Patent ID: 8064365

Claim:
A relay node comprising: a receiving unit receiving a control message for a route trace, which contains route information about a path extending from an ingress node to an egress node and used for forwarding data, from an anterior node on the path; an editing unit, if a self-node is a border node located at a border of a route information shielding zone on the path, editing, in an undistinguishable status, information about the route information shielding zone of route information contained in the route trace control message received by said receiving unit; and a transmitting unit transmitting the route trace control message after being edited to a posterior node on the path, wherein said editing unit deletes the information about the route information shielding zone from the route information, the route information includes a list containing an identifier of a node through which the path extends and a flag indicating whether said node belongs to the route information shielding zone or not, and said editing unit specifies, based on the flag, said node belonging to the route information shielding zone in the list, and deletes the identifier of said specified node from the list.