The ONU (10) includes the optical transceiver (14) capable of an operation in a power-saving mode in which power consumption is reduced by stopping transmission while continuing reception, and the control device (11) that controls to tentatively validate transmission of the optical transceiver and outputs a response signal when a control signal is received from the OLT (1) during an operation in a power-saving state. Moreover, the OLT (1) includes the control device (2) that allocates a transmission bandwidth to the ONU (10-1, 10-2, 10-3) even while the optical transceiver of the ONU (10-1, 10-2, 10-3] operates in a power-saving mode and stops transmission and determines whether a communication failure occurs or the ONU (10-1, 10-2, 10-3) is in operation in a power-saving mode based on the response signal received by a transceiver: of the OLT (1).
展开▼
