Circuit Style Segment Routing Policy
draft-ietf-spring-cs-sr-policy-17

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

I have some comments to share that are provided inline in the idnits o/p of v16 of the document. Please look for the tag  at the end to ensure you have received the full review.

125   A Circuit Style SR Policy (CS-SR Policy) is an association of two co-
126   routed unidirectional SR Policies satisfying the above requirements
127   and allowing for a single SR network to carry both typical IP

perhaps s/for a single SR network/for a SR network ?

210   *  When using PCEP as the communication protocol, the controller is a
211       stateful PCE as defined in [RFC8231].  When using SR-MPLS
212       [RFC8660], PCEP extensions defined in [RFC8664] are used.  When
213       using SRv6 [RFC8754] [RFC8986], PCEP extensions defined in
214       [RFC9603] are used.

The solution described in this document involves multiple CPs of the
same SR Policy and the PCEP extensions for CPs has been specified in RFC9862.
Shouldn't that reference be added here? This may also apply to a few other places.

241   When using link bundles (i.e. [IEEE802.1AX]), parallel physical links
242   are only represented via a single adjacency.  To ensure deterministic

perhaps s/via a single adjacency/via a single L3 adjacency ?


287   *  Thirdly, ensuring that during times of link congestion only non-
288       CS-SR Policy traffic is being buffered or dropped.

Perhaps better way to say would be that CS traffic is not buffered or
dropped?

379         o  may have to be disjoint.

perhaps s/have/need ?

413   The candidate paths of the CS-SR Policy are reported and updated
414   following PCEP procedures of [RFC8231].

This should also refer to RFC9862 since you are talking about CPs? Please
check the same for few other references to RFC8231.

523 8.2.  Policy Deletion when using BGP

525   The controller is using the withdraw procedures of [RFC4271] to
526   instruct headends A and Z to delete a candidate path.

This should be RFC9830. There is no need to refer to the "withdraw
procedures" - rather just says controller withdraws the CP per RFC9830?

592   *  Non-revertive switching: do not activate the higher preference
593       candidate path and keep sending traffic via the lower preference
594       candidate path.

For non-revertive, isn't the reference to no automatic reversion? The
operator should be able to manually trigger a reversion, right? Also, consider
including this situation in section 11.1.1.

603   To avoid pre-allocating protection bandwidth by the controller ahead
604   of failures, but still being able to recover traffic flow over an
605   alternate path through the network in a deterministic way
606   (maintaining the required bandwidth commitment), the second candidate
607   path with lower preference is established "on demand" and activated
608   upon failure of the first candidate path.

Any consideration (or discussion) about the restoration path reusing
portions of the primary path that have not been affected by the failure and hence
have the bandwidth still reserved for them? Please see if you wish to clarify that
the bandwidth allocated is not generally freed for the failed primary path.

[Ballot comment]
Hi Christian, Zafar, Praveen, Reza, and Andrew,

Thank you for the effort put into this document.

Thanks Luigi Iannone for the OPSDIR review. Although there is no reply to his review (at least I missed it), I see that -15 included changes that I suspect are to address of his review.

The document includes a comprehensive list of tools that can be used for CS-SR deployment. I find that list impressive and helpful to be gathered in one place. As a side note, the document can benefit a pointer to RFC9522 where we have a good description of concepts that are required for offering services such as those discussed here (admission control, etc.).

Please note that I filtered my comments to take into account the intended Informational status. Please find some points FWIW:

# How to read/use this document?

The use of the normative language in parts of the document is confusing (at least to me). Given that several options are generally presented for discussed items, I don’t think that we are providing definitive recommendations for how to realize the service. Instead, I read the document more as a sample operational walk through to exemplify how CS-SR policy can be put into effect and operated.

If my understanding is correct, I don’t think that we need to use the normative language at the first place. I think that avoidant key terms use would also fix other issues below.

# Rationale

It is not clear what is the reasoning for when the authors use the normative language. For example,

CURRENT:
  To satisfy the bandwidth requirement for CS-SR Policies it must be
  ensured that packets carried by CS-SR Policies can always be sent up
  to the reserved bandwidth on each hop along the path.

Vs.

  To satisfy the requirements of CS-SR Policies, each link in the
  topology used by or intended to support CS-SR Policies MUST have:

# Lack of justification for the recommendations

For example,

CURRENT:
  Similarly, the use of adjacency-SIDs representing parallel
  adjacencies Section 3.4.1 of [RFC8402] SHOULD also be avoided.

Without helping readers to understand the justification of such reco. Some elaboration for this reco and similar are needed to help who will deploy.

# Hidden assumptions about traffic profile

For example,

  This is done by:

  *  Firstly, CS-SR Policy bandwidth reservations per link must be
      limited to equal or less than the physical link bandwidth.

Makes assumptions on the nature of traffic that will be flying through. For example, this seems to discard that scheduled traffic (e.g., RFC8413) may be handled. In such case, why it would be a problem of sum of reservations exceed the total if these are scheduled in different slots.

Please be explicit about the traffic assumptions you had in mind.

# Lack of scalability considerations

The document includes some proposals such as:

  *  Allocate a dedicated physical link of bandwidth P to CS-SR

However, it does or help readers understand the viability of the option let alone the implication on scalability. Can we consider saying something about the implication of listed options.

# I-D.bashandy-rtgwg-segment-routing-uloop

CURRENT:
      These dedicated
      SIDs used by CS-SR Policies MUST NOT be used by features such as
      TI-LFA [RFC9855] for defining the repair path and microloop
      avoidance [I-D.bashandy-rtgwg-segment-routing-uloop] for defining
      the loop-free path.

Suggests that bashandy-rtgwg-segment-routing-uloop is normative to fulfil this MUST NOT. Are we sure that is what we want?

As I’m there, please double check the classification of your references.

# Unstable References

CURRENT:
  *  Simple Two-Way Active Measurement Protocol (STAMP) in loopback
      measurement mode as described in section 6 and the session state
      described in section 11 of [I-D.ietf-spring-stamp-srpm-mpls] for
      SR-MPLS and [I-D.ietf-spring-stamp-srpm-srv6] for SRv6.

  *  Bidirectional Forwarding Detection (BFD) [RFC5880].

  *  Seamless BFD (S-BFD) [RFC7880].

  The use of STAMP is RECOMMENDED as it leverages a single

draft-ietf-spring-stamp-srpm-mpls was adopted recently, with the document that it replaces expires for a year.

Are we confident these will make it to publication in a timely manner?

Cheers,
Med

[Ballot comment]
Hi Christian, Zafar, Praveen, Reza, and Andrew,

Thank you for the effort put into this document.

Thanks Luigi Iannone for the OPSDIR review. Although there is no reply to his review (at least I missed it), I see that -15 included changes that I suspect are to address of his review.

The document includes a comprehensive list of tools that can be used for CS-SR deployment. I find that list impressive and helpful to be gathered in one place. As a side note, the document can benefit a pointer to RFC9522 where we have a good description of concepts that are required for offering services such as those discussed here (admission control, etc.).

Please note that I filtered my comments to take into account the intended Informational status. Please find some points for DISCUSSion:

# How to read/use this document?

The use of the normative language in parts of the document is confusing (at least to me). Given that several options are generally presented for discussed items, I don’t think that we are providing definitive recommendations for how to realize the service. Instead, I read the document more as a sample operational walk through to exemplify how CS-SR policy can be put into effect and operated.

If my understanding is correct, I don’t think that we need to use the normative language at the first place. I think that avoidant key terms use would also fix other issues below.

# Rationale

It is not clear what is the reasoning for when the authors use the normative language. For example,

CURRENT:
  To satisfy the bandwidth requirement for CS-SR Policies it must be
  ensured that packets carried by CS-SR Policies can always be sent up
  to the reserved bandwidth on each hop along the path.

Vs.

  To satisfy the requirements of CS-SR Policies, each link in the
  topology used by or intended to support CS-SR Policies MUST have:

# Lack of justification for the recommendations

For example,

CURRENT:
  Similarly, the use of adjacency-SIDs representing parallel
  adjacencies Section 3.4.1 of [RFC8402] SHOULD also be avoided.

Without helping readers to understand the justification of such reco. Some elaboration for this reco and similar are needed to help who will deploy.

# Hidden assumptions about traffic profile

For example,

  This is done by:

  *  Firstly, CS-SR Policy bandwidth reservations per link must be
      limited to equal or less than the physical link bandwidth.

Makes assumptions on the nature of traffic that will be flying through. For example, this seems to discard that scheduled traffic (e.g., RFC8413) may be handled. In such case, why it would be a problem of sum of reservations exceed the total if these are scheduled in different slots.

Please be explicit about the traffic assumptions you had in mind.

# Lack of scalability considerations

The document includes some proposals such as:

  *  Allocate a dedicated physical link of bandwidth P to CS-SR

However, it does or help readers understand the viability of the option let alone the implication on scalability. Can we consider saying something about the implication of listed options.

# I-D.bashandy-rtgwg-segment-routing-uloop

CURRENT:
      These dedicated
      SIDs used by CS-SR Policies MUST NOT be used by features such as
      TI-LFA [RFC9855] for defining the repair path and microloop
      avoidance [I-D.bashandy-rtgwg-segment-routing-uloop] for defining
      the loop-free path.

Suggests that bashandy-rtgwg-segment-routing-uloop is normative to fulfil this MUST NOT. Are we sure that is what we want?

As I’m there, please double check the classification of your references.

# Unstable References

CURRENT:
  *  Simple Two-Way Active Measurement Protocol (STAMP) in loopback
      measurement mode as described in section 6 and the session state
      described in section 11 of [I-D.ietf-spring-stamp-srpm-mpls] for
      SR-MPLS and [I-D.ietf-spring-stamp-srpm-srv6] for SRv6.

  *  Bidirectional Forwarding Detection (BFD) [RFC5880].

  *  Seamless BFD (S-BFD) [RFC7880].

  The use of STAMP is RECOMMENDED as it leverages a single

draft-ietf-spring-stamp-srpm-mpls was adopted recently, with the document that it replaces expires for a year.

Are we confident these will make it to publication in a timely manner?

Cheers,
Med

[Ballot discuss]
Hi Christian, Zafar, Praveen, Reza, and Andrew,

Thank you for the effort put into this document.

Thanks Luigi Iannone for the OPSDIR review. Although there is no reply to his review (at least I missed it), I see that -15 included changes that I suspect are to address of his review.

The document includes a comprehensive list of tools that can be used for CS-SR deployment. I find that list impressive and helpful to be gathered in one place. As a side note, the document can benefit a pointer to RFC9522 where we have a good description of concepts that are required for offering services such as those discussed here (admission control, etc.).

Please note that I filtered my comments to take into account the intended Informational status. Please find some points for DISCUSSion:

# How to read/use this document?

The use of the normative language in parts of the document is confusing (at least to me). Given that several options are generally presented for discussed items, I don’t think that we are providing definitive recommendations for how to realize the service. Instead, I read the document more as a sample operational walk through to exemplify how CS-SR policy can be put into effect and operated.

If my understanding is correct, I don’t think that we need to use the normative language at the first place. I think that avoidant key terms use would also fix other issues below.

# Rationale

It is not clear what is the reasoning for when the authors use the normative language. For example,

CURRENT:
  To satisfy the bandwidth requirement for CS-SR Policies it must be
  ensured that packets carried by CS-SR Policies can always be sent up
  to the reserved bandwidth on each hop along the path.

Vs.

  To satisfy the requirements of CS-SR Policies, each link in the
  topology used by or intended to support CS-SR Policies MUST have:

# Lack of justification for the recommendations

For example,

CURRENT:
  Similarly, the use of adjacency-SIDs representing parallel
  adjacencies Section 3.4.1 of [RFC8402] SHOULD also be avoided.

Without helping readers to understand the justification of such reco. Some elaboration for this reco and similar are needed to help who will deploy.

# Hidden assumptions about traffic profile

For example,

  This is done by:

  *  Firstly, CS-SR Policy bandwidth reservations per link must be
      limited to equal or less than the physical link bandwidth.

Makes assumptions on the nature of traffic that will be flying through. For example, this seems to discard that scheduled traffic (e.g., RFC8413) may be handled. In such case, why it would be a problem of sum of reservations exceed the total if these are scheduled in different slots.

Please be explicit about the traffic assumptions you had in mind.

# Lack of scalability considerations

The document includes some proposals such as:

  *  Allocate a dedicated physical link of bandwidth P to CS-SR

However, it does or help readers understand the viability of the option let alone the implication on scalability. Can we consider saying something about the implication of listed options.

# I-D.bashandy-rtgwg-segment-routing-uloop

CURRENT:
      These dedicated
      SIDs used by CS-SR Policies MUST NOT be used by features such as
      TI-LFA [RFC9855] for defining the repair path and microloop
      avoidance [I-D.bashandy-rtgwg-segment-routing-uloop] for defining
      the loop-free path.

Suggests that bashandy-rtgwg-segment-routing-uloop is normative to fulfil this MUST NOT. Are we sure that is what we want?

As I’m there, please double check the classification of your references.

# Unstable References

CURRENT:
  *  Simple Two-Way Active Measurement Protocol (STAMP) in loopback
      measurement mode as described in section 6 and the session state
      described in section 11 of [I-D.ietf-spring-stamp-srpm-mpls] for
      SR-MPLS and [I-D.ietf-spring-stamp-srpm-srv6] for SRv6.

  *  Bidirectional Forwarding Detection (BFD) [RFC5880].

  *  Seamless BFD (S-BFD) [RFC7880].

  The use of STAMP is RECOMMENDED as it leverages a single

draft-ietf-spring-stamp-srpm-mpls was adopted recently, with the document that it replaces expires for a year.

Are we confident these will make it to publication in a timely manner?

The following Last Call announcement was sent out (ends 2025-12-19):

From: The IESG
To: IETF-Announce
CC: draft-ietf-spring-cs-sr-policy@ietf.org, james.n.guichard@futurewei.com, liu.yao71@zte.com.cn, spring-chairs@ietf.org, spring@ietf.org
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Circuit Style Segment Routing Policy) to Informational RFC


The IESG has received a request from the Source Packet Routing in Networking
WG (spring) to consider the following document: - 'Circuit Style Segment
Routing Policy'
  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 2025-12-19. 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 how Segment Routing (SR) policies can be used
  to satisfy the requirements for bandwidth, end-to-end recovery and
  persistent paths within a SR network.  The association of two co-
  routed unidirectional SR Policies satisfying these requirements is
  called "circuit-style" SR Policy (CS-SR Policy).




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-spring-cs-sr-policy/


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

  https://datatracker.ietf.org/ipr/6230/

# 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?

The WG consensus represents broad agreement.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

Before and during the WG Adpotion Call(see [1] [2] [3]), comments were raised
by the WG about:
a) How bandwidth guarantee is achieved with CS-SR policy. The author added some
additional clarifications in the draft, including:
  *to use of dedicated persistent unprotected adjacency-SIDs that are solely
  used by CS-SR traffic
  *to bring down a CS-SR policy in react to failure
Some suggested that network slicing/resource-aware segments should also be
considered as one of the bandwidth guarantee methods and taken as a reference
(see [4] [5]), this suggestion was not taken.

b) Whether this draft defines mechanisms that emulate optical circuits over IP/MPLS.
The authors had claimed that this draft does not talk about that.(see [6] [7])

[1] https://mailarchive.ietf.org/arch/msg/spring/PyJLnOvzzPXsf6i-_K04ghGXzAA/
[2] https://mailarchive.ietf.org/arch/msg/spring/5GAyP-HIAyNZPUkM382y6ji2k_A/
[3] https://mailarchive.ietf.org/arch/msg/spring/D785JyDEmhfEdVbKJHuLifmGAyw/
[4] https://mailarchive.ietf.org/arch/msg/spring/nclV2TB3dUOJ5oe7ntXYsvDcwg4/
[5] https://mailarchive.ietf.org/arch/msg/spring/6z2o-j6HA87WnQEjRRUJT2Ocb3M/
[6] https://mailarchive.ietf.org/arch/msg/spring/BDWzpWaFYJd4W-9EDES9j59SAfU/
[7] https://mailarchive.ietf.org/arch/msg/spring/tu45FAANxc6Cl27ppmG5DLROpTI/

During the WG LC, comments were raised about how to operate after one segment
list has been failed when a CP with multiple segment lists is used for traffic
transmition, this comment had been addressed by adding clarification text in the
draft. (see [8] [9])
[8] https://mailarchive.ietf.org/arch/msg/spring/e8Gt3_oy6Y8yoI2mJ5W8WBXlh0A/
[9] https://mailarchive.ietf.org/arch/msg/spring/SlPbPJ9n7r4NkkrFePLrsdQLMFo/

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)?

The authors claimed that Cisco and Nokia have partial implementations of the
document in response to the shepherd's question about the implementation .
(see https://mailarchive.ietf.org/arch/msg/spring/1P9izug4gpqE69OzvqCjUP0LpV8/)

## 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.

Yes, the contents of this document have intersection with technologies in PCE,
IDR and IPPM WGs, it would benefit from their review to check whether this document
has used the related protocols(e.g, PCEP, BGP, STAMP) correctly.
These reviews have not occured yet.

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 such formal language.

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 module.

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.

No formal language.

## 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?

The shepherd has checked the lists of common issues, no special issue of this
document has been found.
There's no directorate review yet.

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?

The intended RFC status is informational and document reflects it in the datatracker.

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.

All the authors and contributors have explicitly stated that they are unaware of
any undisclosed IPR related with the document.
Their claims can be found at
https://mailarchive.ietf.org/arch/msg/spring/ILJftItJrd7P8ZNn7XQEvrsC7m0/,
and  https://mailarchive.ietf.org/arch/msg/spring/mguEnQ1pKVUUa15vmDYKfPXtseQ/

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.

There are five co-authors on the front page. By responding to the IPR poll, the
authors and contributors have implicitly confirmed their willingness to be listed.

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.)

No remaining I-D nits in this document.
Idnits has been run and error corrected.
Internet-Drafts Checklist done.
Shepherd has reviewed the draft and made comments. Those have been addressed by
the editor.

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?

All references are publicly available.

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?

Yes. The status of the non-RFC documents in the normative references based on
the search of the datatraker and the WG wiki are listed below:

Name                 Status
draft-ietf-idr-bgp-ls-sr-policy          RFC Ed Queue
draft-ietf-idr-sr-policy-safi            RFC Ed Queue
draft-ietf-pce-segment-routing-policy-cp  RFC Ed Queue
draft-ietf-pce-sr-bidir-path              WG Last Call Queue
draft-ietf-idr-sr-policy-path-segment    Expired in April,completion plan unclear
draft-ietf-pce-circuit-style-pcep-extensions In progress,completion plan unclear
draft-ietf-pce-multipath                    In progress,completion plan unclear
draft-ietf-spring-sr-policy-yang            In progress,completion plan unclear
draft-ietf-spring-stamp-srpm             In progress,completion plan unclear

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, this document is standalone.

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]).

This document requires no action from 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?

The WG consensus represents broad agreement.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

Before and during the WG Adpotion Call(see [1] [2] [3]), comments were raised
by the WG about:
a) How bandwidth guarantee is achieved with CS-SR policy. The author added some
additional clarifications in the draft, including:
  *to use of dedicated persistent unprotected adjacency-SIDs that are solely
  used by CS-SR traffic
  *to bring down a CS-SR policy in react to failure
Some suggested that network slicing/resource-aware segments should also be
considered as one of the bandwidth guarantee methods and taken as a reference
(see [4] [5]), this suggestion was not taken.

b) Whether this draft defines mechanisms that emulate optical circuits over IP/MPLS.
The authors had claimed that this draft does not talk about that.(see [6] [7])

[1] https://mailarchive.ietf.org/arch/msg/spring/PyJLnOvzzPXsf6i-_K04ghGXzAA/
[2] https://mailarchive.ietf.org/arch/msg/spring/5GAyP-HIAyNZPUkM382y6ji2k_A/
[3] https://mailarchive.ietf.org/arch/msg/spring/D785JyDEmhfEdVbKJHuLifmGAyw/
[4] https://mailarchive.ietf.org/arch/msg/spring/nclV2TB3dUOJ5oe7ntXYsvDcwg4/
[5] https://mailarchive.ietf.org/arch/msg/spring/6z2o-j6HA87WnQEjRRUJT2Ocb3M/
[6] https://mailarchive.ietf.org/arch/msg/spring/BDWzpWaFYJd4W-9EDES9j59SAfU/
[7] https://mailarchive.ietf.org/arch/msg/spring/tu45FAANxc6Cl27ppmG5DLROpTI/

During the WG LC, comments were raised about how to operate after one segment
list has been failed when a CP with multiple segment lists is used for traffic
transmition, this comment had been addressed by adding clarification text in the
draft. (see [8] [9])
[8] https://mailarchive.ietf.org/arch/msg/spring/e8Gt3_oy6Y8yoI2mJ5W8WBXlh0A/
[9] https://mailarchive.ietf.org/arch/msg/spring/SlPbPJ9n7r4NkkrFePLrsdQLMFo/

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)?

The authors claimed that Cisco and Nokia have partial implementations of the
document in response to the shepherd's question about the implementation .
(see https://mailarchive.ietf.org/arch/msg/spring/1P9izug4gpqE69OzvqCjUP0LpV8/)

## 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.

Yes, the contents of this document have intersection with technologies in PCE,
IDR and IPPM WGs, it would benefit from their review to check whether this document
has used the related protocols(e.g, PCEP, BGP, STAMP) correctly.
These reviews have not occured yet.

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 such formal language.

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 module.

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.

No formal language.

## 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?

The shepherd has checked the lists of common issues, no special issue of this
document has been found.
There's no directorate review yet.

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?

The intended RFC status is informational and document reflects it in the datatracker.

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.

All the authors and contributors have explicitly stated that they are unaware of
any undisclosed IPR related with the document.
Their claims can be found at
https://mailarchive.ietf.org/arch/msg/spring/ILJftItJrd7P8ZNn7XQEvrsC7m0/,
and  https://mailarchive.ietf.org/arch/msg/spring/mguEnQ1pKVUUa15vmDYKfPXtseQ/

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.

There are five co-authors on the front page. By responding to the IPR poll, the
authors and contributors have implicitly confirmed their willingness to be listed.

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.)

No remaining I-D nits in this document.
Idnits has been run and error corrected.
Internet-Drafts Checklist done.
Shepherd has reviewed the draft and made comments. Those have been addressed by
the editor.

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?

All references are publicly available.

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?

Yes. The status of the non-RFC documents in the normative references based on
the search of the datatraker and the WG wiki are listed below:

Name                 Status
draft-ietf-idr-bgp-ls-sr-policy          RFC Ed Queue
draft-ietf-idr-sr-policy-safi            RFC Ed Queue
draft-ietf-pce-segment-routing-policy-cp  RFC Ed Queue
draft-ietf-pce-sr-bidir-path              WG Last Call Queue
draft-ietf-idr-sr-policy-path-segment    Expired in April,completion plan unclear
draft-ietf-pce-circuit-style-pcep-extensions In progress,completion plan unclear
draft-ietf-pce-multipath                    In progress,completion plan unclear
draft-ietf-spring-sr-policy-yang            In progress,completion plan unclear
draft-ietf-spring-stamp-srpm             In progress,completion plan unclear

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, this document is standalone.

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]).

This document requires no action from 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/

This starts the working group last call for this draft.  There was sufficient engagement and interest to justify issueing this call.  Even so, we need to see support to pass the last call.  Please comment, preferably with explanations, as to your support or opposition to handing this draft to our AD for processing.  Silence is not consent.  This call will end at the end of the day on Monday, Feb 3.