FAST ROAMING IN A WIRELESS NETWORK USING PER-STA PAIRWISE MASTER KEYS SHARED ACROSS PARTICIPATING ACCESS POINTS

摘要

A fast roaming (handoff) service is provided for a WLAN infrastructure. Agivenmobile station (STA) obtains a pairwise master key (PMK) when it associateswith an accesspoint (AP) in the infrastructure. A neighbor graph identifies prospective APsto which theSTA may then roam. At initialization, preferably the neighbor graph is fully-connected (i.e.,each AP is assumed to be connected to every other AP). The PMK (obtained bythe STAinitially) is shared proactively with the neighbor APs as indicated in theneighbor graph.Thus, when the STA roams to a neighbor AP, because the PMK is alreadyavailable, there isno requirement that the STA initiate a real-time request to an authenticationserver tore-associate to the new AP. Further, the new AP causes an update to theneighbor graphinformation implicitly by simply issuing a notification that it is nowhandling the STA thatarrived from the prior AP; in this manner, the prior AP is confirmed as aneighbor, but thereis no requirement for any inter-AP dialog before a given neighbor graph isupdated. Asroaming occurs the neighbor graph is pruned down (to reflect the actualneighbor APconnections) using the implicit notification data.