This value sets how long, in seconds, the switch waits while exchanging discovery messages with its link partner before determining the bidirectional status of a port under unidirectional link detection. An admin tunes this value to balance faster fault detection against giving the discovery handshake enough time to complete reliably, especially over longer or less clean fiber runs. For example, raising this from the default of 5 seconds to a higher value might be needed on a link with more variable OAM message round-trip times to avoid false unidirectional-fault detections.