MIGRATION SUBSCRIBER LINE TERMINAL, TRANSFER METHOD AND OPTICAL ACCESS SYSTEM

A transition destination subscriber line terminal station device in an optical access system including: a transition source subscriber line terminal station device before device replacement; and the transition destination subscriber line terminal station device that is a device replacement destination, the transition destination subscriber line terminal station device including: a higher-level device side transition unit including a higher-level port for connecting to the higher-level device and a first transition port that transfers data transferred from the higher-level device to the transition source subscriber line terminal station device; a subscriber side transfer unit including subscriber side connection ports for connecting to one or more subscriber line terminal devices, and a second transition port that transfers data transmitted from the subscriber line terminal devices to the transition source subscriber line terminal station device; a transfer table setting unit that changes a setting of a transfer table in which a port at which data is received, a destination of the data, and a port of a transfer destination of the data are associated with each other; and a transfer control unit that performs data transfer to the transition source subscriber line terminal station device via at least the first transition port in accordance with the transfer table.