The disclosed mobile communication scheme enables easy change of a connected
location of a mobile computer on the IP network when the mobile computer leaves
its home network, without requiring the use of a home agent, while providing a
sufficient level of security. The mobile computer transmits a packet from a visited
site network to a correspondent by encapsulating an inner packet having a home
address as an original source address within an outer packet having a current location
address as a source address. The correspondent which received this encapsulated
packet recognizes the source addresses of the outer and inner packets of the encapsulated
packet as the current location address and the home address of the mobile computer,
respectively, so that the correspondent can transmit a packet to the mobile computer
thereafter by encapsulating an inner packet having the home address as a final
destination address within an outer packet having the current location address
as a destination address.
