Hierarchical control signaling for mobile clients in distributed wireless controller system

A method comprising:

• for a plurality of access switches each configured to serve one or more Internet Protocol (IP) subnets that comprises a plurality of IP addresses, arranging the plurality of access switches arranged in switch peer groups;
• each access switch within a given switch peer group storing information about other access switches in that switch peer group and about locations of wireless client devices that are associated with any wireless access point on any access switch in the switch peer group;
• grouping the plurality of access switches into a corresponding one of a plurality of mobility sub-domains each comprising a plurality of switch peer groups;
• at each access switch, storing information about the locations of wireless client devices at access switches within the same switch peer group;
• at a mobility controller dedicated to a respective mobility sub-domain, storing information about the locations of wireless client devices at access switches within the respective mobility sub-domain;
• at a central controller that communicates with the mobility controllers for all of the mobility sub-domains, storing information about locations of wireless client devices in the mobility sub-domains;
• determining, by the mobility controller dedicated to the first mobility sub-domain, the access switch within the first mobility sub-domain where a particular wireless client device was previously located and forwarding an announce message to the access switch within the first mobility sub-domain where the particular wireless client device was previously located;
• forwarding, by the mobility controller dedicated to the second mobility sub-domain, the announce message from the particular wireless client device to an access switch of the first mobility sub-domain where the particular wireless client device was most previously attached when the particular wireless client device roams from the first mobility sub-domain to the second mobility sub-domain;
• receiving, by the access switch of the first mobility sub-domain where the particular wireless client device was most previously attached, the announce message;
• and
• sending, by the access switch of the first mobility sub-domain where the particular wireless client device was most previously attached, a handoff message to a particular access switch in the second mobility sub-domain where the particular wireless client device is currently located
• wherein the handoff message contains context for the particular wireless client device and other client policies associated with the particular wireless client device.