Path calculation order deciding method, program and calculating apparatus

A program to let a computer storing shortest path group information which represents calculated shortest paths each of which is shortest path between a node pair, whose starting nodes are identical and terminating nodes are different from one another, by use of the plurality of nodes and paths between the node pairs and also storing topology information representing topology of the plurality of nodes about a network comprising a plurality of nodes,

• in a calculation step, select each particular node of the plurality of nodes, which is different from the starting node, in decreasing order of the numbers of the downstream nodes from the particular node in calculated shortest path between the node pair represented by the shortest path group information;
• and calculate, in response to each selection of the particular node, the shortest path between the node pair, which has, as its starting point, the selected particular node and has, as its terminating point, other each node of the plurality of nodes, by use of calculated shortest path between other node pair and the topology information.

A calculating apparatus which calculates, by use of calculated shortest path between a node pair about a network comprising a plurality of nodes, a shortest path between other node pair comprises:

• a memory medium storing shortest path group information which represents calculated shortest paths each of which is shortest path between the node pair, whose starting nodes are identical and terminating nodes are different from one another, by use of the plurality of nodes and each path between the node pair and also storing topology information representing topology of the plurality of nodes,
• and a calculation unit which selects each particular node of the plurality of nodes, which is different from the starting node, in decreasing order of the numbers of the downstream nodes from the particular node in calculated shortest path between the node pair represented by the shortest path group information;
• and calculates, in response to each selection of the particular node, the shortest path between the node pair, which has, as its starting point, the selected particular node and has, as its terminating point, other each node of the plurality of nodes, by use of calculated shortest path between other node pair and the topology information.