PON system, station side device and method for operating the same, and access control device

A station side device that configures a PON system with a plurality of customer side devices, the station side device comprising:

• a first optical transmitting and receiving unit, comprising a first optical transceiver, connectable to a first PON line;
• a second optical transmitting and receiving unit, comprising a second optical transceiver, connectable to a second PON line;
• a first processor of a first access control unit that is programmed to perform normal line control and multiple-line control, the normal line control being upstream multiple access control for the first PON line, and the multiple-line control being the upstream multiple access control for the first and second PON lines;
• a second processor of a second access control unit that is programmed to perform normal line control, the normal line control being the upstream multiple access control for the second PON line;
• an upper switch provided on an upper side of both of the access control units;
• a lower switch provided between both of the access control units and both of the optical transmitting and receiving units;
• and
• a third processor of a fallback control unit that is programmed to switch both of the switches in a manner shown in following (a) and (b):
• (a) output destinations of downstream frames to the first and second PON lines inputted to the upper switch are aggregated into the first access control unit, and output destinations of the downstream frames inputted from the first access control unit to the lower switch are distributed to the first and second optical transmitting and receiving units;
• and
• (b) output destinations of upstream frames inputted from the first and second optical transmitting and receiving units to the lower switch are aggregated into the first access control unit.