| 摘要 |
An OLT 2 transmits an inquiry frame for checking a link and checking a data accumulation amount from an ONU 4. The ONU 4 returns an inquiry response frame as a response. When the ONU 4 detects a state in which an uplink traffic is not present, the ONU 4 writes to that effect on the response frame and transmits the response frame to the OLT 2. The OLT 2 monitors a downlink traffic. When the OLT 2 recognizes, based on a result of the monitoring or the inquiry response frame, a state in which the uplink or downlink traffic is not present, the OLT 2 instructs the ONU 4 to transition to a low power consumption mode. When the ONU 4 receives the instruction, the ONU 4 transitions a function unit corresponding to instruction content to the low power consumption mode. When the ONU 4 does not receive the inquiry frame for a predetermined time, the ONU 4 transitions function units other than a function unit that performs communication control to the low power consumption mode. The OLT 2 stops the transmission of the inquiry frame while the subscriber side apparatus transitions to the low power consumption mode. |
