Optical communication system and communication bandwidth control method

In the communication system, a master station is coupled to slave stations by a fiber network comprising a splitter and a reach extender, the master station includes a first bandwidth control section which determines, based on a request from each slave station, a first data amount of a signal transmitted in a first cycle, the reach extender includes: a distance measurement section which measures a distance or a time between the reach extender and each slave station; and a second bandwidth control section which determines a second data amount and transmission timing of a signal based on a request from each slave station and the first data amount, and each slave station transmits a signal with a data amount, which the first bandwidth control section determined based on a data amount and transmission timing determined in second cycles, to the master station in the first cycle.