Mobile IP introduces the following new functional entities:
Mobile Node (MN)–Host or router that changes its point of attachment from one network to another.
Home Agent (HA)–Router on a mobile node's home network that intercepts datagrams destined for the mobile node, and delivers them through the care-of address. The home agent also maintains current location information for the mobile node.
Foreign Agent (FA)–Router on a mobile node's visited network that provides routing services to the mobile node while the mobile node is registered.