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Cat. 9200 CPU overloaded with SISF Switcher Th process

mitard
Level 1
Level 1

Hi guys,

We have a 3 switches stack (Cat. 9200) running IOS XE 17.6.5 with the CPU overloaded with SISF Switcher Th process :

PID Runtime(ms) Invoked  uSecs   5Sec   1Min   5Min TTY Process
433 1401525420 72375221 19364 79.83% 81.16% 82.11% 0 SISF Switcher Th

As per issue CSCvk32439 I implemented a IPv6 filter on trunk ports but the issue remained. Eventually I disabled the DHCP snooping on all VLANs but this can only be a short term workaround.

Could anyone please suggest a long term remediation ?

Regards, Vincent

 

15 Replies 15

AlexMarques
Level 1
Level 1

Hi

I also had this problem several times and was able to solve it as follows. As soon as I deleted the “ip dhcp snooping vlan xxx” from the configuration, the CPU went from >75-80% “high SISF main thread” back to approx. 2-5%.
Since it was not a solution for the customer and me to switch off the feature, I solved it with the following global switch configuration:

device-tracking policy DT-PROGRAMMATIC
  no protocol ndp
  no protocol dhcp6

First the “ip dhcp snooping vlan xxx” configuration has to be removed and then the device tracing parameters can be added on global level, after that the “ip dhcp snooping vlan xxx” configuration can be added again.

I hope it helps you too!

Regards, Alex