Method and system for assigning home agent

A method for assigning a home agent, comprising:

• indicating, by a visited network, to a home network that the visited network supports the home agent assignment;
• receiving, by the visited network, authorization information from the home network, the authorization information indicates the visited network is authorized for assigning the home agent;
• and
• sending, by the visited network, information about an address of the home agent to a mobile node;
• wherein the information about the address of the home agent comprises information on an address of a home agent assigned by the visited network;
• wherein the information about the address of the home agent further comprises information on an address of a home agent assigned by the home network;
• wherein after receiving the authorization information for assigning the home agent from the home network, the method further comprises receiving a request message to obtain the home agent from the mobile node;
• and
• wherein the step of sending, by the visited network, the information about the address of the home agent to the mobile node comprises:
• sending, by the visited network, corresponding information about the address of the home agent to the mobile node according to the request message, if the request message indicates the home agent is excepted to be assigned by the visited network or by the home network;
• or
• sending, by the visited network, the information about the address of the home agent is assigned by the visited network and/or by the home network to the mobile node, if the request message does not indicate the home agent is excepted to be assigned by the visited network or by the home network.

A method for assigning a home agent, comprising:

• sending, by a mobile node, a request message to a visited network, the request message indicating that the mobile node expects to visit the home agent in the visited network;
• and
• receiving, by the mobile node, information about an address of the home agent in the visited network assigned and sent by the visited network;
• wherein the request message comprises an id-type of a Home Network Identifier Option in the request message that is set as 0 to indicate that the mobile node expects the home agent assigned in the visited network.

A visited network, comprising a first unit, a receiving unit, and a sending unit, wherein:

• the first unit is configured to indicate to a home network that the visited network supports a home agent assignment;
• the receiving unit is configured to receive authorization information from the home network, and is configured to receive a request message from a mobile node, the authorization information indicating that the visited network is authorized for assigning the home agent, wherein the request message indicates to obtain the home agent;
• and
• the sending unit is configured to send corresponding information about an address of the home agent to the mobile node according to the request message, if the request message indicates the mobile node expects to visit the home agent in the visited network or the home agent in the home network.

A mobile node, comprising:

• a transmitter, configured to send a request message to a visited network, the request message indicating that the mobile node expects to visit a home agent in the visited network;
• and
• a receiver, configured to receive information about an address of the home agent in the visited network assigned and sent by the visited network;
• wherein the request message comprises an id-type of a Home Network Identifier Option in the request message that is set as 0 to indicate that the mobile node expects the home agent assigned in the visited network.