[CUWiN-Dev] Re: IBSS Split aka BSSID wars?

[Sven-Ola Tücke]

Hi,

as David wrote in that days. Some of us use a fixed bssid (we use 
02:ca:ff:ee:ba:be). This works fine with current madwifi-ng using "iwconfig 
ap xxx". I think that every ad-hoc net bigger than two dozen nodes need a 
fixed bssid with one exception: you have the same hardware everywhere. 
Anyhow, the ibss merge code in madwifi-ng does not look too clean for me. 
Does not take into account the timedrift needed to execute driver code...

In Berlin, we have mixed atheros, bcm4306 and some other brands. bcm4306 is 
used most. Fixing the bssid on that devices saved us from splits. I think, 
madwifi still has some bad answers on PROBEREQs sent out by a lot of 
braindead cards/drivers in order to "join" an IBSS. Anyhow, every new node 
owner with funny hardware not experimencing good connectivity wil reboot that 
thing until the fixed bssid is accepted. Otherwise he/she put that device 
to /dev/null where it does not disturb the others ;-)

One PS. We had problems with madwifi-ng at least on MIPS. Occasionally frozen 
tx interrupt. Simply stops sending. You send a packet through the HAL, but 
the TX int expected a few msecs later does not show up. According to a bloke 
who knows the HAL sources, this may be a hardware bug. Fixed with a hack. In 
case you need the same:

http://olsrexperiment.de/sven-ola/nylon/packages/madwifi/files/

HTH
// Sven-Ola

Am Freitag, 2. Februar 2007 17:48 schrieb Ronald in 't Velt:
> Hi David, all,
>
> "David Young" <dyoung at pobox.com> wrote in message
> news:20060427195740.GY6939 at che.ojctech.com...
>
> > On Thu, Apr 27, 2006 at 08:52:35PM +0200, Sven-Ola Tuecke wrote:
> >> This is a "Hello" from Berlin / Germany :)
> >>
> >> To my understanding CUWiN is also using AdHoc/IBSS on the wireless side
> >> of
> >> your mesh. Do you have a found a good answer to cope with IBSS splits
> >> situations? IBSS split should be experienced in every bigger mesh
> >> because the underlying technology is the same. Basically this happens in
> >> mixed hardware environments with a lot of different 802.11 protocol
> >> stack implementations. Or is this unknown in BSD only environments?
> >> Sorry if this
> >> questions sounds dumb, but I can assure you that it isn't.
> >
> > I have not noticed serious problems with BSSID splits since we eliminated
> > most of the Intersil Prism II adapters from our network.  Intersil,
> > Lucent, and Cisco/Aironet adapters were notorious for causing splits.
> >
> > Some people have protected against splits by forcing a fixed BSSID on
> > those cards that support it.
> >
> > In NetBSD, I fixed bugs in the 802.11 layer (net80211) and in the Atheros
> > driver that would lead to splits.
> >
> > Dave
>
> If I can briefly revive this old thread: Is there any more information on
> those bugs you fixed? Can you recall / retrieve what changes you made and
> when this was (roughly)? I am using the Madwifi (ng) driver for Atheros
> chipsets under Linux. I believe that the net80211 MAC-layer in that driver
> descends from the NetBSD one. I would like to check whether your fixes are
> also part of Madwifi now.
>
> Thanks,
> Ronald in 't Velt
>
>
>
> _______________________________________________
> CU-Wireless-Dev mailing list
> CU-Wireless-Dev at lists.cuwireless.net
> http://lists.chambana.net/cgi-bin/listinfo/cu-wireless-dev