A technology is disclosed for appropriately providing a certain service desired by a mobile node, even in an environment including overlay network nodes providing different functions. In the technology, a mobile node (MN) 110 implements Monami6 protocol and transmits a binding update message requesting a service based on the Monami6 protocol. On the other hand, an overlay network is present on a network, the overlay network in which a home agent (MCHA) implementing the Monami6 protocol and a home agent (MSHA) not implementing the Monami6 protocol cooperate to provide functions of an HA. In this instance, for example, an MSHA 150 that receives a message from the mobile node via a path 112 sends the request to an MCHA implementing the Monami6 protocol (such as an MCHA 130) and makes the MCHA process the request.