Device switching method and optical communication system

A device switching method to be performed in an optical communication system, the device switching method comprising:

• connecting a switching source optical subscriber line terminal station device to a first port of M first ports of an optical branching unit;
• connecting a switching destination optical subscriber line terminal station device to any one of remaining first ports of the M first ports;
• and
• starting communication by the switching destination optical subscriber line terminal station device after setting, for the switching destination optical subscriber line terminal station device, setting information which is set for the switching source optical subscriber line terminal station device,
• wherein the optical communication system includes an upper-layer device, the switching source optical subscriber line terminal station device that is a device switching source, the switching destination optical subscriber line terminal station device that is a device switching destination, and the optical branching unit to which the switching source optical subscriber line terminal station device and the switching destination optical subscriber line terminal station device are connected, and
• wherein the optical branching unit has a branching ratio of M:N (M and N are integers equal to or larger than 2) and has the M first ports and N second ports.