Patent ID: 7546496

Claim:
A packet transmission device that is connected to a plurality of communication lines, and transmits a packet received, the packet transmission device comprising: a failure detecting unit that monitors a condition of the communication lines, and detects a failure in the communication lines; a packet receiving unit that receives a packet having a same transmission-destination address as an address corresponding to a failure port of a communication line in which the failure has been detected; a command generating unit that generates, when the failure detecting unit detects the failure in the communication line, a flooding command indicating that the received packet is to be sent from all the ports; a storing unit that stores the flooding command; a deleting unit that deletes, while the storing unit stores the flooding command, information of the failure port from port data indicating relationship between the transmission-destination address and a plurality of ports of the packet transmission device; and a packet transmitting unit that transmits, before the deleting unit completes deletion of the information of the failure port, the received packet from all of the ports according to the flooding command stored in the storing unit, and that transmits, after the deleting unit completes the deletion, the received packet from one of the ports according to the port data.