| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a line restoration system, where a substitute transmission line of a transmission block having a fault is obtained by the procedure of path control in a packet routing network, in which transmission lines are installed in a broad area or over a long distance with redundancy and to provide a packet transfer unit conducting the path control by which substitute paths for all paths which are formed logically in a transmission block having the fault can efficiently be secured at a low cost. SOLUTION: Occurrence of a fault disturbing transmission is individually monitored for a transmission block which follows transmission lines with redundant configuration, and when a fault of a specific transmission line continues, the attribute of a packet to be relayed from the preceding transmission block of the specific transmission line to the succeeding transmission block as a connectionless service is discriminated. When the attribute signifies an object of the best-effort type service, transmission lines, other than the specific transmission line among a plurality of the transmission lines, is used to relay the packet.</p> |
