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High CPU Usage on Core 3 Catalyst 3750

Hello everyone,

I have a Catalyst 3750 that we use as our core switch, we additionally have 3 other switches on our infrastructure.

It's been quite a while since I use the command show processes cpu, I get high % usage on core 3 of this switch.

We use Zabbix Monitoring system and we get alerts of high error rates on interface Gigabit Ethernet 1/0/22.

I have followed this guide to troubleshoot High CPU Usage:

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/117594-technote-hicpu3850-00.html

And I was able to get these values, see attached screenshots:

FED being the process using most of the resources.

By following the guide I was able to also get to determine that said interface is causing the problem, so Zabbix is right.

What I need help on, is to continue troubleshooting this and find the root problem, as the advise of "shutting down the interface" is not an option, this interface is connected to another switch of our infrastructure.

Any other info that might help to follow on this?

Everyone's tags (5)
14 REPLIES 14
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VIP Mentor

Re: High CPU Usage on Core 3 Catalyst 3750

follow the below correct guide :

 

https://community.cisco.com/t5/networking-documents/troubleshooting-high-cpu-on-3750/ta-p/3148699

 

Post below information to understand better your environment :

 

1. show ver

2. show switch

3. show process cpu | ex 0.00%

4. show process cpu history

 

 

BB
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Re: High CPU Usage on Core 3 Catalyst 3750

Hi ! Thanks for answering!

Find attached the screenshots of what you've asked.

As far as the guide, I will follow it on Monday once I get back to the office.

I will keep this thread just in case something comes up with the screens I attached.

Highlighted
Contributor

Re: High CPU Usage on Core 3 Catalyst 3750

Please do show proc cpu history.
I try to replay tomorrow , because in my city deep night
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Helping seriously ill children, all together. All information about this, is posted on my blog
Highlighted

Re: High CPU Usage on Core 3 Catalyst 3750

Hey @Oleg Volkov 

Here are the screenshots that have to do with the command you asked for:

See attachments please

Highlighted
VIP Mentor

Re: High CPU Usage on Core 3 Catalyst 3750

The switch model you have C3650 and got only 1 Switch.

 

I see and i believe some bugs related to your issue :

 

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCuz57493/?referring_site=bugquickviewredir

 

if you get a chance to try to upgrade to 3.7.5X and let us know the outcome.

 

BB
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Hall of Fame Community Legend

Re: High CPU Usage on Core 3 Catalyst 3750

The title says "3750" but the screenshots look like 3650/3850.
What firmware is the stack running on and what is the uptime (post the complete version to the command "sh version").
If the stack is running 3.6.X or 3.7.X then this is due to a well-known bug: CSCuo14511
NOTE: The number of TAC Cases associated to this bug has gone so high the actual number of TAC Cases associated to this Bug ID has been removed from public viewing.
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Re: High CPU Usage on Core 3 Catalyst 3750

Hey @Leo Laohoo  back at the office!

Here is the output of "sh version" command:

What's the firmware version I have?

See attachments

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VIP Mentor

Re: High CPU Usage on Core 3 Catalyst 3750

you got 3.6.X, can upgrade to 3.7.5X  as suggested.

 

BB
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Re: High CPU Usage on Core 3 Catalyst 3750

That will be something very difficult to do as that switch is located at the main floor, but there is another switch, actually 3 more, on another floor on the building.

All of our traffic goes to the first switch, it would be our core switch actually.

So, what are the risks of updating, downtime, and maybe other possibilities to sort it?

Are we 100% sure that this is bug-related and not something else?

Highlighted
Hall of Fame Community Legend

Re: High CPU Usage on Core 3 Catalyst 3750

Switch is a 3650/3850.
I suspect it is due to CSCuo14511.
Highlighted

Re: High CPU Usage on Core 3 Catalyst 3750

Hey everyone,

I have not tried any of the possible solutions yet.

However, I was going through the Cisco article on STP and I wanted to share this screenshot with you

I ran this command on the interface having high error rates and high CPU usage:

 

(See attachment)

 

Do you guys think this may have something to do or are we still more on-board with the fact that is a switch bug?

Logically speaking about what I read, issues with infinite STP loops will definitely make the network slower or even unresponsive.

Thanks!

Everyone's tags (1)
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Hall of Fame Community Legend

Re: High CPU Usage on Core 3 Catalyst 3750

Can you please create a new thread?
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Contributor

Re: High CPU Usage on Core 3 Catalyst 3750

Please read this:
https://community.cisco.com/t5/networking-documents/troubleshooting-high-cpu-on-3750/ta-p/3148699

Also try to temporary disable IGMP snooping globally.

Also you can use debug but it may do switch unreachable.
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Helping seriously ill children, all together. All information about this, is posted on my blog
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Hall of Fame Community Legend

Re: High CPU Usage on Core 3 Catalyst 3750