On 10/28/2011 11:28 AM, Helmut Schaa wrote: > On Fri, Oct 28, 2011 at 11:10 AM, Arend Van Spriel <arend@xxxxxxxxxxxx> wrote: >>>> I would expect this to affect the duration field in the >>>> 802.11 header to indicate the shorter use of the medium. >>>> Going through your patch I am not sure this is done. >>> >>> Hmmm. You're right, but that's something we already need to fix in many >>> cases -- as the duration field is overwritten by most hardware these >>> days, we haven't always maintained it very well. >> >> If the station still does the ACK we should not touch the duration field >> in this case (see my reply to Helmut). > > The reason is the following: if you're running a mac80211 AP with multiple > bssids, hostapd will answer to broadcast probe requests sent by STAs with > one probe response per bssid (unicast of course). And since some clients > stay only for a short amount of time on the scan-channel (a few ms) under > some circumstances the probe responses aren't sent out yet before the > scanning STA leaves the channel and thus retried till the maximum retry > limit is reached. And these retries consume quite a lot of airtime. And to > avoid this we just don't want to retry the probe responses in that case. > > Helmut > Hi Helmut, That makes perfect sense. Indeed not doing retries will obviously save airtime. Thanks for taking time to explain the scenario. Gr. AvS -- 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
