Patent ID: 8520574

Claim:
A protocol translating method, the method comprising: transmitting packets between a first terminal belonging to a first network that transfers packets using a first protocol and a second terminal belonging to a second network that transfers packets using a second protocol; upon the first terminal moving to belong to a third network that transfers packets using the first protocol and transmitting a packet having the second terminal specified as a destination according to the first protocol in the third network, identifying address translation information that was used by the first terminal when the first terminal belonged to the first network during packet communication with the second terminal belonging to the second network; updating an address of the first terminal in the identified address translation information using a source address of the packet to form updated address translation information; translating the packet according to the first protocol to a translated packet according to the second protocol by using the updated address translation information to translate a destination address of the packet according to the first protocol to an address according to the second protocol; and transmitting the translated packet according to the second protocol to the second terminal.