Fast handoff for wireless devices in a wired-wireless network

• US 8,532,070 B2
• Filed: 12/18/2006
• Issued: 09/10/2013
• Est. Priority Date: 12/18/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Pandian, Gnanaprakasam, Yadav, Navindra, Yang, Sheausong, Gopalasetty, Bhanu, Arunachalam, Senthil
• Primary Examiner(s): Afshar, Kamran
• Assistant Examiner(s): Zewari, Sayed T
• Application Number:
  US11/640,579
• Publication Number:
  US 20080146230A1
• Time in Patent Office: 2,458 Days
• Field of Search: 455436-448, 370329-332
• US Class Current: 370/338
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
• CPC Class Codes: H04W 40/32 for defining a routing cluster membership
• CPC Class Codes: H04W 40/36 due to handover

Abstract

A method and apparatus for handoff of a wireless client from a first network device to a second network device in a wired network are disclosed. In one embodiment, the method includes receiving data from a new wireless client at the second network device and transmitting a request for a route update for the new wireless client to the wired network. Prior to network convergence for the route update, data traffic for the new wireless client is received from the first network device and forwarded to the new wireless client. Context information for the new wireless client is transmitted from the second network device to other network devices in a proximity group of the second network device.

Claims

1. A method for handoff of a wireless client from a first switch to a second switch in a wired network, the first and second switches in communication with a plurality of access points, the method comprising:

receiving data from the wireless client at the second switch via one of the access points following an inter-switch roam;

transmitting from the second switch, a request for a route update for the wireless client to the wired network, in response to said received data;

prior to network convergence for said route update, receiving at the second switch, data traffic destined for the wireless client from the first switch and forwarding said data traffic to the wireless client;

receiving information identifying other switches in a proximity group; and

transmitting context information for the wireless client from the second switch to said other switches in said proximity group, wherein said other switches in said proximity group are in communication with access points located within a specified radio frequency range of at least one of the access points in communication with the second switch.

2. The method of claim 1 further comprising generating a multicast tree for said proximity group.

3. The method of claim 1 wherein the second switch is in a proximity group of the first switch.

4. The method of claim 1 wherein said proximity group is defined based on the access points connected to the first switch.

5. The method of claim 1 further comprising transmitting a point-of-attachment message to said other switches in said proximity group upon receiving data from the wireless client.

6. The method of claim 1 further comprising receiving said context information for the wireless client prior to receiving data from the wireless client.

7. The method of claim 1 further comprising receiving a disassociation message from the wireless client and forwarding data traffic received for the wireless client to said other switches in said proximity group.

8. The method of claim 1 further comprising, after network convergence for said route update, receiving said data traffic from a router within the wired network and forwarding said data traffic to the wireless client.

9. The method of claim 1 further comprising transmitting a token and authentication message to the wireless client prior to network convergence for said route update.

10. The method of claim 1 further comprising advertising a multicast group joined by the wireless client to said other switches in said proximity group.

11. The method of claim 1 further comprising transmitting upstream multicast traffic from the wireless client to the first switch prior to route convergence.

12. An apparatus for handoff of a wireless client from a switch in a wired network, the apparatus comprising:

a processor configured for transmitting a request for a route update to the wired network upon receiving data from the wireless client via an access point following an inter-switch roam, receiving data traffic destined for the wireless client from the switch prior to network convergence for said route update and forwarding said data traffic to the wireless client, receiving information identifying other switches in a proximity group; and

transmitting context information for the wireless client to said other switches in said proximity group; and

memory for storing information identifying said other switches in said proximity group and said context information for the wireless client received from the switch prior to receiving said data from the wireless client;

wherein said other switches in said proximity group are in communication with access points located within a specified radio frequency range of at least one of the access points in communication with the second switch.

13. The apparatus of claim 12 wherein said context information is stored in a context cache table, the processor configured to age entries in said context cache table after a specified period of time.

14. The apparatus of claim 12 wherein the processor is operable to generate a multicast tree comprising said other switches in said proximity group.

15. The apparatus of claim 12 wherein said proximity group is defined based on the access points in communication with the apparatus.

16. The apparatus of claim 12 wherein the processor is configured for advertising a multicast group joined by the wireless client to said other switches in said proximity group.

17. An apparatus for handoff of a wireless client from a first switch to a second switch in a wired network, the first and second switches in communication with a plurality of access points, the apparatus comprising:

means for transmitting a request for a route update for a wireless client to the wired network, in response to receiving data from a wireless client at the second switch via one of the access points following an inter-switch roam;

means for forwarding to the wireless client, data traffic received for the wireless client from the first switch prior to network convergence for said route update; and

means for transmitting context information for the wireless client from the second switch to other switches in a proximity group of the second switch;

wherein said other switches in said proximity group are in communication with access points located within a specified radio frequency range of at least one of the access points in communication with the second switch.

18. The system of claim 17 further comprising means for receiving said context information for the wireless client prior to receiving data from the wireless client.