Technical Summary
This document introduces the capability to forward 6LoWPAN fragments.
This method reduces the latency and increases end-to-end reliability
in route-over forwarding. It is the companion to using virtual
reassembly buffers which is a pure implementation technique.
Working Group Summary
The topic of fragmentation attracted increased interest from participants at the 6lo working group in 2016-2017, with dedicated fragmentation discussion slots in 6lo at IETF 98 and IETF 99. As a result, a fragmentation Design Team was formed. It was decided that two 6lo wg documents and one lwig wg document would be created, more specifically: a) a document defining a fragment recovery protocol (i.e. the document that is the object of this writeup), b) an informational document giving an overview of minimal fragment forwarding, and c) a document describing the implementation technique that avoids per-hop packet fragmentation and reassembly. The present document is the second one. This decision had good consensus, and the present document was created and has progressed with no controversy. Only after the review of -04 by the INTDIR assigned reviewer (Dave Thaler), and subsequent discussion with the authors, it has become clear that some content of the document had to mandate protocol behavior, thus the Intended Status of Proposed Standard.
Document Quality
Yasuyuki Tanaka, Georgios Papadopoulos and Dominique Barthel carried out deep reviews. The last two were carried out during WGLC, and the comments were addressed in draft-ietf-6lo-minimal-fragment-02. Dave Thaler reviewed -04, on behalf of the INTDIR, and subsequent discussion with the authors led to adding normative text to the document and changing its intended status from Informational to Proposed Standard. There exist implementations of the fragment forwarding technique that avoids per-hop reassembly.
Personnel
The Document Shepherd is Carles Gomez. The Responsible AD is Suresh Krishnan