Mobility management system

• US 6,665,718 B1
• Filed: 08/24/1998
• Issued: 12/16/2003
• Est. Priority Date: 10/14/1997
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Rai, Girish, Chuah, Mooi
• Primary Examiner(s): Burgess, Glenton B.
• Assistant Examiner(s): Kupstas, Tod
• Application Number:
  US09/138,536
• Time in Patent Office: 1,940 Days
• Field of Search: 709/219, 709/227, 709/236, 709/225, 709/249
• US Class Current: 709/225
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 2212/00 Encapsulation of packets
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/164 Adaptation or special uses of UDP protocol
• CPC Class Codes: H04L 69/168 specially adapted for link layer protocols, e.g. asynchronous transfer mode [ATM], synchronous optical network [SONET] or point-to-point protocol [PPP]
• CPC Class Codes: H04L 69/169 Special adaptations of TCP, UDP or IP for interworking of IP based networks with other networks protocols for interworking, protocol conversion H04L69/08
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 36/144 over a different radio air interface technology
• CPC Class Codes: H04W 4/24 Accounting or billing
• CPC Class Codes: H04W 76/00 Connection management
• CPC Class Codes: H04W 8/087 for preserving data network PoA address despite hand-offs
• CPC Class Codes: H04W 8/12 between location registers or mobility servers
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

A wireless data network includes a wireless packet switched data network for end users that divides mobility management into local, micro, macro and global connection handover categories and minimizes handoff updates according to the handover category. The network integrates MAC handoff messages with network handoff messages. The network separately directs registration functions to a registration server and direct routing functions to inter-working function units. The network provides an intermediate XTunnel channel between a wireless hub (also called access hub AH) and an inter-working function unit (IWF unit) in a foreign network, and it provides an IXTunnel channel between an inter-working function unit in a foreign network and an inter-working function unit in a home network. The network enhances the layer two tunneling protocol (L2TP) to support a mobile end system, and it performs network layer registration before the start of a PPP communication session.

Claims

1. A communications system comprising:

a network that includes a first registration server and first and second access points and a first access hub, the network initially communicating data frames between a first mobile end system and the first access hub through the first access point;

wherein the first access hub includes a first module to re-register the first mobile end system with the first access hub without informing the first registration server when a registration request is received from the first mobile end system through the second access point;

wherein the first access hub further includes a second module to link the second access point with the first access hub when the mobile end system re-registers through the second access point; and

wherein the first access hub further includes a third module to de-link the first access point from the first access hub when the second access point is linked with the first access hub.

2. A communications system comprising:

a network that includes a first registration server and first and second access points and a first access hub, the network initially communicating data frames between a first mobile end system and the first access hub through the first access point;

wherein the first access hub includes a first module to re-register the first mobile end system with the first access hub without informing the first registration server when a registration request is received from the first mobile end system through the second access point;

wherein the first access hub further includes a second module to link the second access point with the first access hub when the mobile end system re-registers through the second access point;

wherein the first access hub further includes a third module to de-link the first access point from the first access hub when the second access point is linked with the first access hub,

wherein the network is regarded as a foreign network and the foreign network further includes second and third access hubs and a first inter-working function, the foreign network initially communicating data frames between a second mobile end system and the first inter-working function through the second access hub;

a home network includes a home registration server;

the first registration server includes a first module to re-register the second mobile end system with the first registration server without informing the home registration server when a registration request is received from the second mobile end system through a third access point and through the third access hub; and

the fist registration server further includes a second module to command the third access hub to be linked with the first inter-working function when the second mobile end system re-registers through the third access hub; and

the first registration server further includes a third module to command the second access hub to be de-linked from the first inter-working function after the third access hub is linked with the first inter-working function.

3. The system of clams 2, wherein:

the foreign network further includes a fourth access hub and second and third inter-working functions;

the home network further includes a fourth inter-working function, the foreign network initially communicating data frames between a third mobile end system and the fourth inter-working function through the second inter-working function, the home network initially communicating data frames between the fourth inter-working function and a first communications server;

the home registration server includes a first module to re-register the third mobile end system with the home registration server without de-linking the fourth inter-working function from the first communications server when a registration request is received from the third mobile and system through a fourth access point and through the fourth access hub and through the first registration server, the first module recognizing an indication in the registration request of a change from the second inter-working function to the third inter-working function;

the home registration server further includes a second module to command the fourth inter-working function to be linked with the third inter-working function when the third mobile end system re-registers through the fourth access hub; and

the home registration server further includes a third module to command the fourth inter-working function to be de-linked from the second inter-working function after the third inter-working function is linked with the fourth inter-working function.

4. The system of claim 3, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fifth inter-working function;

a second foreign network includes a second registration server and a fifth access hub and a sixth inter-working function;

the home network further includes a seventh inter-working function, the first foreign network initially communicating data frames between a fourth mobile end system and the seventh inter-working function through the fifth inter-working function, the home network initially communicating data frames between the seventh inter-working function and a second communications server;

the home registration server further includes a fourth module to re-register the fourth mobile end system with the home registration server without de-linking the seventh inter-working function from the second communications server when a registration request is received from the fourth mobile end system through a fifth access point and through the fifth access hub and through the second registration server to the home registration server;

the home registration server further includes a fifth module to command the seventh inter-working function to be linked with the sixth inter-working function when the fourth mobile end system re-registers through the fifth access hub; and

the home registration server further includes a sixth module to command the seventh inter-working function to be de-linked from the fifth inter-working function after the sixth inter-working function is linked with the seventh inter-working function.

5. The system of claim 3, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fifth inter-working function;

a second foreign network includes a second registration server and a fifth access hub and a sixth inter-working function;

the home network further includes seventh and eighth inter-working functions, the first foreign network initially communicating data frames between a fourth mobile end system and seventh inter-working function through the fifth inter-working function, the home network initially communicating data frames between the seventh inter-working function and a second communications server;

the home registration server further includes a fourth module to re-register the fourth mobile end system with the home registration server when a registration request is received from the fourth mobile end system through a fifth access point and through the fifth access hub and through the second registration server to the home registration server;

the home registration server further includes a fifth module to command the eighth inter-working function to be linked with the sixth inter-working function when the fourth mobile end system re-registers through the fifth access hub;

the home registration server further includes a sixth module to command the eighth inter-working function to be linked with the second communications server;

the home registration server further includes a seventh module to command the seventh inter-working function to be de-linked from the second communications server; and

the home registration server further includes an eighth module to command the seventh inter-working function to be de-linked from the fifth inter-working function after the eighth inter-working function is linked with the sixth inter-working function.

6. A communications system comprising:

a foreign network that includes a first registration server and first and second access hubs and a first inter-working function, the foreign network initially communicating data frames between a first mobile end system and the first inter-working function through the first access hub;

a home network that includes a home registration server;

wherein the first registration server includes a first module to re-register the first mobile end system with the first registration server without informing the home registration server when a registration request is received from the first mobile end system through a first access point and through the second access hub to the first registration server;

wherein the first registration server further includes a second module to command the second access hub to be linked with the first inter-working function when the first mobile end system re-registers through the second access hub; and

wherein the first registration server further includes a third module to command the first access hub to be de-linked from the first inter-working function after the second access hub is linked with the first inter-working function.

7. A communications system comprising

a foreign network that includes a first registration server and first and second access hubs and a first inter-working function, the foreign network initially communications data frames between a first mobile end system and the first inter-working function through the first access hub;

a home network that includes a home registration server;

wherein the first registration server includes a first module to re-register the first mobile end system with the first registration server without informing the home registration saver when a registration request is received from the first mobile end system through a first access point and through the second access hub to the first registration server;

wherein the first registration server further includes a second module to command the second access hub to be linked with the first inter-working function when the first mobile end system re-registers through the second access hub; and

wherein the first registration server further includes a third module to command the first access hub to be de-linked from the first inter-working function after the second access hub is linked with the first inter-working function;

wherein the foreign network further includes a third access hub and second and third inter-working functions;

the home network further includes a fourth inter-working function, the foreign network initially communicating data frames between a second mobile end system and the fourth inter-working function through the second inter-working function, the home network initially communicating data frames between the fourth inter-working function and a first communications server;

the home registration server includes a first module to re-register the second mobile end system with the home registration server without de-linking the fourth inter-working function from the first communications server when a registration request is received from the second mobile and system through a second access point and through the third access hub and through the first registration server to the home registration server, the first module recognizing an indication in the registration request of a change from the second inter-working function to the third inter-working function;

the home registration server further includes a second module to command the third inter-working function to be linked with the fourth inter-working function when the second mobile end system re-registers through the third access hub; and

the home registration server further includes a third module to command the second inter-working function to be de-linked from the fourth inter-working function after the third inter-working function is linked with the fourth inter-working function.

8. The system of claim 7, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fifth inter-working function,

a second foreign network includes a second registration server and a fourth access hub and a sixth inter-working function;

the home network further includes a seventh inter-working function, the first foreign network initially communicating data frames between a thud mobile end system and the seventh inter-working function through the fifth inter-working function, the home network initially communicating data frames between the seventh inter-working function and a second communications server;

the home registration server further includes a fourth module to re-register the third mobile and system with the home registration server without de-linking the seventh inter-working function from the second communications server when a registration request is received from the third mobile end system through a third access point and through the fourth access hub and through the second registration server to the home registration server;

the home registration server further includes a fifth module to command the sixth inter-working function to be linked with the seventh inter-working function when the third mobile end system re-registers through the fourth access hub; and

the home registration server further includes a sixth module to command the fifth inter-working function to be de-linked from the seventh inter-working function after the sixth inter-working function is linked with the seventh inter-working function.

9. The system of claim 7, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fifth inter-working function;

a second foreign network includes a second registration saver and a fourth access hub and a sixth inter-working function;

the home network further includes seventh and eighth inter-working functions, the first foreign network initially communicating data frames between a third mobile end system and seventh inter-working function through the fifth inter-working function, the home network initially communicating data frames between the seventh inter-working function and a second communications server;

the home registration server further includes a fourth module to re-register the third mobile end system with the home registration server when a registration request is received from the third mobile end system through a third access point and through the fourth access hub and through the second registration server to the home registration server,

the home registration server further includes a fifth module to command the eighth inter-working function to be linked with the sixth inter-working function when the third mobile end system re-registers through the fourth access hub;

the home registration server further includes a sixth module to command she eighth inter-working function to be linked with the second communications server;

the home registration server further includes a seventh module to command the seventh inter-working function to be de-linked from the second communications server, and

the home registration server further includes an eighth module to command the seventh inter-working function to be de-linked from the fifth inter-working function after the eighth inter-working function is linked with the sixth inter-working function.

10. A communications system comprising:

a foreign network that includes a first registration server and a first access hub and first and second inter-working functions;

a home network that include a home registration server and a third inter-working function, the foreign network initially communicating data frames between a first mobile end system and the third inter-working function through the first inter-working function, the home network initially communicating data frames between the third inter-working function and the first communications server;

wherein the home registration server includes a first module to re-register the first mobile end system with the home registration server without de-linking the third inter-working function from the first communications server when a registration request is received from the first mobile end system through a first access point and through the first access hub and through the first registration server to the home registration server, the first module recognizing an indication in the registration request of a change from the first inter-working function to the second inter-working function;

wherein the home registration server further includes a second module to command the second inter-working function to be linked with the third inter-working function when the first mobile end system re-registers through the first access hub; and

wherein the home registration server further includes a third module to command the first inter-working function to be de-linked from the third inter-working function after the second inter-working function is linked with the third inter-working function.

11. A communications system comprising:

a foreign network that includes a first registration server and a first access hub and first and second inter-working functions;

a home network that include a home registration server and a third inter-working function, be foreign network initially communicating data frames between a first mobile end system and the third inter-working function through the first inter-working function, the home network initially communicating data frames between the third inter-working function and the first communications server;

wherein the home registration server includes a first module to re-register the first mobile end system with the home registration server without de-linking the third inter-working function from the first communications server when a registration request is received from the first mobile end system through a first access point and through the first access hub and through the first registration server to the home registration server, the first module recognizing an indication in the registration request of a change from the first inter-working function to the second inter-working function;

wherein the home registration server further includes a second module to command the second inter-working function to be linked with the third inter-working function when the first mobile end system re-registers through the first access hub;

wherein the home registration server further includes a third module to command the first inter-working function to be de-linked from the third inter-working function after the second inter-working function is linked with the third inter-working function;

wherein the foreign network is regarded as a first foreign network and the first foreign network further includes fourth inter-working function;

a second foreign network includes a second registration server and a second access hub and a fifth inter-working function;

the home network further includes a sixth inter-working function, the first foreign network initially communicating data frames between a second mobile end system and the sixth inter-working function through the fourth inter-working function, the home network initially communicating data frames between the sixth inter-working function and a second communications server;

the home registration server further includes a fourth module to re-register the second mobile end system with the home registration server without de-linking the sixth inter-working function from the second communications server when a registration request is received from the second mobile end system through a second access point and through the second access hub and through the second registration server to the home registration server;

the home registration server further includes a fifth module to command the fifth inter-working function to be linked with the sixth inter-working function when the second mobile end system re-registers through the second access hub; and

the home registration server further includes a sixth module to command the fourth inter-working function to be de-linked from the sixth inter-working function after the fifth inter-working function is linked with the sixth inter-working function.

12. The system of claim 11, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fourth inter-working function;

a second foreign network includes a second registration server and a second access hub and a fifth inter-working function;

the home network further includes sixth and seventh inter-working functions, the first foreign network initially communicating data frames between a second mobile end system and the sixth inter-working function through the fourth inter-working function, the home network initially communicating data frames between the sixth inter-working function and a second communications server;

the home registration server further includes a fourth module to re-register the second mobile end system with the home registration server when a registration request is received from the second mobile end system through a second access point and Through the second access hub and through the second registration server to the home registration server;

the home registration server further includes a fifth module to command the fifth inter-working function to be linked with the seventh inter-working function when the second mobile end system re-registers through the second access hub;

the home registration server further includes a sixth module to command the seventh inter-working function to be linked with the second communications server;

the home registration server further includes a seventh module to command the sixth inter-working function to be de-linked from the second communications server; and

the home registration server further includes an eighth module to command the sixth inter-working function to be de-linked from the fourth inter-working function after the seventh inter-working function is linked with the fifth inter-working function.

13. A communications system comprising:

a first foreign network that includes a first registration server and a first inter-working function;

a second foreign network that includes a second registration server and a first access hub and a second inter-working function;

a home network that includes a home registration server and a third inter-working function, the first foreign network initially communicating data frames between a first mobile end system and the third inter-working function through the first inter-working function, the home network initially communicating data frames between the third inter-working function and the first communications server;

wherein the home registratation server includes a first module to re-register the first mobile end system with the home registration server without de-linking the third inter-working function from the first communications server when a registration request is received from the first mobile end system through a first access point and through the first access hub and through the second registration server to the home registration server;

wherein the home registratation server further includes a second module to command the third inter-working function to be linked with the second inter-working function when the first mobile end system re-registers through the first access hub; and

wherein the home registratation server further includes a third module to command the third inter-working function to be de-linked from the first inter-working function after the third inter-working function is linked with the second inter-working function.

14. A communications system comprising:

a first foreign network that includes a first registration server and a first inter-working function;

a second foreign network that includes a second registration server and a first access hub and a second inter-working function;

a home network that includes a home registration server and third and fourth inter-working functions, the first foreign network initially communicating data frames between a first mobile end system and the third inter-working function through the first inter-working function, the home network initially communicating data frames between the third inter-working function and the first communications server;

wherein the home registratation server includes a first module to re-register the first mobile end system with the home registration server when a registration request is received from the first mobile end system through a first access point and through the first access hub and through the second registration server to the home registration server;

wherein the home registratation server further includes a second module to command the fourth inter-working function to be linked with the second inter-working function when the first mobile end system re-registers through the first access hub;

wherein the home registratation server further includes a third module to command the fourth inter-working function to be linked with the first communications server;

wherein the home registratation server further includes a fourth module to command the third inter-working function to be de-linked from the first communications server when the fourth inter-working function is linked with the first communications server; and

wherein the home registratation server further includes a fifth module to command the third inter-working function to be de-linked from the first inter-working function after the fourth inter-working function is linked with the second inter-working function.

15. In a network that includes a first registration server and first and second access points and a first access hub, a method of handing off a connection of a first mobile end system with the first access hub, the method comprising steps of:

initially communicating data frames between the first mobile end system and the first access hub through the first access point;

sending a registration request from the first mobile end system through the second access point to the first access hub to re-register the first mobile end system with the first access hub without informing the first registration server when the first mobile end system moves and re-registers through the second access point;

linking the second access point with the first access hub when the first mobile end system re-registers through the second access point; and

de-linking the first access point from the first access hub when the second access point is linked with the first access hub.

16. In a network that includes a first registration server and first and second access points and a first access hub, a method of handing off a connection of a first mobile end system with the first access hub, the method comprising steps of:

initially communicating data frames between the first mobile end system and the first access hub through the first access point;

sending a registration request from the first mobile end system through the second access point to the first access hub to re-register the first mobile and system with the first access hub without informing the first registration server when the first mobile end system moves and re-registers through the second access point;

linking the second access point with the first access hub when the first mobile end system re-registers through the second access point;

de-linking the first access point from the first access hub when the second access point is linked with the first access hub;

wherein the network is regarded as a foreign network and the foreign network further includes second and third access hubs and a first inter-working function;

a home network includes a home registration server;

the method further includes a step of initially communicating data frames between a second mobile end system and the first inter-working function through the second access hub;

the method further includes a step of sending a registration request from the second mobile end system through a third access point and through the third access hub to the first registration server to re-register the second mobile end system with the first registration server without informing the home registration server when the second mobile and system moves and re-registers through the third access hub;

the method further includes a step of linking the third access hub with the first inter-working function when the second mobile end system re-registers through the third access hub; and

the method further includes a step of de-linking the second access hub from the first inter-working function after the third access hub is linked with the first inter-working function.

17. The method of claim 16 wherein:

the foreign network further includes a fourth access hub and second and third inter-working functions;

the home network further includes a fourth inter-working function;

the method further includes a step of initially communicating data frames between a third mobile end system and the fourth inter-working function through the second inter-working function;

the method further includes a step of initially communicating data frames between the fourth inter-working function and a first communications server;

the method further includes a step of sending a registration request from the third mobile end system through a fourth access point and through the fourth access hub and through the first registration server to the home registration server to re-register the third mobile end system with the home registration server without de-linking the fourth inter-working function from the first communications server when the third mobile end system moves and re-registers, through the fourth access hub, the step of sending the registration request from the first registration server to the home registration server including a sub-step of sending in indication of a change from the second inter-working function to the third inter-working function;

the method further includes a stop of linking the third inter-working function with the fourth inter-working function when the third mobile end system re-registers through the fourth access hub; and

the method further includes a stop of de-linking the second inter-working function from the fourth inter-working function after the third inter-working function is linked with the fourth inter-working function.

18. The method of claim 17, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fifth inter-working function;

a second foreign network includes a second registration server and a fifth access hub and a sixth inter-working function;

the home network further includes a seventh inter-working function;

the method further includes a step of initially communicating data frames between a fourth mobile end system and the seventh inter-working function through the fifth inter-working function;

the method further includes a step of initially communicating data frames between the seventh inter-working function and a second communications server;

the method further includes a step of sending a registration request from the fourth mobile end system through a fifth access point and through the fifth access hub and through the second registration server to the home registration server to re-register the fourth mobile end system with the home registration server without de-linking the seventh inter-working function from the second communications server when the fourth mobile end system moves and re-registers through the fifth access hub;

the method further includes a step of linking the sixth inter-working function with the seventh inter-working function when the fourth mobile end system re-registers through the fifth access hub; and

the method further includes a step of de-linking the fifth inter-working function from the seventh inter-working function after the sixth inter-working function is linked with the seventh inter-working function.

19. The method of claim 17, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fifth inter-working function;

a second foreign network includes a second registration server and a fifth access hub and a sixth inter-working function;

the home network further includes seventh and eighth inter-working functions;

the method further includes a stop of initially communicating data frames between a fourth mobile end system and seventh inter-working function through the fifth inter-working function;

the method further includes a step of initially communicating data frames between the seventh inter-working function and a second communications server;

the method further includes a step of sending a registration request from the fourth mobile end system through a fifth access point and through the fifth access hub and through the second registration server to the home registration server to re-register the fourth mobile end system with the home registration server when the fourth mobile end system moves and re-registers through the fifth access hub;

the method further includes a step of linking the eighth inter-working function with the sixth inter-working function when the fourth mobile end system re-registers through the fifth access hub, the method further includes a step of linking the eighth inter-working function with the second communications saver;

the method further includes a step of de-linking the seventh inter-working function from the second communications server; and

the method further includes a step of de-linking the seventh inter-working function from the fifth inter-working function after the eighth inter-working function is linked with the sixth inter-working function.

20. In a home network with a home registration server and a foreign network that includes a first registration server and first and second access hubs and a first inter-working function, a method of handing off a connection of a first mobile end system with the first inter-working function, the method comprising steps of:

initially communicating data frames between the first mobile end system and the first inter-working function through the first access hub;

sending a registration request from the first mobile end system through a first access point and through the second access hub to the first registration server to re-register the first mobile end system with the first registration server without informing the home registration server when the first mobile end system moves and re-registers through the second access hub;

linking the second access hub with the first inter-working function when the first mobile end system re-registers through the second access hub; and

de-linking the first access hub from the first inter-working function after the second access hub is linked with the first inter-working function.

21. In a home network with a home registration server and a foreign network that includes a first registration server and first and second access hubs and a first inter-working function, a method of handing off a connection of a first mobile and system with the first inter-working function, the method comprising steps of:

initially communicating data frames between the first mobile end system and the first inter-working function through the firm access hub;

sending a registration request from the first mobile end system through a first access point and through the second access hub to the first registration server to re-register the fist mobile end system with the fifth registration sever without informing the home registration server when the first mobile end system moves and re-registers through the second access hub;

linking the second access hub with the first inter-working function when the first mobile end system re-registers through the second access hub;

de-linking the first access hub from the first inter-working function after the second access hub is linked with the first inter-working function

wherein the foreign network further includes a third access hub and second and third inter-working functions;

the home network further includes a fourth inter-working function;

the method further includes a step of initially communicating data frames between a second mobile end system and the fourth inter-working function through the second interworking function;

the method further includes a step of initially communicating data frames between the fourth inter-working function and a first communications server;

the method further includes a step of sending a registration request from the second mobile end system through a second access point and through the third access hub and through the first registration server to the home registration server to re-register the second mobile end system with the home registration server without de-linking the fourth inter-working function from the first communications server when the second mobile end system moves and re-registers through the third access hub, the step of sending the registration request from the first registration server to the home registration server including a sub-step of sending an indication of a change from the second inter-working function to the third inter-working function;

the method further includes a step of linking the third inter-working function with the fourth inter-working function when the second mobile and system re-registers through the third access hub; and

the method further includes a step of de-linking the second inter-working function from the fourth inter-working function after the third inter-working function is linked with the fourth inter-working function.

22. The method of claim 21, wherein:

the foreign network is regarded as a first foreign network, and the first foreign network further includes a fifth inter-working function;

a second foreign network includes a second registration server and a fourth access hub and a sixth inter-working function;

the home network further includes a seventh inter-working function;

the method further includes a step of initially communicating data frames between a third mobile end system and the seventh inter-working function through the fifth inter-working functions;

the method further includes a step of initially communicating data frames between the seventh inter-working function and a second communications server;

the method further includes a step of sending a registration request from the third mobile end system through a third access point and through the fourth access hub and through the second registration server to the home registration server to re-register the third mobile end system with the home registration server without de-linking the seventh inter-working function from the second communications server when the third mobile end system moves and re-registers through the fourth access hub;

the method further includes a step of linking the sixth inter-working function with the seventh inter-working function when the third mobile end system re-registers through the fourth access hub;

and the method further includes a step of de-linking the fifth inter-working function from the seventh inter-working function after the sixth inter-working function is linked with the seventh inter-working function.

23. The method of claim 21, wherein:

the foreign network is regarded as a first foreign network and the first foreign network further includes a fifth inter-working function;

a second foreign network includes a second registration server and a fourth access hub and a sixth inter-working function;

the home network further includes seventh and eighth inter-working functions;

the method further includes a step of initially communicating data frames between a third mobile end system and seventh inter-working function through the fifth inter-working function;

the method further includes a step of initially communicating data frames between the seventh inter-working function and a second communications server;

the method further includes a step of sending a registration request from the third mobile and system through a third access point and through the fourth access hub and through she second registration server to the home registration server to re-register the third mobile and system with the home registration server when the third mobile end system moves and re-registers through the fourth access hub;

the method further includes a step of linking the eighth inter-working function with the sixth inter-working function when the third mobile end system re-registers through the fourth access hub;

the method further includes a step of linking the eighth inter-working function with the second communications server;

the method further includes a step of de-linking the seventh inter-working function from the second communications server, and

the method further includes a step of de-linking the seventh inter-working function from the fifth inter-working function after the eighth inter-working function is linked with the sixth inter-working function.

24. In a home network with a home registration server and a foreign network that includes a first registration server and a first access hub and first and second inter-working functions, the home network further including a third inter-working function, a method of handing off a connection of a first mobile end system with a first communications server, the method comprising steps of:

initially communicating data frames between the first mobile end system and the third inter-working function through the first inter-working function;

initially communicating data frames between the third inter-working function and the first communications server;

sending a registration request from the first mobile end system through a first access point and through the first access hub and through the first registration server to the home registration server to re-register the first mobile end system with the home registration server without de-linking the third inter-working function from the first communications server when the first mobile end system moves and re-registers through the first access hub, the step of sending the registration request from the first registration server to the home registration server including a sub-step of sending an indication of a change from the first inter-working function to the second inter-working function;

linking the second inter-working function with the third inter-working function when the first mobile end system re-registers through the first access hub; and

de-linking the first inter-working function from the third inter-working function after the second inter-working function is linked with the third inter-working function.

25. In a home network with a home registration server and a foreign network that includes a first registration server and a first access hub and first and second inter-working functions, the home network further including a third inter-working function, a method of handing off a connection of a first mobile end system with a first communications server, the method comprising steps of:

initially communicating data frames between the first mobile end system and the third inter-working function through the first inter-working function;

initially communicating data frames between the third inter-working function and the first communications server;

sending a registration request from the first mobile end system through a first access point and through the first access hub and through the first registration server to the home registration server to re-register the first mobile and system with the home registration server without de-linking the third inter-working function from the first communications server when the first mobile end system moves and re-registers through the first access hub, the step of sending the registration request from the first registration sever to the home registration server including a sub-step of sending an indication of a change from the first inter-working function to the second inter-working function;

linking the second inter-working function with the third inter-working function when the first mobile end system re-registers through the first access hub; and

de-linking the first inter-working function from the third inter-working function after the second inter-working function is linked with the third inter-working function;

wherein the foreign network is regarded as a first foreign network and the first foreign network further includes fourth inter-working function;

a second foreign network includes a second registration server and a second access hub and a fifth inter-working function;

the home network further includes a sixth inter-working function;

the method further includes a step of initially communicating data frames between a second mobile end system and the sixth inter-working function through the fourth inter-working function;

the method further includes a step of initially communicating data frames between the sixth inter-working function and a second communications server;

the method further includes a stop of sending a registration request from the second mobile end system through a second access point and through the second access hub and through the second registration server to the home registration server to reregister the second mobile end system with the home registration server without de-linking the sixth inter-working function from the second communications server when the second mobile end system moves and re-registers through the second access hub;

the method further includes a step of linking the fifth inter-working function with the sixth inter-working function when the second mobile end system re-registers through the second access hub; and

the method further includes a step of de-linking the fourth inter-working function from the sixth inter-working function after the fifth inter-working function is linked with the sixth inter-working function.

26. The method of claim 25, wherein:

the foreign network is regarded as a first foreign network and the fist foreign network further includes a fourth inter-working function;

a second foreign network includes a second registration server and a second access hub and a fifth inter-working function;

the home network further includes sixth and seventh inter-working functions;

the method further includes a step of initially communicating data frames between a second mobile end system and the sixth inter-working function through the fourth inter-working function;

the method further includes a step of initially communicating data frames between the sixth inter-working function and a second communications server;

the method further includes a step of sending a registration request from the second mobile end system through a second access point and through the second access hub and through the second registration server to the home registration server to re-register the second mobile end system with the home registration server when the second mobile end system moves and re-registers through the second access hub;

the method further includes a step of linking the fifth inter-working function with the seventh inter-working function when the second mobile end system re-registers through the second access hub;

the method further includes a step of linking the seventh inter-working function with the second communications server, the method further includes a step of de-linking the sixth inter-working function from the second communications server; and

the method further includes a stop of de-linking the sixth inter-working function from the fourth inter-working function after the seventh inter-working function is linked with the fifth inter-working function.

27. In a home network and first and second foreign networks, the first foreign network including a first registration server and a first inter-working function, the second foreign network including a second registration server and a first access hub and a second inter-working function, the home network including a home registration server and a third inter-working function, a method of handing off a connection of a first mobile end system with a first communications server, the method comprising steps of:

initially communicating data frames between a first mobile end system and the third inter-working function through the first inter-working function;

initially communicating data frames between the third inter-working function and the first communications server;

sending a registration request from the first mobile end system through a first access point and through the first access hub and through the second registration server to the home registration server to re-register the first mobile end system with the home registration server without de-linking the third inter-working function from the first communications server when the first mobile end system moves and re-registers through the first access hub;

linking the third inter-working function with the second inter-working function when the first mobile end system re-registers through the first access hub; and

de-linking the third inter-working function from the first inter-working function after the third inter-working function is linked with the second inter-working function.

28. In a home network and first and second foreign networks, the first foreign network including a first registration server and a first inter-working function, the second foreign network including a second registration server and a first access hub and a second inter-working function, the home network including a home registration server and third and fourth inter-working functions, a method of handing off a connection of a first mobile end system with a first communications server, the method comprising steps of:

initially communicating data frames between a first mobile end system and the third inter-working function through the first inter-working function;

initially communicating data frames between the third inter-working function and the first communications server;

sending a registration request from the first mobile end system through a first access point and through the first access hub and through the second registration server to the home registration server to re-register the first mobile end system with the home registration server when the first mobile end system moves and re-registers through the first access hub;

linking the fourth inter-working function with the second inter-working function when the first mobile end system re-registers through the first access hub;

linking the fourth inter-working function with the first communications server;

de-linking the third inter-working function from the first communications server when the fourth inter-working function is linked with the first communications server; and

de-linking the third inter-working function from the first inter-working function after the fourth inter-working function is linked with the second inter-working function.