[Roll] Dominique's review, bis

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

Hi:

Dominique inserted some comments in the commit I made for his review. I created the follow-up commit:
https://github.com/roll-wg/dao-projection/commit/c8cb3fbea0b1525811d451ede6207df6ade0b1d3

Apart from Typo, there was still a hard to parse sentence about Segments crossing:
> each Track" or "multiple Tracks".
> However, I still don't understand. Some more homework to do, I guess.

I proposed the following rewording:

   "The Segments that join the loose hops of a Leg are installed with the
   same TrackID as the Leg. But each individual Leg and Segment has its
-  own P-RouteID which allows it to be managed separately.  When Legs
-  cross within - meaning that there is a node that belongs to a Segment
-  from each Tracks, so it may reach the destination over either leg -
-  the next loose hop (the current destination of the packet) indicates
-  which Leg is being followed and a Segment that can reach that next
-  loose hop is selected.
+  own P-RouteID which allows it to be managed separately. 2 Legs of the
+  same Track may cross at a common node that participates to a Segment
+  of Each Leg.  In that case the common node has more than one next hop
+  in its RIB associated to the Track, but no specific signal in the
+  packet to indicate which Segment is being followed.  A next hop that
+  can reach the loose hop is selected."


Corollary: I added text to insist that in RPL each Instance creates a RIB that is followed end to end that will help understand the above.

DIFFs 
    " RPL instances operate as ships passing in the night, unbeknownst of one another.
    The RPL Root is responsible for selecting the RPL Instance that is used
    to forward a packet coming from the Backbone into the RPL domain and for setting
-   the related RPL information in the packets. "
+   the related RPL information in the packets. Each Instance creates its own
+   routing table (RIB) in participating nodes, and the RIB associated to the 
+   instance must be used end to end in the RPL domain. To that effect, RPL
+   tags the packets with the Instance ID in a Hop-by-Hop extension Header."

And 

    P-Routes can be used as stand-alone Segments meant to reduce the size of the
    source routing headers, thanks to loose source routing operations down the main RPL DODAG.
    P-Routes can also be combined with other P-Routes to form a more complex
-   Track, consisting of local instances overlaid on an existing main RPL Instance.
+   Track, consisting of local instances overlaid on an existing main RPL Instance, 
+   each with its own RIB that must be followed till the destination
+   is reachable directly as a neighbor, or via a Sibling.

I'm delaying the publication to be able to add whatever we'll agree upon at the meeting. Talk to you in an hour!

Pascal