A node (10N) receives, from a center node (10C), a request packet including a data part in which a MAC address and position information of the center node (10C) are described, determines whether or not there is a request destination node, where determining that there is the request destination node, additionally describes a MAC address and position information of the node (10N) itself in the data part, and transmits the request packet to the request destination node, where determining that there is no request destination node, determines that the node (10N) itself is a terminal node (10N3), where determining that the node (10N) itself is the terminal node (10N3), generates a reply packet including a data part in which all of MAC addresses and all pieces of position information described in the data part of the request packet are described, and transmits the reply packet to a request source node.
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