"Benjamin M. Stocks" <stocksb@ieee.org> hath wroth:
>I have what is hopefully an easy 802.11 question. If I power up an
>802.11 enabled laptop for the first time in a new network, it receives
>the beacon announcing the network and I state that yes I want to
>connect to the network should the laptop still send the probe requests
>or should it try to associate with the source of the beacon?
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.
http://standards.ieee.org/getieee802/802.11.html
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:
http://www.wi-fiplanet.com/tutorials...le.php/1447501
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.
--
Jeff Liebermann
jeffl@comix.santa-cruz.ca.us
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
802.11 Probe Requests 
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