Compressed SRv6 Segment List Encoding (CSID)
draft-ietf-spring-srv6-srh-compression-23

[Ballot discuss]
## DISCUSS

I have a minor and easy-to-fix point I'm flagging as a DISCUSS to make sure it's not missed.

### Section 6.4, what's "NL"?

```
  When receiving a SID advertisement for a REPLACE-CSID flavor SID with
  LNL=16, FL=0, AL=128-LBL-NL-FL, and the value of the Argument is all
  0, the SR source node marks both the SID and its locator as using
  16-bit compression.  All other SIDs allocated from this locator with
  LNL=16, FL=16, AL=128-LBL-NL-FL, and the value of the Argument is all
  0 are also marked as using 16-bit compression.  When receiving a SID
  advertisement for a REPLACE-CSID flavor SID with LNFL=32, AL=128-LBL-
  NL-FL, and the value of the Argument is all 0, the SR source node
  marks both the SID and its locator as using 32-bit compression.
```

"NL" isn't defined anywhere in the document. I assume you meant "LNL". Please fix, or define "NL" if that isn't what you meant.

Also (and this isn't DISCUSS-level, just noting here since it's in the same paragraph), is there some logic behind why you express the same thing two different ways within the same paragraph? Assuming you meant LNL, then is there some merit to writing AL=128-LBL-NL-FL instead of AL=128-LBL-LNFL?

[Ballot comment]
## COMMENT

### Section 4.1, cite for "reduced SRH"

The first time you mention "reduced SRH", please provide the appropriate citation, I believe it's RFC 8754 Section 4.1.1.

### Section 4.1, inconsistent ordering makes me sad

I find it odd that although "the elements in the SRH Segment List appear in reversed order of their processing" the elements in a NEXT-CSID container appear in forward order of processing, especially given that with REPLACE-CSID they appear in reversed order.

Given that it's presumably too late to change this choice now, I don't really care what the reason was. However, I do think that given the asymmetry of the design, it would be a service to the reader to add a note to Section 4.1 pointing it out, along the lines of, "Note that although the elements in the SRH Segment List appear in reversed order of their processing, as specified in Section 4.1 of [RFC8754], the elements within a given CSID container appear in forward order."

### Section 6.2, opaque paragraph

I found this paragraph to be unnecessarily opaque:

```
  It is out of the scope of this document to describe the mechanism
  through which an uncompressed SID list is derived.  As a general
  guidance for implementation or future specification, such a mechanism
  should aim to select the combination of SIDs that would result in the
  shortest compressed SID list.  For example, by selecting a CSID
  flavor SID over an equivalent non-CSID flavor SID or by consistently
  selecting SIDs of the same CSID flavor within each routing domain.
```

As far as I can tell, what you mean is, "Some SID lists will be more compressible than others. We aren't going to tell you how to produce SID lists, but you should try to make them compressible, for example [...]".

I'm not proposing that as actual replacement text since it's more informal than the rest of your document, but hopefully it gets the point across.

### Section 6.3, opaque rule

When I consider these two rules:

```
  2.  When the last Segment List entry (index 0) in the SRH is a NEXT-
      CSID container representing more than one segment, the PSP
      operation is performed at the segment preceding the first segment
      of this NEXT-CSID container in the segment list.  If the PSP
      behavior should be performed at the penultimate segment along the
      path instead, the SR source node MUST NOT compress the ultimate
      SID of the SID list into a NEXT-CSID container.

  3.  If a Destination Options header would follow an SRH with a last
      Segment List entry being a NEXT-CSID container representing more
      than one segment, the SR source node MUST ensure that the PSP
      operation is not performed before the penultimate SR segment
      endpoint node along the path.
```

If I read them correctly, it would be possible to rewrite rule 3 in a more straightforward manner, e.g.,

  3.  If a Destination Options header would follow an SRH with a last
      Segment List entry being a NEXT-CSID container representing more
      than one segment, the SR source node MUST NOT compress the ultimate
      SID of the SID list into a NEXT-CSID container.
     
Is there any other way to obey the MUST in rule 3, other than by obeying the MUST NOT of rule 2? The rewrite exposes a bit of a logical contradiction between the "if" clause and the "then" clause, but at least it's clearer. I'd welcome a better fix, though. (Or a correction if I've misunderstood.)

[Ballot comment]

# Éric Vyncke, INT AD, comments for draft-ietf-spring-srv6-srh-compression-19
CC @evyncke

Thank you for the work put into this document. While the content is rather complex, it is also easy to read.

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

Special thanks to Pablo Camarillo for the shepherd's *very detailed* write-up including the WG consensus *and* the justification of the intended status.

Please note that Benson Muite is the Internet directorate reviewer (at my request) and you may want to consider this int-dir review as well when it will be available (no need to wait for it though):
https://datatracker.ietf.org/doc/draft-ietf-spring-srv6-srh-compression/reviewrequest/21238/

I hope that this review helps to improve the document,

Regards,

-éric

## COMMENTS (non-blocking)

### Erik Kline's comment about section 4.2

I support Erik Kline's DISCUSS about some CSID containers not being valid IPv6 addresses, i.e., not compliant to RFC 8754 (requiring that this document updates RFC 8754).

### Title

Suggest adding the acronym CSID in the title (e.g., like in RFC 7599, 9631, and others) this will help search engines.

### Section 1

Please expand CSID on first use.

### Section 2

Suggest adding the extension of SID at first use.

I wonder whether `If the Locator-Node length ... its CSID encoding is zero.` belongs to terminology or should rather be in the specification part of this document to ease the implementer task.

Unsure how to do it, but should LNFL be expanded ?

### Section 4.1

Should this be an uppercase MAY in `An implementation MUST support a 32-bit Locator-Block length (LBL) and a 16-bit CSID length (LNFL) for NEXT-CSID flavor SIDs, and may support any other Locator-Block and CSID length.` ? (to be consistent with the uppercase MUST)

### Section 4.1.6 (and possibly other places)

s/Destination Option header/Destination Option*s* header/

### Section 5.3

Like Erik Kline, please use the RFC 9602 SRv6 block for the examples rather than 2001:db8::/32

### Section 7.1

I was about to DISCUSS this point but, as I may have misread this section, I am just commenting. Should there be clearly specified that the prefixes being swapped are of the same length ?

It is also a little weird that the title and the PS acronym use "prefix" while it is all about locator block...

### Section 9.5

Below comments are to be consistent with my DISCUSS point about section 7 of RFC 9631 "The IPv6 Compact Routing Header (CRH)" that was easily resolved in the 6MAN WG IETF draft. See
https://mailarchive.ietf.org/arch/msg/ipv6/a_RdmiI3iYk6Sk6mamrppoLTvnc/

The last two paragraphs are useless as they state the obvious and, therefore, could be confusing to the reader. I strongly suggest removing them (I was even about to DISCUSS these points).

`Such SR source nodes leveraging TCP/UDP offload engines may require enhancements to convey the ultimate destination address.` it is obvious to me that current HW / SW do not always support the latest RFC, e.g., when RFC 2460 (IPv6) was published not all routers supported IPv6, this issue did not prevent publication of RFC 2460 nor the deployment of IPv6 (even if I would prefer to have a broader deployment than now ;-) ).

`It was reported that some network node implementations ... may attempt to verify the upper layer checksum of transit IPv6 packets.` These implementations clearly violates the end to end architecture of the Internet, so, why would a standard track document would care about them? And if these box are used for RFC 7258 pervasive monitoring then it is even a benefit of this specification ;-)

### SVG

Thanks for using the nice SVG graphics ;-)

[Ballot discuss]
# Internet AD comments for draft-ietf-spring-srv6-srh-compression-19
CC @ekline

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Discuss

### __general__

* Should this document formally update RFC 8754?

  The 128-bit values in the SRH when REPLACE-CSID is in use are very clearly
  not IPv6 addresses, and the SRH is described as a list of segments which
  are IPv6 addresses.

  To be clear: I have no objection to the REPLACE-CSID behavior, I'm just
  wondering if we should update 8754 since what was described as an IPv6
  address is, when REPLACE-CSID is in use, just "128-bits of other meaning."

### S2, S4, perhaps elsewhere

* I think it should be noted for clarity that regardless of CSID flavor, the
  IPv6 address observable in the IPv6 Header.DA field is a valid SRv6 SID
  conforming to RFC 9602.

[Ballot comment]
# Internet AD comments for draft-ietf-spring-srv6-srh-compression-19
CC @ekline

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Comments

### S4.1

* "An SR segment endpoint node instantiating a SID of this document with
  the NEXT-CSID flavor MUST accept any Argument value for that SID."

  What does this really mean?  Is it trying to say that the node that encaps
  a package with the first CSID in the DA cannot perform any validation
  of the control plane information that told it which CSID/DA to use?
  Or something else?

  If this about the "shift and zero-pad" behavior in the following paragraph,
  trying to ensure that no unnecessary inspection of resulting CSID/DA,
  then I think that makes sense except that (a) it could be more clear and
  (b) it probably belongs at the end of the behavior-describing paragraph.

### S4.2

* "A Locator-Block length of 48, 56, 64, 72, or 80 bits is recommended..."

  Just to be clear: you want this "recommended" to be lowercase? Put another
  way: should this be "RECOMMENDED"?

  I'm not sure it makes a significant difference either way (operationally);
  just checking.

### S5.3

* Feel free to use the dedicate SID prefix from RFC 9602 Section 6 in your
  examples, if you wish.

## Nits

### S4.1, S4.2

* "At high level" -> "At a high level"

IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-spring-srv6-srh-compression-19. 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 SRv6 Endpoint Behaviors registry in the Segment Routing registry group located at:

https://www.iana.org/assignments/segment-routing/

the following early registrations will have their references changed to [ RFC-to-be ]:

Value Description Reference
-----+-----------+----------
43 End with NEXT-CSID [ RFC-to-be ]
44 End with NEXT-CSID & PSP [ RFC-to-be ]
45 End with NEXT-CSID & USP [ RFC-to-be ]
46 End with NEXT-CSID, PSP & USP [ RFC-to-be ]
47 End with NEXT-CSID & USD [ RFC-to-be ]
48 End with NEXT-CSID, PSP & USD [ RFC-to-be ]
49 End with NEXT-CSID, USP & USD [ RFC-to-be ]
50 End with NEXT-CSID, PSP, USP & USD [ RFC-to-be ]
52 End.X with NEXT-CSID [ RFC-to-be ]
53 End.X with NEXT-CSID & PSP [ RFC-to-be ]
54 End.X with NEXT-CSID & USP [ RFC-to-be ]
55 End.X with NEXT-CSID, PSP & USP [ RFC-to-be ]
56 End.X with NEXT-CSID & USD [ RFC-to-be ]
57 End.X with NEXT-CSID, PSP & USD [ RFC-to-be ]
58 End.X with NEXT-CSID, USP & USD [ RFC-to-be ]
59 End.X with NEXT-CSID, PSP, USP & USD [ RFC-to-be ]
85 End.T with NEXT-CSID [ RFC-to-be ]
86 End.T with NEXT-CSID & PSP [ RFC-to-be ]
87 End.T with NEXT-CSID & USP [ RFC-to-be ]
88 End.T with NEXT-CSID, PSP & USP [ RFC-to-be ]
89 End.T with NEXT-CSID & USD [ RFC-to-be ]
90 End.T with NEXT-CSID, PSP & USD [ RFC-to-be ]
91 End.T with NEXT-CSID, USP & USD [ RFC-to-be ]
92 End.T with NEXT-CSID, PSP, USP & USD [ RFC-to-be ]
93 End.B6.Encaps with NEXT-CSID [ RFC-to-be ]
94 End.B6.Encaps.Red with NEXT-CSID [ RFC-to-be ]
95 End.BM with NEXT-CSID [ RFC-to-be ]
96 End.PS with NEXT-CSID [ RFC-to-be ]
97 End.XPS with NEXT-CSID [ RFC-to-be ]
101 End with REPLACE-CSID [ RFC-to-be ]
102 End with REPLACE-CSID & PSP [ RFC-to-be ]
103 End with REPLACE-CSID & USP [ RFC-to-be ]
104 End with REPLACE-CSID, PSP & USP [ RFC-to-be ]
105 End.X with REPLACE-CSID [ RFC-to-be ]
106 End.X with REPLACE-CSID & PSP [ RFC-to-be ]
107 End.X with REPLACE-CSID & USP [ RFC-to-be ]
108 End.X with REPLACE-CSID, PSP & USP [ RFC-to-be ]
109 End.T with REPLACE-CSID [ RFC-to-be ]
110 End.T with REPLACE-CSID & PSP [ RFC-to-be ]
111 End.T with REPLACE-CSID & USP [ RFC-to-be ]
112 End.T with REPLACE-CSID, PSP & USP [ RFC-to-be ]
114 End.B6.Encaps with REPLACE-CSID [ RFC-to-be ]
115 End.BM with REPLACE-CSID [ RFC-to-be ]
116 End.DX6 with REPLACE-CSID [ RFC-to-be ]
117 End.DX4 with REPLACE-CSID [ RFC-to-be ]
118 End.DT6 with REPLACE-CSID [ RFC-to-be ]
119 End.DT4 with REPLACE-CSID [ RFC-to-be ]
120 End.DT46 with REPLACE-CSID [ RFC-to-be ]
121 End.DX2 with REPLACE-CSID [ RFC-to-be ]
122 End.DX2V with REPLACE-CSID [ RFC-to-be ]
123 End.DT2U with REPLACE-CSID [ RFC-to-be ]
124 End.DT2M with REPLACE-CSID [ RFC-to-be ]
127 End.B6.Encaps.Red with REPLACE-CSID [ RFC-to-be ]
128 End with REPLACE-CSID & USD [ RFC-to-be ]
129 End with REPLACE-CSID, PSP & USD [ RFC-to-be ]
130 End with REPLACE-CSID, USP & USD [ RFC-to-be ]
131 End with REPLACE-CSID, PSP, USP & USD [ RFC-to-be ]
132 End.X with REPLACE-CSID & USD [ RFC-to-be ]
133 End.X with REPLACE-CSID, PSP & USD [ RFC-to-be ]
134 End.X with REPLACE-CSID, USP & USD [ RFC-to-be ]
135 End.X with REPLACE-CSID, PSP, USP & USD [ RFC-to-be ]
136 End.T with REPLACE-CSID & USD [ RFC-to-be ]
137 End.T with REPLACE-CSID, PSP & USD [ RFC-to-be ]
138 End.T with REPLACE-CSID, USP & USD [ RFC-to-be ]
139 End.T with REPLACE-CSID, PSP, USP & USD [ RFC-to-be ]
140 End.PS with REPLACE-CSID [ RFC-to-be ]
141 End.XPS with REPLACE-CSID [ 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 2024-12-16):

From: The IESG
To: IETF-Announce
CC: draft-ietf-spring-srv6-srh-compression@ietf.org, gunter@vandevelde.cc, pcamaril@cisco.com, spring-chairs@ietf.org, spring@ietf.org
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Compressed SRv6 Segment List Encoding) to Proposed Standard


The IESG has received a request from the Source Packet Routing in Networking
WG (spring) to consider the following document: - 'Compressed SRv6 Segment
List Encoding'
  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 2024-12-16. 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 over IPv6 (SRv6) is the instantiation of Segment
  Routing (SR) on the IPv6 dataplane.  This document specifies new
  flavors for the SRv6 endpoint behaviors defined in RFC 8986, which
  enable the compression of an SRv6 SID list.  Such compression
  significantly reduces the size of the SRv6 encapsulation needed to
  steer packets over long segment lists.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-spring-srv6-srh-compression/


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

  https://datatracker.ietf.org/ipr/5184/
  https://datatracker.ietf.org/ipr/4960/
  https://datatracker.ietf.org/ipr/4932/
  https://datatracker.ietf.org/ipr/6101/
  https://datatracker.ietf.org/ipr/6102/
  https://datatracker.ietf.org/ipr/6270/
  https://datatracker.ietf.org/ipr/4959/

This is the Shepherd writeup from Pablo Camarillo for draft-ietf-spring-srv6-srh-compression.

## 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?

There is broad agreement for publishing this document.

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

While there was widespread support for this document, a few individuals felt there were unaddressed problems with the draft. There have been threats of appeal [21] based on the relationship of the SRv6 end points behaviors  specified in this document and those implied by certain sections of RFC 8200 and the SPRING charter restrictions against making changes to underlying data planes. The spring chairs subsequently consulted with 6man chairs on the topic and the response from the 6man chairs can be found at [22].

However, the technology described in this document has already been broadly deployed in production networks by multiple early adopters, and the deployments have been detailed at the srv6ops BoF in Brisbane, none of which have raised any such concern on the list.

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.)

Yes, as indicated in previous bullet and the responsible ADs are well aware of the appeal threat.

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)?

Yes, there are several existing and deployed implementations that are listed in Section 10 of the draft. These include routing vendors (Arrcus, Centec, Ciena, Cisco, Huawei, Juniper, Nokia, Ruijie Networks, ZTE), merchant silicon vendors (Broadcom, Marvell), and opensource implementations (Linux Kernel, FD.io VPP, SONiC/SAI, ONOS, P4). There have been various industry interoperability events over the past years with multiple vendors and implementations such as the ones detailed in [23][24]. 

## 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 describes new SRv6 Endpoint Behaviors. There were good reviews in SPRING WG and several people from 6MAN WG expressed support. Note that the SPRING WG chairs have ensured to involve the 6MAN WG throughout the process. [25].

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.

The document has no MIB, YANG model, media type, or URI type.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

N/A. No YANG model.

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

N/A.

## Document Shepherd Checks

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

Yes.

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?
   
There have been multiple directorate reviews (SECDIR, INTDIR, OPSDIR, RTGDIR). The directorate reviews have not found any issue.

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 is requested and indicated in the title page header. This is appropriate for a specification of data plane processing needing interoperability between the different nodes.

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 have been two IPR calls throughout the progression of this draft (WG adoption and WG Last Call). All authors have replied on the mailing list. There have been 7 IPR disclosures, all tracked in the Datatracker.

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, they have shown their willingness to be listed.
The number of authors and editors on the front page is five.

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.)

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 normative references are freely 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?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

I confirm the points.
The IANA section is new codepoint allocations within the SRv6 Endpoint Behaviors registry.
The new codepoints belong to the behaviors defined in this draft. There is no inconsistency between the body of the document and the IANA section.
   
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.

None.

[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/

[21] https://mailarchive.ietf.org/arch/msg/spring/Dj-HjzjvFr8VmgK6H1r1FMbVLMY/
[22] https://mailarchive.ietf.org/arch/msg/ipv6/OX6z1uWHkkDUJcdlrzxMqniYt7A/
[23] https://eantc.de/wp-content/uploads/2023/04/EANTC-InteropTest2023-TestReport.pdf
[24] https://eantc.de/wp-content/uploads/2023/12/EANTC-MPLSSDNInterop2024-TestReport-v1.3.pdf
[25] https://mailarchive.ietf.org/arch/msg/ipv6/hOM8JezKqlxnksz0PdntGH2xO8o/

This is the Shepherd writeup from Pablo Camarillo for draft-ietf-spring-srv6-srh-compression.

## 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?

There is broad agreement for publishing this document.

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

While there was widespread support for this document, a few individuals felt there were unaddressed problems with the draft. There have been threats of appeal [21] based on the relationship of the SRv6 end points behaviors  specified in this document and those implied by certain sections of RFC 8200 and the SPRING charter restrictions against making changes to underlying data planes. The spring chairs subsequently consulted with 6man chairs on the topic and the response from the 6man chairs can be found at [22].

However, the technology described in this document has already been broadly deployed in production networks by multiple early adopters, and the deployments have been detailed at the srv6ops BoF in Brisbane, none of which have raised any such concern on the list.

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.)

Yes, as indicated in previous bullet and the responsible ADs are well aware of the appeal threat.

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)?

Yes, there are several existing and deployed implementations that are listed in Section 10 of the draft. These include routing vendors (Arrcus, Centec, Ciena, Cisco, Huawei, Juniper, Nokia, Ruijie Networks, ZTE), merchant silicon vendors (Broadcom, Marvell), and opensource implementations (Linux Kernel, FD.io VPP, SONiC/SAI, ONOS, P4). There have been various industry interoperability events over the past years with multiple vendors and implementations such as the ones detailed in [23][24]. 

## 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 describes new SRv6 Endpoint Behaviors. There were good reviews in SPRING WG and several people from 6MAN WG expressed support. Note that the SPRING WG chairs have ensured to involve the 6MAN WG throughout the process. [25].

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.

The document has no MIB, YANG model, media type, or URI type.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

N/A. No YANG model.

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

N/A.

## Document Shepherd Checks

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

Yes.

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?
   
There have been multiple directorate reviews (SECDIR, INTDIR, OPSDIR, RTGDIR). The directorate reviews have not found any issue.

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 is requested and indicated in the title page header. This is appropriate for a specification of data plane processing needing interoperability between the different nodes.

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 have been two IPR calls throughout the progression of this draft (WG adoption and WG Last Call). All authors have replied on the mailing list. There have been 7 IPR disclosures, all tracked in the Datatracker.

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, they have shown their willingness to be listed.
The number of authors and editors on the front page is five.

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.)

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 normative references are freely 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?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

I confirm the points.
The IANA section is new codepoint allocations within the SRv6 Endpoint Behaviors registry.
The new codepoints belong to the behaviors defined in this draft. There is no inconsistency between the body of the document and the IANA section.
   
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.

None.

[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/

[21] https://mailarchive.ietf.org/arch/msg/spring/Dj-HjzjvFr8VmgK6H1r1FMbVLMY/
[22] https://mailarchive.ietf.org/arch/msg/ipv6/OX6z1uWHkkDUJcdlrzxMqniYt7A/
[23] https://eantc.de/wp-content/uploads/2023/04/EANTC-InteropTest2023-TestReport.pdf
[24] https://eantc.de/wp-content/uploads/2023/12/EANTC-MPLSSDNInterop2024-TestReport-v1.3.pdf
[25] https://mailarchive.ietf.org/arch/msg/ipv6/hOM8JezKqlxnksz0PdntGH2xO8o/

This starts the WG last call for this document.  Please comment with support or opposition, and explanation of your perspective.  Silence is not consent, and just "support" or "oppose" is not helpful.  This call will run through the end of Feb 4, 2024.
Yours, Joel Halpern - responsible Spring co-chair

PS: I would appreciate a document shepherd from the WG for the bnext step.  Email me if you are willing.

Request for posting confirmation emailed to previous authors: Aihua Liu , Bruno Decraene , Cheng Li , Clarence Filsfils , Dan Voyer , Dezhong Cai , Francois Clad , Jim Guichard , Robert Raszuk , Shay Zadok , Weiqiang Cheng , Zhenbin Li , spring-chairs@ietf.org