Hello,
I began testing the opensource firmware on b43 when running ad-hoc
mode and I faced a strange problem that drove me to investigate about
how ad-hoc mode is implemented inside the wireless stack. Note that
what follows holds for both Broadcom original firmware and opensource
one, however I did all these tests switching back to original BCM
firmware.
It turned out that Apple Macs with 4328 hardware (bot a/b/g and n)
running different version of OSX never succeed in joining ad-hoc
networks initiated by b43 while they can join without problems ad-hoc
networks run by ath5k (with initiated or run I mean "the first node
that is configured with that SSID"). I attach a complete description
of the tests at the end of this message.
I then captured some traffic and it seems that b43 never sends beacon
when initiating ad-hoc networks, it just sends probes to itself and
responds to broadcast probe requests. Note that ath5k instead sends
beacons as long as it is the first node. Probably I'm missing
something, so just responding to broadcast probes could be a correct
alternative procedure to advertise ad-hoc network, however this seems
to be the only difference to explain the different behavior of newer
Apple Macs when joining ath5k or b43 ad-hoc initiated networks.
Please note that if I invert roles (ad-hoc initiated by those Apple
Macs, b43 joining the network) everything is fine, so this is not an
issue involving send and receive operations, nodes do not have
communication problems.
Has anyone ever experienced such issues? Is it correct to not send
beacon when starting an ad-hoc network? I did some tests and OSX does
send beacon when initiating an ad-hoc network (as ath5k does).
Cheers,
-FG
----- testbed scenarios
When I initiate an ad-hoc network on a Linux PC with a 4306 card, I
can't join it using any of my Apple Macs equipped with BCM hardware.
I tried two different Apple, one is a new MacBook Pro with 4328 BCM N-
PHY, the other is a two years old iMac 17 with a a/b/g 4328 BCM
hardware. The Kernel I used on the x86 PC was 2.6.29-rc2-wl, the
firmware was the original Broadcom ucode5, I did not use encryption. I
did extensive testing but I never succeeded.
I then tried the same setup, using this time a 4318 card to initiate
the ad-hoc network on the Linux box, and I got the same behavior.
Finally I repeated the experiment this time initiating the ad-hoc
network with a Linksys WRT54GL (BCM 4320), same result, the two Apple
Macs never joined the network, they reported a generic error and
nothing more.
Please note that if I repeat the experiments using a MacBook Pro with
Atheros hardware everything works fine. Also all other Linux PC I have
do not have problems in joining these b43-run ad-hoc networks
independently of the kind of Atheros or BCM hardware they use.
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