An information processing apparatus retains topology information indicating how all nodes are connected in a predetermined target area within a network divided into plural areas. The information processing apparatus includes an ingress/egress determining unit that determines, by referring to connected area information indicative of which area an area border node is connected to, an ingress-node group and an egress-node group, a disjoint determining unit that determines, by referring to the topology information, whether two or more disjoint routes from a node(s) of the ingress-node group to reach a node(s) of the egress-node group are present, a summarized-information generating unit that generates summarized information indicating a route from the adjacent area through the target area to the other adjacent area according to determination result by the disjoint determining unit, and a summarized-information reporting unit that reports the summarized information to another area.