ONU management method and optical line termination

A passive optical network system in which an optical line termination at a station side and plural optical network units at user side are connected through an optical fiber and an optical splitter, and communication between the optical line termination and each of the plural optical network units are performed using identifiers which the optical line termination assigned to each of the optical network units, wherein the plural optical network units have a unique number respectively and the unique numbers of the optical network units are different from each other,

• the optical line termination comprising:
• a first storage area in which at least the unique numbers and information relating to operation of the optical network units are stored correspondingly to the identifiers arbitrarily assigned to the optical network units;
• a second storage area in which the unique number of one of the optical network units as a replacement object is stored correspondingly to the identifier of the one optical network unit;
• and
• a replacement processing unit to perform a processing to replace the one of the optical network units by another optical network unit connected to the optical line termination,
• wherein in a case of replacing arbitrary optical network unit from among among the optical network units connected to the optical line termination by other optical network unit, the replacement processing unit of the optical line termination:
• receives a replacement instruction including the identifier assigned to a first optical network unit as the replacement object from an operation system;
• acquires a first unique number of the first optical network unit as the replacement object corresponding to the identifier from the first storage area, stores the acquired unique number into the second storage area, and deletes the first unique number from the first storage area;
• searches the first unique number or a second unique number of a second optical network unit newly connected instead of the first optical network unit as the replacement subject;
• judges whether the unique number acquired by the search is stored in the second storage area with reference to the second storage area;
• in a case where the second unique number is acquired thereby being judged that the acquired unique number is not stored in the second storage area, stores, into the first storage area, the second unique number correspondingly to the received identifier;
• and
• in a case where the first unique number is acquired thereby being judged that the acquired unique number is stored in the second storage area, repeats the searching, the judging and the storing into the first storage area.