Subject: [6tsch] 6tus support to installing Tracks

From: Qin Wang <[email-masked]>
Date: Wed, 19 Jun 2013 20:57:06 +0800

Hi all,

We have had many discussions on Track related topic in threads like
"Routing vs switching". I would like to discuss more about what 6tus should
provide to install a Track, including installing both hard cell based Track
and soft cell based Track.

My understanding is what we can do now is as follows.
(1)  add hard cells along the path, with Cell Commands
(2) specify the mapping between each incoming cell and outgoing cell along
the path, with Label Switching Commands

If my understanding is correct, I can see the following problem: It need
more bandwidth. For example, when you add a hard cell between nodeA and
nodeB, one global communication from PCE to nodeA, and one local
communication from nodeA to nodeB are needed. But for the Label Switching
command, additional two communications, i.e. from PCE to nodeA and from PCE
to nodeB are also needed. In addition, if a given track consists more than
one incoming cells and outgoing cells, more bandwidth for installing the
track will be consumed.

Thus, I would like to suggest to use TrackID to associate incoming cells
and outgoing cells. For sure, the TrackID will not appear in packet, it is
just used to establish the relationship between incoming cells and outgoing
cells. i.e.
(1) add TrackID as a parameter of Cell commands.
(2) same procedure of adding/removing hard cell or soft cell as before.
(3) while receiving adding hard cell or soft cell command,  fill the Track
table with the TrackID. In the Track table, Rx cells are the incoming cells
and Tx cells are the outgoing cells. And then, from TSCH's point of view,
 the schedule is the overlap of all Track tables.

How do you think?

Qin