Patent ID: 7486951

Claim:
A method of dynamically assigning external home agent (x-HA) for mobile Virtual Private Networks (VPNs), the method establishing VPN between at least one external network and an internal network and enabling at least one mobile node (MN) to roam in the external networks with security, the method comprising the steps of: the MN sending a Registration Request (Reg-Req) message to an external foreign agent (x-FA) when the MN roams to the external network for the first time, wherein the Reg-Req message comprises fields including an external home address (x-HoA) request, and an external home agent (x-HA) address request; the x-FA sending an AA-Mobile-Node-Request (AMR) message to a foreign authentication, authorization and accounting (AAAF) server, the AAAF server requesting a home authentication, authorization, and accounting (AAAH) server to assign a candidate x-HA by sending the AMR message to the AAAH server acting as an agent assigner; the AAAH server establishing security associations (SAs) among the candidate x-HA, the x-FA and the MN and generating a first Home-Agent-Mobile Internet Protocol Request (Home-Agent-MIP-Request) (HAR) message for sending with the Reg-Req message to the candidate x-HA; the x-HA allocating an external home address (x-HoA) for the MN and filling the x-HoA and its x-HA address thereof in a first Home-Agent-MIP-Answer (HAA) message, the x-HA then sending the first HAA message to the AAAH server; the AAAH sever establishing a second HAR message using a pre-configured Virtual Private Network-Tunnel Inner Address (VPN-TIA) as an internal Care Of Address (CoA) of the MN for registration to an internal-Home Agent (i-HA), the i-HA generating a second HAA message to acknowledge the second HAR message; the AAAH server receiving both the first and the second HAA messages, and sending an AA-Mobile-Node-Answer (AMA) message to the x-FA; and the x-FA obtaining a Reg-Reply message from the AMA message and containing the allocated x-HoA and the x-HA address; and sending the Reg-Reply message to the MN; when the MN roams in the external network, the MN uses the x-HoA for registration to the assigned x-HA with the x-HA address.