Path-finding device, path-finding method, and path-finding program

A route search device that searches for a 0-system route that is a main route and a 1-system route that is a redundant route, which are routes from a start point node to an end point node, in a network including a plurality of nodes connected by edges, the route search device comprising:

• one or more memory devices;
• and
• one or more central processors configured to perform operations including:
• storing cost and shared risk link group (SRLG) information set to each of the edges;
• setting a search section from the start point node via the end point node to the start point node again and divide the set search section into a plurality of sections;
• and
• creating a route of an entire search section by sequentially searching for a route in each section based on the cost set to each of the edges and create the 0-system route and the 1-system route by dividing the route of the entire search section at the end point node,
• wherein based on a route in each section being sequentially searched for, the one or more central processors is configured to perform operations including recording the searched route and the SRLG information of an edge indicated by the route, and based on a route in a next section being searched for, the one or more central processors is configured to perform operations including searching for a route that does not overlap with a route in a previous section and searching for a route in each section from the end point node to the start point node so that the SRLG information does not overlap with the SRLG information of the route searched for in each section from the start point node to the end point node.