During normal in-line fail-open operation of the Sensor, the fail-open switch constantly sends a heartbeat signal to the Sensor. If this signal does not return to the fail-open switch within a programmed interval, the fail-open switch removes the Sensor from the data path and moves into bypass mode, providing continuous data flow with little network interruption.
While the fail-open switch is in bypass mode, traffic passes directly through it, bypassing the Sensor.
When normal Sensor operation resumes, you might or might not need to manually re-enable the monitoring ports from the IPS Manager interface, depending on the activity leading up to the Sensor's failure.
The following section describes how to return the Sensor to in-line mode.