Patent ID: 8345297

Claim:
A data communication system including an address management apparatus and a data communication apparatus capable of communicating with each other, said address management apparatus comprising: a destination storage portion to store address data having a destination address indicating an address of a destination and related information on said destination associated with each other, said data communication apparatus comprising: a data receiving portion to receive data from another apparatus; a local storage portion to store local address data having a destination address indicating an address of a destination and related information on said destination associated with each other; the data received from the another apparatus having a source address indicating an address of a source and related information about said source, a first local updating portion, in response to reception of the data by said data receiving portion, to rewrite said related information associated with the destination address in said local address data stored in said local storage portion corresponding to the source address included in said received data with the related information included in said received data; an update requesting portion, in response to reception of the data by said data receiving portion, to transmit an update request to said address management apparatus, said update request including the source address indicating an address of a source of the data received by said data receiving portion and related information on the source included in the data; an address data acquiring portion to transmit an address request to said address management apparatus and receive said address data from said address management apparatus; and a data transmitting portion to transmit data to said destination address included in said received address data, said address management apparatus further comprising: an updating portion, in response to reception of said update request from said data communication apparatus, to rewrite said related information associated with the destination address in the address data stored in said destination storage portion corresponding to said source address included in the update request with said related information included in said update request, said data communication apparatus further comprises: a second local updating portion, in response to reception of said address data from said address management apparatus by said address data acquiring portion, to rewrite said related information associated with said destination address included in said received address data by said local address data stored in said local storage portion with said related information associated with said destination address by said received address data, wherein said data transmitting portion in said data communication apparatus transmits data to said destination address included in said received address data or said local address data.