100% cpu utilization in cisco 3850

[donnie]

Hi all,

I realise cpu core0 of my cisco 3850 switch stack of 4 switches is having high cpu utilization of 100% constantly when i do a "show process cpu | ex 0.0". The other cpu core are fine at below 20% utilization. This command would also list the processes as shown below but it would not add up to 100%

5sec 1min 5min     Process

26.6  28.2  27.8     fed

0.15 0.13  0.11      platform_mgr

0.65 0.53  0.48      stack-mgr

4.64 0.38  0.26      cli_agent

0.15 0.12 0.13       wcm

Hence i have 2 questions. Why does the processes not add up to 100%? Secondly following the portal http://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/117594-technote-hicpu3850-00.html i could identify the cpu queue which resulted in high cpu utilization which also lead me to discover that it is tied to switch's uplink port. I tried adding another uplink and disabling the original uplink but cpu resource remain high at 100%. What other steps can i take to verify? TIA!

[mehulnangru]

I think its a known bug - 

https://tools.cisco.com/bugsearch/bug/CSCus46997/?referring_site=bugquickviewredir

You must be using a stacked switch.  Correct ?

I have faced the same problem try upgrading IOS to 03.03.05-SE or higher . 

[donnie]

Hi Mehulnangru,

Yes i am using a stack of 4 cisco switches. My IOS is 03.07.01E. Base on the link you provided it mentioned known affected release is 3.7(0), hence does it mean my IOS version is affected? The link also mentioned the workaround is to disable session monitoring, however my session monitoring is not enabled. Hence the solution to my problem would be to upgrade to latest IOS? THk you.

[Mark Malone]

you shouldnt really be effected on 3.7(1) its specific to that release 3.7(0) but that doesnt mean you have not hit it as  , 3.6.3 is the recommeneded release anyway the least amount of software issues , we use a combination of scanners along with other Cisco tools to check these ios-xe versions for vulnerbilities

if your running that command below and getting the output the bug is showing chances are you have hit it , i wouldnt upgarde i would downgrade to the safe harbour image less chnace of hitting something else
show proc cpu detailed process iosd sorted result:

you shoukld always avoid upgrading to the latest ios youll become the guinea pig for new bugs half of them Cisco wont even know about yet  , youll see the release your on and the ones in front of you are ED while 3.6.3 is MD a main release you should always try stick with MD images

[mehulnangru]

Hi Donnie ,

If possible , let us know if the issue was resolved after the upgrade to 3.7(1).