Re: [PATCH 2/2] mac80211: Always send EAPOL frames at lowest rate

Christian Lamparter schrieb:

On Saturday 30 July 2011 22:03:34 Andreas Hartmann wrote:

quoted

Jouni Malinen schrieb:

quoted

On Fri, Jul 29, 2011 at 07:22:17PM +0200, Helmut Schaa wrote:

quoted

Since EAPOL frames are normal data frames they are treated by the
rate control algorithm as such. Thus it can happen that the rate
control algorithm chooses an inappropriate rate (minstrel_ht uses
MCS rates for example) for the 4-way handshake and under low signal
conditions the handshake may time out.

To fix this issue always treat EAPOL frames the same as management 
frames and send them with the lowest available rate.

I don't think that this should be applied for the reasons given (and 
alternative mechanisms proposed) in the discussion.

I tested it with AP (rt2860) (with STA rt3572sta) under load and
couldn't see any improvement. The first PTK-rekeying didn't work as
usual. Or should it be applied to STA?

might be a shot into the dark. But who's assigning a proper frame sequence
to each eapol? Hostapd certainly can't because it doesn't know what's the
current sequence at the moment... and mac80211 won't assign one because
the frame is injected by a monitor interface. So when the receiver gets the
EAPOL it might drops it because the empty sequence might be not in the
BA window anymore. Does this sound reasonable, or did I miss something?

Meanwhile I tested with the patch on both sides, AP (rt2800pci / rt2860)
and STA (ath9k / ar9582) and compat-wireless-2011-07-28. The result is
unchanged the same: the first ptk rekeying (4 way handshake) just didn't
work.

Another thing: I don't think, that the wireless modules are the reason
of the problem. If I'm using the following test setup, I get no problem
at all:

AP: (rt2800pci / rt2860 - without patch)
STA: (rt3572 / rt3572sta - used without wpa_supplicant, but just
rt3572sta stack - rt3572sta ships with an own WPA2-PSK-stack)

-> Why is it working without any problems, if wpa_supplicant isn't used
at all?


Andreas