Optical subscriber network system and fault supervising method for optical subscriber network system

An optical subscriber network system of a passive optical network construction wherein a plurality of network units are accommodated in a station apparatus through an optical transmission line using a passive optical element, comprising:

• bypass transmission lines for mutual supervision control between said network units;
• a faulty network unit which is any one of said network units which is not capable of communicating with said station apparatus through said optical transmission line including transmission means for transmitting a network unit mutual supervision control signal to one of non-faulty ones of said network units other than the faulty network unit through an available one of said bypass transmission lines;
• the non-faulty network unit including means for transmitting the network unit mutual supervision control information received from the faulty network unit to said station apparatus through said optical transmission line connected to the non-faulty network unit;
• said station apparatus including means for supervising a fault from the network unit mutual supervision control information.

A fault supervising method for an optical subscriber network system of a passive optical network construction wherein a plurality of network units are accommodated in a station apparatus through an optical transmission line using a passive optical element, comprising the steps of:

• providing bypass transmission lines for mutual supervision control between said network units;
• communicating a network unit mutual supervision control signal between said network units through said bypass transmission lines;
• transmitting the network unit mutual supervision control information received by each of said network units to said station apparatus through said optical transmission line;
• and
• supervising a fault based on the network unit mutual supervision control information by said station apparatus.