A communication device includes a processor. The processor updates, when a port which is received a packet is connected to a first path or a second path, an identifier assigned to the packet from a value according to the path to a first value or a second value. The processor learns a correspondence relationship between a destination address of the packet and a transmission port by flooding the packet, and determines the transmission port based on the correspondence relationship. The processor updates, when the transmission port is connected to the first path or the second path, the identifier assigned to the packet of which the transmission port is determined to a value according to the first path or the second path. The processor discards the packet of which the identifier is updated to the second value by the first process and the transmission port is connected to the second path.