Patent ID: 7403520

Claim:
A method of routing each of a plurality of IPv4 multicast packets transmitted through an IPv4 network to a plurality of IPv6 networks, the method comprising the steps of: receiving from an arbitrary one of the plurality of IPv6 networks a message requesting a reception of an IPv6 multicast packet; when the IPv6 multicast packet, the reception of which has been requested, is generated by conversion of one of the plurality of IPv4 multicast packets, matching the arbitrary IPv6 networks that have transmitted the message with a part of header information of the one IPv4 multicast packet and storing them in memory, the arbitrary IPv6 networks being taken as a network requesting the reception of the IPv6 multicast packet; receiving one of the plurality of IPv4 multicast packets; converting the received IPv4 multicast packet into the IPv6 multicast packet including converting an IPv4 header of the received IPv4 multicast packet into an IPv6 header based on a relation between IPv4 multicast addresses and IPv6 multicast addresses and generating the IPv6 multicast packet; and transmitting the IPv6 multicast packet that was generated by the conversion to the IPv6 networks that were matched with a part of the header information of the received IPv4 multicast packet and which was stored in memory.