A method is provided for managing mobility of an Access Terminal (AT) in a mobile communication
system using a
Mobile Internet Protocol (MIP). The method includes generating, by an AT that has entered a new network, a
Security Parameter Index (SPI) and a security key for
mutual authentication with a Home Agent (HA) of the new network, sending, by the AT, a registration request message including
authentication information including the SPI, the
authentication information being generated using the security key, upon
receipt of the registration request message, searching, by the HA, a
database for the SPI included in the
authentication information, verifying the
authentication information according to the search result, upon successful
verification of the
authentication information, generating, by the HA, mobility binding information of the AT, and sending, by the HA, a registration response message including the HA's
IP address.