Shepherd writeup

As required by RFC 4858, this is the current template for the Document 
Shepherd Write-Up.
Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?
SHEPHERD RESPONSE:  Proposed Standard (the title page header shows the “Standards Track” label). 
This is the proper type of RFC because the document updates RFC 4944 (a Standards Track RFC that defines the original 6LoWPAN fragmentation functionality) with a protocol for recovering individual fragments in a route-over mesh network, and a minimal flow control.

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

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

  Was there anything in WG process that is worth noting? For 
  example, was there controversy about particular points or 
  were there decisions where the consensus was particularly 


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

  Are there existing implementations of the protocol? Have a 
  significant number of vendors indicated their plan to 
  implement the specification? 
One WG participant expressed on the mailing list that he was working on an implementation. His feedback contributed to improving the document.

   Are there any reviewers that 
  merit special mention as having done a thorough review, 
  e.g., one that resulted in important changes or a 
  conclusion that the document had no substantive issues?

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).

 If  there was a MIB Doctor, Media Type or other expert review, 
  what was its course (briefly)? In the case of a Media Type 
  review, on what date was the request posted?



Document Shepherd: Carles Gomez
Responsible Area Director: Suresh Krishnan

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.
I first reviewed revision -03 of the document. My comments were addressed in version -04. As the shepherd, I reviewed again the document, and found few other issues more related with the shepherd write-up, which were addressed in -05 and -06. In my opinion, the document is now (-07) ready  for IESG review. 

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.
SHEPHERD RESPONSE: As mentioned in the response to question (2), Laurent Toutain and Carles Gomez performed comprehensive reviews of recent versions of the draft. Both reviewers have a background in fragmentation in constrained node networks. No other particular reviews were needed.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.
SHEPHERD RESPONSE: The document author has confirmed that he is unaware of IPR on this document.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR

(9) How solid is the WG consensus behind this document? Does it 
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it?   
SHEPHERD RESPONSE: as mentioned in the response to question (2), the consensus behind this document is solid, with the WG as a whole understanding and agreeing with it.

(10) Has anyone threatened an appeal or otherwise indicated extreme 
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.) 

(11) Identify any ID nits the Document Shepherd has found in this
document. (See and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
SHEPHERD RESPONSE: One downref “error” has been identified (see the answer to question (15)). There are also comments from the idnits tool. The relevant details from the idnits tool output follow: 
-- The document seems to lack a disclaimer for pre-RFC5378 work, but may
     have content which was first submitted before 10 November 2008.  If you
     have contacted all the original authors and they are all willing to grant
     the BCP78 rights to the IETF Trust, then this is fine, and you can ignore
     this comment.  If not, you may need to add the pre-RFC5378 disclaimer. 
-- The document date (April 2020) is 175 days in the future.  Is this
** Downref: Normative reference to an Informational draft:
     draft-ietf-6lo-minimal-fragment (ref. 'I-D.ietf-6lo-minimal-fragment')

     Summary: 1 error (**), 0 flaws (~~), 0 warnings (==), 2 comments (--).

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

(13) Have all references within this document been identified as
either normative or informative?

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in 
the Last Call procedure. 
SHEPHERD RESPONSE: Yes, there is 1 downward normative reference, which is draft-ietf-6lo-minimal-fragment. This reference is an informational document located in the normative references subsection. In fact, this reference qualifies as a document that “must be read to understand or implement the technology in the new RFC, or whose technology must be present for the technology in the new RFC to work” ( 

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.
SHEPHERD RESPONSE: this document updates RFC 4944, as listed on the title page header, mentioned in the Abstract and explained in the Introduction (although the verb “update” is not used in the latter). Section 3 is entitled “Updating RFC 4944”. 

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).
The document defines 2 new 6LoWPAN Dispatch types (and allocates 4 values) in Page 0 from the "Dispatch Type Field" registry (RFC 4944, RFC 8025). Section 9 of the document, entitled "IANA considerations", details the IANA actions needed. The actions requested from IANA are appropriate from the point of view of the shepherd.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.
SHEPHERD RESPONSE: Not applicable as there are no formal language constructs in the document.