US Patent 7710863 Relay device

To provide a device and a method enabling a user to judge which route a path used at the present traces without being aware of whether the now-in-use path is a working path or a recovery path. A relay device positioned at a diverging node between the working path and the recovery path, when forwarding a message (e.g., a Path message and a Resv message each containing RRO) used for route trace, judges which type of path the path employed for forwarding the data at the present is coincident with and forwards the data to the relay device disposed on the in-use path, thereby actualizing the trace of the route used for forwarding the data at the present.