A switch which includes a plurality of ports, each being assigned to any of VLAN groups, and outputs a packet received at any of the ports, the switch include: recording means in which partition information and an address table are recorded, the partition information indicating which of extended VLAN groups into which the ports are further logically partitioned, and the address table containing an entry in which a destination address, an output port, a VLAN group, and an extended VLAN group are associated with each other; acquisition means for acquiring a source address and acquiring group information of a VLAN; identification means for identifying group information of an extended VLAN; and registration means for registering in the address table the source address acquired by the acquisition means as the destination address, the port, the group information of the VLAN, and group information of the extended VLAN group.