Symptom

FNF ucode crash when add or remove interface on ISR1100-6G

Conditions

interface flapping(delete and remove interface) and FNF policy flapping (trigger by changing cflowd template or reconnecting to vsmart) at the same time, when interface is in deleting state, FNF policy disable could not remove the FNF sb from the interface, it will lead to invalid FNF mon sb on the interface, and when the interface is reused, it will lead to crash. It's a timing issue and corner case

Workaround

don't delete/add interface and change FNF policy at one transaction is helpful

Further Problem Description