Methods and apparatus for supporting proxy mobile IP registration in a wireless local area network

• US 7,471,661 B1
• Filed: 02/20/2002
• Issued: 12/30/2008
• Est. Priority Date: 02/20/2002
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Leung, Kent K., Wang, Huizhao, Siddiqi, Waseem A., Andiazabal, Christine
• Primary Examiner(s): Ryman; Daniel J
• Application Number:
  US10/080,995
• Time in Patent Office: 2,505 Days
• Field of Search: None
• US Class Current: 370/338
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 8/06 Registration at serving network Location Register, VLR or user mobility server
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 88/182 Network node acting on behalf of an other network entity, e.g. proxy

Abstract

Methods and apparatus for enabling mobility of a node that does not support Mobile IP are disclosed. Access point information is maintained for all functioning access points. In accordance with one embodiment, an authoritative access point (AAP) maintains access point information for all functioning access points (APs) and sends updates for all additions or other modifications to the continually changing access point information to enable APs to store a local copy of the AP information. For instance, when an AP goes offline, the access point information for that AP will be removed from the set of access point information, and notification of this removal is sent to other APs so that the local copy of the AP information may be similarly updated. As another example, when an AP comes online, it will send its AP information to the AAP. The AAP will store the AP information and provide this new AP information to other “active” APs. The AP information preferably includes an AP subnet and a gateway. When an AP receives a data packet, the AP may compare the data packet (e.g., source address) with the AP information (e.g., AP subnet) for one or more APs to determine whether to send a registration request on behalf of the node. For instance, the registration request may specify the gateway as the node'"'"'s Home Agent.

Claims

1. In a first access point, a method of supporting mobility for a node that does not support Mobile IP, comprising:

receiving access point information from a second access point;

storing the access point information received from the second access point such that a list of active access points is updated to include the access point information received from the second access point, the list of active access points including access point information associated with one or more active access points, the access point information received from the second access point including information identifying an access point subnet and a gateway associated with the second access point; and

sending the access point information received from the second access point to a third access point that supports Mobile IP to notify the third access point that the second access point is an active access point, thereby enabling the third access point to compare a received data packet with the access point subnet to determine whether to send a registration request on behalf of the node using the gateway as the node'"'"'s Home Agent.

2. The method as recited in claim 1, further comprising:

receiving a data packet from the node, the data packet specifying a source address;

determining from the source address whether the node is currently attached to a subnet identical to a subnet of the first access point;

when it is determined from the source address that the node is currently attached to the subnet identical to the subnet of the first access point, no Mobile IP service is required on behalf of the node; and

when it is determined from the source address that the node is not currently attached to the subnet identical to the subnet of the first access point, composing and sending a mobile IP registration request on behalf of the node.

3. The method as recited in claim 2, wherein determining from the source address whether the node is currently attached to a subnet identical to a subnet of the first access point comprises:

comparing the source address with the access point information.

4. The method as recited in claim 2, wherein the mobile IP registration request specifies the gateway as the node'"'"'s Home Agent.

5. The method as recited in claim 2, wherein determining from the source address whether the node is currently attached to a subnet identical to a subnet of the first access point comprises:

ascertaining the access point subnet identical to that of the node; and

determining whether the access point subnet identical to that of the node is different from that of the first access point.

6. The method as recited in claim 5, further comprising:

when the access point subnet identical to that of the node is different from that of the first access point, obtaining the access point information including the gateway.

7. The method as recited in claim 1, further comprising:

sending a request to the second access point for access point information associated with one or more active access points prior to receiving the access point information from the second access point, wherein the access point information received from the second access point includes access point information associated with one or more active access points.

8. The method as recited in claim 1, further comprising:

receiving a request from the third access point for access point information associated with one or more active access points, wherein the access point information sent to the third access point includes access point information associated with one or more active access points.

9. The method as recited in claim 1, further comprising:

receiving a remove message indicating that access point information associated with a specified access point is to be deleted prior to deleting the access point information associated with the specified access point; and

deleting the access point information associated with the specified access point.

10. The method as recited in claim 1, further comprising:

sending a remove message to one or more access points indicating that the access point information associated with a specified access point is to be deleted.

11. The method as recited in claim 1, further comprising:

sending a remove message to the second access point indicating that active access points are to delete the access point information associated with a specified access point.

12. The method as recited in claim 1, further comprising:

sending access point information associated with the first access point to one or more access points, the access point information associated with the first access point including an access point subnet and a gateway associated with the first access point.

13. The method as recited in claim 1, wherein the access point information is received from the second access point when the second access point powers up, wherein the access point information received from the second access point indicates that the second access point is active.

14. The method as recited in claim 1, wherein the access point information received from the second access point indicates that the second access point is active.

15. The method as recited in claim 1, wherein the access point information received from the second access point indicates that one or more access points are active.

16. The method as recited in claim 1, wherein the access point information does not include information associated with one or more nodes.

17. The method as recited in claim 1, wherein the access point information does not identify one or more nodes.

18. A first access point that supports mobility for a node that does not support Mobile IP, comprising:

means for receiving access point information from a second access point;

means for storing the access point information received from the second access point such that a list of active access points is updated to include the access point information information received from the second access point, the list of active access points including access point information associated with one or more active access points, the access point information received from the second access point including information identifying an access point subnet and a gateway associated with the second access point; and

means for sending the access point information received from the second access point to a third access point that supports Mobile IP to notify the third access point that the second access point is an active access point, thereby enabling the third access point to compare a received data packet with the access point subnet to determine whether to send a registration request on behalf of the node using the gateway as the node'"'"'s Home Agent.

19. A first access point that supports mobility for a node that does not support Mobile IP, comprising:

a processor; and

a memory, at least one of the processor and the memory being configured for;

receiving access point information from a second access point;

storing the access point information received from the second access point such that a list of active access points is updated to include the access point information received from the second access point, the list of active access points including access point information associated with one or more active access points, the access point information received from the second access point including information identifying an access point subnet and a gateway associated with the second access point; and

sending the access point information received from the second access point to a third access point that supports Mobile IP to notify the third access point that the second access point is an active access point, thereby enabling the third access point to compare a received data packet with the access point subnet to determine whether to send a registration request on behalf of the node using the gateway as the node'"'"'s Home Agent.

20. The first access point as recited in claim 19, wherein the first access point and the second access point support Mobile IP.

21. The first access point as recited in claim 19, wherein the first access point is responsible for sending the access point information received from the second access point to one or more additional access points.

22. The first access point as recited in claim 19, wherein the first access point is responsible for sending the access point information received from the second access point to one or more active access points.

23. The first access point as recited in claim 19, wherein the second access point is an active access point.

24. The first access point as recited in claim 19, wherein the third access point is an active access point.

25. The first access point as recited in claim 24, at least one of the processor and the memory being further configured for:

identifying the third access point in the list of active access points that identifies one or more active access points prior to sending the access point information to the third access point.

26. The first access point as recited in claim 19, wherein the list of active access points comprises an IP address for each of the active access points.

27. The first access point as recited in claim 19, at least one of the processor and the memory being further configured for:

sending access point information for one or more additional access points to the second access point, the access point information including an access point subnet and a gateway.

28. The first access point as recited in claim 19, wherein the access point information further comprises at least one of a netmask and an IP address associated with the second access point.

29. The first access point as recited in claim 19, wherein storing the access point information comprises:

storing the access point information in a subnet mapping table including a plurality of entries, each of the plurality of entries being associated with a different access point.

30. The first access point as recited in claim 19, at least one of the processor and the memory being further configured for:

deleting the access point information associated with the second access point if it is determined that the second access point is no longer active; and

instructing the third access point to delete the access point information associated with the second access point.

31. The first access point as recited in claim 30, at least one of the processor and the memory being further configured for:

removing an IP address associated with the second access point from a list of active access points.

32. A computer-readable medium storing thereon computer-readable instructions for supporting mobility for a node that does not support Mobile IP in a first access point, comprising:

instructions for storing access point information received from a second access point such that a list of active access points is updated to include the access point information received from the second access point, the list of active access points including access point information associated with one or more active access points, the access point information received from the second access point including information identifying an access point subnet and a gateway associated with the second access point; and

instructions for sending the access point information received from the second access point to a third access point that supports Mobile IP to notify the third access point that the second access point is an active access point, thereby enabling the third access point to compare a received data packet with the access point subnet to determine whether to send a registration request on behalf of the node using the gateway as the node'"'"'s Home Agent.