A Framework for Fast Reroute with Bit Index Explicit Replication (BIER-FRR)
draft-ietf-bier-frr-11

Request for posting confirmation emailed to previous authors: Aijun Wang , Gyan Mishra , Huaimo Chen , Michael Menth , Mike McBride , Steffen Lindner , bier-chairs@ietf.org

[Ballot discuss]

# Éric Vyncke, INT AD, comments for draft-ietf-bier-frr-10
CC @evyncke

Thank you for the work put into this document, since my previous DISCUSS ballot on -08, the changes have addressed neither my comments nor Brian Haberman's int-dir comments, hence my ballot stays as a blocking DISCUSS.

Please find below some blocking DISCUSS points, some non-blocking COMMENT points/nits (replies would be appreciated even if only for my own education).

Special thanks to Zheng Zhang for the shepherd's write-up including the WG consensus, the justification of the intended status *BUT* it lacks a real justification for having *SIX* authors.

Other thanks to Brian Haberman, the Internet directorate reviewer (at my request), please consider this int-dir review:
https://datatracker.ietf.org/doc/review-ietf-bier-frr-08-intdir-telechat-haberman-2025-06-03/ (and I have yet to read authors' reply)

I hope that this review helps to improve the document,

Regards,

-éric

## DISCUSS (blocking)

As noted in https://www.ietf.org/blog/handling-iesg-ballot-positions/, a DISCUSS ballot is just a request to have a discussion on the following topics:

### Abstract

It is basically Brian's point 1): s/describes a mechanism/describes *two* mechanisms/

### Informational status ?

Like Brian's point 2), I wonder why this I-D is informational while the basis BIER RFC is experimental.

### Section 6.1

If traffic goes into a tunnel as a back-up path, then how is path MTU change applied ? There should be some text arount PMTU in this section.

[Ballot comment]
Hi Huaimo, Mike, Steffen, Michael, Aijun, and Gyan,

Thank you for the effort put into this specification.

I updated my ballot of 27/05/25 to remove items that I think were addressed in -09 (06/06/25).

Please find some comments below:

# Main comments

## Lack of Operations considerations

The analysis can be strengthened by analyzing the deployment/ops implications of the options discussed in the spec. I noted that there are very few deployment pre-requisites (e.g., 6.2.1), though.

Also, some of the analyzed approach have implications on forwarding path stretch that is worth discussed vs. service objectives.

See rfc8279#section-7 for how this is handled for the base BIER spec.

## Leverage existing frameworks/discussions

For example, I was expecting a discussion about which matters from RFC7916 can be leveraged.

Also, have a discussion whether the proposed approaches are immune against micro loops (or at least call guards, if any); see for example RFC8333. Such discussion is also meant to back early claims in the document such as “minimizing packet loss and service disruption”.

# Misc.

## Routing underly

Please cite rfc8279#section-4.1 early in the document

## Encap over the routing underlay

Seems to always assume one single underly, while the base spec has this right:

  If multiple routing underlays are used in a single BIER domain, each
  BIER sub-domain MUST be associated with a single routing underlay
  (though multiple sub-domains may be associated with the same routing
  underlay).

## There are many controllers in networks

Please consider s/the controller/a controller, through the doc

## IP-FRR/”Normal” BIER-LFA

CURRENT:
      alternative neighbors in the event of a failure.  It applies the
      principles of IP-FRR, requiring that LFAs are also BFRs.  Normal
      BIER-LFAs can be reached without tunneling, remote BIER-LFAs

### Please cite an authoritative reference for I-FRR

### What is meant by “Normal BIER-LFAs”?

## Network layer

CURRENT:
  A BFR-NBR is considered directly connected if it is a next-hop at the
  network layer,

There is no such layer in the base spec. Please use consistent concepts.

## Packets are forwarded

OLD: that the packet is not routed through

NEW: that the packet is not forwarded through

## One or multiple backups

CURRENT:
  *  Backup Forwarding Bit Mask (BF-BM)

  *  Backup BFR Neighbor (BBFR-NBR)

There is only one backup? Or multiple entries can be used for multiple backups? How this is expected to work?

## Desired level

CURRENT:
  Protection coverage refers to the set of BFERs that can be protected
  with a desired level of protection by a particular type of BIER-LFA.

How these are supplied to an implementation?

## BFD Extension

CURRENT:
  If
  the primary BFR-NBR is indirectly connected, a Bidirectional
  Forwarding Detection (BFD) [RFC5880] session between the BFR as PLR
  and the BFR-NBR may be used to monitor its reachability.

Do we need draft-ietf-bier-bfd or only the base BFD is sufficient here?

## Figures are actually tables through the doc.

## Not sure what is the value of Section 5? Maybe point to similar discussion in, e.g., Overview and Principles of Internet Traffic Engineering (RFC 9522).

Cheers,
Med

[Ballot comment]
Thanks to Erica Olson for their secdir review.

This draft is well outside my normal expertise area: 

The word 'tunnel' is used many times in this draft.  There is no definition of what is meant by tunnel(s), I have to assume that they are not for security purposes.  If they are specific types of tunnels, e.g. MPLS or other security tunnel options (IPsec), then it would be nice to have that defined.

I see that RFC 8279 has been changed to 'Proposed Standard' from 'Experimental', which is good.

[Ballot discuss]

# Éric Vyncke, INT AD, comments for draft-ietf-bier-frr-08
CC @evyncke

Thank you for the work put into this document.

Please find below some blocking DISCUSS points, some non-blocking COMMENT points/nits (replies would be appreciated even if only for my own education).

Special thanks to Zheng Zhang for the shepherd's write-up including the WG consensus, the justification of the intended status *BUT* it lacks a real justification for having *SIX* authors.

Other thanks to Brian Haberman, the Internet directorate reviewer (at my request), please consider this int-dir review:
https://datatracker.ietf.org/doc/review-ietf-bier-frr-08-intdir-telechat-haberman-2025-06-03/ (and I have yet to read authors' reply)

I hope that this review helps to improve the document,

Regards,

-éric

## DISCUSS (blocking)

As noted in https://www.ietf.org/blog/handling-iesg-ballot-positions/, a DISCUSS ballot is just a request to have a discussion on the following topics:

### Abstract

It is basically Brian's point 1): s/describes a mechanism/describes *two* mechanisms/

### Informational status ?

Like Brian's point 2), I wonder why this I-D is informational while the basis BIER RFC is experimental.

### Section 6.1

If traffic goes into a tunnel as a back-up path, then how is path MTU change applied ? There should be some text arount PMTU in this section.

[Ballot comment]

## COMMENTS (non-blocking)

### Nits tool

Please check https://author-tools.ietf.org/api/idnits?url=https://www.ietf.org/archive/id/draft-ietf-bier-frr-08.txt and fix the below points

  == The document doesn't use any RFC 2119 keywords, yet seems to have RFC
    2119 boilerplate text.

  == Unused Reference: 'RFC5880' is defined on line 1178, but no explicit
    reference was found in the text

  == Unused Reference: 'I-D.chen-bier-egress-protect' is defined on line
    1208, but no explicit reference was found in the text

### Section 1

I fail to see the logical link between `Typically, BIER packets are forwarded without an outer IP header.` and the consequence `if a link or node failure occurs, the corresponding BFR Neighbor (BFR-NBR) becomes unreachable`. Strongly suggest adding some explanations.

s/Typically, BIER packets are forwarded without an outer IP header./Typically, BIER packets are not encapsulated in IP./ ?

Please expand LFA at first use (i.e., before section 2)

### Section 3.1

s/link layer technology/link-layer technology/

s/without encapsulation in a tunnel header/without encapsulation in a tunnel/

Should a reference be provide for SR in `If segment routing is employed` ?

The last paragraph does not mention the 'explicit' forwarding action, is it on purpose ? If so, the read will welcome an explanation.

[Ballot discuss]
** Could the status of this document be explained?  What is the anticipated relationship between the experiment being conducted in RFC8279 and the procedures described in this document?  Practically, what does it mean for an informational status document to provide additional “mechanisms” for an experimental status RFC.  Is it adding or refining the experiment?

I observe that both the INTDIR and RTGDIR reviews asked similar questions. The INTDIR review has no response, but for the response to the RTGDIR review framed this document as a “primer” (https://mailarchive.ietf.org/arch/msg/rtg-dir/utbskA_QdV1GAwulOxKYQydI4pA/)

I reviewed the charter for guidance and the closest I could find is:
“1) Transition Mechanisms and Partial Deployments: The WG will define mechanisms to integrate BIER into existing multicast networks,
…
(Intended status: Experimental, Informational or Proposed Standard).”

A “primer” doesn’t seem consist with this charter scope.

[Ballot comment]
** Thank you to Joel Halpern for the GENART review.

** I am not an expert in this topic.  The INTDIR review (https://datatracker.ietf.org/doc/review-ietf-bier-frr-08-intdir-telechat-haberman-2025-06-03/) seemed to pose critical questions for which there was no response.

** Section 10.2.  Can more details be provided for this reference.  Is this a paper or a talk? 
[BrAl17]  Braun, W., Albert, M., Eckert, T., and M. Menth,
            "Performance Comparison of Resilience Mechanisms for
              Stateless Multicast Using BIER", May 2017.

** idnits reports:
  == Unused Reference: 'RFC5880' is defined on line 1178, but no explicit
    reference was found in the text

  == Unused Reference: 'I-D.chen-bier-egress-protect' is defined on line
    1208, but no explicit reference was found in the text

  == The document doesn't use any RFC 2119 keywords, yet seems to have RFC
    2119 boilerplate text.

[Ballot comment]
Two minor observations:

There appear to be a few superfluous references in this document. Please review and see whether there's additional text required or references that can be dropped:

- RFC2119 boilerplate is present and RFC2119 is referenced, but there don't appear to be any of the referenced terms present in the document.
- I-D.chen-bier-egress-protect is in the references, but not used in the text.

In 3.3, a space is missing: "[RFC5880]session" => "[RFC5880] session"

[Ballot comment]
Thanks to the authors and the WG for this document.

Please find below some comments provided inline in the idnits output of v08 of the document.

122   derived from a routing underlay or set by a controller.  In case of a
123   persistent link or node failure, BIER traffic may not be delivered
124   until the BIFT has been updated based on the reconverged routing
125   underlay or by the controller.

Could you clarify what is meant by persistent here? Isn't this the
case for any link failure and especially so for a node failure (even if the
node would just reload)


166       recalculation of the BIFT.  When the routing underlay utilizes FRR
167       mechanisms, its forwarding capabilities are restored well before
168       reconvergence is completed.  To benefit from the rapid restoration

perhaps s/reconvergence/control plane reconvergence

172   *  LFA-based BIER-FRR: This approach reroutes BIER traffic to
173       alternative neighbors in the event of a failure.  It applies the
174       principles of IP-FRR, requiring that LFAs are also BFRs.  Normal
175       BIER-LFAs can be reached without tunneling, remote BIER-LFAs

Please provide a reference or explanation of "normal BIER-LFAs". Did
you mean RFC5286? Same goes for the other types - please provide references

563   NBR itself.  Consequently, the backup path with link protection
564   cannot protect against the failure of the primary BFR-NBR..

Please remove extra "." I saw a few other similar instances in the document

770   with the backup action applied for that IP-LFA at the IP layer.  A
771   normal IP-LFA corresponds to the backup action Plain, a remote IP-LFA
772   to Tunnel, and a TI-IP-LFA to Explicit.

Is that IP-TI-LFA ? Same Q for TI-BIER-LFA.

840   *  TI-BIER-LFAs

842       -  They complement the protection coverage of normal and remote
843         BIER-LFAs to achieve 100% coverage.

Isn't that 100% theoretical? Practically, there are limits of platform
and implementations. Also, all routers should be BFRs.


875 6.2.5.  Link Protection

877   In the following, LFA-based BIER-FRR with link protection is

In the following ? ... perhaps "In this subsection," ?

1056 7.1.  Comparison of LFA-Based Protection for IP-FRR and BIER-FRR

References to respective RFCs related to different types of LFA/FRR
unicast mechanisms would be helpful in this section as well.

[Ballot comment]
Hi Huaimo, Mike, Steffen, Michael, Aijun, and Gyan,

Thank you for the effort put into this specification.

Please find some comments below:

# Main comments

## Lack of Operations considerations

The analysis can be strengthened by analyzing the deployment/ops implications of the options discussed in the spec. I noted that there are very few deployment pre-requisites (e.g., 6.2.1), though.

Also, some of the analyzed approach have implications on forwarding path stretch that is worth discussed vs. service objectives.

See rfc8279#section-7 for how this is handled for the base BIER spec.

## Leverage existing frameworks/discussions

For example, I was expecting a discussion about which matters from RFC7916 can be leveraged.

Also, have a discussion whether the proposed approaches are immune against micro loops (or at least call guards, if any); see for example RFC8333. Such discussion is also meant to back early claims in the document such as “minimizing packet loss and service disruption”.

# Misc.

## Routing underly

Please cite rfc8279#section-4.1 early in the document

## Encap over the routing underlay

Seems to always assume one single underly, while the base spec has this right:

  If multiple routing underlays are used in a single BIER domain, each
  BIER sub-domain MUST be associated with a single routing underlay
  (though multiple sub-domains may be associated with the same routing
  underlay).

## There are many controllers in networks

Please consider s/the controller/a controller, through the doc

## Deployment-specific

OLD:
  that BIER often carries multicast traffic with real-time
            ^^^^^^^^^^^^
  requirements, there is a particular need to protect BIER traffic
  against prolonged outages following failures.

NEW:
  that BIER may carry multicast traffic with real-time
  requirements, there is a particular need to protect BIER traffic
  against prolonged outages following failures.

## IP-FRR/”Normal” BIER-LFA

CURRENT:
      alternative neighbors in the event of a failure.  It applies the
      principles of IP-FRR, requiring that LFAs are also BFRs.  Normal
      BIER-LFAs can be reached without tunneling, remote BIER-LFAs

### Please cite an authoritative reference for I-FRR

### What is meant by “Normal BIER-LFAs”?

## Network layer

CURRENT:
  A BFR-NBR is considered directly connected if it is a next-hop at the
  network layer,

There is no such layer in the base spec. Please use consistent concepts.

## Packets are forwarded

OLD: that the packet is not routed through

NEW: that the packet is not forwarded through

## One or multiple backups

CURRENT:
  *  Backup Forwarding Bit Mask (BF-BM)

  *  Backup BFR Neighbor (BBFR-NBR)

There is only one backup? Or multiple entries can be used for multiple backups? How this is expected to work?

## BEA flag

CURRENT:
  The BEA flag indicates whether the backup forwarding
  entry is currently active. 

How is this set? Can this be managed by a controller such the one mentioned in the introduction?

## Derived?

CURRENT:
  The primary forwarding action is not explicitly stated in the BIFT as
  it is derived from the BFR-NBR. 

What does that mean?

## Desired level

CURRENT:
  The values
  for the BBFR-NBR and the BFA depend on the desired level of
  protection and the chosen backup strategy. 

How these are supplied to an implementation?

## BFD Extension

CURRENT:
  If
  the primary BFR-NBR is indirectly connected, a Bidirectional
  Forwarding Detection (BFD) [RFC5880] session between the BFR as PLR
  and the BFR-NBR may be used to monitor its reachability.

Do we need draft-ietf-bier-bfd or only the base BFD is sufficient here?

## Figures are actually tables through the doc.

## Not sure what is the value of Section 5? Maybe point to similar discussion in, e.g., Overview and Principles of Internet Traffic Engineering (RFC 9522).

Cheers,
Med

IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-bier-frr-07, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any registry actions.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, we do not object.

If this assessment is not accurate, please respond as soon as possible.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

David Dong
IANA Services Sr. Specialist

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?
No opposition.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?
No controversy.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize 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.)
No.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?
An implementation of Tunnel-Based BIER-FRR has been documented in
https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9361548
The other parts have no implementations.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.
The work on LFA-Based BIER-FRR is aligned with LFAs for IP FRR. Therefore,
it should be reviewed by someone in rtgwg.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
Not required.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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 [RFC 8342][5]?
N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.
The version 04 has no nits found.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?
Yes.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?
No issues.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?
Informational.
By default, BIER can inherit the fast convergence and FRR capabilities directly from IGP.
The discussion can be found by: https://mailarchive.ietf.org/arch/msg/bier/_hkJHD_hur1KqibUlDOgMf0R3Mc/
This draft provides more optional information for BIER FRR.
All datatracker state attributes correctly relect this intent.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.
There are three IPR disclosure:
5658 Huawei Technologies Co.,Ltd's Statement about IPR
5654 Huawei Technologies Co.,Ltd's Statement about IPR
5652 Mike McBride's Statement about IPR belonging to Cisco Technology, Inc.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.
Yes. There are six authors. It's OK if all the co-author made contribution and
have agreement.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)
The version 04 has no nits found.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].
No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?
N/A

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.
No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?
No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.
No.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).
No requirements for IANA.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.
N/A

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

The following Last Call announcement was sent out (ends 2025-03-06):

From: The IESG
To: IETF-Announce
CC: bier-chairs@ietf.org, bier@ietf.org, draft-ietf-bier-frr@ietf.org, gunter@vandevelde.cc, zhang.zheng@zte.com.cn
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (BIER Fast ReRoute) to Informational RFC


The IESG has received a request from the Bit Indexed Explicit Replication WG
(bier) to consider the following document: - 'BIER Fast ReRoute'
  as Informational RFC

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2025-03-06. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This document describes a mechanism for Fast Reroute (FRR) in Bit
  Index Explicit Replication (BIER) networks.  The proposed solution
  enhances the resiliency of BIER by providing a method to quickly
  reroute traffic in the event of a link or node failure, thereby
  minimizing packet loss and service disruption.  The document details
  the procedures for detecting failures and selecting backup paths
  within the BIER domain, ensuring that multicast traffic continues to
  reach its intended destinations without requiring per-flow state or
  additional signaling.  This FRR mechanism is designed to integrate
  seamlessly with existing BIER operations, offering a robust solution
  for improving network reliability.





The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-bier-frr/


The following IPR Declarations may be related to this I-D:

  https://datatracker.ietf.org/ipr/5658/
  https://datatracker.ietf.org/ipr/5652/
  https://datatracker.ietf.org/ipr/5654/

Changed action holders to Mike McBride, Michael Menth, Huaimo Chen, Aijun Wang, Gyan Mishra, Steffen Lindner (Thank for the updated version. From the update it appears that the shepherding AD review email was cut in the middle by recipient email client. Full AD review found at https://mailarchive.ietf.org/arch/msg/bier/VCdpQIYeHdfkKRwv5JFPpBpz0RI/)

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?
It reaches broad agreement. No opposition.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?
No controversy.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize 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.)
No.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?
An implementation of Tunnel-Based BIER-FRR has been documented in
https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9361548
The other parts have no implementations.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.
The work on LFA-Based BIER-FRR is aligned with LFAs for IP FRR. Therefore,
it should be reviewed by someone in rtgwg.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
Not required.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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 [RFC 8342][5]?
N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.
The version 04 has no nits found.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?
Yes.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?
No issues.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?
Informational. This draft provides information for BIER FRR.
All datatracker state attributes correctly relect this intent.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.
There are three IPR disclosure:
5658 Huawei Technologies Co.,Ltd's Statement about IPR
5654 Huawei Technologies Co.,Ltd's Statement about IPR
5652 Mike McBride's Statement about IPR belonging to Cisco Technology, Inc.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.
Yes. There are six authors. It's OK if all the co-author made contribution and
have agreement.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)
The version 04 has no nits found.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].
No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?
N/A

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.
No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?
No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.
No.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).
No requirements for IANA.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.
N/A

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?
It reaches broad agreement. No opposition.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?
No controversy.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize 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.)
No.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?
An implementation of Tunnel-Based BIER-FRR has been documented in
https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9361548
The other parts have no implementations.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.
The work on LFA-Based BIER-FRR is aligned with LFAs for IP FRR. Therefore,
it should be reviewed by someone in rtgwg.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
Not required.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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 [RFC 8342][5]?
N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.
The version 04 has no nits found.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?
Yes.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?
No issues.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?
Informational. This draft provides information for BIER FRR.
All datatracker state attributes correctly relect this intent.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.
There are three IPR disclosure:
5658 Huawei Technologies Co.,Ltd's Statement about IPR
5654 Huawei Technologies Co.,Ltd's Statement about IPR
5652 Mike McBride's Statement about IPR belonging to Cisco Technology, Inc.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.
Yes. There are six authors. It's OK if all the co-author made contribution and
have agreement.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)
The version 04 has no nits found.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].
No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?
N/A

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.
No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?
No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.
No.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).
No requirements for IANA.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.
N/A

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

Request for posting confirmation emailed to previous authors: Aijun Wang , Gyan Mishra , Huaimo Chen , Lei Liu , Michael Menth , Mike McBride , Steffen Lindner , Xufeng Liu , Yanhe Fan , Yisong Liu , bier-chairs@ietf.org

Request for posting confirmation emailed to previous authors: Aijun Wang , Gyan Mishra , Huaimo Chen , Lei Liu , Michael Menth , Mike McBride , Steffen Lindner , Xufeng Liu , Yanhe Fan , Yisong Liu , bier-chairs@ietf.org