Multicast-only Fast Reroute Based on Topology Independent Loop-free Alternate (TI-LFA) Fast Reroute
draft-ietf-pim-mofrr-tilfa-14

[Ballot comment]
Please find below some comments inline in the idnits output of the v12 of the draft:

General Comment: I found it odd that this document that is titled TI-LFA has text
and description for a solution for rLFA. TI-LFA subsumes rLFA in a manner of
speaking and the document would not have lost anything if instead of rLFA it had
used the same example to illustrate a TI-LFA repair path with a single PQ node
using the RFP Vector Attribute and then gone on to solve the more complex TI-LFA
repair path using a mix of RPF Vector and Explicit RFP Vector attributes. I will
leave this to the authors and the WG given the time that this document has spent
going back/forth.


94   This document introduces a new mechanism for MoFRR using Topology
95   Independent Loop-Free Alternate (TI-LFA)
96   [I-D.ietf-rtgwg-segment-routing-ti-lfa] fast reroute.  Unlike
97   conventional methods, TI-LFA is independent of network topology,
98   enabling broader coverage across diverse network environments.  The
99   applicability of this mechanism extends to PIM networks, such as
100   scenarios where PIM operates over native IP.

TI-LFA works only in SR networks. The solution specificies a solution
for PIM over native IP, however, this works only in an SR network. This
applicablity part is not stated very clearly. This should also result in the
references to the SR RFCs becoming normative reference (based on the solution
using the SR information from the IGP LSDB).


119   The approach does not alter the existing management and operation of
120   LFA, RLFA, and TI-LFA [RFC7916] [RFC8102]
121   [I-D.ietf-rtgwg-segment-routing-ti-lfa].  Also, this approach is not
122   affected by micro-loops [RFC5715] occurring during the network re-
123   converges.

Please check
https://www.ietf.org/archive/id/draft-ietf-rtgwg-segment-routing-ti-lfa-21.html#section-2
regarding micro-loops. Would you still like to claim that this solution is not
affected at all by micro-loops?


125   Note that this document introduces an optional approach for backup
126   join paths, designed to enhance the protection scope of existing
127   multicast systems.  It is fully compatible with current protocol
128   implementations and does not necessitate any changes to the protocols
129   or forwarding functions on intermediate nodes.  If there is a choice

The solution requires support specific PIM protocol extensions and
support for RFC5496 and RFC7891 to be support pretty much across all routers
in the IGP area/level where this solution is to be deployed. This is not
specifically listed in an applicability section (ideally) or at least
covered in the text above.


178                 10          20
179             [S1]----(R1)-------------(R4)
180                     |                |
181                     |                |
182                     |10              |10
183                 10  |                |
184             [S2]----(R2)-------------(R3)----[R]
185                     |        10      |  10
186                     |                |
187                     |10              |10
188                 10  |                |
189             [S3]----(R5)-----(R6)----(R7)
190                             100      10

Please update the ASCII art to place the metric values 100 and 10 in the
center of the R5-R6 and R6-R7 links respectively.

192                     Figure 1: Example Network Topology


194 2.2.  RLFA for MoFRR

196   The Remote Loop-Free Alternate (RLFA), as defined in [RFC7490],
197   extends the LFA mechanism, to accommodate a broader range of network
198   deployments by utilizing a tunnel as an alternate path.  The RLFA
199   requires that there exists at least one node, denoted as node N, in
200   the network where the fault node is neither on the path from the
201   source node to node N nor on the path from node N to the destination
202   node.  The source node and the destination node are the tunnel
203   endpoints of the RLFA repair path.

Isn't is better to direct the reader to the RLFA RFC than trying to
oversimply with a couple of sentences?


326 4.  Illustration

Any reason why the same topology in Figure 1 with the source
as S3 is not being used as an illustration instead of a new one? Seems very
odd to me when there is a TI-LFA solution for that. Instead, the document
introduces an entirely new topology for TI-LFA.

328   This section provides an illustration of MoFRR based on TI-LFA.  The
329   example topology is depicted in Figure 2.  The metric for the R3-R4
330   link is 100, while the metrics for the other links are 10.  All link
331   metrics are bidirectional.


470 5.  Join Conflict Considerations

472   This section illustrates the resolution of PIM Join conflicts.  When
473   intermediate nodes must choose between PIM Join messages with an RPF

I believe this is already covered/specified in RFC7891. A reference to
the specific section and some text saying ... this is nothing new ... would be
helpful.

[Ballot comment]
Hi Yisong, Mike, Zheng, Jingrong, and Changwang,

Thank you for addressing all my previous comments [1] and also some remaining comments from Jürgen's opsdir review.

Cheers,
Med

[1] https://mailarchive.ietf.org/arch/msg/pim/acks1tazEShLwMB0tzQOZ6WdlNY/

[Ballot comment]
Hi Yisong, Mike, Zheng, Jingrong, and Changwang,

Thank you for the effort put into this specification.

Please find below some comments:

# Abstract

CURRENT:

  The
  document outlines the necessary protocol extensions and operational
  considerations to implement TI-LFA in conjunction with MoFRR for PIM,
  ensuring that multicast traffic is rapidly rerouted in the event of a
  failure.

## On “protocol extensions”: Seems conflicting with the intended Info status and also the clarification note included in the intro and another section.

## On “operational considerations” or lack of

(1) Which part of the document are you referring to? 
(2) I was expecting to see at least RFC8102 referenced in the main body on the manageability aspects
(3) Also, is the approach immune against micro loops? If not a concern, can we explicit that in the doc?

# Introduction:

(1)

CURRENT:
  The increasing deployment of video services has heightened the
  importance for network operators to implement solutions that minimize
  service disruptions caused by faults in the IP networks ... 

One would argue that the increase is related to unicast delivery, mainly. Deleting this sentence and starting with the sentence right after would be fine. No need to over motivate the need ;-)

(2)

CURRENT:
  fast reroute defined in [RFC7431], has limitations in certain
  multicast deployment scenarios.

Can we call these limitations out or point to the section where this is discussed?

(3)

CURRENT:
    The
  applicability of this mechanism extends to PIM networks, including
  scenarios where PIM operates over native IP, as well as public
  network multicast trees established by PIM .  Additionally, this
  document addresses scenarios involving Multicast Distribution Tree
  (MDT) SAFI for Multicast VPN (MVPN) in [RFC6037] and [RFC6514],..

* “public network multicast trees”: Do you mean inter-domain? If so, some discussion on the implications/deployment considerations are needed.
* “[RFC6037] and [RFC6514]”: Why is this cited? Why this specific flavor? What about RFC6513? If you maintain this mention, can we have an example to illustrate the use?

# Section 2.1

* “For multicast source S1, …”: The receiver should be mentioned also.
* Better to include the metrics directly in the graph as this eases following the example.
* Mention that all link metrics are bidirectional?

# Section 2.2

“is neither on the path from the source node to node N”: The source node should be clarified to avoid confusion with multicast source.

# Section 5

CURRENT:
  This document specifies an optional approach for backup join paths,
  intended to enhance the protection scope of existing multicast
  systems.  It is fully compatible with existing protocol
  implementations and does not require changes to protocols or
  forwarding functions on intermediate nodes.  In the event of PIM Join
  conflicts, Join messages without the RPF Vector attribute are prioritized to
  ensure that the original PIM forwarding functionality remains
  unaffected.

Already mentioned in the introduction. Any reason this text repeated? I would delete it.

# Full review

More comments, edits, nits, etc. can be found here:

* pdf: https://github.com/boucadair/IETF-Drafts-Reviews/blob/master/2025/draft-ietf-pim-mofrr-tilfa-09-rev%20Med.pdf
* doc: https://github.com/boucadair/IETF-Drafts-Reviews/blob/master/2025/draft-ietf-pim-mofrr-tilfa-09-rev%20Med.doc

IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-pim-mofrr-tilfa-09, 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

The following Last Call announcement was sent out (ends 2025-02-18):

From: The IESG
To: IETF-Announce
CC: draft-ietf-pim-mofrr-tilfa@ietf.org, gunter@vandevelde.cc, pim-chairs@ietf.org, pim@ietf.org, stig@venaas.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Multicast-only Fast Reroute Based on Topology Independent Loop-free Alternate Fast Reroute) to Informational RFC


The IESG has received a request from the Protocols for IP Multicast WG (pim)
to consider the following document: - 'Multicast-only Fast Reroute Based on
Topology Independent Loop-free
  Alternate 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 2025-02-18. 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 specifies the use of Topology Independent Loop-Free
  Alternate (TI-LFA) mechanisms with Multicast Only Fast ReRoute
  (MoFRR) for Protocol Independent Multicast (PIM).  The TI-LFA
  mechanism is designed for standard link-state Interior Gateway
  Protocol (IGP) shortest path and Segment Routing (SR) scenarios.  TI-
  LFA provides fast reroute protection for unicast traffic in IP
  networks by precomputing backup paths that avoid potential failures.
  By integrating TI-LFA with MoFRR, this document extends the benefits
  of fast reroute mechanisms to multicast traffic, enabling enhanced
  resilience and minimized packet loss in multicast networks.  The
  document outlines the necessary protocol extensions and operational
  considerations to implement TI-LFA in conjunction with MoFRR for PIM,
  ensuring that multicast traffic is rapidly rerouted in the event of a
  failure.  This document uses the backup path computed by TI-LFA
  through IGP as a secondary Upstream Multicast Hop (UMH) for PIM.  By
  using the TI-LFA backup path to send PIM secondary join messages hop-
  by-hop, it achieves the generation of a fast reroute backup path for
  PIM multicast.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-pim-mofrr-tilfa/


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

  https://datatracker.ietf.org/ipr/5730/

Waiting for some more details about the fact that a router cannot forward multiple copies and what limitations that imposes which seems to be the crucial points Toerless raised.

[Ballot comment]
Thanks for addressing my DISCUSS [*], I hope that all authors have agreed on the copyright change (I a trusting the responsible AD). Thanks also for addressing my comments kept below for archiving.

Regards

-éric

[*] https://mailarchive.ietf.org/arch/msg/pim/4-xtXMuxD8VO4dJKJLF8_XKEigg/


# COMMENTS (non-blocking)

## Section 1

It seems that draft-ietf-rtgwg-segment-routing-ti-lfa is about segment routing, is it also the case for this I-D ? If so (as indicated further in the text), suggest to add this to the abstract.

Should "MDT" be expanded ?

## Section 1.1

There is a single occurence of BCP14 terms (in the security section), consider removing this section.

## Section 2.1

`current MoFRR` won't age well once this I-D is published as an RFC; suggest using "RFC7381 MoFRR"

Cosmetic: the aasvg tool may render the figure 1 in a much nicer way.

[Ballot comment]
I support Roman's DISCUSS position.

In Security Considerations, there's this:

  The security
  considerations of LFA, R-LFA, and MoFRR described in [RFC5286],
  [RFC7490], and [RFC7431] SHOULD apply to this document.

How can you establish a normative interoperability requirement against a document?

For that matter, since this is Informational, why is BCP 14's inclusion appropriate?

[Ballot comment]
Thank you for this document. I have no technical comments, and I found the document easy to digest and follow. However, I would like to question the structure of the document as it does not follow https://datatracker.ietf.org/doc/html/rfc7322#section-4.1.1 where the 'Abstract' should be before 'Status of this memo' and 'Copyright notice'. Please bring the Abstract to the front of the document.

[Ballot discuss]
# Éric Vyncke, INT AD, comments for draft-ietf-pim-mofrr-tilfa-06

Thank you for the work put into this document.

Please find below one blocking DISCUSS points (trivial to address), some non-blocking COMMENT points (but replies would be appreciated even if only for my own education).

Special thanks to Stig Venaas for the shepherd's detailed write-up including the WG consensus ***but it lacks*** the justification of the intended status and I am supportive of John Scudder's point about intended status.

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 a request to have a discussion on the following topics:

## Copyright

This I-D appears to use a very old template and the copyright text is wrong and no more valid... E.g., s/Simplified BSD License text/Revised BSD License text/ and approved by the authors of course.

[Ballot comment]

# COMMENTS (non-blocking)

## Section 1

It seems that draft-ietf-rtgwg-segment-routing-ti-lfa is about segment routing, is it also the case for this I-D ? If so (as indicated further in the text), suggest to add this to the abstract.

Should "MDT" be expanded ?

## Section 1.1

There is a single occurence of BCP14 terms (in the security section), consider removing this section.

## Section 2.1

`current MoFRR` won't age well once this I-D is published as an RFC; suggest using "RFC7381 MoFRR"

Cosmetic: the aasvg tool may render the figure 1 in a much nicer way.

[Ballot discuss]
(Directed primarily to the PIM WG chairs and responsible AD) While related to PIM, this document does not appear to be in-scope for the current PIM WG charter.

==[ snip from the charter ]==
1) Management: YANG models for PIM, IGMP, and MLD will be developed, for both configuration and operational states. If updates to existing MIB modules are necessary, the WG may work on those.
2) Improve PIM authentication.
3) Improve and Extend PIM Join Attributes to support different types of multicast applications.
4) Optimization approaches for IGMP and MLD to adapt to link conditions in wireless and mobile networks and be more robust to packet loss.
==[ snip ]==

This draft not a YANG module per (1), is not related to authentication per (2), does not specify new join attributes per (3) and is not an optimization for IGMP/MLD per (4).

[Ballot comment]
I’m conflicted as to whether Informational is the right type for this document — it doesn’t change wire encodings, but it does change elements of procedure, albeit in backward-compatible ways. I grant it’s an arguable point though. Too bad the shepherd writeup fails to answer the question “Why is this the proper type of RFC?” 😢

Also, I was sad there was no HTML rendering available. If you’d be willing to share what motivated you to go to the extra work of uploading a non-XML source format, I’d be interested in knowing.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-pim-mofrr-tilfa-05, 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

The following Last Call announcement was sent out (ends 2024-09-23):

From: The IESG
To: IETF-Announce
CC: draft-ietf-pim-mofrr-tilfa@ietf.org, gunter@vandevelde.cc, pim-chairs@ietf.org, pim@ietf.org, stig@venaas.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Multicast-only Fast Reroute Based on Topology Independent Loop-free Alternate Fast Reroute) to Informational RFC


The IESG has received a request from the Protocols for IP Multicast WG (pim)
to consider the following document: - 'Multicast-only Fast Reroute Based on
Topology Independent Loop-free
  Alternate 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 2024-09-23. 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 specifies the use of Topology Independent Loop-Free
  Alternate (TI-LFA) mechanisms with Multicast Only Fast ReRoute
  (MoFRR) for Protocol Independent Multicast (PIM). TI-LFA provides
  fast reroute protection for unicast traffic in IP networks by
  precomputing backup paths that avoid potential failures. By
  integrating TI-LFA with MoFRR, this document extends the benefits of
  fast reroute mechanisms to multicast traffic, enabling enhanced
  resilience and minimized packet loss in multicast networks. The
  document outlines the necessary protocol extensions and operational
  considerations to implement TI-LFA in conjunction with MoFRR for
  PIM, ensuring that multicast traffic is rapidly rerouted in the
  event of a failure.






The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-pim-mofrr-tilfa/


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

  https://datatracker.ietf.org/ipr/5730/

# 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?
Broad agreement. Good support for the document, no one against it.

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

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)?
Not aware of implementations, but note that it is just Informational.

## 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.
It does make use of segment routing, but I don't think additional reviews are needed.

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.
No formal reviews needed.

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]?
No YANG.

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.
N/A

## 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, except for a couple of nits, see 14 below.

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 have been identified.

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.

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.
IPR has been filed for draft-liu-pim-mofrr-tilfa which was the initial version before WG adoption. This IPR also applies to this version. Authors have stated that they are not aware of any additional IPR.

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.
I believe they are willing. As part of starting publication they all answered questions about IPR. There are 5 authors.

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.)
There are a couple of minor editorial nits. In some places it says 2023 instead of 2024 as the expiry date. It is correctly shown at the first page. There are 2 references in the Introduction that should have brackets added to show they are references. Some language is a bit hard to read, but it is easy enough to understand the meaning. I expect the RFC editor will improve the English a bit.

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?
There is a reference to draft-ietf-rtgwg-segment-routing-ti-lfa.
This needs to be normative. It is actively being worked on from what I know.

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]).
There are none.

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?
Broad agreement. Good support for the document, no one against it.

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

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)?
Not aware of implementations, but note that it is just Informational.

## 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.
It does make use of segment routing, but I don't think additional reviews are needed.

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.
No formal reviews needed.

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]?
No YANG.

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.
N/A

## 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, except for a couple of nits, see 14 below.

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 have been identified.

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.

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.
IPR has been filed for draft-liu-pim-mofrr-tilfa which was the initial version before WG adoption. This IPR also applies to this version. Authors have stated that they are not aware of any additional IPR.

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.
I believe they are willing. As part of starting publication they all answered questions about IPR. There are 5 authors.

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.)
There are a couple of minor editorial nits. In some places it says 2023 instead of 2024 as the expiry date. It is correctly shown at the first page. There are 2 references in the Introduction that should have brackets added to show they are references. Some language is a bit hard to read, but it is easy enough to understand the meaning. I expect the RFC editor will improve the English a bit.

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?
There is a reference to draft-ietf-rtgwg-segment-routing-ti-lfa.
This needs to be normative. It is actively being worked on from what I know.

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]).
There are none.

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/