Hello Jussi!

Just to warn you: I don't have any good news.

One month ago I tried to obtain exactly the same
information.
After having tried everything (iwspy, SNMP, hacking
iwconfig) I wrote an e-mail to Jean Tourrilhes, author
of the wireless tools. Here's his reply:

On Tue, Jun 12, 2001 at 03:26:13PM +0200, Attila Weyland wrote:
>
> -- CUT --
>
> My goal is this:
> I want to measure the link quality of two acces points
> from different subnets at the same time.

        Not possible yet (no documentation). Would be done with APLIST
if ever implemented.

> I had a look at iwspy.

        Nope. Will work only within the cell.

>
> -- CUT --
>

As you see the lack of information is the source
for the trouble we have.

Lucent (Agere now) doesn't even provide the WaveLAN
MIB AP. Although I found a little tool which does
read out the information needed.
But: Gathering the information via SNMP was not
very reliable for me. Read-out takes too long and
displays only the client which are currently
connected.
Of even more concern is that according to the 802.11
standard a station can only be connected to one AP
at the same time. That means you can't get
simultaneous statisitics for two or more APs.

As you correctly mentioned the fact that these
information is really "flying" around can be seen
with the Site Monitor under Windows.

When I made my investigations, I started at the
LINK layer. After reading the driver and the specs
I was at the MAC layer.

A probably time intensive and not guarantied to work
way might be to generate your own wirless "ethernet"
frames, to initiate a channel sweep and collect some
beacons which contain the information.
Of course these must be done in kernel space.

As the collection of statistics was only the beginning
of my diploma thesis I have to continue and can not
spend much more time on it.

Sorry for the bad news, but what we need, might not be
available any time soon.

Regards,

Attila

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