3750X High CPU - HULC Process

[mbeckley2]

The responses I see from Cisco, that this is "Moderate Severity" and expected is not acceptable.  If this starts occurring in release 12.2(55) then it is clearly created by a bug.  The switch did not exhibit this behavior prior to this release.  Because of this additional 20% CPU usage, my 3-swith stack, has now become unusable. I consistently see 45-100% CPU utilization depending upon load. 

[Leo Laohoo]

Aside from "12.2(55)", what is the EXACT IOS version? 

How many switches in the stack? 

[mbeckley2]

There are 3 Switches in the Stack 3750 (WS-C3750x-48P). I originally was running 12.2(58) and had a constant CPU utilization for just the HULC Process of 19-21%.  This would cause an continual 45% CPU utilization.  When network activity would spike I would often see 85-99% CPU utilization.  Interrupts never exceeded 1%, so following documentation it led me to believe it was NOT input traffic. 

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCtn42790/?referring_site=bugquickviewclick

I have tried an upgrade to 15.2 (1)E1 and still see the same issue.  From reading Cisco's most recent posing about Bug CSCtn42790, they are stating that Severity is Moderate and there is no workaround.  Basically, live with it.  I see that it shows the affected IOS version of 12.2(53) or later. I am considering downgrading to something prior to 12.2(53).  Would that be recommended?

[Leo Laohoo]

Let me repeat my first question, what is the EXACT IOS version?

And please don't reply with another "12.2(55)".  

[mbeckley2]

Leo,

I don't think you fully understood my previous response or you wouldn't be asking for my EXACT IOS version.  I stated above, "I have tried 15.2 (1)E1".  This is what I am currently running. I was ORIGINALLY running 12.2 (58)SE2. I experienced the issue first with 12.2 (58) SE2. BOTH of these IOS version give me the same HULC Process Utilization of 19-21%.

Following the documentation in BUG:CSCtn42790, it states that the BUG begins in 12.2(53)SE or LATER. 

Does anyone else have any experience with this issue.  I see all kinds of posts online about it.  Cisco appears to have decided to NOT address the bug moving forward.

Thanks for your help on this Leo.

[Leo Laohoo]

High CPU caused by HULC is a living monster that Cisco has been trying to tame.  

All 15.X IOS for the 3560G/E/X & 3750G/E/X will have HULC issues.  All of them. 12.2(58)SE train has been deferred by Cisco due to numerous security and bug issues, among them are HULC issues. 

Kindly try 12.2(55)SE10 and see if there are any improvements.