Symptom

In a rare case, the overall CPU of the Firepower chassis can increase due to bcm_usd process CPU utilization. When the issue appears, the increase is also related to the traffic load of the chassis. During this increase, the overall functionality of the box remains stable. Sample output: firepower(local-mgmt)# show processes | i bcm ; show clock 4964 root -2 0 367m 121m 33m S 133 1.5 12761:18 /isan/bin/bcm_usd Thu Nov 18 13:21:53 CET 2021 firepower(local-mgmt)# firepower(local-mgmt)# show processes | i bcm ; show clock 4964 root -2 0 367m 121m 33m S 130 1.5 12761:20 /isan/bin/bcm_usd Thu Nov 18 13:21:54 CET 2021 firepower(local-mgmt)#

Conditions

A traffic spike is the trigger of the issue. Note, that once the issue is triggered, it remains until a Workaround is applied no matter what is the traffic load.

Workaround

Contact Cisco TAC for the Workaround since it requires secure-login access. NOTE: The workaround does not survive a chassis reload. In case of a chassis reload, the workaround has to be reapplied by TAC.

Further Problem Description