A Wireless Connection

Using Figures 7-11 through 7-18, you can step through a simple discovery and association process.

1. The AP sends beacons every 2 seconds, as shown in Figure 7-11.


2. Client A is passively scanning and hears the beacon. This enables the client to deter- mine whether it can connect. You can see this in Figure 7-12.

3. A new client (Client B) arrives. Client B is already configured to look for the AP, so in- stead of passive scanning, it sends a probe request for the specific AP (see Figure 7-13).


4. The AP sends a probe response, seen in Figure 7-14, which is similar to a beacon. This lets Client B determine if it can connect.


5. From this point on, the process would be the same for Client A and Client B. In Figure 7-15, Client B sends an authentication request.

6. Also seen in Figure 7-15, the AP returns an authentication response to the client.

7. The client then sends an association request, as seen in Figure 7-16.

8. Now the AP sends an association response, also seen in Figure 7-16.

9. When the client wants to send, it uses an RTS, assuming this is a mixed b/g cell. The RTS includes the duration, as you can see in Figure 7-17.

10. Also seen in Figure 7-17, the AP returns a CTS.

11. The client sends the data (see Figure 7-17).

12. The AP sends an ACK after each frame is received (Figure 7-17).

13. In Figure 7-18, the client sends a disassociation message.

14. The AP replies with a disassociation response (Figure 7-18).

15. The client returns and sends a reassociation message (Figure 7-18).

16. The AP responds with a reassociation response (Figure 7-18).


Again, this process has other variations, but this should give you a pretty good under- standing of how to manage a connection.