[Olsr-users] 802.11 hardware for ad-hoc networks [was: Probleme of]

[Juliusz Chroboczek]

>> Broadcom cards suffer from BSSID partitioning. I thought Atheros cards
>> were the platform of choice for OLSR? Is there something better?

> Maybe someone here on this list has more experience and is willing to  
> share it concerning drivers.

BSSID partitioning is something that happens at the MAC sublayer.  In
older designs, the MAC sublayer is implemented in firmware; in newer
(``softmac'') designs, the MAC sublayer is implemented in the driver.

In current Linux kernels, softmac designs use a common MAC implementation,
originally known as Devicescape and now renamed to mac80211.  Mac80211
does suffer from BSSID partitioning up to and including 2.6.26, but
this has been fixed in the current net-2.6 tree; hence, this issue
should be solved by 2.6.27 for all drivers using mac80211.  (But
I haven't tested it.)

After this short introduction, here's what I know about Linux drivers.

Atheros is a softmac design.  There are two drivers, the partly-binary
madwifi and the reverse-engineered ath5k.  Madwifi has its own MAC
implementation, and does not suffer from BSSID partitioning.  Older
versions of the Madwifi drivers had issues with ad-hoc mode, but
I believe that they have been solved by now.  (Can anyone confirm
that?)  Ath5k uses mac80211, see above.

Broadcom is a softmac design.  The binary-only ``wl'' driver has its
own MAC implementation, and does suffer from BSSID partitioning.  The
reverse-engineered ``b43'' driver uses mac80211, see above.

Intel has two distinct families of hardware designs which are handled
by the ipw2200 and iwlwifi drivers respectively.  The ipw2200 family
is a hardmac design, and I believe that it does not suffer from BSSID
partitioning (can anyone confirm that?).  The more recent iwlwifi
family is softmac and uses mac80211, see above.

Ralink is softmac, and uses mac80211, see above.  However, older
versions of the ralink driver did not support ad-hoc mode at all;
I haven't checked whether this has been fixed in recent releases.

Hope this helps,

                                        Juliusz Chroboczek