> On Mon, 2013-11-04 at 15:31 +0100, Simon Wunderlich wrote: > > > > Thanks for checking back - I've read the part in the spec again [1], > > > > and appearently you are right. > > > > > > > > With your proposed change, shouldn't we also change the behaviour if > > > > the userspace requests a channel switch with count = 0? I guess we > > > > should immediately change the channel then without waiting for > > > > beacons? I don't see the point in changing the beacons if we don't > > > > send them, after all. > > > > > > You're right, changing the beacons doesn't make sense in this case. > > > I'll change that and send v2. > > > > > > Another thing is that we are missing the action frames. The idea with > > > the count == 0 is that the STA's should start listening on the other > > > channel immediately after receiving the action frame (because the > > > switch will happen at any time). > > > > > > If we don't send the action frame, passing context == 0 from the > > > userspace doesn't much make sense, because the clients won't know we're > > > switching. Well, maybe it makes a bit of sense, if there are no > > > clients connected, but nevertheless. > > > > Yeah, switching without actionframe and count == 0 is pretty useless. > > Actually, if the userspace requests count == 1, we won't have any > beacons either, because 1 means "just before the next TBTT". So for > count == 1 (coming from the userspace) we shouldn't configure the > beacon, since we won't send it. We need the action frame for this case > too. > Hmm, right, we will decrement the counter before sending it out ... > > For AP mode, I guess the right place to implement the action frames would > > be hostap? This would at least allow great flexibility with CSA, ECSA > > and all the new channel switch IEs coming now. The beacons are also > > generated in userspace, after all. > > What new channel channel switch IEs? Right now we also have extendended channel switch announcements (ECSA), and secondary channel offset, and there are more to come with 802.11ac I think. I have not studied it yet (and I don't have access to 802.11 drafts), but have a look at that: https://mentor.ieee.org/802.11/dcn/13/11-13-0105-00-00ac-lb190-proposed- resolution-on-cid-7367-and-7368.docx&ei=T_N4UuHWGcmt4ATQj4DwBg&usg=AFQjCNE5E- bpqRGQM7-QwG0L4TiU3OOLig&bvm=bv.55980276,d.bGE&cad=rja (not only the .doc format is ugly) > > You're right that it might make sense to implement the action frames in > hostap. But OTOH, the action frame is quite simple and mac80211 should > have all the information needed to send it out. > > > BTW, I've just checked and the WiFi Alliance requires at least 5 beacons > > with CSA-IEs to pass the 802.11h test. :) > > Do you mean that the tests only check when count starts as > 5? > It checks if the last beacon hast a CSA IE in the beacon, and also if there are 4 beacons before that including a CSA IE. It does not check for the count though, but that's implicitly given ... Cheers, Simon -- 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
