Patent ID: 7486670

Claim:
A method for packet communication, comprising: before a first node moves from a first network to a second network receiving a first packet from said first node in said first network by a first address changing device in said first network, said first packet including a private sender address corresponding to said first node and destination address information corresponding to another node in a third network, changing said private sender address of said received first packet by the first address changing device from said private sender address to a global address, the changing performed by mapping the global address to the private sender address with first translation information held within said first address changing device, and sending the changed first packet from the first address changing device to the another node; after said first node moves from said first network to said second network receiving a second packet from the first node by a second address changing device in said second network, said second packet including said private sender address and said destination address information corresponding to the another node in the third network, sending a notification message from the second address changing device to the first address changing device indicating that the first node has contacted the second address changing device, sending sender address translation information from said first address changing device to said second address changing device so as to create second translation information in said second address translation device, changing said private sender address of said received second packet by the second address changing device from said private sender address to said global address, the changing performed by mapping the global address to the private sender address by said second translation information held within said second address changing device; and sending the changed second packet from the second address changing device to the another node; and periodically exchanging updated translation information between said first and second address changing devices.