Disclosed is a system providing a VPN service by connecting a VPN (virtual Private Network) to a mobile communication network. A home agent (HA) stores location information of a mobile node (MN) and information on whether the MN is registered in the VPN. A foreign agent (FA) transmits a location registration...http://www.google.de/patents/US7512687?utm_source=gb-gplus-sharePatent US7512687 - System and method for assigning a mobile IP to a mobile node
