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Re: Broadcom B43 Wireless Card / Driver Issues

On Tue, Jan 29, 2008 at 09:53:27AM -0200, Martin Marques wrote:
> Manish Kathuria escribió:
> >I am using Fedora 8 x86_64 (kernel on my Dell Vostro
> >laptop which has a Broadcom Corporation BCM94311MCG wireless mini PCI
> >lan device which has been automatically detected and uses the b43
> >wireless driver.
> >
> >I have configured the wireless device wlan0 using a static IP address
> >and have provided the ESSID, CHANNEL, MODE, RATE settings. The
> >wireless device comes up and gets associated with the  Access Point /
> >Wireless Router when the system is started. However if the wireless
> >router is restarted the wireless device on the laptop fails to
> >associate with it again and I have to restart the network service in
> >order to connect to it. If I remember correctly, the Intel Centrino
> >ipw2200 device on my older laptop never had this problem and nor does
> >a PCI wireless card (Realtek 8180) which I have configured using
> >ndiswrapper. What could be the reason for this problem ? Any tips or
> >suggestions ?
> Use NetworkManager.

Good advice.  Alternatively you could use wpa_supplicant (whether or
not you are using WPA encryption), or you could simply do "iwconfig
wlan0 essid $ESSID" whenever you detect that your AP has been reset.

If you want a technical explanation...the hardware in question is
"soft MAC" device which uses the mac80211 infrastructure in the
kernel.  The mac80211 component has a limited MLME implemenation
which relies on userland intervention at a number of points.  One of
those points is for triggering associations.  When you reset your AP,
your association is lost.  So, you must trigger a new association.
wpa_supplicant (which is also used by NetworkManager) is smart enough
to trigger the association for you.

As for why it works for the other devices cited, the ipw2200 has a
robust MLME implemented in firmware.  It does not require userland
intervention.  The rtl8180 actually is a "soft MAC" device, but since
you are using ndiswrapper (which should not be needed in F8 BTW)
the Windows driver must contain it's own MLME implementation.


John W. Linville
linville redhat com

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