| 摘要 |
PROBLEM TO BE SOLVED: To realize a system whose redundancy is reduced including excessively redundant points which are not used by the present system, and to reduce a time and labor required or system construction and maintenance, and to reduce system costs as a result. SOLUTION: A ring network is divided into two first and second blocks, and intervals among nodes (node A - node F - node E) belonging to the first block are the spans connected by ether a present line or a preliminary line, and those among nodes (node B - node C - node D) belonging to the second block are the spans connected by the present line and the preliminary line, and the present line and the preliminary line are constituted as physically different cables, and installed on different paths. |
