Abstract: A monitoring node periodically transmits an active/inactive monitoring signal to selection target nodes. Upon receipt of the active/inactive monitoring signal, each selection target node calculates a current subscriber accommodated ratio, which is load information, creates an active/inactive monitoring response signal based on the load information, and transmits the active/inactive monitoring response signal to the monitoring node. Upon receipt of the active/inactive monitoring response signal from the selection target node, the monitoring node extracts the load information from the active/inactive monitoring response signal, determines the relevant acquisition ratio based on the load information, and performs the selection procedure of a destination node based on the determined acquisition ratio.