[6tisch] Cell types for 6top protocol

["Pascal Thubert (pthubert)" <[e-mail]>]

Dear all :

I took an action item at the 6tisch interim to address cell types in the 6top protocol:

As you know, a chunk is like a malloc heap, a set of resources that a node ( a RPL parent) attributes to be able to serve dynamic bandwidth needs with the 6top protocol.
Currently, the assumption was that the chunks are a partition of the CDU matrix, so chunks are not overlapping, and all cells in chunked space are identical, meant for dedicated unicast traffic like we foresee for tracks.
I pointed out at the interim today that for statistical traffic we may want to have overlapping chunks, in which case cells from different chunks but overlapping chunks may have a chance of collision *.
We discussed that the requester of cells in the 6top protocol may have a say on which type of cell is to be allocated, like high priority, unicast vs. shared, guaranteed non overlapping vs not.
This raises a number of questions:


1)      Do people see value in doing that?

2)      If so, should a chunk have properties, like should cells in a chunk have homogeneous properties?

3)      Should the type (unicast vs. shared) be a permanent property of the cell while it is free (it sits in a chunk), or one attributed by the parent when the cell is placed in a bundle and for the direction of that attribution?

What do you think?

Pascal

* note there is some Cisco IPR around overlapping chunks that that I need to dig if we pursue this direction.