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

• US 20060187878A1
• Filed: 07/15/2005
• Published: 08/24/2006
• Est. Priority Date: 02/18/2005
• Status: Active Grant

• 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.
• Granted Patent: US 7,596,376 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• 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 operative to facilitate roaming in wireless networks, comprising

a network interface;

a processor;

a memory;

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

store a network address of the wireless network access device;

receive an association request from a wireless client, wherein the association request includes a second network address of a second wireless network access device;

transmit an association response to the wireless client;

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

transmit a mobility notification message to the second wireless network access device, wherein the mobility notification message identifies the wireless client.

2. The wireless network access device of claim 1 wherein the network 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 network 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 association request transmitted by the wireless client includes a handoff counter value;

and wherein the wireless network access application further comprises instructions operable to cause the processor and the network interface to

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

receive a mobility notification message from a wireless network access device, wherein the mobility notification message identifies a wireless client and a handoff counter value; and

compare the handoff counter value, stored in the data structure, corresponding to the wireless client identified stored in the received mobility notification message to the handoff counter value in the mobility notification message.

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

conditionally respond to the received mobility notification message based on the handoff counter values in the data structure and the mobility notification message.

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 received mobility notification message, wherein the response includes connection state information corresponding to the identified wireless client, if the handoff counter value stored in the data structure is less than the hand off counter in the received mobility notification message.

7. 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 received mobility notification message, wherein the response indicates instructions to delete connection state information, if the handoff counter value stored in the data structure is greater than the hand off counter in the received mobility notification message.

8. In a wireless network access device operably connected to a network and having

a network address, a method comprising

receiving an association request from a wireless client, wherein the association request includes a second network address of a second wireless network access device;

transmitting an association response to the wireless client;

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

transmitting a mobility notification message to the second wireless network access device, wherein the mobility notification message identifies the wireless client.

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

10. The method of claim 8 wherein the providing step comprises appending the network address of the wireless network access device to a wireless network management frame.

11. The method of claim 8 wherein the association request transmitted by the wireless client includes a handoff counter value;

and wherein the method further comprises

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

receiving a mobility notification message from a wireless network access device, wherein the mobility notification message identifies a wireless client and a handoff counter value; and

comparing the handoff counter value, stored in the data structure, corresponding to the wireless client identified stored in the received mobility notification message to the handoff counter value in the mobility notification message.

12. The method of claim 11 further comprising

conditionally responding to the received mobility notification message based on the handoff counter values in the data structure and the mobility notification message.

13. The method of claim 11 further comprising

transmitting a response to the received mobility notification message, wherein the response includes connection state information corresponding to the identified wireless client, if the handoff counter value stored in the data structure is less than the hand off counter in the received mobility notification message.

14. The method of claim 11 further comprising

transmitting a response to the received mobility notification message, wherein the response indicates instructions to delete connection state information, if the handoff counter value stored in the data structure is greater than the hand off counter in the received mobility notification message.

15. A wireless network access device operative to facilitate roaming in wireless networks, comprising

means for storing a network address of the wireless network access device;

means for receiving an association request from a wireless client, wherein the association request includes a second network address of a second wireless network access device, for transmitting an association response to the wireless client, providing the network address of the wireless network access device to the wireless client; and

means for transmitting a mobility notification message to the second wireless network access device, wherein the mobility notification message identifies the wireless client.

16. A wireless client, comprising

a wireless network interface;

a processor;

a memory;

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

associate with a first wireless network access device;

cache a network address corresponding to, and transmitted by, the first wireless network access device; and

provide, during an association with a second wireless network access device, the network address of the first wireless network access device to the second network access.

17. The wireless client of claim 16 wherein the wireless network interface driver application further comprises instructions operable to cause the processor and the wireless network interface to

transmit an association request to the second wireless network access device, wherein the association request includes the network address of the first wireless network access device.

18. The wireless client of claim 17 wherein the network address of the first wireless network access device is contained in an information element appended to the association request.

19. The wireless client of claim 16 wherein the wireless network interface driver application further comprises instructions operable to cause the processor and the wireless network interface to

receive an association response from the first wireless network access device, wherein the association response includes the network address of the first wireless network access device.

20. The wireless client of claim 16 wherein the wireless network interface driver application further comprises instructions operable to cause the processor and the wireless network interface to

maintain a handoff counter;

increment the handoff counter in connection with transmitting an association request to a wireless network access device; and

provide the value of the handoff counter value during associations with wireless network access devices.

21. A wireless client, comprising

means for wireless communicating and associating with a first wireless network access device;

means for caching a network address corresponding to, and transmitted by, the first wireless network access device; and

means for providing, during an association with a second wireless network access device, the network address of the first wireless network access device to the second network access.

22. The wireless client of claim 21 further comprising

a handoff counter;

means for incrementing the handoff counter in connection with transmitting an association request to a wireless network access device; and

means for providing the value of the handoff counter value during associations with wireless network access devices.

23. In a wireless client, a method facilitating roaming in a wireless network, the method comprising

associating with a first wireless network access device;

caching a network address corresponding to, and transmitted by, the first wireless network access device; and

providing, during an association with a second wireless network access device, the network address of the first wireless network access device to the second network access.

24. The method of claim 23 wherein the providing step comprises

transmitting an association request to the second wireless network access device, wherein the association request includes the network address of the first wireless network access device.

25. The method of claim 24 wherein the network address of the first wireless network access device is contained in an information element appended to the association request.

26. The method of claim 23 wherein the associating step comprises receiving an association response from the first wireless network access device, wherein the association response includes the network address of the first wireless network access device.

27. The method of claim 23 further comprising

maintaining a handoff counter;

incrementing the handoff counter in connection with transmitting an association request to a wireless network access device; and

providing the value of the handoff counter value during associations with wireless network access devices.

28. A wireless network system facilitating roaming in a wireless network environment, comprising

a plurality of access elements for wireless communication with at least one wireless client and for communication with a central control element;

wherein the access elements are each operative to

establish and maintain, in connection with a central control element, wireless connections with wireless clients;

at least one central control element for supervising the access elements, wherein the central control element is operative to

manage wireless connections between the access elements and corresponding wireless clients, and

store a network address of the central control element;

receive, through an access element, an association request from a wireless client, wherein the association request includes a second network address of a second central control element;

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

provide the network address of the central control element to the wireless client; and

transmit a mobility notification message to the second central control element, wherein the mobility notification message identifies the wireless client.