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IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Selective Fragment Recovery
RFC 8931

Approval announcement
Draft of message to be sent after approval:


From: The IESG <>
To: IETF-Announce <>
Cc:,,,,, Carles Gomez <>,, The IESG <>
Subject: Protocol Action: '6LoWPAN Selective Fragment Recovery' to Proposed Standard (draft-ietf-6lo-fragment-recovery-21.txt)

The IESG has approved the following document:
- '6LoWPAN Selective Fragment Recovery'
  (draft-ietf-6lo-fragment-recovery-21.txt) as Proposed Standard

This document is the product of the IPv6 over Networks of
Resource-constrained Nodes Working Group.

The IESG contact persons are √Čric Vyncke and Suresh Krishnan.

A URL of this Internet Draft is:

Ballot Text

Technical Summary

This document updates RFC 4944 with a simple protocol to recover
individual fragments across a route-over mesh network, with a minimal
flow control to protect the network against bloat.

Working Group Summary

Older versions of a precursor of this document existed as an individual submission discussed in the 6lowpan working group between 2008 and 2010, and were discussed again during the initial stages of the 6lo working group lifetime (e.g. at IETF 88). Some concerns were expressed at the time, such as potential interactions across layers. The topic of fragmentation attracted increased interest from participants at the 6lo working group again 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. This decision had good WG consensus, and no controversy has occurred since then regarding any of the three mentioned documents.

Document Quality

Michel Veillette carried out a thorough review of the document before it became a 6lo wg document.
Laurent Toutain and Carles Gomez, both with a background in fragmentation in constrained node networks, did comprehensive reviews of recent versions of the document, based on revisions -02 and -03, which led to revisions -03 and -04.  As a result of the shepherd (Carles Gomez) review, the document was again updated, leading to versions -05 and -06). Another WG participant provided comments in parallel, leading to the current version as of the writing (i.e. -07). One WG participant expressed on the mailing list that he was working on an implementation. His feedback contributed to improving the document.


The Document Shepherd is Carles Gomez. The Responsible AD is Suresh Krishnan.

RFC Editor Note

RFC Editor Note

Unless overridden by a more specific specification, that unit is the
byte, which allows fragments up to 1024 bytes.

Unless overridden by a more specific specification, that unit is the
byte, which allows fragments up to 1023 bytes.