Methods, apparatuses and systems facilitating client handoffs in wireless network systems

• US 7,596,376 B2
• Filed: 07/15/2005
• Issued: 09/29/2009
• Est. Priority Date: 02/18/2005
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Calhoun, Patrice R., Broch, Joshua Glenn, O'Hara, Robert B. Jr.
• Primary Examiner(s): Corsaro; Nick
• Assistant Examiner(s): Ajayi; Joel
• Application Number:
  US11/182,239
• Publication Number:
  US 20060187878A1
• Time in Patent Office: 1,537 Days
• Field of Search: None
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0033 with transfer of context information
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 92/20 between access points

Abstract

Methods, apparatuses, and systems directed to facilitating roaming and client handoffs in wireless networks. In one implementation, the present invention is directed to a coordination mechanism facilitating handoffs of wireless clients in a wireless network infrastructure. In one implementation, the coordination mechanism minimizes the use of group- or multi-casting to provide a scalable wireless network roaming infrastructure.

Claims

1. A wireless network access device, comprising:

a network interface;

a processor;

a memory; and

a wireless network access application, stored in the memory, comprising instructions operable to cause the processor and the network interface to;

store an Internet Protocol (IP) address of the wireless network access device;

receive an association request from a wireless client, wherein the association request comprises a second IP address of a second wireless network access device with which the wireless client has been associated and a handoff counter value;

transmit an association response to the wireless client;

provide the IP address of the wireless network access device to the wireless client;

transmit a mobility notification message identifying the wireless client to the second wireless network access device, the mobility notification message comprises the second IP address and the handoff counter value identified in the association request;

store the handoff counter value in association with an identifier for the wireless client;

receive a second mobility notification message from a third wireless network access device, the second mobility notification message identifies a second wireless client and a second handoff counter value, and the second wireless client has been associated with the wireless network access device; and

compare the handoff counter value corresponding to the wireless client with the second handoff counter value corresponding to the second wireless client.

2. The wireless network access device of claim 1, wherein the IP address of the wireless network access device is appended to the association response transmitted to the wireless client.

3. The wireless network access device of claim 1, wherein the IP address of the wireless network access device is appended to a wireless network management frame.

4. The wireless network access device of claim 1, wherein the wireless network access application further comprises instructions operable to cause the processor and the network interface to conditionally respond to the second mobility notification message based on the handoff counter value and the second handoff counter value.

5. The wireless network access device of claim 4, wherein the wireless network access application further comprises instructions operable to cause the processor and the network interface to transmit a response to the second mobility notification message, wherein the response comprises connection state information corresponding to the second wireless client, if the handoff counter value is less than the second handoff counter value.

6. The wireless network access device of claim 4, wherein the wireless network access application further comprises instructions operable to cause the processor and the network interface to transmit a response to the second mobility notification message, wherein the response comprises instructions to delete connection state information corresponding to the second wireless client, if the handoff counter value is greater than the second handoff counter value.

7. In a wireless network access device operably connected to a wireless network and having an Internet Protocol (IP) address, a method comprising:

receiving an association request from a wireless client, wherein the association request comprises a second IP address of a second wireless network access device with which the wireless client has been associated and a handoff counter value;

transmitting an association response to the wireless client;

providing the IP address of the wireless network access device to the wireless client;

transmitting a mobility notification message identifying the wireless client to the second wireless network access device, the mobility notification message comprises the second IP address and the handoff counter value identified in the association request;

storing the handoff counter value in association with an identifier for the wireless client;

receiving a second mobility notification message from a third wireless network access device, wherein the second mobility notification message identifies a second wireless client and a second handoff counter value, and the second wireless client has been associated with the wireless client has been associated with the wireless network access device; and

comparing the handoff counter value corresponding to the wireless client with the second handoff counter value corresponding to the second wireless client.

8. The method of claim 7, wherein the providing step comprises appending the IP address of the wireless network access device to the association response transmitted to the wireless client.

9. The method of claim 7, wherein the providing step comprises appending the IP address of the wireless network access device to a wireless network management frame.

10. The method of claim 7, further comprising conditionally responding to the second mobility notification message based on the handoff counter value and the second handoff counter value.

11. The method of claim 10, further comprising transmitting a response to the second mobility notification message, wherein the response comprises connection state information corresponding to the second wireless client, if the handoff counter value is less than the second handoff counter value.

12. The method of claim 10, further comprising transmitting a response to the second mobility notification message, wherein the response comprises instructions to delete connection state information corresponding to the second wireless client, if the handoff counter value is greater than the second handoff counter value.

13. A wireless network access device, comprising:

means for storing an Internet Protocol (IP) address of the wireless network access device;

means for receiving an association request from a wireless client, wherein the association request comprises a second IP address of a second wireless network access device with which the wireless client has been associated and a handoff counter value;

means for transmitting an association response to the wireless client;

means for providing the IP address of the wireless network access device to the wireless client;

means for transmitting a mobility notification message identifying the wireless client to the second wireless network access device, the mobility notification message comprises the second IP address and the handoff counter value identified in the association request;

means for storing the handoff counter value in association with an identifier for the wireless client;

means for receiving a second mobility notification message from a third wireless network access device, the second mobility notification message identifies a second wireless client and a second handoff counter value, and the second wireless client has been associated with the wireless network access device; and

means for comparing the handoff counter value corresponding to the wireless client with the second handoff counter value corresponding to the second wireless client.

14. A wireless network system, comprising:

a plurality of access elements, wherein each access element is capable of;

communication with one of at least one central control element; and

wireless communication with at least one wireless client in connection with the central control element; and

the at least one central control element, wherein each central control element is capable of supervising at least one of the plurality of access elements and is operative to;

Manage wireless connections between the access elements supervised by the central control element and their corresponding wireless clients;

store an Internet Protocol (IP) address of the central control element;

receive, through a first access element, an association request from a wireless client, wherein the association request comprises a second IP address of a second central control element that supervises a second access element with which the wireless client has been associated and a handoff counter value maintained by the wireless client;

transmit, through the first access element, an association response to the wireless client;

provide the IP address of the central control element to the wireless client;

transmit a mobility notification message identifying the wireless client to the second central control element, wherein the mobility notification message comprises the second IP address and the handoff counter value identified in the association request;

store the handoff counter value in association with an identifier for the wireless client;

receive a second mobility notification message from the second central control element or a third central control element, wherein the second mobility notification message identifies a second wireless client and a second handoff counter value;

compare the wireless client with the second wireless client and the handoff counter value corresponding to the wireless client with the second handoff counter value corresponding to the second wireless client;

when the wireless client is the same as the second wireless client and the handoff counter value is greater than the second handoff counter value, then ignore the second mobility notification message; and

when the wireless client is the same as the second wireless client and the handoff counter value is less than the second handoff counter value, then respond to the second mobility notification message by transmitting connection state information corresponding to the wireless client to the second or the third central control element.