Hi , i have cisco 5 3750 X switches in stack wherein am getting high cpu utilization and i couid see my tcam is full for mac

[kiran.jatap]

Hi Team,

i have 5 cisco 3750 switches in stack and i could see high CPU utilization , i found that sdm prefer is desktop and tcam is utilizing full resources for MAC address . please suggest how to avoid this . Am posting some out the outputs as below  :

HIST2A-DIST-LAN#sh platform tcam utilization 

CAM Utilization for ASIC# 0                      Max            Used
                                             Masks/Values    Masks/values

 Unicast mac addresses:                       6364/6364       6474/6474  
 IPv4 IGMP groups + multicast routes:         1120/1120          1/1     
 IPv4 unicast directly-connected routes:      6144/6144       2623/2623  
 IPv4 unicast indirectly-connected routes:    2048/2048        204/204   
 IPv4 policy based routing aces:               452/452          12/12    
 IPv4 qos aces:                                512/512          21/21    
 IPv4 security aces:                           964/964         165/165   

Am not seeing any genuine process using the CPU but have enabled CPU logs and found that process number 394 HULC running process is spiking .Could you please suggest on some reason for that . 

Note : I have some more 3750 stack switches but am not having any problem with the same . 

[Leo Laohoo]

And what is your IOS version?

[kiran.jatap]

Current IOS version is as below :

c3750e-universalk9-mz.152-1.E1.bin"

[Leo Laohoo]

15.2(1)E1????

Do yourself a favour, downgrade to 15.0(2)SE4 and see if you see any improvements.

[Sanjay Shaw]

Hi ,

I had experience this in many switches and even had words with cisco, they had said that this series has shown HULC high in many cases and it will not impact the end user even it shows 100%.

[kiran.jatap]

Hi Leo , Thanks for your input . Would definately try downgrading the IOS . It would be great help if you can suggest was there any bug in the earlier IOS like this . I have this issue with many of other 3750 stack switches as well with different IOS .

[Leo Laohoo · Accepted solution]

It would be great help if you can suggest was there any bug in the earlier IOS like this.

I need to be very "diplomatic" about this ... 15.2(1)E train never passed my testing.  And I have tested a lot of IOS versions.  

IOS train 15.2(1)E is notorious for sending your CPU/memory through the roof.  Whether it's cosmetic or not, I have cases where the CPU went 100% I cannot even console into the appliance.  

[Sanjay Shaw]

Hi Kiran,

could u post the exact model of the device or paste the show ver. I will suggest a working IOS from my existing enviroment.

[kiran.jatap]

Hi Sanjay ,

In this case i see high process utilization is quite often that is spike . But in normal situation i do not see all the processes taking 50 percent utilization as well but aggregate CPU is showing as 80-95% and in turn affecting our end users like packet drops and slowness issues . Please suggest if we can resolve it somehow 

[zenzenzen]

How it was resolved?