Patent ID: 7085270

Claim:
A communication network for connecting a plurality of networks conforming to a first protocol by an address translation unit, wherein the address translation unit mutually translates the first protocol and a second protocol inside the address translation unit, has information and communication means necessary for communication with a server unit, and cooperates with the server unit to prepare and stores translation information containing a correspondence relation between an address in the first protocol and an address in the second protocol, in accordance with information provided by a Domain Name Service-Application Level Gateway (DNS-ALG) unit connected to the address translation unit, the DNS-ALG unit managing the translation information necessary for translation represented by a correspondence relation between the first protocol and the second protocol; the server unit includes the translation information necessary for mutual translation of the first and second protocols in the address translation unit, an address conforming to the second protocol in correspondence to the network conforming to the first protocol, and communicates with another server unit or another address of the server unit in order to prepare the translation information; and in communication from a first network conforming to the first protocol to a second network conforming to the second protocol, the address translation unit refers to the translation information to translate the address conforming to the first protocol to the address conforming to the second protocol, and to further translate the translated address conforming to the second protocol back to the address conforming to the first protocol.