Symptom

ISR4K branch site router might get reloaded unexpectedly with external collector configured in release 16.9.2, 16.9.3 and 16.9.4. This could happen when router boot up or the branch master controller or border router gets flap via manually shut/no shutdown with external collector. The branch router will not experience such issue if it works stable without router reload or PfRv3 MC or BR process flap via shut/no shutdown command.

Conditions

Ucode crash is due to an invalid random MTU size getting used by PFR external collector without explicit configured MTU size in the mentioned release in Symptoms. It is a very low chance to hit such an invalid value between 10240 and 16635 bytes during process bring up, collector config update or process flap via shut/no shutdown, one Jumbo netflow packet size exported from IOS getting injected to platform forward processor could lead to such ucode crash unexpectedly which is not supported on software platform like ISR4300 or CSR1000v.

Workaround

No effective known workaround for this; one possible workaround is to disable external netflow collector which might be not acceptable in customer network.

Further Problem Description