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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 1 November 2019.

(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?

Standards Track.  This document specifies a new BIER specific extension to the
BGP Link-state address-family in order to advertise BIER information to
NorthBound interface to a Centralized Controller for both intra-as and inter-as
provisioning of BIFT forwarding table for MVPN stateless X-PMSI P2MP tree &
programming in hardware the BIFT forwarding table.

(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:

Relevant content can frequently be found in the abstract and/or introduction of
the document. If not, this may be an indication that there are deficiencies in
the abstract or introduction.

   Bit Index Explicit Replication (BIER) is an architecture that
   provides optimal multicast forwarding through a "BIER domain" without
   requiring intermediate routers to maintain any multicast related per-
   flow state.  BIER also does not require any explicit tree-building
   protocol for its operation.  A multicast data packet enters a BIER
   domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
   BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
   The BFIR router adds a BIER header to the packet.  The BIER header
   contains a bitstring in which each bit represents exactly one BFER to
   forward the packet to.  The set of BFERs to which the multicast
   packet needs to be forwarded is expressed by setting the bits that
   correspond to those routers in the BIER header.

  This document specifies a BIER specific extension to the BGP Link-state
  address-family in order to advertise BIER information for both intra-as and
  inter-as stateless tree provisioning.

Working Group Summary:

The Working Group achieved consensus.  No controvercial issues to report.

Document Quality:

As the industry has been moving from distributed architecture to hybrid and now
a centralized controller based architcutre for both RSVP-TE and now Segment
Routing SR-MPLS & SRv6 SR-TE to provide inter-as visibility for path
computation and path instantiation, this draft now along those same PCE
centralized controller based concept provide a means of meeting an industry
requirement for BIFT forwarding plane programming  and provisioning of BIER
stateless trees.   I brought up during my shepherd review as an expert review
of the specification that the use of BIER extension for BGP-LS use case to
clarify the use case verbiage that the extension is for a centralized PCE
controller to provision the intra-as or inter-as stateless BIER tree.


Document Shepherd is Gyan Mishra.  Area Director is Alvaro Retana.

(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 document was reviewed and is well written and succinct.  The document is
ready for publication.

(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.


(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.

No concerns or issues with this document.

(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?

Authors were polled for IPRs and one IPR filed.

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

Yes.  One IPR was filed below.  The IPR was disclosed & recorded on the

2019-03-06      3456    ZTE Corporation's Statement about IPR related to

(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 has full consensus and is behind this document.

(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.

 idnits check was run and minor issues were found and sent to authors.   An xml
 file was not posted to run xml2rfc check.

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

Document meets all IETF specifications and all applicable formal review criteria

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

All references are listed as normative.  I have contacted the author to list
some of them as 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?

Yes.  I have contacted the author on an expired draft listed as normative
reference below.

(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.

The publication will not update any RFC's.

(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).

I confirm that the BGP LS protocol extensions on the IANA registry TLV requests
are clearly identified and defined correctly to make the appropriate
reservation for allocation.  At this time IANA codepoints allocations have not
been requested and I have asked the authors on the status of the IANA codepoint
allocation request and to update the draft to reflect the allocations stated as

(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.

This document requests assigning code-points from the registry for
the new Prefix Attribute TLVs for BIER Information TLV, BIER MPLS   
Encapsulaion TLV, BIER Non-MPLS Encapsulation TLV.

(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.

idnits 2.16.05  was run and output sent to the authors to review.

(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

No Yang modules are defined in this draft