When a Sensor fails with a Fail-Open module in place, the following events occur in the stated order:
The Manager reports a Sensor in bad health or a Port pair is in bypass mode error in the System Health page.
The Sensor reboots and the Fail-Open module begins forwarding traffic. All traffic now bypasses the Sensor and flows through the Fail-Open module with minimal traffic disruption (within milliseconds).
Upon reboot completion, the Sensor resumes its heartbeat, and one of the following occurs:
If the reboot occurred during normal operation as described, the Fail-Open module resumes passing data through the Sensor and the Sensor returns to Inline Fail-Open mode.
If the reboot occurred due to an error, the Fail-Open module continues to bypass the Sensor until the administrator manually re-enables Sensor ports in the Manager.
After the ports are re-enabled, the Fail-Open module resumes passing data through the Sensor and the Sensor returns to in-line mode.
The errors on the Manager disappear and normal health is reported.