Re: Passive Scanning Bugreport

On Wed, 2006-08-09 at 14:56 +0200, Thomas King wrote:
> However, I have another question about the DTIM interval. If I get it
> right, the DTIM timer defines how often a DTIM frame is send out by
> the AP. If I miss a DTIM frame the scan will be aborted by the
> ipw_handle_missed_beacon function. Is this correct?

No. DTIM cannot be missed. When you request a scan, the firmware
calculate how much time is left before the next DTIM. It must make
itself tuned back to the associated channel before that time even though
there are some channels left to be scanned. In this case, you will
receive a SCAN_ABORT event.

> Why do we abort a scan after we missed a DTIM frame? It is already
> missed, so why not accomplishing the running scan?

See above.

> I have another question: If I activate the rtap feature and wiretap
> this interface I see a lot of beacons sent out on neighboring
> channels. Lets say I am associated to channel 8, I still see beacons
> from an access point using channel 6. I guess this is due to the
> overlapping of 802.11b/g channels, isn't it? Do you have more
> information about this phenomena? How many channels can be reached?
> Does the power measurement of the wireless network card still work if
> I receive a beacon from an neighbor channel?

Yes, for example 802.11b uses 25MHz spacing, which is 5 channels. It is
possible to receive signals from the neighbor channel, but the power is
weaker.

> My last question for today :-): Do we have a timetable for the next
> release of the driver?

I'm going to release 1.1.4 this week or early next. But I'm not sure I
should merge your passive_scan patch this time. I'm still waiting for
the result for your problem: is it caused by the DTIM setting in your
APs or some other reason.

Thanks,
-yi

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