want to see the backplane utilisation for switched traffic, you need to use the show system command. Though, the 2 commands are not displaying the same type of utilisation:

1) show proc cpu shows which processes (e.g. spanning-tree) are using the CPU

2) show system shows the backplane utilisation in other words the amount of packets which are being switched on the backplane

Can you provide us with both outputs from the 5500 ?