| 摘要 |
<P>PROBLEM TO BE SOLVED: To compose a ring system in which using efficiency of ET path is high during trouble or maintenance time, composition of an alternative route with a little delay difference is possible, high speed trouble recovery is possible even for an ultra long distance ring according to the trouble condition, and reliability at trouble time is high. <P>SOLUTION: In a condition that an ET (Extra Traffic, Stand-by Access) path of wave length λ1 is composed between a node 109 to a node 107 on a stand-by ring 104, if a disconnection trouble occurs in an optical fiber of an active ring 101 between a node 106 and the node 109, a supervisory control device in the node 107 detects the trouble in the optical path 601, carries out messaging to relating nodes, and separates the ET path from the node 109 to the node 107 in order to carry out separation of a short path (stand-by path 602) on the standby ring 104. If the node 107 confirms separation of the ET path, it requests sending of a main signal light to the node 106 via the stand-by ring 104. The node 106 changes over an optical switch to send the light also to the stand-by ring 104 in accordance with the request. In this method, stand-by resources which are used in trouble or maintenance time, can be used effectively used, and a system in which the delay difference of active path and the stand-by path during maintenance time can be composed. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
