WO2008120068A2

WO2008120068A2 - Mechanism to select and assign a home agent to a mobile node

Info

Publication number: WO2008120068A2
Application number: PCT/IB2008/000724
Authority: WO
Inventors: Meghana Sahasrabudhe; Yinghua Ye; Kevin Tang; Cedric Westphal; Naheed Vora
Original assignee: Nokia Corporation; Nokia, Inc.
Priority date: 2007-03-30
Filing date: 2008-03-27
Publication date: 2008-10-09
Also published as: WO2008120068A3; WO2008120068A9

Abstract

Various embodiments for addressing lists of home agents are disclosed, together with associated methods, computer programs, apparatuses, and the like. For example, an apparatus can include a communicator configured to communicate with home agents in a communication network regarding home agent ability. The apparatus can also include a monitor configured to monitor for a registration request from a user equipment. The apparatus can further include a processor configured to process the registration request to identify whether the apparatus is a best home agent based on home agent ability and the registration request. The communicator can be configured to respond to the registration request when the apparatus is the best home agent. The apparatus can itself be a home agent.

Description

TITLE OF THE INVENTION:

MECHANISM TO SELECT AND ASSIGN A HOME AGENT TO A

MOBILE NODE

CROSS REFERENCE TO RELATED APPLICATIONS:

This application is related to and claims the priority of U.S. Provisional Patent Application 60/907,383 filed March 30, 2007, the entire content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION: Field of the Invention

Certain embodiments of the present invention are related to selecting and assigning a home agent from a plurality of home agents in a wireless communication network.

Background of the Related Art

The MobileIPv4 (MIPv4) protocol supports the ability for a network to have multiple home agents but it does not provide a mechanism to select and assign a specific home agent to a mobile node. Currently, there may be multiple home agents available and all home agents may respond to mobile node's registration request and in the end, mobile node selects one of these as the home agent (HA).

In the MobileIP protocol in general, it has been recognized that the home agent becomes a bottleneck when there are a number of mobile nodes registered with it. This is due to the fact that all incoming traffic for the mobile node has to be processed by the home agent to be sent to the mobile node's current point of attachment. Also, when a mobile node is using a reverse tunneling mechanism, as can be the case when the mobile node wants to hide its current point of attachment for example, the reverse traffic also flows through the home agent. This traffic is in addition to the binding and associated information that a home agent has to maintain for the mobile node. If there is any failure at the home agent, all the registrations for mobile nodes on the network will be lost and all the mobiles will have to start with fresh registrations. This makes it a single point of failure in the network.

To alleviate this problem the Mobile IP protocol allows the use of multiple home agents on a network. The current MobileIPv4 specification, RPC 3344, specifies a mechanism to support multiple home agents. But in this mechanism all the home agents on a given network will respond to a mobile node and it is up to the mobile node's discretion to choose any home agent it wants.

The procedure for discovering a Home Agent as specified in the MIPv4 specification, however, does not assign a Home Agent to the Mobile Node. All Home Agents on the Home Link reject a mobile's registration when they notice that the mobile node is trying to get a Home Agent address and in the rejection each Home Agent adds its own internet protocol address. Based on the reject replies the mobile node receives, it chooses a Home Agent to send another registration to. MobilelPvό similarly describes a dynamic home agent discovery mechanism but does not provide an assignment mechanism.

SUMMARY OF THE INVENTION

One embodiment of the present invention is an apparatus. The apparatus can include a communicator configured to communicate with home agents in a communication network regarding home agent ability. The apparatus can also include a monitor configured to monitor for a registration request from a user equipment. The apparatus can further include a processor configured to process the registration request to identify whether the apparatus is a best home agent based on home agent ability and the registration request. The communicator can be configured to respond to the registration request when the apparatus is the best home agent. Another embodiment of the present invention can also be an apparatus. The apparatus can include communication means for communicating with home agents in a communication network regarding home agent ability. The apparatus can also include monitor means for monitoring for a registration request from a user equipment. The apparatus can further include processor means for processing the registration request to identify whether the apparatus is a best home agent based on home agent ability and the registration request. The communication means can be configured to respond to the registration request when the apparatus is the best home agent.

A further embodiment of the present invention can be a method. The method can include communicating, by a home agent, with other home agents in a communication network regarding home agent ability. The method can also include monitoring, by the home agent, for a registration request from a user equipment. The method can additionally include processing, by the home agent, the registration request to identify whether the home agent is a best home agent based on home agent ability and the registration request. The method can further include responding, by the home agent, to the registration request when the home agent is the best home agent.

An additional embodiment of the present invention is a computer- readable medium encoded with instructions that, when executed by a computer, perform a process. The process includes communicating, by a home agent, with other home agents in a communication network regarding home agent ability. The process also includes monitoring, by the home agent, for a registration request from a user equipment. The process further includes processing, by the home agent, the registration request to identify whether the home agent is a best home agent based on home agent ability and the registration request. The process additionally includes responding, by the home agent, to the registration request when the home agent is the best home agent.

An embodiment of the present invention can be a system that includes a user equipment and a plurality of home agents. Each home agent can include a communicator configured to communicate with other home agents in a communication network regarding home agent ability, a monitor configured to monitor for a registration request from a user equipment, and a processor configured to process the registration request to identify whether the home agent is a best home agent based on home agent ability and the registration request. The communicator can be configured to respond to the registration request when the home agent is the best home agent.

Another embodiment of the present invention is an apparatus. The apparatus includes a communicator configured to communicate with home agents in a communication network regarding home agent ability. The apparatus also includes a monitor configured to monitor for a registration request from a user equipment. The apparatus further includes a processor configured to process the registration request and to create a list of at least one home agent with corresponding home agent ability. The communicator can be configured to provide the list to the user equipment.

A further embodiment of the present invention is an apparatus including communication means for communicating with home agents in a communication network regarding home agent ability. The apparatus can also include monitor means for monitoring for a registration request from a user equipment. The apparatus can further include processor means for processing the registration request and to create a list of at least one home agent with corresponding home agent ability. The communication means can be configured to provide the list to the user equipment.

An additional embodiment of the present invention is a method. The method can include communicating, by a home agent, with other home agents in a communication network regarding home agent ability. The method can also include monitoring, by the home agent, for a registration request from a user equipment. The method can further include processing, by the home agent, the registration request. The method can additionally include creating, by the home agent, a list of at least one home agent with corresponding home agent ability. The method can also include providing, by the home agent, the list to the user equipment.

An embodiment of the present invention is a computer-readable medium encoded with instructions that, when executed by a computer, perform a process. The process can include communicating, by a home agent, with other home agents in a communication network regarding home agent ability. The process can also include monitoring, by the home agent, for a registration request from a user equipment. The process can additionally include processing, by the home agent, the registration request. The process can further include creating, by the home agent, a list of at least one home agent with corresponding home agent ability. The process can additionally include providing, by the home agent, the list to the user equipment.

Another embodiment of the present invention is a system that includes a user equipment and a plurality of home agents. Each home agent of the plurality of home agents can include a communicator configured to communicate with other home agents in a communication network regarding home agent ability, a monitor configured to monitor for a registration request from a user equipment, and a processor configured to process the registration request and to create a list of at least one home agent with corresponding home agent ability. The communicator can be configured to provide the list to the user equipment.

A further embodiment of the present invention can be an apparatus. The apparatus can include a communicator configured to send a registration request to a home agent and to receive a list in response to the request. The apparatus can also include a processor configured to select a particular home agent from the list based on home agent ability. The communicator can be configured to register to a selected home agent from the list.

An additional embodiment of the present invention can also be an apparatus. The apparatus can include communication means for sending a registration request to a home agent and for receiving a list in response to the request. The apparatus can also include processor means for selecting a particular home agent from the list based on home agent ability. The communicator can be configured to register to the selected home agent from the list.

Another embodiment of the present invention can be a method. The method can include sending, by a user equipment, a registration request to a home agent. The method can also include receiving, by a user equipment, a list in response to the request. The method can further include selecting, by a user equipment, a particular home agent from the list based on home agent ability. The method can additionally include registering, by a user equipment, to the selected home agent from the list.

A further embodiment of the present invention can be a computer- readable medium encoded with instructions that, when executed by a computer, perform a process. The process can include sending, by a user equipment, a registration request to a home agent. The process can also include receiving, by a user equipment, a list in response to the request. The process can further include selecting, by a user equipment, a particular home agent from the list based on home agent ability. The process can additionally include registering, by a user equipment, to the selected home agent from the list.

BRIEF DESCRIPTION OF THE DRAWINGS:

For proper understanding of the invention, reference should be made to the accompanying drawings, wherein:

Figure 1 illustrates a system according to an embodiment of the present invention; and

Figure 2 provides a flow chart according to certain embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S):

In view of the shortcomings of the conventional techniques for home agent selection, certain embodiments, for example, a mechanism for selection and assignment of a home agent for a user equipment such as a mobile node are provided, and, for a more specific example, a mechanism for optimization of Mobile IPv4 Home Agent assignments are provided.

Thus, as will be discussed below, an example synchronization protocol that home agents can run between themselves is provided. Additionally provided are rules by which one particular home agent is selected. Lowest preference value of a home agent, lifetime of the home agent, and the like can be used within the rules. The addition of an extension to the Registration Reply message to send back the address of the assigned home agent to the mobile node is also provided.

Certain embodiments of the present invention are based purely on the MobileIPv4 protocol and addresses assignment of the home agent in an infrastructureless scenario, although these implementations are provided for purposes of illustration rather than limitation.

A network (and its elements such as routers) may always be in a better position to know traffic and load conditions on the home agents. Hence, when the network picks a home agent for a mobile node, it can take away the guesswork involved in a mobile node picking a home agent for itself. By refining the protocol further, certain embodiments of the present invention can also reduce the number of messages in the network.

For example, in certain embodiments, only the home agent that has been selected as the designated home agent replies to the mobile node, avoiding a flood of responses from all the available home agents in the network.

In certain embodiments of the present invention, the home agents on a certain network can run a protocol between them that synchronizes the home agent information. Each router that works as a home agent broadcasts a message in the home network detailing information related to its home agent functionality. Among other things, this information can carry the global internet protocol (IP) address(es) that the home agent uses and its preference to accept new mobile nodes.

Every time any information regarding the home agent changes, the home agent can send out a new message with the updated information to all other home agents.

A mobile node that needs home agent assignment, can send a Registration Request message with the Home Agent field set to the subnet- directed broadcast address of the mobile's home network. Any home agent that sees the request can respond with a Registration Reply unicast to the mobile node.

Depending on how the home agents have been provisioned, the Registration Reply can carry information about all the home agents in the home network so the mobile node can choose the home agent it will use or a particular home agent can be assigned to the mobile node based on a predetermined priority agreed upon by the home agents. In a particular embodiment, only one home agent responds to the mobile node, namely the home agent that knows it is (or will be) the selected home agent. Both alternatives (the home agents picking the best home agent, or the user equipment or mobile node picking the best home agent) are detailed further in this document.

The Home Agents' Protocol

Every home agent can send periodic router advertisements that are seen by other home agents on the home network. To this Router Advertisement the Home Agent can add the following information to be used by other home agents:

1) Its global home agent IP address can be among the included information. If the home agent has more than one IP address it can randomize which address(es) to send out in each advertisement. 2) Its preference for accepting new registrations can be among the included information. The value of its preference can range from 0 to 9, 0, for example, indicating that the home agent is ready to accept any new registrations and 9, for example, indicating it is not ready to accept any new registrations. This preference value can change in future Router Advertisements. When a home agent decides to change its preference value, it can courteously send out a Router Advertisement immediately advertising this change to be updated at the other home agents. One way a home agent can decide its preference value is based on its current traffic conditions. A home agent can monitor the amount of traffic going through it. The most rudimentary way of doing so is to keep a count of inbound and outbound packets and to keep track of buffer sizes. Based on the amount of load a preference value can be picked. Revision of preference value can be done periodically to keep up with the changing registrations and usage at the home agent.

3) A bit to indicate if the router is still functioning as a Home Agent can be among the included information. When a router wants to also be a home agent it can set the "H" bit to 1 in the outgoing Router Advertisement message. When the router wants to stop being a Home Agent, it can send out a Router Advertisement message with the "H" bit set to zero.

4) A lifetime field can also be among the included information. The Home Agent can set a lifetime field with a value indicating for how long it will continue to function as a Home Agent. Every time a home agent receives a Router Advertisement message from another home agent it can update the corresponding entry for that home agent with the latest value in the lifetime field. If the value of the lifetime is zero, it can be understood that the entry for the home agent is to be deleted from the Home Agents list. A particular home agent may keep counting down the lifetime values associated with all entries in its home agents list. Once a lifetime value reaches zero, the particular home agent may delete the entry from its list. When a home agent receives a Registration Request message from a mobile node where the home agent field is set to the subnet-directed broadcast address of its home network, it can first check the validity of the Registration request. If the validity check is passed, the home agent can construct a Registration Reply for the mobile node with the destination address set to the address in the Home Address field of the Registration Reply. The setting of the source address is, for example, a place where the protocol has two options.

1) Designating a Home Agent to a mobile node

In this option it is the home network that can decide which home agent a mobile node should use for its registration. It can do so by having only the selected home agent reply to the mobile node. The selected home agent can include only its own home agent address in the Registration Reply message it sends back to the mobile node on receiving a request for dynamic home agent address. An example selection process for selecting the home agent will be discussed below.

Every home agent that receives a request chooses a home agent from its list based on certain criteria. For example, it can look for home agents with the lowest preference value, zero. If none have the value zero, it can then look for home agents with the second lowest value, 1, and so on. Once it has found a value and if there is only one home agent with that value, then that can be determined to be the home agent to be delegated. If there are multiple home agents, a pool of home agents with the same lowest preference value, then the home agent can look at the remaining lifetime of the home agents. It can choose the Home Agent with the highest remaining lifetime as the delegated home agent. If there are multiple home agents with the same lifetime value (highly unlikely) then the home agent can select the home agent with the lower value of IP address (IP address compared numerically).

As long as each home agent has the same information, each home agent following this predetermined scheme will come to the same conclusion and end up choosing only one home agent address (the same one) upon using the predetermined algorithm. It is this home agent that should reply to the mobile node in certain embodiments of the present invention, such as those discussed above in which only a single home agent responds to the registration request.

An example packet format of a Registration Reply message is given below. At the end of the "mandatory" part, any extensions can be added to a Registration Reply message. The term "mandatory" here is not used with respect to the scope of the invention, but as the term would be understood within the art of protocol implementation.

The Home Agent address can be added as a skippable extension to the Registration Reply. A mobile node that does not recognize this extension, can simply skip this extension.

0 1 3 4

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

I Type I Code | Lifetime |

I Home Address |

+ - + - + - + -H 1 ) J ) 1 1 1 i 1 1 H — 1 1 1 1 1 1 1 1 1 1 1 1 1 1 { 1 1-

I Home Agent |

I I

+ Identification +

I Extensions ...

An example extension for providing a Home Agent address along with the preference value and the remaining lifetime is shown below, in which RSVD indicates reserved bits.

0 1 3 4

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

I Type I Length | Sub-type | RSVD |

-1 1 i i 1 1 1 ! 1 1 ! 1 1 1 1 f--H 1 1 1 1 1 1 1 1 1 1 1 1 1-- + - + - +

I Home Agent Preference | Home Agent Lifetime |

I Home Agent Address |

+-H—1--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

2) Allowing the mobile node to choose a Home Agent

In this option any home agent on the home network can return a list of home agents to the mobile node so that the mobile node can choose a home agent for its registration. This option can require modifications to the Registration Reply message. Each Home Agent can add a list of home agents to the Registration Reply. Each entry can be made up of a certain home agent's global home agent IP address, remaining lifetime, and preference value. The entire packet size should not be greater than the path maximum transmission unit (MTU). Therefore, the list may contain the home agents in order of preference values from low to high, thereby permitting suitable truncation of the "high" preference value home agents from the list to accommodate the path MTU if necessary.

The following example extension shows multiple home agent addresses being sent back to the mobile node.

0 1 3 4

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

I Type I Length ) Sub-type | RSVD |

I Home Agentl Preference | Home Agentl Lifetime |

I Home Agentl Address |

I Home Agent2 Preference | Home Agent2 Lifetime |

I Home Agent2 Address j

I More HA Addresses ...

Procedure at Mobile Node

When the mobile node receives a Registration Reply with just one home agent information, it can choose that as the home agent for registration. It can then send out a Registration request message with the Home Agent field set to this home agent's address.

When the mobile node gets the addresses of multiple home agents in a registration reply, it can choose a home agent at its discretion. It can then send a new Registration Request to this Home Agent. The mobile node can use an algorithm such as that described above under the first option. Alternatively, the mobile node can select the home agent based on a random selection process, or a weighted random selection process in case many mobile nodes may be seeking to register essentially simultaneously in a given geographic location.

If a mobile node does not get a reply from any home agent within a certain time period, it can send out a new dynamic home agent address discovery message. It should cease sending anymore request after a certain predetermined number of tries.

The above-described mechanism can be implemented, for example, to any mobile IPv4 stack as extension to the MIP v4 protocol. It should be understood, however, that the invention is not necessarily limited to the MIPv4 protocol.

In certain embodiments of the present invention, it may be suitable for the home agent to be implemented as a router. Routers in a communication network can be configured such that they avoid filtering out the various messages, including sub-net broadcast messages employed.

An infrastructure mode means some additional support from other protocols/infrastructure for assigning a home agent. For example, an Access, Authorization, and Accounting (AAA) server can assign a home agent. By adding extensions to the MobileIP protocol itself, certain embodiments of the present invention can enable a home agent to be assigned to a mobile station in a infrastructureless mode, in the absence of additional protocols and network elements to assign a home agent. Hence certain embodiments of the present invention can be broadly applicable to various networks, including those in which MobileIPv4 is used. The systems, home agents, methods, and user equipment presented, thus, are not applicable only to a specific network/environment as those approaches designed for specific infrastructures are.

Figure 1 illustrates a system according to an embodiment of the present invention. The system includes several network elements including a user equipment 110, and two home agents 120. Each of the network elements can include a memory 130, and an antenna 140 or other communication technology. The memory 130 can be an internal or external memory, and can be a local or network memory. It should be noted that a home agent may more typically connected to a communication network by wired technology such as wireline ethernet or the like. Thus, the illustration of the home agent using an antenna should not be viewed as required or limiting.

The user equipment can include a communication unit 112 and processor unit 114. The communication unit 112 can include communication hardware and/or software as appropriate to perform concrete, tangible, and useful communication tasks such as communicating information. The communication unit can also be referred to as a communicator. The processor unit 114 can be in the form of a general purpose computer, an application specific integrated circuit or any other similar computing hardware capable of assisting in communications and similar computing tasks. The processor unit 114 can also be referred to as a processor.

Each home agent can include a communication unit 122 (which like the communication unit 112 of the user equipment, can be referred to as a communicator), a monitor unit 123 (which can also be referred to as simply a monitor), and a processor unit 124 (which like the processor unit 114 of the user equipment, can be referred to as a processor). The communication unit 122 can include communication hardware and/or software as appropriate to perform concrete, tangible, and useful communication tasks such as communicating information. The processor unit 124 can be in the form of a general purpose computer, an application specific integrated circuit or any other similar computing hardware capable of assisting in communications and similar computing tasks.

Each home agent's monitor unit 123 (aka monitor) (which can be implemented on a single processor chip with the processor unit 124 and/or the communication unit 122) can be configured to monitor the other home agent over a network _.150, and thus each monitor unit 123 can include a suitable network interface including, for example, a network card if suitable.

Figure 2 provides a flow chart according to certain embodiments of the present invention. As shown in Figure 2, a user equipment can send, and a home agent can receive 210, a registration request. Meanwhile, the home agent can have been monitoring 220 other home agents in a network. The home agent can then process 230 the request, and conditionally respond 240 to the request. The home agent can respond to the request conditioned upon whether the home agent is the best home agent according to a predetermined algorithm.

One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.

Claims

What is claimed is:

1. An apparatus, comprising: a communicator configured to communicate with home agents in a communication network regarding home agent ability; a monitor configured to monitor for a registration request from a user equipment; and a processor configured to process the registration request to identify whether the apparatus is a best home agent based on home agent ability and the registration request, wherein the communicator is configured to respond to the registration request when the apparatus is the best home agent.

2. The apparatus of claim 1, wherein the apparatus is a home agent.

3. The apparatus of claim 1, wherein the communicator is configured to include an address of the apparatus when responding to the registration request.

4. The apparatus of claim 1, wherein the processor is configured to identify the best home agent based on a corresponding preference value for each of the home agents and of the apparatus, and a corresponding lifetime of each of the home agents and of the apparatus.

5. The apparatus of claim 1, wherein the communicator is configured to communicate with the user equipment only when the apparatus is the best home agent.

6. The apparatus of claim 1, wherein the communicator is configured to detail its own home agent functionality information in a broadcast message or a multicast message to the home agents.

7. The apparatus of claim 14, wherein the home agent functionality information comprises at least one of any global internet protocol addresses of the home agent, a preference of the home agent for accepting a new user equipment, and a remaining lifetime of the home agent.

8. The apparatus of claim 1, wherein the home agent field is set to a subnet-directed broadcast address of a home network of the user equipment.

9. The apparatus of claim 1, wherein the communicator is configured to send out a new message with updated information to the home agents when home agent functionality information regarding the apparatus changes.

10. The apparatus of claim 1, wherein the processor is configured to identify the best home agent using a predetermined priority scheme.

11. The apparatus of claim 1, wherein the apparatus comprises or is comprised in a router.

12. The apparatus of claim 1, wherein the apparatus is configured to count down lifetime values of the other home agents and to remove the corresponding other home agents from the a home agent list, when a respective lifetime value for the other home agents is zero.

13. The apparatus of claim 1, wherein the apparatus is configured to check the validity of the registration request.

14. The apparatus of claim 1, wherein the home agent and the other home agents are configured to agree on which home agent from the home agent and the other home agents is the best home agent.

15. An apparatus, comprising: communication means for communicating with home agents in a communication network regarding home agent ability; monitor means for monitoring for a registration request from a user equipment; and processor means for processing the registration request to identify whether the apparatus is a best home agent based on home agent ability and the registration request, wherein the communication means is configured to respond to the registration request when the apparatus is the best home agent.

16. A method, comprising: communicating, by a home agent, with other home agents in a communication network regarding home agent ability; monitoring, by the home agent, for a registration request from a user equipment; processing, by the home agent, the registration request to identify whether the home agent is a best home agent based on home agent ability and the registration request; and responding, by the home agent, to the registration request when the home agent is the best home agent.

17. The method of claim 16, further comprising: including an address of the home agent when responding to the registration request.

18. The method of claim 16, further comprising: identifying the best home agent based on a corresponding preference value for each of the home agents, and a corresponding lifetime of each of the home agents.

19. The method of claim 16, further comprising: communicating with the user equipment only when the home agent is the best home agent.

20. The method of claim 16, further comprising: detailing the own home agent functionality information of the home agent in a broadcast message or a multicast message to the other home agents.

21. The method of claim 16, wherein the home agent functionality information comprises at least one of any global internet protocol addresses of the home agent, a preference of the home agent for accepting a new user equipment, and a remaining lifetime of the home agent.

22. The method of claim 16, further comprising: sending out a new message with updated information to the other home agents when home agent functionality information regarding the home agent changes.

23. The method of claim 16, further comprising: identifying the best home agent using a predetermined priority scheme.

24. The method of claim 16, further comprising: counting down lifetime values of the other home agents; and removing the corresponding other home agents from the a home agent list, when a respective lifetime value for the other home agents is zero.

25. The method of claim 16, further comprising: checking the validity of the registration request.

26. A computer-readable medium encoded with instructions that, when executed by a computer, perform: communicating, by a home agent, with other home agents in a communication network regarding home agent ability; monitoring, by the home agent, for a registration request from a user equipment; processing, by the home agent, the registration request to identify whether the home agent is a best home agent based on home agent ability and the registration request; and responding, by the home agent, to the registration request when the home agent is the best home agent.

27. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: including an address of the home agent when responding to the registration request.

28. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: identifying the best home agent based on a corresponding preference value for each of the home agents, and a corresponding lifetime of each of the home agents.

29. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: communicating with the user equipment only when the home agent is the best home agent.

30. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: detailing the own home agent functionality information of the home agent in a broadcast message or a multicast message to the other home agents.

31. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: sending out a new message with updated information to the other home agents when home agent functionality information regarding the home agent changes.

32. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: identifying the best home agent using a predetermined priority scheme.

33. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: counting down lifetime values of the other home agents; and removing the corresponding other home agents from the a home agent list, when a respective lifetime value for the other home agents is zero.

34. The computer-readable medium of claim 26, wherein the instructions, when executed by the computer, further perform: checking the validity of the registration request.

35. A system, comprising: a user equipment; and a plurality of home agents, wherein each home agent comprises a communicator configured to communicate with other home agents in a communication network regarding home agent ability, a monitor configured to monitor for a registration request from a user equipment, and a processor configured to process the registration request to identify whether the home agent is a best home agent based on home agent ability and the registration request, and wherein the communicator is configured to respond to the registration request when the home agent is the best home agent.