Yatch, Can you confirm Tero has answered your question? Thomas On Tue, Nov 15, 2016 at 12:02 PM, Tero Kivinen <kivi...@iki.fi> wrote:
> Yasuyuki Tanaka writes: > > To my understanding, the scheduled cell in 6tisch-minimal can be used > > for both of unicast and broadcast. The destination address of a frame > > to be sent with the cell may have the MAC address of a particular > > neighbor or the broadcast address. > > > > But I'm not sure how we can handle that use case with the MAC Layer > > defined by IEEE 802.15.4-2015. > > > > According to IEEE 802.15.4-2015, each scheduled cell has a node > > address associated with it, which is called "macNodeAddress" and > > listed as a TSCH MAC PIB attribute in Table 8-85. By definition, this > > is "(an) address of neighbor device connected to this link or the > > broadcast address." It sounds like we cannot use a single cell for > > unicast and broadcast at the same time; more generally, a cell cannot > > be associated with more than one distinct MAC address. This also > > implies that a node has to know the address of a correspondent > > beforehand to receive frames from it. > > In 802.15.4-2015 there is 3 bits that affect this. TxLink, RxLink and > SharedLink. SharedLink means that the link is used by multiple senders > at the same time, and senders need to use different retransmission > mechanims on the link, as there might be collisions. If the link is > not SharedLink, it is dedicated link, thus node can send to it without > caring about collsions. SharedLink only has real mening on the > TxLinks. > > In addition to that the TxLink might either have one mac address > assigned to it, or it might be breadcast address. This affects whether > this node can be used to send to that node. I.e. if node is trying to > send node xxx, it can either wait for TxLink having macNodeAddress of > xxx, or it can wait TxLink having macNodeAddress of broadcast. > > macNodeAddress does not really have any meaning for the RxLinks > (unless they also have TxLinks). There is nothing in the 802.15.4-2015 > which says how macNodeAddress is for RxLinks (i.e., the section 6.7.2 > does not have any filter rules based on that. > > > I thought there might be a special MAC address for internal use which > > matches any address, like 0.0.0.0 or ::/0, and we could set the > > address to "macNodeAddress." However, I cannot find such an address... > > > > In practice, is the broadcast address used for "any" as well as for > > "broadcast"? Do you have any thoughts? > > Yes, I think you can use broadcast for NodeAddress for RxLinks. > -- > kivi...@iki.fi > > _______________________________________________ > 6tisch mailing list > 6tisch@ietf.org > https://www.ietf.org/mailman/listinfo/6tisch > -- _______________________________________ Thomas Watteyne, PhD Research Scientist & Innovator, Inria Sr Networking Design Eng, Linear Tech Founder & co-lead, UC Berkeley OpenWSN Co-chair, IETF 6TiSCH www.thomaswatteyne.com _______________________________________
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