People recently started to ask me how the user device like a Laptop / Mobile phone will restart the wireless connection (open authentication and association) when the user device, like a mobile phone or Laptop, leaves the wireless coverage area and the user device comes back to the wireless coverage area?
In a wired connection, we all know that disconnecting and reconnecting the cable between the user device and switch will trigger complete authentication because there is a Physical status change of the port going up and down.
As there is no cable or physical connectivity in wireless, how does the user device know to restart the complete association and authentication process to establish a wireless connection?
Let's take an example with the below diagram.
In the Diagram, let's assume the Wireless Coverage area is represented by green color. Example user at Position 1 can see the SSID and has no issues with wireless connectivity. If the user goes to position 2 cannot see the SSID broadcasted by the AP.
So when the user device goes out of the coverage area, the user device will send a Disassociate frame to the AP, which will not reach the AP.
The client will send disassociation more than once as the client will not receive the ACK frame from AP, which we can see in the screenshot showing 1 in the Retry Frame field.
The user device sends Disassociate frames when leaving the coverage area (BSS), and user devices know that got disconnected from wireless.
To conclude, the Disassociate frames sent by the User devices help to know the wireless connection state and helps to restart the Authentication and Association to the wireless when the user device comes back into coverage area or BSS.
Comments