Reassociation Request frame sent only by a STA to an AP & used when the STA already associated to the ESS & want to associate to another AP connecting to the same ESS. This frame can also be used if the STA left the cell for a short duration & want to rejoin the cell again.
We will use the below topology to look into Reassociation Request/Response frames detail. In this post we will not discuss 802.11r process in detail & refer this post if you require more on that.
Here is the Reassociation Request send by iPhone5. It is a management frame with subtype 2. Note that it will ist the Current AP Address (LAP2- B8:38:61:99:1A:AE) STA is associated to. STA can be associated to ONE AP at any given time where as it can be authenticated to multiple AP. Note that FTE & MDIE information element is there because BSS is configured for 802.11r FT.
Then AP will respond with Reassociation Response frame. It is a management frame with subtype 3. Depend on the information provided in Reassociation Request, AP may or may not be allow STA to join. In given scenario status code=0 implies a successful reassociation & AID is given for the client (AID=1 in my case).
1. 802.11 Mgmt Frame Types
2. 802.11 Mgmt : Beacon
3. 802.11 Mgmt : Association Request/Response
4. 802.11 Mgmt : Probe Req/Response
5. 802.11 Mgmt : Authentication Frame
6. 802.11 Deauthentication & Disassociation
7. 802.11 Mgmt : Action Frames
8. 802.11 Mgmt : Spectrum & TPC
9. 802.11 Mgmt : Admission Control