| 摘要 |
PROBLEM TO BE SOLVED: To provide a ring system, which can effectively utilize auxiliary resources to be used in the case of fault or maintenance and reduces a delay difference between active and detour paths at the time of maintenance. SOLUTION: When a disconnection fault occurs on the optical fiber of an active ring 101 between nodes 106 and 109 in the state of constituting the ET path of wavelength λ1 from the node 109 to a node 107 on a reserve ring 104, a supervisory controller in the node 107 detects the fault on an optical path 601, performs messaging to related nodes in order to disconnect a short path (reserve path 602) on the reserve ring 104 and disconnects the ET path of wavelength λ1 from the node 109 to the node 107. When the disconnection of the ET path is confirmed, the node 107 requests the transmission of main signal light through the reserve ring 104 to the node 106. According to that request, at the node 106, an optical switch is changed over for sending light to the reserve ring 104 as well. |
