Method, system and apparatus for layer 3 roaming in wireless local area networks (WLANs)

• US 20060245393A1
• Filed: 04/27/2005
• Published: 11/02/2006
• Est. Priority Date: 04/27/2005
• Status: Abandoned Application

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bajic, Zeljko
• Application Number:
  US11/116,673
• Publication Number:
  US 20060245393A1
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 8/087 for preserving data network PoA address despite hand-offs
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Techniques are provided for allowing a client, initially associated with a home wireless switch and having a client IP address from within a first subnet, to layer 3 roam from the home wireless switch to a visited wireless switch configured to support a second subnet. These techniques can be implemented, for example, in a wireless local area network.

Claims

1. A wireless local area network, comprising:

a home wireless switch configured to support a first subnet;

a visited wireless switch configured to support a second subnet;

a UDP/IP tunnel between the home wireless switch and the visited wireless switch; and

a client, initially associated with the home wireless switch and having a client IP address from within the first subnet,

wherein the client maintains the client IP address when the client roams from the home wireless switch to the visited wireless switch, and

wherein the visited wireless switch is configured to receive an IP packet from the client and forwards the IP packet through the UDP/IP tunnel to the home wireless switch.

2. The wireless local area network of claim 1, wherein the home wireless switch is configured to receive a second IP packet for the client and forward the second IP packet to the client through the UDP/IP tunnel to the visited wireless switch.

3. The wireless local area network of claim 2, further comprising:

a registration server, coupled to home wireless switch and the visited wireless switch, configured to create an active client list using the registration information from each client, and send a copy of the active client list to each wireless switch in the wireless local area network

wherein the registration information from each client comprises a MAC address of the client, the client IP address of the client, the home wireless switch of the client, the visited wireless switch of the client, inactivity timers for the home wireless switch and the visited wireless switch.

4. The wireless local area network of claim 3, wherein the visited wireless switch uses the active client list to determine that the client IP address belongs to the first subnet and that the client was originally associated with the home wireless switch.

5. The wireless local area network of claim 4, wherein the visited wireless switch obtains the client IP address from registration information sent to the registration server by the home wireless switch when the client gets its IP address from the home wireless switch.

6. The wireless local area network of claim 5, when the client roams from the home wireless switch to the visited wireless switch, the client 802.11 authenticates with the visited wireless switch, 802.11 associates with the visited wireless switch, 802.1x authenticates with the visited wireless switch and issues a Dynamic Host Configuration Protocol (DHCP) request, and wherein the visited wireless switch relays the DHCP request to the home wireless switch through the tunnel.

7. The wireless local area network of claim 6, wherein the active client list comprises a record for the client comprising a MAC address of the client, the client IP address of the client, the home wireless switch of the client, the visited wireless switch of the client, inactivity timers for the home wireless switch and the visited wireless switch, and

wherein the client 802.11 re-authenticates and searches the record to get the home wireless switch from the MAC address of the client.

8. The wireless local area network of claim 7, further comprising:

a Dynamic Host Configuration Protocol (DHCP) server, wherein the home wireless switch passes the DHCP request to the DHCP server, and wherein the DHCP server re-assigns the client IP address to the client and forwards a DHCP response to the visited wireless switch and the client.

9. The wireless local area network of claim 7, wherein the client 802.11 reautheticates and 802.1x authenticates and generates a new transient keys and continues with an existing TCP session.

10. The wireless local area network of claim 7, wherein the client 802.11 reautheticates and 802.1x authenticates and generates a new transient keys and continues with an existing UDP session.

11. The wireless local area network of claim 3, wherein if the inactivity timers of the client indicate that the client is inactive on its home switch and its visited switch, then the client is forced to reauthenticate and get a new client IP address on a new wireless switch.

12. In a wireless local area network a method for allowing a client, initially associated with a home wireless switch and having a client IP address from within a first subnet, to roam from the home wireless switch to a visited wireless switch configured to support a second subnet, the method comprising:

creating a UDP/IP tunnel between the home wireless switch and the visited wireless switch; and

maintaining the client IP address of the client when the client roams from the home wireless switch to the visited wireless switch;

receiving an IP packet from the client at the visited wireless switch; and

forwarding the IP packet through the UDP/IP tunnel to the home wireless switch.

13. The method of claim 12, further comprising:

receiving a second IP packet for the client at the home wireless switch; and

forwarding the second IP packet through the UDP/IP tunnel to the visited wireless switch; and

sending the second IP packet from the visited wireless switch to the client.

14. The method of claim 13, further comprising:

sending registration information associated with each client to a registration server;

creating an active client list using the registration information from each client; and

sending a copy of the active client list to each wireless switch in the wireless local area network.

15. The method of claim 14, wherein the registration information from each client comprises a MAC address of the client, the client IP address of the client, the home wireless switch of the client, the visited wireless switch of the client, inactivity timers for the home wireless switch and the visited wireless switch.

16. The method of claim 15, further comprising:

using the active client list at the visited wireless switch to determine that the client IP address belongs to the first subnet and that the client was originally associated with the home wireless switch.

17. The method of claim 16, wherein using the active client list a the visited wireless switch to determine that the client IP address belongs to the first subnet and that the client was originally associated with the home wireless switch, comprises:

obtaining the client IP address from a portion of the active client list including the registration information associated with the home wireless switch.

18. The method of claim 12, wherein maintaining the client IP address at the client when the client roams from the home wireless switch and the visited wireless switch, comprises:

802.11 authenticating the client with the visited wireless switch;

802.11 associating the client with the visited wireless switch;

802.1x authenticating the client with the visited wireless switch; and

issuing a Dynamic Host Configuration Protocol (DHCP) request from the client to the visited wireless switch;

relaying the DHCP request from the visited wireless switch to the home wireless switch through the UDP/IP tunnel;

passing the DHCP request from the home wireless switch to a Dynamic Host Configuration Protocol (DHCP) server, wherein the DHCP server re-assigns the client IP address to the client; and

forwarding a DHCP response from the DHCP server to the visited wireless switch and the client.

19. The method of claim 18, wherein 802.11 authenticating the client with the visited wireless switch, comprises:

802.11 authenticating the client with the visited wireless switch; and

using the record of the client to obtain the home wireless switch from the MAC address of the client.

20. The method of claim 18, further comprising:

generating new transient keys and continuing with an existing TCP session.

21. The method of claim 18, further comprising:

generating new transient keys and continuing with an existing UDP session.

22. The method of claim 14, wherein if the inactivity timers of the client indicate that the client is inactive on its home switch and its visited switch, further comprising:

making the client reauthenticate and get a new client IP address on a new wireless switch.

23. A registration server coupled to a home wireless switch configured to support a first subnet and a visited wireless switch configured to support a second subnet in wireless local area network comprising a UDP/IP tunnel between the home wireless switch and the visited wireless switch and a client, initially associated with the home wireless switch and having a client IP address from within the first subnet, comprising:

a receiver configured to receive registration information associated with each client from each of the wireless switches;

a processor configured to create an active client list using the registration information from each client, wherein the registration information from each client comprises a MAC address of the client, the client IP address of the client, the home wireless switch of the client, the visited wireless switch of the client, inactivity timers for the home wireless switch and the visited wireless switch; and

a transmitter configured to send a copy of the active client list to each wireless switch in the wireless local area network.

24. A visited wireless switch configured to support a second subnet in a wireless local area network comprising a home wireless switch configured to support a first subnet, a UDP/IP tunnel between the home wireless switch and the visited wireless switch, and a client, initially associated with the home wireless switch and having a client IP address from within the first subnet, wherein the client maintains the client IP address when the client roams from the home wireless switch and the visited wireless switch, comprising:

a receiver configured to receive, after the client has roamed from the home wireless switch to the visited wireless switch, an IP packet sent from the client; and

a transmitter configured to send, after the client has roamed from the home wireless switch to the visited wireless switch, the IP packet through the UDP/IP tunnel to the home wireless switch.

25. The visited wireless switch of claim 24, wherein the receiver is configured to receive a second IP packet for the client sent from the home wireless switch through the UDP/IP tunnel.

26. The visited wireless switch of claim 25, wherein the receiver is configured to receive an active client list from the registration server, wherein the active client list comprises registration information from each client comprises a MAC address of the client, the client IP address of the client, the home wireless switch of the client, the visited wireless switch of the client, inactivity timers for the home wireless switch and the visited wireless switch.

27. The visited wireless switch of claim 26, further comprising:

a processor configured to use the active client list to determine that the client IP address belongs to the first subnet and that the client was originally associated with the home wireless switch.

28. The visited wireless switch of claim 27, wherein the processor obtains the client IP address from the registration information sent to the registration server by by the home wireless switch when the client gets its IP address from the home wireless switch.

29. The visited wireless switch of claim 28, wherein the processor searches the record associated with the client to get the home wireless switch from the MAC address of the client.

30. The visited wireless switch of claim 24, wherein the transmitter is configured to send registration information for each client in the second subnet to the registration server, wherein the registration information for each client in the second subnet comprises a MAC address of the client, the client IP address of the client, the home wireless switch of the client, the visited wireless switch of the client, inactivity timers for the home wireless switch and the visited wireless switch.

31. The visited wireless switch of claim 24, when the client roams from the home wireless switch to the visited wireless switch, wherein the visited wireless switch is configured to 802.11 authenticate with the client, 802.11 associate with the client, 802.1x authenticate with the client, and relay a DHCP request to the home wireless switch through the UDP/IP tunnel, and wherein the receiver is configured to receive a Dynamic Host Configuration Protocol (DHCP) response from the home wireless switch.

32. A home wireless switch configured to support a first subnet in a wireless local area network comprising a visited wireless switch configured to support a second subnet, a UDP/IP tunnel between the home wireless switch and the visited wireless switch, and a client, initially associated with the home wireless switch and having a client IP address from within the first subnet, wherein the client maintains the client IP address when the client roams from the home wireless switch and the visited wireless switch, comprising:

a plurality of ports, wherein a first one of the ports is configured to be coupled to the UDP/IP tunnel;

a receiver coupled to the first port and configured to receive, after the client has roamed from the home wireless switch to the visited wireless switch, an IP packet sent from the visited wireless switch through the UDP/IP tunnel, wherein the IP packet originates at the client, and wherein the receiver is configured to receive a second IP packet addressed to the client; and

a transmitter coupled to the first port and configured to send, after the client has roamed from the home wireless switch to the visited wireless switch, the second IP packet to the visited wireless switch through the UDP/IP tunnel, wherein the visited wireless switch sends the second IP packet to the client.

33. The home wireless switch of claim 32, wherein a second one of the ports is configured to be coupled to a registration server, and wherein the receiver is configured to receive an active client list from the registration server, wherein the active client list comprises registration information from each client comprises a MAC address of the client, the client IP address of the client, the home wireless switch of the client, the visited wireless switch of the client, inactivity timers for the home wireless switch and the visited wireless switch.

34. The visited wireless switch of claim 33, further comprising:

a processor configured to use the active client list to determine that the client is now associated with the home wireless switch.

35. The home wireless switch of claim 34, when the client roams from the home wireless switch to the visited wireless switch, the client 802.11 authenticates with the visited wireless switch, 802.11 associates with the visited wireless switch, 802.1x authenticates with the visited wireless switch and issues a Dynamic Host Configuration Protocol (DHCP) request to the visited wireless switch, and

wherein the receiver is configured to receive the DHCP request from the visited wireless switch through the tunnel.

36. The home wireless switch of claim 35, wherein the transmitter is configured to send the DHCP request to a Dynamic Host Configuration Protocol (DHCP) server which re-assigns the client IP address to the client.

37. The home wireless switch of claim 36, wherein the transmitter is configured to send a Dynamic Host Configuration Protocol (DHCP) response to the visited wireless switch and the client.