| 摘要 |
PROBLEM TO BE SOLVED: To protect preferential communication, when damage or a failure occurs by constructing an optical communication network with internal and external optical fiber links whose the carrier directions are reverse, termination communication channels of their 1st and 2nd parts, a detection circuit and plural light switches. SOLUTION: When a failure occurs, light switches 131 to 134 on nodes A/B are energized, and optical entrances of receivers RX1 and optical exits of transmitters TX1 are disconnected from use ring paths and are connected to complementary paths. Receivers RX2 and transmitters TX2 are disconnected from a communication network. The node A transmitter TX1 redetermines its direction to the node A communication device TX2 and transmits it up to the node B transmitter RX2 along an external fiber 110 via a generic node Y. The node B transmitter TX1 redetermines its direction to the node B transmitter TX2, so as to transmit it up to the node A receiver RX2 on an internal fiber 120, and the receivers RX2 redetermine their direction to the receivers RX1. |
