Re: [RFC PATCH v1 3/3] mac80211: add beacon filtering support

[Kalle Valo <kalle.valo@iki.fi>]

Jouni Malinen <j@w1.fi> writes:

> On Mon, Feb 23, 2009 at 06:20:58PM -0800, Johannes Berg wrote:
>
>> We used to go through a probe request cycle once to make sure, but I'm
>> not sure there's a point in that. Just pointing out the change here.
>
> Having seen some hardware implementations of Beacon miss getting out of
> sync with the AP timing and causing way too frequent disconnections, I
> would think that there may well be good reasons to check in software
> that report was indeed correct, e.g., by sending the probe request
> before giving up on the AP.

I see your point, I also have had to suffer because of buggy APs
having unstable TBTT. But the cost for this is high, currently it
increases two seconds the time to signal a lost connection to the user
space. I would hope to have something faster.

>> The code looks pretty good, but this will lead to an interesting
>> situation where "iwlist wlan1 scan last" ("iw dev wlan1 scan dump") will
>> not show _any_ BSS, which will probably trip up NM; this happens because
>> the BSS will not be updated and expire after 10 seconds. I think we need
>> a way to "hold on" to the BSS.
>
> Dropping the BSS is not good.. The scan results should always include
> the current BSS so that information from it is available for things like
> 4-way handshake (WPA/RSN IE is needed from Beacon/ProbeResp).

Understood. Thanks for bringing this up.

-- 
Kalle Valo