Subject: [lp-wan] Case for splitting the fragmentation piece from the SCHC IP draft

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Thu, 30 Mar 2017 16:48:46 +0000

Dear all:

<chair hat off>

Yesterday at the LPWAN WG meeting in Chicago, we discussed the possibility to split the fragmentation piece off the SHCH/IP document - we also discussed splitting the framework piece but quickly dismissed that, see the minutes to be published soon.

Here are some arguments in favor of splitting:
- the fragment piece is a sublayer below IP in order to enable IP, but it is not IP
- the mechanisms involved are completely different, the fragmentation has very basic rules. Splitting the docs improves the clarity of what is needed for what.
- the expectations on the network are different e.g. fragmentation requires in-order delivery, IP requires 1280 MTU.
- which relates to the fact that the backend device that handles the fragmentation may be different (e.g. the fragmentation could be done at the NS as opposed to SCHC/IP and CoAP that could be run in some MEC or cloud location)

And then there are reasons related to the standardization process. Putting it all together like we did with RFC 4944 can probably be seen as a mistake with the historical perspective that we have now. With the split:
- going through the review process would be streamlined; we have a very constrained agenda
- maintenance of the docs for future revision / deprecation would be easier, either updating one or the others.

With this in mind, I encourage the split...

<chair hat on>

but would like to hear about reasons not to split before we make a decision.

Take care,

Pascal