Abstract: In a switch supporting a multiple spanning tree protocol and a bridged network formed of such a switch, the switch includes a default spanning tree in a multiple spanning tree, transmits, upon receipt of a frame having an individual destination address from a terminal side, an inquiry frame to a destination terminal of the individual destination address through the default spanning tree, transmits inquiry response frames to all of the spanning trees in the multiple spanning tree if the destination terminal is connected to the switch, and selects an optimum spanning tree based on information in the inquiry response frames from all of the spanning trees.