On Fri, Jul 29, 2011 at 2:44 PM, Helmut Schaa <helmut.schaa@xxxxxxxxxxxxxx> wrote: > Hi, > Hi Helmut, > 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. I am occasionally seeing this issue in ath9k Station under heavy traffic conditions and low signal(only when I the distance between STA and AP is very much significant), some times I could no recreate the issue. I use ath9k-rate control and I still found that the EAPOL frames are being sent at lower rate. with the sniffer capture there are lot of retries for 2nd message. the timeout comes after 2nd message > > I haven't found anything in 802.11-2007 if EAPOL frames have to be sent > at a low rate but I'd argue that it makes sense to send them at a basic > rate just like it's done for management frames. > > We've got a nice little helper in mac80211 (rate_control_send_low) that > allows the rc algorithm to check if a frame should be sent at a low rate. > I thought I'd hook in there and just check skb->protocol to force EAPOL > frames to the lowest rate. However, this didn't work out because in AP > mode the EAPOL frames are injected through a monitor interface and as > such skb->protocol is never initialized (ieee80211_monitor_start_xmit). > > The injected frames however already have an 802.11 header and therefore > figuring out the ethertype of the injected frame is not as straightforward as > I liked it to be :( > > Can I always be sure that an injected data frame (!=nullfunc) has a rfc1042 > header following after the 802.11 header? > > Another option would be to let hostapd specify a fixed tx rate in the radiotap > header (and extend mac80211 to understand it). However, since some drivers > also make use of skb->protocol (to forbid aggregation for example) it sounds > more sane to initialize it also for injected frames. in ath9k Raj pointed out that we are not doing aggregation if the frame is of EAPOL, I can check if I am missing something. > > Any other ideas? > > Thanks, > Helmut > -- > To unsubscribe from this list: send the line "unsubscribe linux-wireless" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- shafi -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
