Method of measuring distance between equipments on lan and distance measuring apparatus

In measuring the distance and the positional relationship between the equipments on a LAN, a first equipment transmits a request packet to each of the other equipments at a predetermined interval of time. When each of the other equipments receives the request packet, it supplies the response packet to the first equipment. The first equipment calculates the distance between the first equipment and each of the other equipments on the basis of the time at which the request packet has been transmitted and the time at which the response packet has been received, and stores the calculated distance in the network structure information table NWT. Since the packet transmission speed changes in accordance with the traffic volume, the calculated distance is compared with the distance stored in the network structure information table NWT, and only when the calculated distance is shorter, it is stored in the network structure information table NWT.