On 2011-07-29 7:55 PM, Helmut Schaa wrote:
On Fri, Jul 29, 2011 at 7:37 PM, Jouni Malinen<j@xxxxx> wrote:
On Fri, Jul 29, 2011 at 11:14:20AM +0200, Helmut Schaa wrote:
I just noticed that EAPOL frames generated by hostapd during the 4-way
handshake are sent out by mac80211 using a rate as selected by the rc
algorithm for data frames. In my case minstrel_ht selects a MCS rate for
11n clients which sometimes results in a 4-way handshake timeout under
low signal conditions.
That sounds like an issue that should be fixed in the rate control
algorithm if it is indeed using unsuitable rate immediately after
association. Dropping data frames completely is not really a good thing
regardless of whether they are EAPOL packets or not..
True. Nevertheless other drivers like madwifi or the ralink legacy drivers also
force EAPOL frames to a low rate. That's why I had the idea in the first place.
I think this mainly occurs on devices/drivers that use minstrel_ht, but
lack proper multi-rate retry. minstrel_ht may pick a high rate for
probing and on devices with a simple fallback table (e.g. rt2x00), it
may give up on the frame before having tried a low enough rate.
On ath9k this shouldn't be an issue with minstrel_ht, because it always
keeps the max_prob_rate in a retry slot.
- Felix
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