A mobile node that is in communication with a correspondent node via a
home agent initiates a process for establishing a route optimized mode of
communication between the mobile node and the correspondent node. The
mobile node sends a first initiating message to the home agent for
delivery to the correspondent node and sends a second initiating message
directly to the correspondent node. The mobile node secures the first
initiating message by including an initiating-message authentication code
that can be validated by the home agent or by an authentication server.
The correspondent node responds by sending a first responsive message to
the home agent for delivery to the mobile node and by sending a second
responsive message directly to the mobile node. The home agent secures
the first responsive message by adding a responsive-message
authentication code that can be validated by the mobile node.