[6lo] Comments on draft-ietf-6lo-schc-15dot4

[Kiran Makhijani <[e-mail]>]

Hello authors,
Apologies for late comments. May be we can talk about the detailed review
later, instead  I wanted to discuss high-level points first. Please take
them as comments from a newbie...

1. I found it bit challenging to catch up with all  the past 4-digit
RFC-soup that this document need to reference (3 from SCHC, 3 from base
6lowPAN, a few on RPL).  It becomes  arduous to follow everything (I had to
read 4 to 5 documents before getting reasonable understanding on how I
could help with review). I am not sure how can this be addressed but
something to consider as a broader assumption when writing the document.

2. One suggestion is to re-write architecture section.
 2.1. Since 6lowPAN is using SCHC,  I find it odd that it does not talk
about adapting SCHC architecture in LLN. i.e. say what node will need to
support what SCHC functionality. Then the document will become easier to
read. For instance, you could draw a LLN with 6LRs, BRs etc. and say what
SCHC gateway functionality will fit where instead of saying in
straight-forward RPL rules should be installed in all LRs...
2.2 So I suggest first present both the architecture then map
functions will be better and then develop cases.
2.3 Ques: how are SCHC rules distributed  in LPWAN? Can same techniques be
used or RPL is the only approach? (sorry, I am not finished reading SCHC
and don’t know this yet).

3. I would have really liked to see 'SCHC dispatch' discussed earlier as
part of the architecture instead of dealing with it later. This is a key
LLN dataplane enhancement and everything builds on top of it. The key is
you are not adding new rules, you are using LLN data plane to carry SCHC
and nodes with knowledge of this feature will process accordingly.

To summarize, when you put this together, reading of document will be very
simple:
  - adapt SCHC architecture
  - describe new dataplane enhancement
  - describe routing mechanisms
  - formats...

What do you think? It's possible I must have misunderstood, in that case
please bear with my ignorance :-).
Thanks
Kiran