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Shepherd writeup

Changes are expected over time. This version is dated 1 November 2019.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)?

draft-ietf-bier-te-arch is proposed Standard track.

Why is this the proper type of RFC?

This is indicated on the title page. This document defines BIER tree
engineering mechanism by changing the semantics of bit position that has been
defined in RFC 8279, which provides traffic steering within BIER forwarding

Is this type of RFC indicated in the title page header?


(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 draft presents a stateless path steering mechanism for BIER, called BIER
TE (Tree Engineering for Bit Index Explicit Replication). Bitstring sematic of
BIER-TE is different from BIER defined in RFC 8279, which indicates
adjacencies, but it could reuse the forwarding engine of BIER. The BIFT of each
BFR only contains the BPs that are adjacent to the BFR in BIER-TE topology.
BIER-TE doesn’t depend on any IGP protocols as routing underlay.

Working Group Summary:

The name of the mechanism defined in the draft has been discussed during last
call, which was changed from “BIER traffic engineering” to “BIER tree
engineering”, considering that it only covers the path steering function in the
overall solution of traffic engineering. Any BIER traffic engineering mechanism
could use this mechanism. As the result of the WG discussion, “Name
explanation” part is added to the document, which will be removed in the next

Document Quality:

After full discussions and multiple revisions, there is solid consensus for
this document in WG. It is ready for publication . No implementation was yet
announced in the BIER WG. No formal language is used in the document (there is
some informal pseudo-code without formal verification tools). No aspects of the
document required expert review.


Who is the Document Shepherd? Who is the Responsible Area Director?

Geng Xuesong is the shepherd and Alvaro Retana is the Responsible Area Director

(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.

The shepherd has reviewed the version 8 of draft-ietf-bier-te-arch. Her
concerns where addressed by the authors in version 9. She believes this version
is now ready for forwarding to the IESG for publication.

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

Yes. See acknowledgement section for list of key reviewers, including Lou
Berger, TEAS chair. This document has been reviewed, and there is no concern
about depth or breadth about the previous reviews.

(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.


(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.

The shepherd has no concerns.

(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?

The Shepherd received confirmation from all authors that all IPR they are aware
of has been disclosed to the IETF:

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

There is no IPR-related discussion.

(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?

The WG consensus for this draft is very solid.

(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 thorough.

The shepherd has verified idnits. Only warnings where found by the tools which
have been identified to be issues of the idnits tools, not of the document. The
intend status of the document is correctly indicated, formal review criteria
are met (are not applicable).

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

Not relevant.

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

Yes the document is split to normative and informative references. Documents
that are normative references are in a clear state (no pending or downrevs).

(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


(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.


(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 8126).

This document requests no action by IANA.

(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.

Not relevant.

(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, YANG modules, etc.

Not relevant.

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
( for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in

Not relevant.