Extension for Stateful PCE to allow Optional Processing of PCE Communication Protocol (PCEP) Objects
draft-ietf-pce-stateful-pce-optional-13

[Ballot comment]
Like Warren, I find this document difficult to read, possibly due to my lack of knowledge of PCE, i.e., this ballot is more "no opinion" rather than "no objection".

Like for the other PCE draft in this telechat, I wonder why Dhruv Dhody is not explicitly cited as contributor and does not even appear in the acknowledgements section.

[Ballot comment]
Section 3.2.1:  It seems like the use of the R flag changes how the PCE handles the P flag.  I'm not sure SHOULD (or BCP14 language) is optimal in this section.  Does the PCE try hard to respect the P flag, but if it can't, then it ignores it?  This sounds more like 'best effort'.  I can't tell if this also might apply to the case where the 'PCC SHOULD set the P flag by default'.  [note:  I'm well outside of my expertise area here, I'm just trying to interpret what is here in a logical fashion.]

Sections 3.2 and 3.3: Would a small table with P, R, and I flags against PCC, PCE, and maybe the various extensions/message types might help?

Section 4:  The last () is a bit puzzling.  It might need some explanation.  Is there something specific that is anticipated?  RFC8253 is old enough that TLS1.3 wasn't published yet, but RFC 9325 obviously covers both TLS 1.2 and 1.3.

[Ballot comment]
Thanks for this document. I have two questions:

### Section 2, why not MUST?

```
When the P flag is set in the PCRpt message received on a PCEP session on which the R bit was set by both peers, the object SHOULD be taken into account by the PCE.

```

Under what circumstances is it OK for the PCE to ignore an object whose P flag is set? In other words, why isn't this a MUST?

### Section 4, explicitly set aside

```
As per [RFC8231], it is RECOMMENDED that these PCEP extensions can only be activated on authenticated and encrypted sessions across PCEs and PCCs belonging to the same administrative authority, using Transport Layer Security (TLS) [RFC8253] as per the recommendations and best current practices in [RFC9325] (unless explicitly set aside in [RFC8253]).

```

I'm curious about the parenthetical comment. Can you provide an example of a recommendation or best current practice that was explicitly set aside in RFC 8253? I did go look at the Security Considerations of RFC 8253 and didn't see anything like that.

[Ballot comment]
Thanks for this document. I have two questions:

### Section 2, why not MUST?

```
When the P flag is set in the PCRpt message received on a PCEP session on which the R bit was set by both peers, the object SHOULD be taken into account by the PCE.
```

Under what circumstances is it OK for the PCE to ignore an object whose P flag is set? In other words, why isn't this a MUST?

### Section 4, explicitly set aside

```
As per [RFC8231], it is RECOMMENDED that these PCEP extensions can only be activated on authenticated and encrypted sessions across PCEs and PCCs belonging to the same administrative authority, using Transport Layer Security (TLS) [RFC8253] as per the recommendations and best current practices in [RFC9325] (unless explicitly set aside in [RFC8253]).
```

I'm curious about the parenthetical comment. Can you provide an example of a recommendation or best current practice that was explicitly set aside in RFC 8253? I did go look at the Security Considerations of RFC 8253 and didn't see anything like that.

[Ballot comment]
Thanks to Tianran Zhou for the OpsDir review: https://datatracker.ietf.org/doc/review-ietf-pce-stateful-pce-optional-10-opsdir-lc-zhou-2024-10-07/

I found this document quite difficult to read, but that may be because I'm unfamiliar with PCE.

I have some nits:
1:The behaviour for P and I flag in other messages defined in [RFC5440] and other extension was not specified.
P: The behaviour for P and I flag in other messages defined in [RFC5440] and other extensions were not specified.
C: I'm actually not sure what this sentence is trying to say -- is it that "the behavior for the flags, and also the behavior in other extensions" was not specified, or "the behavior of the flags which are specified in RFC5440 and other extensions" was not specified?


2: "In these cases, it would be useful to mark the objects as 'optional' and it could be ignored by the PCEP peer."
P: "In these cases, it would be useful to mark the objects as 'optional', and they could be ignored by the PCEP peer." (I think).

3: "Thus, this document specifies how the already existing P and I flag in the PCEP common object header could be used during the stateful ..."
P: "Thus, this document specifies how the already existing P and I flags in the PCEP common object header could be used during the stateful ..." (this occurs in many places in the document.)

4: "In case the bit is unset, it indicates that the PCEP Speaker would not handle the P and I flags in the PCEP common object header for stateful PCE messages."
P: "If the bit..."

5: "The P flag for the mandatory objects such as the LSP and the ERO (Explicit Route Object) object (intended path) MUST be set in the PCRpt message. "
P: "The P flag for the mandatory objects, such as the LSP and the ERO (Explicit Route Object) object (intended path), MUST be set in the PCRpt message."
C: It's really hard to read without the commas. This occurs in multiple places in the documents.

6: "On a PCEP session on which R bit was set by both peers, the PCC SHOULD set the P flag by default, "
P: "On a PCEP session in which the R bit was set by both peers, the PCC SHOULD set the P flag by default, "

7: "In case PCC cannot accept this, it would react as per the processing rules of unacceptable update in [RFC8231]."
P: "If the PCC cannot accept this, it would react as per the processing rules of unacceptable update in [RFC8231]."
C: The "it would react" is very unclear -- is this "it MUST"? "SHOULD"? Why might the PCC not accept this?

[Ballot comment]
"Abstract", paragraph 0
> Abstract

The shepherd's write-up was done in 2022. Has there been no change in the document since then that would require an update to the writeup?

Section 1, paragraph 3
>    [RFC5440] defined the P flag (Processing-Rule) in the Common Object
>    Header to allow a PCC to specify in a Path Computation Request
>    (PCReq) message (sent to a PCE) whether the object must be taken into
>    account by the PCE during path computation or is optional.  The I
>    flag (Ignore) is used by the PCE in a Path Computation Reply (PCRep)
>    message to indicate to a PCC whether or not an optional object was
>    considered by the PCE during path computation.  Stateful PCE
>    [RFC8231] specified that the P and I flags of the PCEP objects
>    defined in [RFC8231] is to be set to zero on transmission and ignored
>    on receipt, since they are exclusively related to the path
>    computation requests.  The behaviour for P and I flag in other
>    messages defined in [RFC5440] and other extension was not specified.
>    This document specifies how the P and I flag could be used in the
>    stateful PCE model to identify optional objects in the Path
>    Computation State Report (PCRpt) [RFC8231], the Path Computation
>    Update Request (PCUpd) [RFC8231], and the LSP Initiate Request
>    (PCInitiate) [RFC8281] message.


I would have imagined that this would be a good place to introduce the fact that the document is trying to define a new flag (R) in this document.

Section 3.1, paragraph 3
>    The R flag MUST be set by both PCC and PCE to indicate support for
>    the handling of the P and I flag in the PCEP common object header to
>    allow relaxing some constraints by marking objects as 'optional to
>    process'.  If the PCEP speaker did not set the R flag but receives
>    PCEP objects with P or I bit set, it MUST behave as per the
>    processing rule in [RFC8231].  Note that while [RFC8231] stated that
>    P and I flags of the PCEP objects defined in [RFC8231] are set to 0
>    on transmission and ignored on receipt, it did not say anything about
>    already existing PCEP objects and thus the behaviour remained
>    undefined.  To safely use this feature, both peers need to set the R
>    flag.

It is unclear from this paragraph what it means when it states that "it did not say anything about already existing PCEP objects". Already existing PCEP objects that have the P and I flags set to 1?? It appears that the behavior of when it is set to 0 is known, so it would seem that we are talking about when the value is not set to 0. Can this be made clear?

Section 7, paragraph 0
> 7.  Manageability Considerations

It is great to see that this document has a separate manageability consideration section called out.

Section 7.2, paragraph 0
>    An implementation supporting this document SHOULD allow the operator
>    to view the capability defined in this document.  To serve this
>    purpose, the PCEP YANG module [I-D.ietf-pce-pcep-yang] could be
>    extended in the future.

Is this captured in the charter as a milestone, or in a draft that is being considered by the WG?

-------------------------------------------------------------------------------
NIT
-------------------------------------------------------------------------------

All comments below are about very minor potential issues that you may choose to
address in some way - or ignore - as you see fit. Some were flagged by
automated tools (via https://github.com/larseggert/ietf-reviewtool), so there
will likely be some false positives. There is no need to let me know what you
did with these suggestions.

Section 3.3.2, paragraph 1
> g in the common object header in a similar way as [RFC5440], i.e. if a PCEP
>                              ^^^^^^^^^^^^^^^^
Consider replacing this phrase with the adverb "similarly" to avoid wordiness.

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

IANA has completed its review of draft-ietf-pce-stateful-pce-optional-09. If any part of this review is inaccurate, please let us know.

IANA understands that, upon approval of this document, there is a single action which we must complete.

In the STATEFUL-PCE-CAPABILITY TLV Flag Field registry in the Path Computation Element Protocol (PCEP) Numbers registry group located at:

https://www.iana.org/assignments/pcep/

a single new registration will be made as follows:

Value: [ TBD-at-Registration ]
Description: RELAX
Reference: [ RFC-to-be ]

We understand that this is the only action required to be completed upon approval of this document.

NOTE: The action requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the action that will be performed.

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 2024-10-03):

From: The IESG
To: IETF-Announce
CC: dd@dhruvdhody.com, draft-ietf-pce-stateful-pce-optional@ietf.org, pce-chairs@ietf.org, pce@ietf.org, rdd@cert.org
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Extension for Stateful PCE to allow Optional Processing of PCE Communication Protocol (PCEP) Objects) to Proposed Standard


The IESG has received a request from the Path Computation Element WG (pce) to
consider the following document: - 'Extension for Stateful PCE to allow
Optional Processing of PCE
  Communication Protocol (PCEP) Objects'
  as Proposed Standard

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 2024-10-03. 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 introduces a mechanism to mark some of the Path
  Computation Element (PCE) Communication Protocol (PCEP) objects as
  optional during PCEP messages exchange for the Stateful PCE model to
  allow relaxing some constraints during path computation and setup.
  This document introduces this relaxation to stateful PCE and updates
  RFC 8231.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-pce-stateful-pce-optional/



No IPR declarations have been submitted directly on this I-D.

# Document Shepherd Write-Up for Group Documents for draft-ietf-pce-stateful-pce-optional

*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 represents a strong concurrence of a few with no objections from others.

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)?

The Implementation Status section says that there are no known implementations yet but some vendors are considering it.

## 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.

No.

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.


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

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?

This document has been reviewed by the chair. The document is clear and ready to be shipped.


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?

N/A

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?

Proposed Standard
This I-D defines a protocol extension and thus standards track makes sense.
All attributes in Datatracker are set correctly.


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 no IPRs. Poll was conducted during adoption and WGLC.

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.

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.)

None

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.

None

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?

N/A

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.

This document updates RFC 8231, it is captured in the metadata and abstract.

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]).

The IANA section is consistent with the document's body and has been reviewed.

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.

No need for Designated Expert

[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 for draft-ietf-pce-stateful-pce-optional

*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 represents a strong concurrence of a few with no objections from others.

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)?

The Implementation Status section says that there are no known implementations yet but some vendors are considering it.

## 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.

No.

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.


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

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?

This document has been reviewed by the chair. The document is clear and ready to be shipped.


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?

N/A

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?

Proposed Standard
This I-D defines a protocol extension and thus standards track makes sense.
All attributes in Datatracker are set correctly.


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 no IPRs. Poll was conducted during adoption and WGLC.

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.

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.)

None

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.

None

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?

N/A

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.

This document updates RFC 8231, it is captured in the metadata and abstract.

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]).

The IANA section is consistent with the document's body and has been reviewed.

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.

No need for Designated Expert

[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/