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. -- [email protected] _______________________________________________ 6tisch mailing list [email protected] https://www.ietf.org/mailman/listinfo/6tisch
