Authentication— A station asks an AP to be authenticated. The two authentication methods are open system or shared key.
Deauthentication— A station or AP sends notice that it wishes to deauthenticate and end communication. Deauthentication cannot be refused.
Association Request— A station asks an AP to be associated.
Association Response— After an association request is received, the AP will respond with an approval or denial of the request.
Reassociation Request— When a station roams from one AP to another, it will send a reassociation request (instead of an association request) to the new AP. This tells the new AP that it may need to communicate with the old AP to pick up any buffered packets, etc.
Reassociation Response ...