PON SYSTEM, AND REGISTRATION METHOD OF TERMINAL DEVICE

PROBLEM TO BE SOLVED: To quickly and reliably register a terminal device which intends to subscribe to a PON system.SOLUTION: A PON system carries out communication at a plurality of types of transmission rates (L, M, H) in an upstream direction from a plurality of terminal devices 2 to 4 connected with a station-side device 1 via optical fibers 5 and 7 to 9. In the PON system, within a discovery period for causing the station-side device 1 to recognize an unregistered terminal device, the terminal device carries out discovery response at one type transmission rate (L). Thus, the station-side device 1 can wait the discovery response while causing a receiving function of the station-side device 1 to correspond to the transmission rate (L).