A obstruction determination process by a program stored in a recording medium comprises (i) in cases in which a connection data has been received from a plurality of transfer devices connected to a non-transmitting transfer device which is not transmitting the connection data, identifying a non-transmitting transfer device transfer path on which the non-transmitting transfer device is positioned; and (ii) determining for each of the identified transfer paths whether or not an obstruction has occurred on the identified transfer path, and in cases in which the identified transfer path is the non-transmitting transfer device transfer path identified, employing the transfer volume data that has been received from another transfer device positioned on the non-transmitting transfer device transfer path as the transfer volume data of the non-transmitting transfer device to determine whether or not an obstruction has occurred on the identified transfer path.