| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To shorten the time required for switching to a spare transfer path when a main transfer path fails. <P>SOLUTION: By preparing a spare transfer path on each link on the main transfer path, the path can be switched over on a middle node. When setting the spare transfer path, the link on the path for the main transfer path is excluded when the spare path on the link is calculated, whereby the main transfer path is divided into two partial path trees T1 including the starting point of the main transfer path and T2 not including the starting point. A temporary starting point coupling all nodes included in T1 is created. The shortest path to all of nodes passing through the main transfer path in T2 is calculated. Among the calculated shortest paths, the node is the minimum, which does not intersect with a link used by the main transfer path and, if the path is to serve as a spare transfer path, becomes incapable of receiving conventional communication through the main transfer path via the spare transfer path by the switchover of the path. The path with the minimum tree cost in the node is to serve as the spare transfer path. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
