Hi Xavi,
I think there are two scenarios which may result in the number of cells in the
CellList of response packet less than numCells_max, (1) when node B has N
cells, where Offset<N and N<Offset+numCells_max cells; (2) when node B has more
than Offset+numCells_max cells, but numCells_max cells cannot be fitted in the
packet.
My question is how to distinguish one from another from node A side? Did I miss
something?
ThanksQin
On Tuesday, September 6, 2016 4:45 AM, Xavier Vilajosana
<[email protected]> wrote:
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
proposalhttps://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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