| 摘要 |
An optical communications system employs a plurality of optical nodes interconnected in an optical ring transmission configuration by at least two optical transmission media, for example, optical fiber. The at least two optical transmission media, in this example, provide optical service transmission capacity and optical protection transmission capacity. Efficient restoration of optical communications between optical nodes in the optical ring transmission configuration, after an optical transmission media failure, is realized by employing an autonomous optical restoration arrangement and technique. To this end, each node autonomously controls an optical switch matrix in the node in effecting the desired restoration without the need of switch control signals transmitted from any other node in the ring, from a main controller or from a central controller. Specifically, each optical node in the optical ring transmission configuration has the capability to detect the presence or absence of optical signals at its input optical ports. Upon detecting a loss of optical signal on an incoming service capacity port, the node autonomously switches its optical switch matrix configuration to route a copy of its outgoing optical signal in a direction away from the fault. Then, upon detecting the presence of an optical signal on an incoming protection capacity port, the node autonomously switches its optical switch matrix configuration to supply the optical signal incoming on the protection capacity port to terminal equipment associated with the node. Additionally, each node has the capability of detecting a change of signal state at its protection capacity input ports. Upon a change from no signal to detection of an optical at a protection capacity input port, the node autonomously switches the switch matrix to pass the detected optical signal through to a protection capacity output port. A technical advantage of the invention is that through the autonomous switching of the node optical switch matrix transitions between switching states are faster thereby resulting in faster overall restoration in the optical ring transmission configuration. Furthermore, restoration is still effected even if the node main controller is out of service for maintenance or otherwise.
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