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High CPU Utilisation on 5308XL

Matt Chan
Occasional Contributor

High CPU Utilisation on 5308XL

One of our 5308's is cosntantly running up to 99% cpu, we have another in the same lan doing the same work which sits at around 1-2%. It's just started happening so I'm guessing a hardware problem of some sort.

Does anyone know if its possible to list the processes active on the switch and show which is consuming the cpu cycles?

Cheers
Matt Chan
5 REPLIES
Matt Hobbs
Honored Contributor

Re: High CPU Utilisation on 5308XL

You can't break it down per process unfortunately. Most likely though it's something occurring on the network itself (e.g. broadcast traffic, spanning-tree instability). I doubt it will be hardware related.
Matt Chan
Occasional Contributor

Re: High CPU Utilisation on 5308XL

Thanks for the reply Matt.

My first thought was something in the environment, but spanning tree is stable, and the port utilisations are very low nothing is showing in the log, yet the cpu persists in extremely high usage.

I'm going to place a hardware call anyway as I'm having trouble seeing what else it could be.

Cheers
Matt Chan
Vishwas Pai
Regular Advisor

Re: High CPU Utilisation on 5308XL

I'm not very sure which version of the firmware supports this, but you can try and see if yours does.

(enable per task utilization)
# task-monitor cpu

then,
"# show cpu" should show you task specific usage. That can help you identify what might be consuming more cpu.

vishwas


Matt Chan
Occasional Contributor

Re: High CPU Utilisation on 5308XL

hi Vishwas, thanks for the info, we have 4 switches, 2 on 10.74 and 2 on 11.03, but none have that command available.

I may have found the culprit though, it appears it may have been syslog traffic from a firewall to a syslog server which had become unstable and not accepting traffic, it appears the firewall sent something in the order of 56 GB of syslog data.

Strangely, neither of the the ports by which these devices were connected to the switch seemed to show unusual utilisation so I'm guessing it was many small packets (it appears there were 111 million packets. but the actual utilisation was very low.

Cheers
Matt Chan
Mohieddin Kharnoub
Honored Contributor

Re: High CPU Utilisation on 5308XL

Hi

Whats the firewall you have ?
if you can afford some downtime, then you will be having a choice to figure out whats happening by narrowing down the issue if its related to the environment
try after each of following points to monitor the CPU utilization:
- disconnect uplinks to other switches
- disconnect redundant links if you have.
- disconnect Firewall link.
- if you have left up with only end devices ports then it could be from one of these ports.

try also to syslog only Critical info.

Good Luck !!!
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