investigating/understanding CPU on 4006 units

CPU issues on Cisco is a bit infuriating. Different hardware acts and reports totally different profiles and processes. Each model has to be troubleshot a bit different. One model may never seen less than 50% cpu while another never rises above 1%. The hardware design is the major factor. On the 4006s with high cpu, the command prompt is very slow and we have obvious (user complaints) poor performance when we get bursts of traffic.

We see a lot of sluggish performance on 4006 units. Most of them average 55-75% cpu used in the middle of the night when nothing is happening. I've gone through and done some manual pruning(very large network here) and knocked off about 10% of the load on some.

At teh bottom of the post is a trimmed down SHO PROC CPU.

Anybody have success freeing up CPU on 4006. A lot of shops apparently report 50% as a baseline, but we have a few units that average 4% all month.

The obvious suspects from reading are

- inline power modules--yes we have them...but I see no specifics on how much CPU load they generate. How much per blade/per port? Does a

48port generate more cpu load than a 24 port? 5% 1%, 0.5% 0.05% Does it matter if they are shutdown?

- large vlans/STP - yep got em here. I've trimmed the trunks as best as possible. I'm also wrestling down poor spanning tree configs. I have a test which has been waiting for change management approval for

6-8 weeks now to determine just how much impact each vlan has. Once I know the benefit of eliminating a vlan, I know which is my worst and most worth concentrated cleanup effort.

- supervisor module. All three of the lowest cpus have a L3 module, and all the processes in SHO PROC CPU are totally different from the others so there is no comparing them.

- OS? Those running IOS have the L3 modules and average 3%. Those runnign catalyst average 57-77% monthly, with one except at 25%.

Here is one of many with problems...

4006> (enable) sho proc cpu

CPU utilization for five seconds: 77.75% one minute: 72.47% five minutes: 71.12%

PID Runtime(ms) 5Sec 1Min 5Min TTY Process

--- ----------- ------- ------- ------- --- ---------------

1 801900128 22.25% 27.53% 28.88% -2 Kernel and Idle 21 22367422 0.79% 0.92% 0.98% -2 cdpdtimer 22 13528969 0.77% 0.00% 0.00% -2 SptTimer 23 44299574 2.14% 2.92% 2.98% -2 SptBpduRx 24 82325330 4.10% 4.00% 4.00% -2 SptBpduTx 28 254372176 13.13% 12.84% 12.96% -2 McastRx 145 2833 0.75% 0.00% 0.00% 1084524308 telnet145 193 149538297 8.07% 7.02% 6.69% 0 Packet forwardi 194 416881467 27.40% 24.99% 21.39% 0 Switching overh 195 283801024 14.04% 12.88% 11.75% 0 Admin overhead

DiGiTAL_ViNYL (no email)

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