Last Post: October 5, 2006:
Please correct me if by FSM State Machine you mean anything other than the set of finite state machines that comprise the MAC protocol.
Concerning authentication and association state variables kept by each station, you already know that a station (A) receiving a frame of a class higher than its state variables allow for the source (B) is required to send a disassociation or deauthentication notification to the source (B). This causes the source (B) to reset its state variables to match the first station (A).
I do not find instructions for when a station (A) receives authentication request from an already authenticated and/or associated station (B).
I (an amateur) would send the same authentication response as if the station (B) had never been heard from before, and change my state variables regarding that station (B) to match.
Similarly if station (A) receives association request from an already associated station (B), I would send the same association response as if the station (B) had been merely authenticated, and change my state variables regarding that station (B) to match.
I hope this helps. Thanks. /criss