Access router based mobile IPv6 fast handover method

• US 8,000,297 B2
• Filed: 05/06/2004
• Issued: 08/16/2011
• Est. Priority Date: 11/26/2003
• Status: Expired due to Fees

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Hyoung-Jun, Shin, Myung-Ki, Park, Jung-Soo, Park, Ki-Shik, Hong, Yong-Geun
• Primary Examiner(s): Afshar; Kamran
• Assistant Examiner(s): Sarwar; Babar
• Application Number:
  US10/580,479
• Publication Number:
  US 20070109997A1
• Time in Patent Office: 2,658 Days
• Field of Search: 4554321-442, 455/450, 455/509, 455/516, 370331-338, 370/341, 370/469, 370/351, 370/328, 370/395.32, 726/5, 726/18, 726/19, 726/28, 726/29, 709217-220
• US Class Current: 370/331
• CPC Class Codes: H04L 67/04 specially adapted for terminals or networks with limited capabilities; specially adapted for terminal portability
• 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: H04W 36/0055 Transmission or use of information for re-establishing the radio link
• CPC Class Codes: H04W 36/16 Performing reselection for specific purposes
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support

Abstract

Provided is a mobile IPv6 fast handovers method, which includes the steps of: a) if a mobile node is moved in a layer 2, receiving a modified RS message from a mobile node in the access router, b) detecting movement of the mobile node in a layer 3 in the access router, c) if the mobile node makes a movement in the layer 3, generating CoA of the mobile node in the access router; d) performing Duplicate Address Detection in the access router to inspect uniqueness of the generated CoA; and e) transmitting a modified RA message to the mobile node in the access router. The Fast Handovers method of the present research performs fast movement detection by using layer 2 information simply and efficiently for fast handover in the mobile IPv6 and generates CoA in the access router instead of the mobile node without operations of many additional messages.

Claims

1. A method for performing mobile IPv6 fast level 2 handover between access points (APs) and a mobile node (MN) and optionally performing layer 3 handover between access routers (ARs) and the MN, each AR having a subnet composed of at least one access point (AP) that can interface between the MN and each corresponding AR, the method comprising the steps of:

receiving, at a given AR, a modified Router Solicitation (RS) message from the MN after completion of a layer 2 handover between the MN and a newly connected AP, the modified RS message having a message format comprising a ‘

C’

flag used for signifying that a current Care of Address (CoA) is set and comprising a source link-layer address option used for indicating a layer 2 identifier of the MN;

transmitting, from the given AR, a general Router Advertisement (RA) message to the MN when the layer 2 identifier from the source link-layer address option of the modified RS message is found to be in a neighbor cache value of the given AR which corresponds to layer 2 handover of the MN between a previously connected AP to the newly connected AP such that the previously connected AP and the newly connected AP both belong to the same subnet of the given AR;

continuing to use the current CoA as a new interface address when the layer 2 identifier from the source link-layer address option of the modified RS message is found to be in the neighbor cache value of the given AR;

generating, at the given AR a modified RA message when the layer 2 identifier from the source link-layer address option of the modified RS message is found not to be in the neighbor cache value of the given AR such that the modified RA message comprises a new CoA which corresponds to when layer 3 handover of the MN occurs between the previous connected AP and the newly connected AP such that the previously connected AP does not belong to a subnet of the given AR and the newly connected AP belongs to the subnet of the given AR;

replacing the current CoA with the new CoA as the new network interface address when the layer 2 identifier from the source link-layer address option of the modified RS message is found not to be in the neighbor cache value of the given AR;

performing, at the given AR a Duplicate Address Detection (DAD) process only when the layer 2 identifier from the source link-layer address option of the modified RS message is found not to be in the neighbor cache value of the given AR, such that the DAD process is used to inspect a uniqueness of the new CoA wherein the performing step is performed subsequent to the generating step; and

transmitting, from the given AR to the MN, a modified RA message containing the new CoA to update a network address of the MN, wherein the transmitting step is performed subsequent to the performing step.

2. The method as recited in claim 1, wherein the MN transmits the modified RS as soon as the layer 2 handover is complete.

3. The method as recited in claim 2, wherein movement of the MN in layer 3 is detected by the given AR when the given AR determines that the previously connected AP does not belong to the subnet of the given AR.

4. The method as recited in claim 1, wherein the modified RA message includes a flag which signifies the generation of the new CoA.

5. The method as recited in claim 1, wherein the MN does not perform the DAD process after receiving the modified general RA message.