Patent ID: 8031716

Claim:
A communication apparatus which performs communication between a first apparatus using IPv4 and a second apparatus using IPv6, comprising: an IP transmitter/receiver which receives a first message requesting an IPv4 address as an IP address of said second apparatus from said first apparatus and sends a second message inquiring of the IP address of said second apparatus to a manager apparatus which manages address information; and an address notification processor which receives a third message containing the IP address of said second apparatus, said third message being sent from said manager apparatus in response to said second message, wherein if the IP address of said second apparatus contained in said third message is an IPv6 address then the IPv6 address of said second apparatus is converted into an IPv4 address, corresponding to the IPv6 address of said second apparatus, and a fourth message containing the IPv4 address thus converted is sent from said IP transmitter/receiver to said first apparatus.