Patent ID: 6920137

Claim:
A method for notifying a first apparatus using IPv6 as a communication protocol of an IP address of a second apparatus using IPv4 as a communication protocol, comprising the steps of: receiving a first message requesting an IPv6 address as an IP address of said second apparatus, said first message being sent from said first apparatus; sending a second message inquiring of an IP address of said second apparatus to a manager apparatus which manages address information; when receiving a third message containing an IPv4 address of said second apparatus, said third message being sent from said manager apparatus in response to said second message, performing recognition that the IPv4 address thus received of said second apparatus differs in a protocol version from the IPv6 address requested by said first apparatus; converting the IPv4 address of said second apparatus into an IPv6 address corresponding to the IPv4 address of said second apparatus; and sending a fourth message containing the IPv6 address thus converted to said first apparatus as an IP address of said second apparatus, said IPv6 address thus converted having a same protocol version as that of the IP address requested by said first apparatus.