Patent ID: 7116681

Claim:
A method of establishing a tunnel from a first interface between a first network and a second network to a second interface between the second network and a third network, the first and third networks operating in accordance with a first transmission protocol and having addresses in accordance with a first addressing convention, and the second network operating in accordance with a second transmission protocol and having addresses in accordance with a second addressing convention, the tunnel being for the transport of messages from a first host on the first network to a second host on the third network, the method comprising: sending from the first host an address request message in accordance with the first transmission protocol, referred to herein as a first type address request message, containing the name of the second host; upon receipt of the address request message at a name to address conversion system of the third network, returning an address response message in accordance with the first transmission protocol, referred to herein as a first type address response message, and containing the address of the second host in a response address field; upon receipt of that first type address response message at the second interface, converting it to an address response message in accordance with the second transmission protocol, referred to herein as a second type address response message; and augmenting that converted second type address response message by fields respectively containing the address of the second interface in accordance with the second addressing convention and the address of the second host in accordance with the first addressing convention; and upon receipt of that augmented that converted second type address response message at the first interface, converting it to a first type address response message, retrieving the contents of the augmenting fields, storing at the first interface a mapping of the retrieved address of the second host and the retrieved address of the second interface for use in encapsulating messages from the first host addressed to the second host, and replacing the content of the response address field of the resulting first type address response message by the retrieved address of the second host.