Patent ID: 8149807

Claim:
A communication system having one or more home agents provided in a first provider providing a mobility service and a home agent allocation server provided in the first provider, and causing a mobile node to acquire a home address from a home agent, the communication system comprising: a section that causes the home agent allocation server to hold, in advance, correspondences between the one or more home agents and a second provider providing an access service; a section that causes the mobile node which is connected only to the second provider to transmit, to an address of the home agent allocation server, a home agent allocation request message including identification information of the second provider to which the mobile node is currently connected; and a section that causes the home agent allocation server to select a home agent based on the held correspondences between the one or more home agents and the second provider in response to the home agent allocation request message including the identification information of the second provider and transmit a notification of the selected home agent to the mobile node, wherein the mobile node acquires a home address from the selected home agent.