Hi, according to our discussion during the last 6TiSCH meeting I want to follow up Tero's proposal for the LIST cmd.
here you will find his initial proposal https://www.ietf.org/mail-archive/web/6tisch/current/msg04719.html As a summary, the proposal enables 6P list to return a best effort set of cells, this is as many as can be fitted in a packet below a maximum. This makes the list command robust to the presence of other IEs in the packet (which sometimes may be present and some times don't and hence would make two identical requests to succeed or fail. With this approach LIST is independent of the remaining space in the packet) I follow up the discussion by proposing these changes to 6P. 1- change numCells field to numCells_max as follow: 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| Code | SFID | SeqNum|GAB|GBA| Metadata +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Metadata | Offset | numCells_max +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+ where numCells_max: The maximum number of requested cells. Less cells than numCells_max can be returned if they do not fit in the packet. Then I propose the following text 4.3.10. Listing Cells When a node A issues a LIST_AB or LIST_BA command, it specifies: o Through the "Offset" field, the offset of the first cell to be present in the returned list. The cell ordering policy is defined by the SF. o Through the "numCells_max" field, the maximum number of cells to be present in the reponse. If numCells_max cannot be fitted in the packet less cells will be returned. When receiving a LIST_AB command, node B returns the cells that are scheduled from A to B in its schedule (i.e. receive cells from node A). When receiving a LIST_BA command, node B returns the cells that are scheduled from B to A in its schedule (i.e. transmit cells to node A). The RECOMMENDED format of each 6P Cell is defined in Section 4.2.5. The SF MAY redefine the format of the CellList field. Depending on how many cells node B has in its schedule which match the LIST_AB or LIST_BA request, the cellList returned in the 6P Response contains between 0 and numCells_max cells: o If node B has more than Offset+numCells cells, the cellList it returns contains exactly numCells cells as long as the cellList fits in the packet. Otherwise it returns a cellList containing the maximum number of cells that fit in the packet. o If node B has N cells, where Offset<N and N<Offset+numCells_max cells, the cellList it returns contains exactly N-Offset cells. If that number of cells do not fit in the packet, the cellList containing the maximum number of cells that fit in the packet is returned. o If node B has less than Offset cells, the cellList it returns is empty. Please, raise any pros and cons you may find in this approach.
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