Patent ID: 7191226

Claim:
A method for routing data packets to a mobile node in a communication system which includes at least a first subnetwork of a first type supporting a first IP version and a second subnetwork of a second type supporting a second IP version, the method comprising attaching the mobile node to a foreign network of the first type supporting only the first IP version, the foreign network having a foreign agent supporting the first IP version registering the mobile node's care-of address in the foreign network with a home agent located in said mobile node's home network; providing the mobile node with a set of protocol stacks for handling data packets at least according to the first and the second IP version so that the mobile node supports both the first IP version and the second IP version; providing the mobile node with a home address at least according to the first and the second IP version; providing the home agent with means for intercepting at least data packets addressed to the mobile node's home address according to the first and the second IP version so that the home agent supports both the first IP version and the second IP version; and encapsulating in the home agent a data packet addressed to the mobile node's home address according to the second IP version in a packet according to the first IP version, thereby providing an encapsulated data packet, encapsulating in the home agent the encapsulated data packet in a further data packet according to the first IP version, thereby providing a twice-encapsulated data packet, routing the twice-encapsulated data packet to the foreign agent of the foreign network of the first type decapsulating the twice-encapsulated data packet in the foreign agent, thereby extracting the encapsulated data packet, routing the extracted encapsulated data packet to the mobile node over the foreign network of the first type, decapsulating the restored extracted data packet in the mobile node, thereby extracting the data packet addressed to the mobile node's home address according to the second IP version.