Abstract: Identifier information (LLID) of an ONU and transfer instruction information indicating a transmission system as the output destination of a downstream frame are registered in a table (22) in correspondence with each of the destination IDs of the ONUs or user apparatuses connected to the ONUs. Upon receiving a downstream frame from a host apparatus, a frame transfer processing unit (20) acquires an LLID and transfer instruction information corresponding to the destination ID of the downstream frame from the table (22).

Abstract: In a control frame processing unit (14), the number of control frames from a frame demultiplexing unit (13) is counted for each of LLIDs given to the control frames. If the number of frames during a predetermined count period is equal to or smaller than a preset threshold, some or all of the control frames are written in a storage device (30) as processing data. When the number of frames has exceeded the threshold, writing data of the control frames having the LLID in the storage device is stopped. Hence, even when the number of control frames from ONUs increases, software processing can be executed properly.

Abstract: Out of one constantly fed block (B0) and one power saving block (B1) provided by dividing in advance circuit units constituting an OLT (10), a power supply control unit (40) constantly supplies power to circuit units belonging to the constantly fed block. For circuit units belonging to the power saving block, the power supply control unit starts power supply to the power saving block starts in synchronism with the start of the period of an upstream bandwidth allocated to each ONU, and stops the power supply to the power saving block in synchronism with the end of the period of the upstream bandwidth. The power supply control unit starts power supply at a timing specified based on the start timing of the upstream bandwidth, and stops the power supply at a timing decided based on the end timing of the upstream bandwidth. This reduces the power consumption of an overall OLT.

Abstract: In a control frame processing unit (14), the number of control frames from a frame demultiplexing unit (13) is counted for each of LLIDs given to the control frames. If the number of frames during a predetermined count period is equal to or smaller than a preset threshold, some or all of the control frames are written in a storage device (30) as processing data. When the number of frames has exceeded the threshold, writing data of the control frames having the LLID in the storage device is stopped. Hence, even when the number of control frames from ONUs increases, software processing can be executed properly.

Abstract: Identifier information (LLID) of an ONU and transfer instruction information indicating a transmission system as the output destination of a downstream frame are registered in a table (22) in correspondence with each of the destination IDs of the ONUs or user apparatuses connected to the ONUs. Upon receiving a downstream frame from a host apparatus, a frame transfer processing unit (20) acquires an LLID and transfer instruction information corresponding to the destination ID of the downstream frame from the table (22).