An intermediate node device, for which a method of control is provided and of which a provided network system includes a plurality, may receive a data packet from an upper intermediate node device and generate a first acknowledgement (ACK) message and a second ACK message with respect to the received data packet. Also, the intermediate node device may transmit the first ACK message to the upper intermediate node device, and transmit the second ACK message to an upper intermediate node device which is separated by a predetermined number of hops.