Synchronized is a good thing in a 6TiSCH world :-) On Wed, 16 Nov 2016 at 19:56 Yasuyuki Tanaka <yasuyuki9.tan...@toshiba.co.jp> wrote:
> Hi Tero, > Thank you for the clear explanation!! > > I check Figure 6-5 and Figure 6-6 that you referred. Indeed, there is > no distinction on a sending frame between unicast or broadcast. > > Now I've got synchronized. :-) > > Best, > Yatch > > On 2016/11/16 4:05, Tero Kivinen wrote: > > Yasuyuki Tanaka writes: > >> In this sense, the purpose of macNodeAddress is only to make something > >> like a priority cell for outgoing frames to a certain MAC address > >> other than the broadcast address. And, we cannot allocate a cell > >> exclusively used for sending broadcast frames. I wish IEEE > >> 802.15.4-2015 could elaborate what is expected to do with > >> macNodeAddress... Everybody may have no confusion about these things > >> except me... > > > > We had long discussion about that when 802.15.4-2015 revision was > > being made, and we tried to clear things as much as possible, but as > > people also had bit different things what 4e meant it was bit hard... > > > >> With regard to Link Options or Cell Options, I believe I have the same > >> understanding as Tero's. I'm relieved here. :-) But, I have one thing > >> I want to confirm about this. > >> > >> If a cell is "shared", this means that there is a possibility of > >> contention or collision as you mentioned. This attribute, shared or > >> not, is orthogonal to which type of communication, unicast and/or > >> broadcast, to be done, isn't it? > > > > Yes. The 802.15.4-2015 [1] CSMA-CA algorithms (section 6.2.5.1) state > > machines Figure 6-5 and TSCH CSMA-CA retransmission algorithm (section > > 6.2.5.3) Figure 6-6 do not make difference whether the slot is > > broadcast or not. It just have steps "Wait for next TX link to > > destination" and that can be either broadcast link or link only for > > it. The shared bit affects the next step which is "Dedicated Link?" / > > "Shared slot?" questions. > > > > [1] http://standards.ieee.org/getieee802/download/802.15.4-2015.pdf > > > >> Therefore, in theory, we may have a dedicated (non-shared) TX cell > >> whose macNodeAddress is the broadcast address. > > > > Yes. I.e. you are the only one allowed to send to that link, but there > > are multiple listeneres in there. So, as it does not have shared bit > > on, there will not be other transmitters, but there can be multiple > > listeners on it. > > > >> In this case, a node having such a TX cell is supposed to be the > >> unique sender in its neighborhood. We may also have a shared TX cell > >> whose macNodeAddress is a unicast address. In this case, more than > >> one pairs of devices could share such a cell for their > >> communication. > > > > Yes. > > > > _______________________________________________ > 6tisch mailing list > 6tisch@ietf.org > https://www.ietf.org/mailman/listinfo/6tisch >
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