On Thu, 2016-10-06 at 13:53 +0200, michael-dev wrote: > Am 05.10.2016 13:58, schrieb Johannes Berg: > > > > > > Anyway, perhaps this needs to change to take DMS/per-station into > > account? > > > > Then again, this kind of setting - global multicast-to-unicast - > > fundamentally *cannot* be done on a per-station basis, since if you > > enable it for one station and not for another, the first station > > that has it enabled would get the packets twice... > > as I see it, that is exactly how DMS is standarized. > > IEEE 802.11-2012 section 10.23.15 DMS procedures: > > "If the requested DMS is accepted by the AP, the AP shall send > subsequent group addressed MSDUs that > match the frame classifier specified in the DMS Descriptors to the > requesting STA as A-MSDU subframes > within an individually addressed A-MSDU frame (see 8.3.2.2 and > 9.11)." > > -> so the multicast packets shall go out as unicast A-MSDU frames > to stations that requested this Correct. > "The AP shall continue to transmit the matching frames as group > addressed frames (see 9.3.6, and 10.2.1.16) if at least one > associated > STA has not requested DMS for these frames." > > -> so it will continue to send it as multicast frames as well. > > As with DMS the station requested DMS for a specific multicast > address, it could then drop multicast frames addressed to the > multicast address it registered for DMS. Yes, the DMS spec tells it to do this. However, we can't implement non- DMS similarly, because then the station won't request it and won't drop the duplicates. So for this non-standard multicast-to-unicast, it's all or nothing, it can't be done for some stations only. johannes
