Performance Measurement for Segment Routing Networks with MPLS Data Plane
draft-ietf-mpls-rfc6374-sr-17

Closed request for Last Call review by RTGDIR with state 'Overtaken by Events': As per Jeffrey, "I did not have technical concerns and the authors have addressed my comments."

[Ballot comment]
Thanks for this well-written document. I have a few small comments.

### Section 2.3

  The channel may be a directly connected link enabled with MPLS
  (Section 2.9.1 of [RFC6374]) or a Point-to-Point (P2P) SR-MPLS path
  [RFC8402].  The link may be a physical interface, a virtual link, or

I don't see either "point-to-point" or "p2p" in RFC 8402. Would the quoted section be just as valid if you removed these adjectives?

### Section 4.1.2

  by the intended responder, the Destination Address TLV (Type 129)
  [RFC6374] containing the address of the responder can be sent in the

Shouldn't that be "an address of the responder" since in general it will have more than one?

### Section 9

  responder.  If the responder does not support the new Mandatory TLV
  Types defined in this document; it MUST return Error 0x17:
  Unsupported Mandatory TLV Object as per [RFC6374].

That seems like a misuse of the RFC 2119 keyword; by definition, this spec can't dictate any requirements to a responder that doesn't implement this spec. Probably you mean something like,

NEW:
  responder.  If the responder does not support the new Mandatory TLV
  Types defined in this document it will return Error 0x17:
  Unsupported Mandatory TLV Object as per [RFC6374].

(I also removed a spurious semicolon.)

[Ballot comment]
Thanks for working on this specification. Thanks to Markus Ihlar for his TSVART review.

It seems the URO defined in RFC7876 is operating according to RFC 8085 ( obsolates RFC 5405 ) - UDP usage guideline. No objection from transport protocol point of views.

[Ballot comment]
There are two SHOULDs in this document, and I wonder for each of them what the impact is if an implementer were to deviate from that advice, or under what circumstances one might legitimately do so.  There might be more to say in each case.

[Ballot comment]

# Éric Vyncke, INT AD, comments for draft-ietf-mpls-rfc6374-sr-14

Thank you for the work put into this document, it is always important to understand the performance of a system.

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

Special thanks to Tony Li for the shepherd's write-up including the WG consensus *and* the justification of the intended status.

Other thanks to Brian Haberman, the Internet directorate reviewer (at my request), he found no issue in his int-dir review:
https://datatracker.ietf.org/doc/review-ietf-mpls-rfc6374-sr-13-intdir-telechat-haberman-2024-10-10/

I hope that this review helps to improve the document,

Regards,

-éric

# COMMENTS (non-blocking)

## IPPM

Was this document also reviewed by the IPPM WG where there is a lot of knowledge about measurement?

## Section 3

Make the reader's task easy by providing a section reference for `Return Path TLV extension`.

## Section 4.2.3

Where is "circular SR-MPLS path" defined ?

Suggest adding a figure showing the forward & return paths in the label stack.

## Sections 5.1 and 6.1

Suggest not using sub-sections but simply having the text in sections 5 and 6

## Section 6.2

This seems a weird location in the flow. Suggest merging 5 & 6 in a single section "Measurements"

## Section 7.1

I was about to DISCUSS this point but shouldn't s/Length MUST NOT be 0/Length MUST NOT be less than 2/ to take into account the length of the reserved field

Suggest having the last sentence (about reserved field) on its own paragraph. (Same for section 7.1.1)


# NITS (non-blocking / cosmetic)

## Abstract

The abstract could be shorter, e.g., by not explaining for SR is or not listing twice a set of RFCs.

## Section 2.3

Consider using aasvg for the graphical elements (nicer on HTML rendering).

## Section 3

Consider avoiding text repetition in the delay / loss bullets.

## Section 9 (and possibly others)

s/ISIS/IS-IS/

[Ballot comment]
Thank you to Roni Even for the GENART review.

Thank you for addressing my previous DISCUSS feedback.

** Section 13.  Is the WG confident that such a small range of only 176-239 is best allocated through a FCFS registration policy?

[Ballot discuss]
Table 2 outlines that a value of 255 is allocated for Private Use.  However, Table 3 then says that a value of 255 is Reserved.  How can one reserve something in a “Private Use” range?

[Ballot comment]
Thank you to Roni Even for the GENART review.

** Section 13.  Is the WG confident that such a small range of only 176-239 is best allocated through a FCFS registration policy?

[Ballot comment]
        The Length is a one-byte field and is equal to the length of the
        Return Path Sub-TLV and the Reserved field in bytes. Length MUST
        NOT be 0.

Since the Reserved field is two octets, doesn't this mean the Length
field MUST NOT be 0 or 1 ? (and likely more since the Sub TLV also has
a minimal structure length. This occurs twice in the document.

The Security Considerations contains both "may" and "MAY" in a similar
way (as in I think these should be done similarly, but I don't think
it matters which is picked)

[Ballot comment]
# Gunter Van de Velde, RTG AD, comments for draft-ietf-mpls-rfc6374-sr-12

# line numbers are derived with the idnits tool https://author-tools.ietf.org/api/idnits?url=https://www.ietf.org/archive/id/draft-ietf-mpls-rfc6374-sr-12.txt
# Thank you for this document, It reads well and explains the objectives well. It is a useful solution.
# In this review you will find observations i had when reviewing the document. I suspect majority will be easy to resolve or address and will be clarifications

#DETAILED COMMENTS
#=================

19   Segment Routing (SR) leverages the source routing paradigm.  SR
20   applies to the Multiprotocol Label Switching data plane (SR-MPLS) as
21   specified in RFC 8402.  RFC 6374 and RFC 7876 specify protocol
22   mechanisms to enable efficient and accurate measurement of packet
23   loss, one-way and two-way delay, as well as related metrics such as
24   delay variation in MPLS networks.  RFC 9341 defines the Alternate-
25   Marking Method using Block Number as a data correlation mechanism for
26   packet loss measurement.  This document utilizes mechanisms from RFC
27   6374, RFC 7876, and RFC 9341 for performance delay and loss
28   measurements in SR-MPLS networks, covering both links and end-to-end
29   SR-MPLS paths, including SR Policies.

GV> What about the following proposal for a more compact abstract explaining the objective of the document:

"
This document specifies the application of the MPLS loss and delay measurement techniques, originally defined in RFC 6374, RFC 7876, and RFC 9341 within Segment Routing (SR) networks that utilize the MPLS data plane. Segment Routing enables the forwarding of packets through an ordered list of instructions, known as segments, which are imposed at the ingress node. By applying the mechanisms from RFC 6374, RFC 7876, and RFC 9341 to SR-MPLS networks, this document facilitates accurate measurement of packet loss and delay for Segment Routing paths. It defines the procedures and extensions necessary to perform performance monitoring and fault management in SR-MPLS environments, ensuring that network operators can effectively measure and maintain the quality of service across their SR-based MPLS networks. This includes coverage of links and end-to-end SR-MPLS paths, as well as SR Policies.
"

104   Segment Routing (SR) leverages the source routing paradigm.  SR
105   applies to both Multiprotocol Label Switching (SR-MPLS) and IPv6
106   (SRv6) data planes as specified in [RFC8402].  SR takes advantage of
107   the Equal-Cost Multipaths (ECMPs) between source and transit nodes,
108   between transit nodes and between transit and destination nodes.  SR
109   Policies as defined in [RFC9256] are used to steer traffic through
110   specific, user-defined paths using a list of Segments.  A
111   comprehensive SR Performance Measurement toolset is one of the
112   essential requirements for measuring network performance to provide
113   Service Level Agreements (SLAs).

GV> This section reads strange. What about the following readability rewrite. I split the requirement for a comprehensive toolset off from the paragraph to add to its importance.

"
Segment Routing (SR), as specified in [RFC8402], leverages the source routing paradigm and applies to both the Multiprotocol Label Switching (SR-MPLS) and IPv6 (SRv6) data planes. SR takes advantage of Equal-Cost Multipaths (ECMPs) between source and transit nodes, between transit nodes, and between transit and destination nodes. SR Policies, defined in [RFC9256], are used to steer traffic through specific, user-defined paths using a list of segments.

A comprehensive SR Performance Measurement toolset is one of the essential requirements for measuring network performance to provide Service Level Agreements (SLAs).
"

121   defined in [RFC6374].  These mechanisms are also well-suited to SR-
122   MPLS networks.

GV> s/are also well-suited to SR-MPLS networks./can be applied to SR-MPLS networks./

132   This document defines Return Path and Block Number TLV extensions for
133   [RFC6374] for performance delay and loss measurement in SR-MPLS

GV> the document talks about "performance delay". Is there a definition what that exactly means or describes?

132   This document defines Return Path and Block Number TLV extensions for
133   [RFC6374] for performance delay and loss measurement in SR-MPLS
134   networks.  These TLV extensions also apply to the MPLS Label Switched
135   Paths (LSPs) [RFC3031].  However, the procedure for performance delay
136   and loss measurement of MPLS LSPs is outside the scope of this
137   document.

GV> should here be explicit mentioned that this document proposes a new a registry for "Return Path Sub-TLV Type" and allocate values for Mandatory TLV Types for [RFC6374] from the "MPLS Loss/Delay Measurement TLV Object" to be more accurate?

197   SR is enabled with MPLS data plane on nodes Q1 and R1.  The nodes Q1
198   and R1 may be directly connected via a link enabled with MPLS
199   (Section 2.9.1 of [RFC6374]) or a Point-to-Point (P2P) SR-MPLS path
200   [RFC8402].  The link may be a physical interface, a virtual link, or
201   a Link Aggregation Group (LAG) [IEEE802.1AX], or LAG member link.
202   The SR-MPLS path may be an SR-MPLS Policy [RFC9256] on node Q1
203   (called head-end) with destination to node R1 (called tail-end).

GV> This paragraph reads a bit odd. I think it intends to describe all different manners to connect Q1 with R1. Why is this section ot using the terminology from section 2.9.1 that talks about "Types of Channel" A channel may be a link or some other constructs.

220   For delay and loss measurement in SR-MPLS networks, the procedures

GV> earlier the terminology "performance delay" was used. Is that different from "delay" mentioned here? I suspect it is the same. Maybe define once and inform that performance delay = delay as used in this document

218 3.  Overview

220   For delay and loss measurement in SR-MPLS networks, the procedures
221   defined in [RFC6374], [RFC7876], and [RFC9341] are used in this
222   document.  Note that the one-way, two-way, and round-trip delay
223   measurements are defined in Section 2.4 of [RFC6374] and are further
224   described in this document for SR-MPLS networks.  Similarly, the
225   packet loss measurement is defined in Section 2.2 of [RFC6374] and is
226   further described in this document for SR-MPLS networks.

228   The packet loss measurement using Alternate-Marking Method defined in
229   [RFC9341] may use Block Number for data correlation.  This is
230   achieved by using the Block Number TLV extension defined in this
231   document.

233   In SR-MPLS networks, the query and response messages defined in
234   [RFC6374] are sent as follows:

236   *  For delay measurement, the query messages MUST be sent on the same
237       path as data traffic for links and end-to-end SR-MPLS paths to
238       collect both transmit and receive timestamps.

240   *  For loss measurement, the query messages MUST be sent on the same
241       path as data traffic for links and end-to-end SR-MPLS paths to
242       collect both transmit and receive traffic counters.

244   If it is desired in SR-MPLS networks that the same path (same set of
245   links and nodes) between the querier and responder be used in both
246   directions of the measurement, it is achieved by using the Return
247   Path TLV extension defined in this document.

249   The performance measurement procedure for links can be used to
250   compute extended Traffic Engineering (TE) metrics for delay and loss
251   as described in this document.  The metrics are advertised in the
252   network using the routing protocol extensions defined in [RFC7471],
253   [RFC8570], and [RFC8571].

GV> This section could use some edits to make the text easier to digest when reading. What about the following:

"
In this document, the procedures defined in [RFC6374], [RFC7876], and [RFC9341] are utilized for delay and loss measurement in SR-MPLS networks. Specifically, the one-way, two-way, and round-trip delay measurements described in Section 2.4 of [RFC6374] are further elaborated for application within SR-MPLS networks. Similarly, the packet loss measurement procedures outlined in Section 2.2 of [RFC6374] are extended for use in SR-MPLS networks.

Packet loss measurement using the Alternate-Marking Method defined in [RFC9341] may employ the Block Number for data correlation. This is achieved by utilizing the Block Number TLV extension defined in this document.

In SR-MPLS networks, the query and response messages defined in [RFC6374] are transmitted as follows:

* For delay measurement, the query messages MUST be sent along the same path as the data traffic for links and end-to-end SR-MPLS paths to collect both transmit and receive timestamps.

* For loss measurement, the query messages MUST be sent along the same path as the data traffic for links and end-to-end SR-MPLS paths to collect both transmit and receive traffic counters.

If it is desired in SR-MPLS networks that the same path (i.e., the same set of links and nodes) between the querier and responder be used in both directions of the measurement, this can be achieved by using the Return Path TLV extension defined in this document.

The performance measurement procedures for links can be used to compute extended Traffic Engineering (TE) metrics for delay and loss, as described herein. These metrics are advertised in the network using the routing protocol extensions defined in [RFC7471], [RFC8570], and [RFC8571].
"

261   The query message as defined in [RFC6374] is sent over the links for
262   both delay and loss measurement.  In each Label Stack Entry (LSE)
263   [RFC3032] in the MPLS label stack, the TTL value MUST be set to 255.

GV> What is the motivation to set this to 255? would that in-case the routing is bad not potentially cause looping packets? would a TTL = 1 not be a protection mechanism against this attack potential vector?

267   An SR-MPLS Policy Candidate-Path may contain a number of Segment
268   Lists (SLs) (i.e., stack of MPLS labels) [RFC9256].  For delay and/or
269   loss measurement for an end-to-end SR-MPLS Policy, the query messages
270   MUST be transmitted for every SL of the SR-MPLS Policy Candidate-
271   Path.

GV> From a clarification perspective: If a single sr-policy as 3 Segment lists, then it MUST transmit 3 individual queries. How is tracking done to correlate which response aligns with which query? or how all queries are responded towards?

345   The loopback measurement mode defined in Section 2.8 of [RFC6374] is
346   used to measure round-trip delay for a bidirectional circular SR-MPLS
347   path.  In this mode for SR-MPLS, the received query messages are not

GV> Not sure what 'circular' accurately describes? Is this when the upstream and downstream path are exactly the same? is this when the segment lists are identical but in reverse order? is this something else?

354   The loopback mode is done by generating "queries" with the Response
355   flag set to 1 and adding the Loopback Request object (Type 3)
356   [RFC6374].  The label stack, as shown in Figure 2, in query messages
357   in this case carries both the forward and reverse paths in the MPLS
358   header.  The GAL is still carried at the bottom of the label stack
359   (with S=1) (example as shown in Figure 2).

GV> Maybe a clarification. Is it assumed here that the segments in the stack are node segments? I suspect that adj segments MUST not be used? Maybe this is detailed in other specifications though for this type of measurement?

363 5.1.  Delay Measurement Message Format

GV> earlier 'performance' measurements terminology was used. i suspect it is all identical, but maybe add text to explicitly point that out

532   The Return Path TLV is defined in the Mandatory TLV Type registry
533   space [RFC6374].  The querier MUST only insert one Return Path TLV in
534   the query message.  The responder that supports this TLV, MUST only
535   process the first Return Path TLV and ignore the other Return Path
536   TLVs if present.  The responder that supports this TLV, also MUST
537   send response message back on the return path specified in the Return
538   Path TLV.  The responder also MUST NOT add Return Path TLV in the
539   response message.  The Reserved field MUST be set to 0 and MUST be
540   ignored on the receive side.

GV> Is this impacted in any way when the query is sent on all SL's within the sr-policy?
Will all these queries use the same return path? Would this not be a restriction of using return path TLV that all return responses are using the same return path?

566   The MPLS Label Stack contains a list of 32-bit LSE that includes a
567   20-bit label value, 8-bit TTL value, 3-bit TC value, and 1-bit EOS
568   (S) field.  An MPLS Label Stack Sub-TLV may carry a stack of labels
569   or a Binding SID label [RFC8402] of the Return SR-MPLS Policy.

GV> any dependency on labels corresponding to node or adjacency SIDs

616 8.  ECMP for SR-MPLS Policies

GV> Is the ECMP when for example there are multiple paths between two hops in the segment list (for example multiple parallel links between two nodes)? or is this ECMP between multiple SL (Segment Lists) that exist within a sr-policy? I suspect this is about the first, but am not sure.

639   The extended TE metrics for link delay and loss can be computed using
640   the performance measurement procedures described in this document and
641   advertised in the routing domain as follows:

GV> Is this document defining how to compute the measurement metrics? Would it not be the process for measuring performance metrics.

[Ballot comment]
Thank you for writing this document, I found it interesting and useful.

Also, thank you *very* much to Dhruv Dhody for the excellent OpsDir review (https://datatracker.ietf.org/doc/review-ietf-mpls-rfc6374-sr-11-opsdir-lc-dhody-2024-09-04/), and for addressing their comments.

Request for Last Call review by GENART Completed: Ready with Nits. Reviewer: Roni Even. Sent review to list. Submission of review completed at an earlier date.

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

IANA has completed its review of draft-ietf-mpls-rfc6374-sr-11. If any part of this review is inaccurate, please let us know.

We understand that, upon approval of this document, there are two actions which we must complete.

First, in the MPLS Loss/Delay Measurement TLV Object registry in the Generic Associated Channel (G-ACh) Parameters registry group located at:

https://www.iana.org/assignments/g-ach-parameters/

two new registrations will be made from the mandatory range as follows:

Code: [ TBD-at-Registration ]
Description: Return Path TLV
Reference: [ RFC-to-be ]

Code: [ TBD-at-Registration ]
Description: Block Number TLV
Reference: [ RFC-to-be ]

Second, a new sub-registry is to be created for the new Return Path TLV Type created in action one above. The new registry will be created as a sub-registry of the MPLS Loss/Delay Measurement TLV Object registry in the Generic Associated Channel (G-ACh) Parameters registry group located at:

https://www.iana.org/assignments/g-ach-parameters/

The new sub-registry will be managed via the following rules based on [RFC8126]:

0 - 175: IETF Review
176 - 239: First Come First Served
240 - 251: Experimental Use
252 - 255: Private Use

There are three initial registrations in the new sub-registry as follows:

Value Description Reference
-----+-----------+----------
0 Reserved [ RFC-to-be ]
1 SR-MPLS Segment List of the Return Path [ RFC-to-be ]
2-254 Unassigned
255 Reserved [ RFC-to-be ]

We understand that these two actions are the only ones required to be completed upon approval of this document.

NOTE: The actions 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 list of actions 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 2024-09-06):

From: The IESG
To: IETF-Announce
CC: draft-ietf-mpls-rfc6374-sr@ietf.org, james.n.guichard@futurewei.com, mpls-chairs@ietf.org, mpls@ietf.org, tony.li@tony.li, tsaad@cisco.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Performance Measurement for Segment Routing Networks with MPLS Data Plane) to Proposed Standard


The IESG has received a request from the Multiprotocol Label Switching WG
(mpls) to consider the following document: - 'Performance Measurement for
Segment Routing Networks with MPLS Data
  Plane'
  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 2024-09-06. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  Segment Routing (SR) leverages the source routing paradigm.  SR is
  applicable to Multiprotocol Label Switching data plane (SR-MPLS) as
  specified in RFC 8402.  RFC 6374 and RFC 7876 specify protocol
  mechanisms to enable efficient and accurate measurement of packet
  loss, one-way and two-way delay, as well as related metrics such as
  delay variation in MPLS networks.  RFC 9341 defines Alternate-Marking
  Method using Block Number (BN) for data correlation mechanism for
  packet loss measurement.  This document utilizes these mechanisms for
  Performance Delay and Loss Measurements in SR-MPLS networks, for both
  links and end-to-end SR-MPLS paths including Policies.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-mpls-rfc6374-sr/



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

Document shepherd writeup for draft-ietf-mpls-rfc6374-sr

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 reached broad agreement.

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

No, this was a smooth path to consensus.

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.)

There are no outstanding conflicts.

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 recommends) or elsewhere
(where)?

There are no reported implementations

Additional Reviews
==================

5. Do the contents of this document closely interact with technologies in other
IETF working groups or external organizations, and would it therefore benefit
from their review? Have those reviews occurred? If yes, describe which
reviews took place.

The document was reviewed by the RTG directorate and the SPRING WG.

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

Not applicable.

7. If the document contains a YANG module, has the final version of the module
been checked with any of the recommended validation tools for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module
comply with the Network Management Datastore Architecture (NMDA) as specified
in RFC 8342?

Not applicable.

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.

Not applicable.

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?

I have one comment outstanding, otherwise yes.

10. Several IETF Areas have assembled lists of common issues that their
reviewers encounter. For which areas have such issues been identified
and addressed? For which does this still need to happen in subsequent
reviews?

The document has been reviewed with respect to the Routing Area AD
Nits issues list. No open issues remain.

11. What type of RFC publication is being requested on the IETF stream (Best
Current Practice, Proposed Standard, Internet Standard,
Informational, Experimental or Historic)? Why is this the proper type
of RFC? Do all Datatracker state attributes correctly reflect this intent?

This is being submitted as a proposed standard. This is the correct
classification as it is an interoperable protocol. The datatracker
correctly reflects this.

12. Have reasonable efforts been made to remind all authors of the intellectual
property rights (IPR) disclosure obligations described in BCP 79? 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.

Immediately before WGLC, an IPR poll was conducted of all authors and
contributors.  All asserted that there were no outstanding IPR claims.
There are no IPR disclosures on the document.

13. Has each author, editor, and contributor shown their willingness to be
listed as such? If the total number of authors and editors on the front page
is greater than five, please provide a justification.

Yes. There are five authors and three contributors.

14. Document any remaining I-D nits in this document. Simply running the idnits
tool is not enough; please review the "Content Guidelines" on
authors.ietf.org. (Also note that the current idnits tool generates
some incorrect warnings; a rewrite is underway.)

There are no known nits.

15. Should any informative references be normative or vice-versa? See the IESG
Statement on Normative and Informative References.

Everything seems appropriate.

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

Not applicable, all normative references are RFCs.

17. Are there any normative downward references (see RFC 3967 and BCP
97) that are not already listed in the DOWNREF registry? If so,
list them.

Not applicable, all normative references are Proposed Standards.

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?

Not applicable, all normative references are RFCs.

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 will not change the status of any other RFC.

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).

The IANA considerations section seems complete and clear. The document
creates one new registry, which looks to be properly done.

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.

The one requested registry is under the "IETF Review" process.

Document shepherd writeup for draft-ietf-mpls-rfc6374-sr

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 reached broad agreement.

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

No, this was a smooth path to consensus.

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.)

There are no outstanding conflicts.

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 recommends) or elsewhere
(where)?

There are no reported implementations

Additional Reviews
==================

5. Do the contents of this document closely interact with technologies in other
IETF working groups or external organizations, and would it therefore benefit
from their review? Have those reviews occurred? If yes, describe which
reviews took place.

The document was reviewed by the RTG directorate and the SPRING WG.

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

Not applicable.

7. If the document contains a YANG module, has the final version of the module
been checked with any of the recommended validation tools for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module
comply with the Network Management Datastore Architecture (NMDA) as specified
in RFC 8342?

Not applicable.

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.

Not applicable.

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?

I have one comment outstanding, otherwise yes.

10. Several IETF Areas have assembled lists of common issues that their
reviewers encounter. For which areas have such issues been identified
and addressed? For which does this still need to happen in subsequent
reviews?

The document has been reviewed with respect to the Routing Area AD
Nits issues list. No open issues remain.

11. What type of RFC publication is being requested on the IETF stream (Best
Current Practice, Proposed Standard, Internet Standard,
Informational, Experimental or Historic)? Why is this the proper type
of RFC? Do all Datatracker state attributes correctly reflect this intent?

This is being submitted as a proposed standard. This is the correct
classification as it is an interoperable protocol. The datatracker
correctly reflects this.

12. Have reasonable efforts been made to remind all authors of the intellectual
property rights (IPR) disclosure obligations described in BCP 79? 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.

Immediately before WGLC, an IPR poll was conducted of all authors and
contributors.  All asserted that there were no outstanding IPR claims.
There are no IPR disclosures on the document.

13. Has each author, editor, and contributor shown their willingness to be
listed as such? If the total number of authors and editors on the front page
is greater than five, please provide a justification.

Yes. There are five authors and three contributors.

14. Document any remaining I-D nits in this document. Simply running the idnits
tool is not enough; please review the "Content Guidelines" on
authors.ietf.org. (Also note that the current idnits tool generates
some incorrect warnings; a rewrite is underway.)

There are no known nits.

15. Should any informative references be normative or vice-versa? See the IESG
Statement on Normative and Informative References.

Everything seems appropriate.

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

Not applicable, all normative references are RFCs.

17. Are there any normative downward references (see RFC 3967 and BCP
97) that are not already listed in the DOWNREF registry? If so,
list them.

Not applicable, all normative references are Proposed Standards.

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?

Not applicable, all normative references are RFCs.

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 will not change the status of any other RFC.

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).

The IANA considerations section seems complete and clear. The document
creates one new registry, which looks to be properly done.

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.

The one requested registry is under the "IETF Review" process.