The central terminal and a frame transfer method

A table (22), the transfer instruction information indicating the destination of the transmission system of the identifier information (LLID) and downlink frames of ONU, are registered for each destination ID of the user device or ONU connected to the ONU. When receiving a downlink frame from the higher-level device, the frame transfer processing unit (20), the LLID and transfer instruction information corresponding to the destination ID of the downlink frame, and acquires from the table (22).