Methods, Apparatuses and Systems Facilitating Client Handoffs in Wireless Network Systems

• US 20090296658A1
• Filed: 08/13/2009
• Published: 12/03/2009
• 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 7,917,146 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, 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;

advertise a network address of the wireless network access device in one or more wireless network management frames;

establish wireless connections with one or more wireless stations, one or more of the wireless stations each providing a network address of a wireless network access device with which the wireless station has been associated and a handoff counter value;

store the handoff counter values in association with wireless station identifiers;

maintain connection state information for the wireless stations in association with the corresponding wireless station identifiers;

receive a mobility notification message from a remote wireless network access device, wherein the mobility notification message includes a wireless station identifier and a handoff counter value; and

respond to the mobility notification message by transmitting the connection state information corresponding to the wireless station identifier of the mobility notification message, if the stored handoff counter value corresponding to the wireless station is less than the handoff counter value in the mobility notification message.

2. 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.

respond to the mobility notification message by transmitting instructions to delete connection state information corresponding to the wireless station, if the stored handoff counter value corresponding to the wireless station is greater than the handoff counter value in the mobility notification message.

3. 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

transmit, using the network addresses provided by the wireless stations, mobility notification messages identifying the wireless station and the wireless network access device to the wireless network access devices with which the wireless stations has been associated, wherein the mobility notification messages each comprise the respective handoff counter values provided by the wireless stations.

4. The wireless network access device of claim 3, wherein the wireless network access application further comprises instructions operable to cause the processor and the network interface to

receive responses to the transmitted mobility notification messages and storing connection state information contained in the responses in association with respective wireless station identifiers.

5. The wireless network access device of claim 3, wherein the wireless network access application further comprises instructions operable to cause the processor and the network interface to

receive responses to the transmitted mobility notification messages and, responsive to deletion instructions in the one or more responses, deleting connection state information stored in association with respective wireless station identifiers identified in the deletion instructions.

6. The wireless network access device of claim 3, wherein the wireless network access application further comprises instructions operable to cause the processor and the network interface to

broadcast or multicast association announcements corresponding to wireless stations for which responses to the transmitted mobility notification messages have timed out.

7. The wireless network access device of claim 1, wherein the network address is an Internet Protocol (IP) address.

8. A method, comprising:

advertising, from a wireless network access device, a network address of the wireless network access device in one or more wireless network management frames;

establishing, at the wireless network access device, wireless connections with one or more wireless stations, one or more of the wireless stations each providing a network address of a wireless network access device with which the wireless station has been associated and a handoff counter value;

storing, at the wireless network access device, the handoff counter values in association with wireless station identifiers;

maintaining, at the wireless network access device, connection state information for the wireless stations in association with the corresponding wireless station identifiers;

receiving, at the wireless network access device, a mobility notification message from a remote wireless network access device, wherein the mobility notification message includes a wireless station identifier and a handoff counter value; and

responding to the mobility notification message by transmitting the connection state information corresponding to the wireless station identifier of the mobility notification message, if the stored handoff counter value corresponding to the wireless station is less than the handoff counter value in the mobility notification message.

9. The method of claim 8, further comprising:

responding to the mobility notification message by transmitting instructions to delete connection state information corresponding to the wireless station, if the stored handoff counter value corresponding to the wireless station is greater than the handoff counter value in the mobility notification message.

10. The method of claim 8, further comprising:

transmitting, using the network addresses provided by the wireless stations, mobility notification messages identifying the wireless station and the wireless network access device to the wireless network access devices with which the wireless stations has been associated, wherein the mobility notification messages each comprise the respective handoff counter values provided by the wireless stations.

11. The method of claim 10, further comprising:

receiving responses to the transmitted mobility notification messages and storing connection state information contained in the responses in association with respective wireless station identifiers.

12. The method of claim 10, further comprising:

receiving responses to the transmitted mobility notification messages and, responsive to deletion instructions in the one or more responses, deleting connection state information stored in association with respective wireless station identifiers identified in the deletion instructions.

13. The method of claim 10, further comprising:

broadcasting or multicast association announcements corresponding to wireless stations for which responses to the transmitted mobility notification messages have timed out.

14. The method of claim 8, wherein the network address is an Internet Protocol (IP) address.

15. A system comprising:

a first wireless network access device and a second wireless network access device;

wherein first wireless network access device configured to;

store a network address of the first wireless network access device;

advertise the network address of the first wireless network access device in one or more wireless network management frames;

establishing a wireless connection with a wireless station, the wireless station providing a network address of the second wireless network access device with which the wireless station has been associated and a handoff counter value;

store the handoff counter values in association with a wireless station identifier corresponding to the wireless station;

maintain connection state information for the wireless station in association with the corresponding wireless station identifier;

transmit, using the network address of the second wireless network access device, a mobility notification message identifying the wireless station and the first wireless network access device, wherein the mobility notification message further comprises the handoff counter value provided by the wireless station;

wherein the second wireless network access device is operative to;

receive the mobility notification message; and

respond to the mobility notification message by transmitting connection state information corresponding to the wireless station identifier of the mobility notification message, if a handoff counter value stored at the second wireless network access device and corresponding to the wireless station is less than the handoff counter value in the mobility notification message.

16. The system of claim 15 wherein the second wireless network access device is further operative to:

respond to the mobility notification message by transmitting instructions to delete connection state information corresponding to the wireless station, if the stored handoff counter value stored at the second wireless network access device and corresponding to the wireless station is greater than the handoff counter value in the mobility notification message.

17. The system of claim 15 wherein the first wireless network access device is further operative to:

receive a response to the transmitted mobility notification message and store connection state information contained in the response in association with the wireless station identifier corresponding to the wireless station.

18. The system of claim 16 wherein the first wireless network access device is further operative to:

receive a response to the transmitted mobility notification message and, responsive to deletion instructions in the response, deleting connection state information stored in association with the wireless station identifier identified in the deletion instructions.

19. The system of claim 16 wherein the first wireless network access device is further operative to:

broadcast or multicast an association announcement corresponding to the wireless station if an expected response from the second wireless network access device times out.

20. The system of claim 15 wherein the network address is an Internet Protocol (IP) address.