Patent ID: 7630374

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 includes a function of mutually translating the first protocol and a second protocol inside the address translation unit, information and communication means necessary for communication with a server unit, and a function of cooperating with the server unit to prepare translation information containing a correspondence relation between an address in the first protocol and an address in the second protocol; the server unit includes 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 a function of communicating with another server unit or another address of the server unit in order to prepare the translation information; 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 to the address conforming to the first protocol; the address translation unit connects the first and second networks in accordance with information provided by a DNS-ALG unit connected with the address translation unit through an IP network; and the DNS-ALG unit is arranged so as to be shared by each of the first and second networks and the address translation unit.