Method and apparatus for providing IP mobility for mobile networks

• US 20030095523A1
• Filed: 11/19/2001
• Published: 05/22/2003
• Est. Priority Date: 11/19/2001
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lewis, Adam Cory, Korus, Michael F.
• Granted Patent: US 6,721,297 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/50 Address allocation
• 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: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 40/36 due to handover
• CPC Class Codes: H04W 60/00 Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 84/005 Moving wireless networks

Abstract

An IP mobility solution for mobile network(s) that combines features of IP multicast and mobile IPv6. The mobile network defines a mobile router (106) attached to one or more mobile network hosts (102). Upon movement of the mobile network from a home network to a foreign network, the mobile router obtains a multicast care of address on behalf of the attached mobile network hosts and creates a binding between the mobile subnet prefix and the multicast care of address. The mobile router communicates the binding information, via binding update messages, to a home agent (150). When a correspondent node sends packets to a mobile network nodes home address, they are intercepted by the home agent and tunneled to the mobile router via the multicast care of address. The mobile router receives the packet and forwards the packet to the targeted mobile network node. Optionally, the mobile router may send a binding update to the correspondent node so that future packets may travel the shortest tree and avoid the overhead of tunneling.

Claims

1. In a communication system comprising a mobile network including one or more mobile network hosts attached to a mobile router, the mobile router being operably connected to one or more external networks, a method comprising the mobile router:

obtaining a multicast care of address associated with the mobile network, the multicast care of address being used as a proxy address for the mobile network hosts responsive to mobility of the mobile network from a home network to a foreign network.

2. The method of claim 1, further comprising communicating the multicast care of address to one or more correspondent nodes.

3. The method of claim 2, wherein the correspondent nodes include a home agent associated with the mobile network.

4. The method of claim 2, wherein the step of communicating the multicast care of address to one or more correspondent nodes is accomplished by sending one or more binding update messages to the correspondent nodes.

5. The method of claim 4, wherein the step of sending binding update messages comprises informing the correspondent nodes of an association between the multicast care of address and a mobile network prefix associated with the mobile network.

6. The method of claim 4, wherein the step of sending binding update messages comprises piggybacking the binding updates on payload packets addressed to the correspondent nodes.

7. The method of claim 1, further comprising the mobile router joining the multicast care of address to enable the mobile router to receive payload via the multicast care of address.

8. In a communication system comprising a mobile router attached to a mobile network, a method comprising:

communicating information, via a multicast routing tree, between the mobile network and a selected external network;

determining, while the mobile network is joined to the selected external network via the multicast routing tree, that an alternative external network is preferred;

selecting the alternative external network for communication with the mobile network; and

issuing commands to a packet network causing the packet network to establish a new branch of the multicast routing tree leading to the alternative external network.

9. The method of claim 8, further comprising:

issuing commands to a packet network causing the packet network to remove any portion of the multicast routing tree not required for communication with the alternative external network.

10. The method of claim 8 wherein the step of selecting the alternative external network is accomplished in response to determining at least an availability of the alternative external network to support a communication with the mobile network.

11. The method of claim 8 wherein the step of selecting the alternative external network is accomplished in response to determining an impaired availability of the selected external network to support a communication with the mobile network.

12. The method of claim 8, wherein the selected external network comprises one of:

a narrowband external network, a wideband external network, and a broadband external network.

13. The method of claim 12, wherein the alternative external network comprises one of:

a narrowband external network, a wideband external network, and a broadband external network.

14. In a communication system comprising a mobile network including one or more mobile network nodes attached to a mobile router, the mobile router being operably connected to a correspondent node, a method comprising the mobile router performing steps of:

receiving one or more IP packets sent from the correspondent node to a mobile network node, the one or more IP packets being addressed to a multicast care of address associated with the mobile network;

determining whether the packets were non-optimally routed to the mobile router;

if the packets are determined to have been non-optimally routed, sending the packets to the mobile network node and sending a binding update identifying the multicast care of address to the correspondent node.

15. The method of claim 14, wherein the step of determining comprises determining that the packets were tunneled from a home agent of the mobile network and thereby were non-optimally routed to the mobile router.

16. The method of claim 14, wherein the step of sending a binding update comprises sending a mobile network prefix associated with the mobile network to the correspondent node.

17. The method of claim 14, wherein the step of determining comprises determining that the packets were sent directly from the correspondent node and thereby were optimally routed to the mobile router.

18. The method of claim 17, further comprising sending the packets to a targeted mobile network node.

19. The method of claim 18, wherein the step of determining that the packets were sent directly from the correspondent node comprises determining that the packets include a router header extension defining a unicast address of the targeted mobile network node, the method further comprising:

placing the unicast address of the targeted mobile network node into a target destination field; and

removing the router header extension.

20. In a communication system comprising a mobile router operably connected to a mobile network node, a method comprising the mobile router performing steps of:

intercepting one or more IP packets sent from the mobile network node to a correspondent node, the one or more IP packets including a source address field defining a source IP address of the mobile network node;

replacing, in the source address field, the source IP address of the mobile network node with a care of source address associated with an external network interface;

adding, to the one or more IP packets, a home address extension field including the source IP address of the mobile network node; and

sending the one or more IP packets to the correspondent node, via the external network interface.

21. The method of claim 20, performed for a plurality of mobile network nodes defining a mobile network.

22. The method of claim 21, performed only for packets sent to a correspondent node external from the mobile network.

23. A mobile router comprising:

a mobile network interface operably connecting the mobile router to one or more mobile network hosts defining a mobile network;

a multicast care of address binding management element for obtaining, responsive to movement of the mobile network from a home network to a foreign network, a multicast care of address adapted for use as a proxy address of the mobile network hosts.

24. The mobile router of claim 23 further comprising:

one or more external network interfaces operably connecting the mobile router to one or more external networks; and

a routing element operable to exchange messages between the mobile router and a correspondent node of at least one selected network of the one or more external networks.