Distributed seamless roaming in wireless networks
One embodiment of the present invention provides a system for configuring an access point in a wireless network. During operation, the access point discovers one or more existing access points associated with the wireless network. The access point then obtains a set of configuration information from one existing access point, and synchronizes a local timestamp counter to a selected existing access point, thereby allowing the access point to be configured without using a centralized management station.
1. A method for conducting a maintenance procedure at an access point without disrupting access to a wireless network, comprising:
responsive to a local access point of the wireless network detecting a maintenance condition for performing a maintenance procedure, handing over one or more user stations associated with the local access point to other access points of the wireless network;
performing the maintenance procedure;
responsive to the local access point completing the maintenance procedure, obtaining a set of configuration information from an existing access point that belongs to the wireless network; and
in response to determining that the local access point has the best signal strength of a user station, allowing the user station to be associated with the local access point.
2. The method of claim 1 , wherein performing the maintenance procedure involves conducting a spectrum scan to select a best available frequency.
3. The method of claim 1 , wherein performing the maintenance procedure involves upgrading a firmware of the local access point.
4. The method of claim 1 , further comprising:
multicasting a station query message to the other access points, wherein the station query message includes at least a media access control (MAC) address for the user station; and
receiving signal strength values for the user station from the other access points.
5. The method of claim 1 , wherein allowing the user station to be associated with the local access point involves:
comparing the local access point's signal strength value for the user station to signal strength values for the user station from the other access points; and
determining that the local access point's signal strength value is the highest signal strength for the user station.
6. The method of claim 1 , wherein handing over a user station to a remote access point involves:
flushing out any remaining packets for the user station in a local buffer; and
responsive to determining that the local buffer does not include a packet for the user station, removing the user station from an associated station list for the local access point.
7. The method of claim 1 , wherein handing over a user station to a remote access point involves:
sending a handover request message to the remote access point; and
in response to receiving a switch request message from the remote access point, sending to the remote access point a switch response message that includes at least an association identifier for the user station.
8. The method of claim 7 , wherein the switch response message also includes one or more of:
one or more 802.11 association information elements;
station information; and
802.11 block-ACK and aggregation states for one or more traffic identifiers (TIDs).
9. A wireless access point, comprising a processor and a memory coupled to the processor and storing instructions which when executed by the processor cause the processor to perform a method for conducting a maintenance procedure at the wireless access point without disrupting access to a wireless network, the method comprising:
responsive to the local wireless access point detecting a maintenance condition for performing a maintenance procedure, handing over one or more user stations associated with the local access point to other access points of the wireless network;
performing the maintenance procedure;
responsive to the local wireless access point completing the maintenance procedure, obtaining a set of configuration information from an existing access point that belongs to the wireless network; and
in response to determining that the local wireless access point has the best signal strength of a user station, allowing the user station to be associated with the local wireless access point.
10. The wireless access point of claim 9 , wherein performing the maintenance procedure involves conducting a spectrum scan to select a best available frequency.
11. The wireless access point of claim 9 , wherein performing the maintenance procedure involves upgrading a firmware of the local wireless access point.
12. The wireless access point of claim 9 , further comprising:
multicasting a station query message to the other access points, wherein the station query message includes at least a media access control (MAC) address for the user station; and
receiving signal strength values for the user station from the other access points.
13. The wireless access point of claim 9 , wherein allowing the user station to be associated with the local wireless access point involves:
comparing the local wireless access point's signal strength value for the user station to signal strength values for the user station from the other access points; and
determining that the local wireless access point's signal strength value is the highest signal strength for the user station.
14. The wireless access point of claim 9 , wherein handing over a user station to a remote access point involves:
flushing out any remaining packets for the user station in a local buffer; and
responsive to determining that the local buffer does not include a packet for the user station, removing the user station from an associated station list for the local wireless access point.
15. The wireless access point of claim 9 , wherein handing over a user station to a remote access point involves:
sending a handover request message to the remote access point; and
in response to receiving a switch request message from the remote access point, sending to the remote access point a switch response message that includes at least an association identifier for the user station.
16. The wireless access point of claim 15 , wherein the switch response message also includes one or more of:
one or more 802.11 association information elements;
station information; and
802.11 block-ACK and aggregation states for one or more traffic identifiers (TIDs).
17. A method for conducting a maintenance procedure at an access point without disrupting access to a wireless network, comprising:
responsive to a local access point of the wireless network detecting a maintenance condition for performing a spectrum scan, handing over one or more user stations associated with the local access point to other access points of the wireless network;
performing the spectrum scan to select a best available frequency for the local access point;
responsive to the local access point completing the spectrum scan, obtaining configuration information from an existing access point that belongs to the wireless network; and
in response to determining that the local access point has the best signal strength of a user station, allowing the user station to be associated with the local access point.
18. A wireless access point, comprising a processor and a memory coupled to the processor and storing instructions which when executed by the processor cause the processor to perform a method for conducting a maintenance procedure at the wireless access point without disrupting access to a wireless network, the method comprising:
responsive to the local wireless access point detecting a maintenance condition for performing a firmware upgrade procedure, handing over one or more user stations associated with the local access point to other access points of the wireless network;
performing the firmware upgrade procedure to upgrade a firmware of the local wireless access point;
responsive to the local wireless access point completing the firmware upgrade procedure, obtaining a set of configuration information from an existing access point that belongs to the wireless network; and
in response to determining that the local wireless access point has the best signal strength of a user station, allowing the user station to be associated with the local wireless access point.