Patent ID: 8488964

Claim:
A line control method to be implemented in an optical network having an optical line unit (OLT), an optical switching device connected to the OLT, and a plurality of optical network unit (ONU) connected to the optical switching device, the optical switching device having: a downlink optical switch that includes an input port connected to the OLT and N output ports respectively connected to the ONUs, and outputs a signal from the OLT to an output port selected from the N output ports by a control signal supplied from the OLT; and an uplink optical switch that comprises N input ports respectively connected to the ONUs and an output port connected to the OLT, and outputs an input signal from an input port selected by a control signal supplied from the OLT to the output port, the line control method comprising: a first step in which the OLT transmits a first message sequentially to the ONUs by controlling the downlink optical switch; a second step in which an ONUS that have received the first message consecutively transmit second messages; a third step in which the OLT controls the uplink optical switch so that optical signals transmitted from the ONUS are sequentially output to the OLT; and a fourth step in which, based on the second messages received in the third step, the OLT determines timing of transmission for the ONU that has transmitted the second message, and notifies the ONU of the timing of transmission.