LIGHT WAVELENGTH BRANCH/INSERT DEVICE AND TROUBLE RECOVERING METHOD

摘要

A light wavelength branch/insert unit and a trouble recovering method capable of realizing high-speed switching of a transmission line due to trouble of the transmission line and having the best receiving characteristic at all times without being affected by switching of the transmission line in a ring network having a redundant transmission line of an operating system and a standby system. The light wavelength branch/insert device is arranged at each node in a ring network consisting of first and second ring transmission lines through which optical signals are transmitted in the opposite directions. The device having an optical receiver for receiving an optical signal from a ring transmission line selected according to a path switch signal from the first and second ring transmission lines is provided with a means for setting an optimal reception threshold in the selected ring transmission line.