Patent ID: 8737238

Claim:
A congestion detection method for a network where a forward path and a return path are set up, the forward path leading from a reference node to a turn node via at least one relay node, the return path leading from the turn node to the reference node via at least the one relay node, the method comprising: transmitting an inspection signal including inspection information corresponding to an inspection of one of forward-path communication and return-path communication, from the reference node, the inspection information including target address information; transmitting a response signal to the inspection signal in a priority class from one or more of the relay node and the turn node of the forward path to the reference node based on the target address information; transmitting a replica of the response signal in a non-priority class from one or more of the relay node and the turn node of the forward path to the return path, and transferring the replica in a priority class to the reference node by using the relay node that receives the replica of the response signal, when the inspection information of the inspection signal corresponds to the inspection of return-path communication; transmitting a replica of the inspection signal in a non-priority class from the relay node of the forward path to the forward path, and transmitting a replica of the response signal in a priority class from one of more of the relay node and the turn node that receive the replica of the inspection signal to the reference node, when the inspection information of the inspection signal corresponds to the inspection of forward-path communication; and calculating, by a controller of the reference node, a difference between time needed for a response signal, which is transmitted from the relay or turn node, to arrive at the reference node and time needed for a replica thereof, which is transmitted from the same relay or turn node, to arrive at the reference node, and determining, when the arrival-time difference exceeds a threshold value, that congestion occurs in forward-path or return-path communication of the relay or turn node.