| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and device for optical transmission, by which the relay of optical signals can be performed easily at an arbitrary node on the way of a detouring route which is set, when a fault occurs in when the detouring route exceeds a limit transmitting distance, at the time of transmitting a plurality of optical signals, having different wavelength for a long distance between a plurality of node devices connected to each other in a ring-like state by multiplexing the signal upon another. SOLUTION: When the transmitting distance through the detouring route which is when a fault occurs in a transmission line between nodes exceeds a prefixed limit transmitting distance at the time of transmitting multiplexed optical signals through the detouring route, a node device is selected as the relay node of the optical signals, based on the distance between node devices on the way of the detouring route, and the selected node device is caused to relay the optical signals to be transmitted through the detouring route, by restoring the optical signals by using an already existing electrical signal level processing function section. |
