802.11 Probe Requests

"Benjamin M. Stocks" hath wroth:

I'm going to be lazy and NOT read IEEE 802.11-1999 for exact details. Reading 802.11-1999 turns my brain to mush and I need maximum brain power today to survive todays worthless and endless meeting.

Basically, the beacon announces the network, not the individual access point. (Why it needs to do this 10 times every second will be left as an academic exercise). If the network consists of just one access point, these are one and the same. Somewhat larger wireless networks will have more than one access point with the same SSID. The beacon offers insufficient information to differentiate between multiple AP's with the same SSID.

There is also not enough information in the beacon to initiate a connection. For example, the available speeds are missing. (I'm still resisting the temptation to read IEEE 802.11-1999 and get the exact list of missing parameters).

Some non-brain numbing details can be found here:

A probe request will return more info that a beacon, especially the client capabilities and detected S/N ratio necessary for the access point to set the speed. Then, the client can initiate an association request frame to perhaps the strongest access point with the desired SSID, and so on.

In short, there's not enough data in the beacon to initiate a connection.