Message-ID: <47CE8ED6.7030302@aitel.hist.no> (sfid-20080305_122119_741216_EF442F9F)
Date: Wed, 05 Mar 2008 13:15:18 +0100
From: Helge Hafting <helge.hafting@aitel.hist.no>
MIME-Version: 1.0
To: linux-wireless@vger.kernel.org
Subject: iwl3945 associated and _worked_ with a *wrong* essid!
Content-Type: text/plain; charset=UTF-8; format=flowed
Sender: linux-wireless-owner@vger.kernel.org

I recently wrote about my iwl3945 problems - I usually
have to try 20-50 times before I can use a wep-encrypted access point.
Once the link goes up - no more problems. But getting the first
connection takes time.

Yesterday something weird happened.
I run the same iwconfig command over and over. Then a wild guess:
Perhaps the driver or linux is clever enough to see that I
just set the same essid and key as last time, and optimize the
operation away completely? I have no idea if this actually happens,
but I changed the essid (added a few garbage characters)
in order to force a difference. I was about to run iwconfig again
with the correct essid, when I noticed that the link was up!

An "iwconfig" without parameters showed that the PC indeed
had associated to the usual access point, and the essid was wrong one 
indeed.
I then ran "dhclient", got an IP address, and used my home network
for a few hours. No problems, but the essid was wrong all the time.

I thought this ought to be impossible - so I can only guess that
the essid is stored in several places - one place used by "iwconfig"
to display the current essid, and somewhere else used to program
the radio. And the latter place is not necessarily updated when
"iwconfig essid <something>" is run - and therefore the link
worked anyway. This could possibly explain why things fail
so much - perhaps the essid is set correctly only occationally?

Kernel: 2.6.25-rc3, SMP 64-bit. Other sw from debian testing.

Helge Hafting