When a Sensor fails with a fail-open switch 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 pane.
The Sensor reboots and the fail-open switch begins forwarding traffic. All traffic now bypasses the Sensor and flows through the fail-open switch with minimal traffic disruption.
Note
A Sensor reboot breaks the link connecting the devices on either side of the Sensor and requires the renegotiation of the network link between the two devices surrounding the Sensor. Depending on the network equipment, this disruption ranges from a couple of seconds to more than a minute with certain vendors' devices.
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 switch resumes passing data through the Sensor and the Sensor returns to in-line fail-open mode.
If the reboot occurred due to an error, the fail-open switch 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 switch resumes passing data through the Sensor and the Sensor returns to in-line mode.
Note
A brief link disruption is likely to occur while the links are renegotiated to place the Sensor back in in-line mode.
The errors on the Manager disappear and normal health is reported.