Signaling Entropy Label Capability and Entropy Readable Label Depth Using IS-IS
draft-ietf-isis-mpls-elc-13

[Ballot comment]
Thank you for educating me, and addressing the minor residual remains of my discuss point
that were left after that, as well as my comments.

[Ballot comment]
I had the weirdest sense of deja vu when reviewing this document -- enough that I went back to see if it had been on a previous telechat -- and then realized that it was the IS-IS version of draft-ietf-ospf-mpls-elc :-)

[Ballot discuss]
As for other reviewers, many of my comments duplicate those for the OSPF
document; I expect that the analogous responses apply and am fine if
they only appear for one document's review.

Here, the question I have about normative language applies to the text
in Section 3:

  When a router propagates a prefix between ISIS levels ([RFC5302], it
  MUST preserve the ELC signaling for this prefix.

The scenario in question is analogous to the OSPF cross-area case: is
the router propagating the prefix between ISIS levels required to
implement this document; is preservation of the flag value a new
requirement from this document vs. a preexisting property; and is this
document trying to make normative requirements of devices that don't
implement this document?

Likewise, the ASBR case for cross-protocol redistribution seems to
rather inherently require understanding the semantics of the flags being
translated.

[Ballot comment]
Section 1

Should we add a sentence at the end of the last paragraph about how
"this document defines a mechanism to signal the ERLD using IS-IS"?

  In cases where LSPs are used (e.g., SR-MPLS [RFC8660], it would be

side note(?): I don't know that SR-MPLS is so popular so as to be
privileged as the only example given for LSP usage.  If we instead
talked about using IGPs to signal labels, this selection would seem less
surprising to me.

Section 3

  unless all of its interfaces are capable of processing ELs.  If a
  router supports ELs on all of its interfaces, it SHOULD set the ELC
  for every local host prefix it advertises in IS-IS.

Do we want to say anything about (not) advertising the ELC for other
prefixes?

Section 4

I agree with Roman's comment about code 2 vs TBD2.

  ERLD in the range between 0 to 255.  The scope of the advertisement
  depends on the application.  If a router has multiple interfaces with

Just to check: w.r.t. "scope", both this document and the OSPF one only
define usage of this MSD type at the scope of a single node, right?  (I
don't see a particular reason to preclude using it at a different
scope.)

Section 6

      - Bit 3 in the Bit Values for Prefix Attribute Flags Sub-TLV
      registry has been assigned to the ELC Flag.  IANA is asked to

Is there an "IS-IS" in the name of this registry?

Section 7

Should we say anything about considerations for redistributing ELC/ERLD
information at the ASBR with respect to exposing "internal information"
to external parties?

  This document specifies the ability to advertise additional node
  capabilities using IS-IS and BGP-LS.  As such, the security
  considerations as described in [RFC7981], [RFC7752], [RFC7794],
  [RFC8491], [RFC8662], [I-D.ietf-idr-bgp-ls-segment-routing-ext] and

RFC 8662's security considerations have a pretty hard dependency on RFC
6790's security considerations; it might be worth mentioning 6790
directly in this list as well.

  [I-D.ietf-idr-bgp-ls-segment-routing-msd] are applicable to this
  document.

Could we also have a brief note that the normal IS-IS authentication
mechanisms serve to protect the ELC/ERLD information?

  Incorrectly setting the E flag during origination, propagation or
  redistribution may lead to black-holing of the traffic on the egress
  node.

This is what happens when the E flag should not be set but is
erroneously set.  Should we also say what happens if we should set the E
flag but erroneously clear it (e.g., that poor or no load-balancing may
occur)?

Section 8

I do see the note in the shepherd writeup about the sixth author (thank
you!); if we're already breaking through the 5-author limit, did we
consider making those who "should be considered as co-authors" listed as
co-authors?

Section 10.1

Should we reference RFC 7981 from Section 4 as well?  Right now we seem
to only use it for the security considerations, which is not necessarily
enough to qualify it as a normative reference.

[Ballot comment]
Two editorial nits:
** Section 3.  Editorial.  s/ When a router propagates a prefix between ISIS levels ([RFC5302],/When a router propagates a prefix between ISIS levels [RFC5302],/

** Section 4.  Figure 2.  The text says that “A MSD-Type Code 2 has been assigned by IANA”, but Figure 2 says “MSD-Type=TBD2”.

[Ballot comment]
Hi,

Same comment as for equivalent OSPF draft.

Is there any associated YANG module required to manage this protocol enhancement?  If so, is that already being worked or, or planned work for the WG?

Regards,
Rob

[Ballot comment]
Thank you for the work put into this document. The document is easy to read.

Like other ADs, I wonder why the IS-IS and OSPF are separate documents.

Please find below one NIT.

I hope that this helps to improve the document,

Regards,

-éric

== NIT ==

-- section 4 --
The "one" is ambiguous in "the router MUST advertise the smallest one." even if we can guess that it is not "interface" ;-)

[Ballot comment]
Just a few editorial nits:

— Section 1 —

  In cases where LSPs are used (e.g., SR-MPLS [RFC8660], it would be

Nit: you need a closing parenthesis instead of the second comma.

  This capability, referred to as Entropy Readable Label
  Depth (ERLD) as defined in [RFC8662] may be used by ingress LSRs to

Nit: this needs a comma after the citation.

— Section 3 —

  originator.  Similarly in a multi-domain network, the identity of the

Nit: “Similarly” needs a comma after it.

  When a router propagates a prefix between ISIS levels ([RFC5302], it

Nit: remove the open parenthesis.

  an Autonomous System Boundary Router (ASBR) is outside of the scope

Nit: the abbreviation “ASBR” is not used elsewhere in the document, so there’s no reason to include it.

— Section 4 —

  A new MSD-type [RFC8491], called ERLD-MSD is defined to advertise the

Nit: 8491 capitalizes the “T” in “MSD-Type”.
Nit: there needs to be a comma after “ERLD-MSD”.

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

The IANA Functions Operator has completed its review of draft-ietf-isis-mpls-elc-11. If any part of this review is inaccurate, please let us know.

The IANA Functions Operator understands that, upon approval of this document, there are two actions which we must complete.

First, in the Bit Values for Prefix Attribute Flags Sub-TLV registry on the IS-IS TLV Codepoints registry page located at:

https://www.iana.org/assignments/isis-tlv-codepoints/

the existing, early registration for:

Bit #: 3
Name: E-bit

will be made permanent with its name changed to ELC Flag and its reference changed to [ RFC-to-be ].

Bit #: 3
Name: ELC Flag (E-flag)
Reference: [ RFC-to-be ]

Second, in the IGP MSD-Types registry on the Interior Gateway Protocol (IGP) Parameters registry page located at:

https://www.iana.org/assignments/igp-parameters/

the existing, early registration for:

Value: 3
Name: Entropy Label Readable Depth (ERLD)

will be made permanent with its name changed to ERLD-MSD and its reference changed to [ RFC-to-be ].

Value: 3
Name: ERLD-MSD
Reference: [ RFC-to-be ]

The IANA Functions Operator understands that these are the only actions 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.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2020-05-05):

From: The IESG
To: IETF-Announce
CC: aretana.ietf@gmail.com, lsr-chairs@ietf.org, draft-ietf-isis-mpls-elc@ietf.org, Acee Lindem , lsr@ietf.org, acee@cisco.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Signaling Entropy Label Capability and Entropy Readable Label Depth Using IS-IS) to Proposed Standard


The IESG has received a request from the Link State Routing WG (lsr) to
consider the following document: - 'Signaling Entropy Label Capability and
Entropy Readable Label Depth
  Using IS-IS'
  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 2020-05-05. 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


  Multiprotocol Label Switching (MPLS) has defined a mechanism to load-
  balance traffic flows using Entropy Labels (EL).  An ingress Label
  Switching Router (LSR) cannot insert ELs for packets going into a
  given Label Switched Path (LSP) unless an egress LSR has indicated
  via signaling that it has the capability to process ELs, referred to
  as the Entropy Label Capability (ELC), on that tunnel.  In addition,
  it would be useful for ingress LSRs to know each LSR's capability for
  reading the maximum label stack depth and performing EL-based load-
  balancing, referred to as Entropy Readable Label Depth (ERLD).  This
  document defines a mechanism to signal these two capabilities using
  IS-IS.




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

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-isis-mpls-elc/ballot/

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

  https://datatracker.ietf.org/ipr/2311/

The authors have addressed all my comments for this document.  I am now waiting for draft-ietf-ospf-mpls-elc to catch up so we can progress both of them together through IETF LC and beyond.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
    Standard, Informational, Experimental, or Historic)? Why is this the
    proper type of RFC? Is this type of RFC indicated in the title page
    header?

      A Standards Track RFC is being requested and is indicated in the
      title page header.

(2) The IESG approval announcement includes a Document Announcement
    Write-Up.  Please provide such a Document Announcement Write-Up.
    Recent examples can be found in the "Action" announcements for
    approved documents. The approval announcement contains the following
    sections:

Technical Summary:

      This document specifies extensions to IS-IS Prefix attribute
      advertisement to indicate whether or not a prefix is Entropy
      Label Capable (ELC), i.e., eligible for entropy label processing.
      Additionally, a new MSD type is defined to advertise the Entropy
      Readable Label Depth (ERLD). The ELRD will be advertised using the
      existing Maximum SID Depth (MSD) encodings defined in RFC 8476.
      Finally, the mapping of these extensions to existing BGP-LS encodigs
      is specified.

Working Group Summary:
   
    The draft went through multiple iterations due to a change in
    requirements. Originally, the ELC was a node-level attribute. However,
    a Service Provider (SP) use case relating to external prefix
    advertisement required per-prefix advertisement. A second change was
    required when the BGP-LS encodings specification was incorporated into
    the draft. Since this incorporation obviated the BGP-LS draft, a sixth
    author was added.
   

Document Quality:

      This document has been a WG document over 4 years. While it has gone
      through several iterations, we are now confident that it is ready
      for publication. There have also been several side meetings.

Personnel:

      Acee Lindem is the Document Shepherd.
      Alvaro Retana is the Responsible Area Director.

(3) Briefly describe the review of this document that was performed by
    the Document Shepherd. If this version of the document is not ready
    for publication, please explain why the document is being forwarded
    to the IESG.

    The document shepherd has reviewed each revision of the document
    and followed the discussion on the LSR  mailing list. The document
    shepherd fully believes that the document is ready for publication.


(4) Does the document Shepherd have any concerns about the depth or
    breadth of the reviews that have been performed?

      No.

(5) Do portions of the document need review from a particular or from
    broader perspective, e.g., security, operational complexity, AAA,
    DNS, DHCP, XML, or internationalization? If so, describe the review
    that took place.

      No.

(6) Describe any specific concerns or issues that the Document Shepherd
    has with this document that the Responsible Area Director and/or
    the IESG should be aware of? For example, perhaps he or she is
    uncomfortable with certain parts of the document, or has concerns
    whether there really is a need for it. In any event, if the WG has
    discussed those issues and has indicated that it still wishes to
    advance the document, detail those concerns here.

      None.

(7) Has each author confirmed that any and all appropriate IPR
    disclosures required for full conformance with the provisions of BCP
    78 and BCP 79 have already been filed. If not, explain why?

    Yes.

(8) Has an IPR disclosure been filed that references this document? If
    so, summarize any WG discussion and conclusion regarding the IPR
    disclosures.

      Yes - there is one IPR.

https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-ietf-isis-mpls-elc

(9) How solid is the WG consensus behind this document? Does it
    represent the strong concurrence of a few individuals, with others
    being silent, or does the WG as a whole understand and agree with it?

      There is consensus from the WG and others outside the WG that
      this document can progress.

(10) Has anyone threatened an appeal or otherwise indicated extreme
    discontent?  If so, please summarise 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.

(11) Identify any ID nits the Document Shepherd has found in this
    document.  (See http://www.ietf.org/tools/idnits/ and the
    Internet-Drafts Checklist).  Boilerplate checks are not enough;
    this check needs to be thorough.

      Nits are all resolved other than some of date references. I will
      ask the authors to update.

(12) Describe how the document meets any required formal review
    criteria, such as the MIB Doctor, media type, and URI type reviews.

      Not applicable.

(13) Have all references within this document been identified as either
    normative or informative?

      Yes.

(14) Are there normative references to documents that are not ready for
    advancement or are otherwise in an unclear state? If such
    normative references exist, what is the plan for their completion?
 
      No. Publication for "IS-IS ELC" will be requested concurrently.

(15) Are there downward normative references references (see RFC 3967)?
    If so, list these downward references to support the Area Director
    in the Last Call procedure.

      No.

(16) Will publication of this document change the status of any existing
    RFCs?  Are those RFCs listed on the title page header, listed in
    the abstract, and discussed in the introduction? If the RFCs are
    not listed in the Abstract and Introduction, explain why, and point
    to the part of the document where the relationship of this document
    to the other RFCs is discussed. If this information is not in the
    document, explain why the WG considers it unnecessary.

      No.

(17) 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 protocol extensions that the
    document makes are associated with the appropriate reservations in
    IANA registries. Confirm that any referenced IANA registries have
    been clearly identified. Confirm that newly created IANA registries
    include a detailed specification of the initial contents for the
    registry, that allocations procedures for future registrations are
    defined, and a reasonable name for the new registry has been
    suggested (see RFC 5226).

    The IANA considerations section is clear and early allocations have
    been made for the requested code points.

  https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#prefix-attribute-flags
  https://www.iana.org/assignments/igp-parameters/igp-parameters.xhtml#igp-msd-types
 
(18) List any new IANA registries that require Expert Review for future
    allocations. Provide any public guidance that the IESG would find
    useful in selecting the IANA Experts for these new registries.

    No new registries are required.

(19) Describe reviews and automated checks performed by the Document
    Shepherd to validate sections of the document written in a formal
    language, such as XML code, BNF rules, MIB definitions, etc.

      Not applicable.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
    Standard, Informational, Experimental, or Historic)? Why is this the
    proper type of RFC? Is this type of RFC indicated in the title page
    header?

      A Standards Track RFC is being requested and is indicated in the
      title page header.

(2) The IESG approval announcement includes a Document Announcement
    Write-Up.  Please provide such a Document Announcement Write-Up.
    Recent examples can be found in the "Action" announcements for
    approved documents. The approval announcement contains the following
    sections:

Technical Summary:

      This document specifies extensions to OSPFv2/OSPFv3 Prefix
      advertisement to indicate whether or not a prefix is Entropy
      Label Capable (ELC), i.e., eligible for entropy label processing.
      Additionally, a new MSD type is defined to advertise the Entropy
      Readable Label Depth (ERLD). The ELRD will be advertised using the
      existing Maximum SID Depth (MSD) encodings defined in RFC 8476.
      Finally, the mapping of these extensions to existing BGP-LS encodigs
      is specified.

Working Group Summary:
   
    The draft went through multiple iterations due to a change in
    requirements. Originally, the ELC was a node-level attribute. However,
    a Service Provider (SP) use case relating to external prefix
    advertisement required per-prefix advertisement. A second change was
    required when the BGP-LS encodings specification was incorporated into
    the draft. Since this incorporation obviated the BGP-LS draft, a sixth
    author was added.
   

Document Quality:

      This document has been a WG document over 4 years. While it has gone
      through several iterations, we are now confident that it is ready
      for publication. There have also been several side meetings

Personnel:

      Acee Lindem is the Document Shepherd.
      Alvaro Retana is the Responsible Area Director.

(3) Briefly describe the review of this document that was performed by
    the Document Shepherd. If this version of the document is not ready
    for publication, please explain why the document is being forwarded
    to the IESG.

    The document shepherd has reviewed each revision of the document
    and followed the discussion on the OSPF mailing list. Additionally,
    the document shepherd provided editorial updates for consistency
    with other OSPF RFCs. The document shepherd fully believes that the
    document is ready for publication.


(4) Does the document Shepherd have any concerns about the depth or
    breadth of the reviews that have been performed?

      No.

(5) Do portions of the document need review from a particular or from
    broader perspective, e.g., security, operational complexity, AAA,
    DNS, DHCP, XML, or internationalization? If so, describe the review
    that took place.

      No.

(6) Describe any specific concerns or issues that the Document Shepherd
    has with this document that the Responsible Area Director and/or
    the IESG should be aware of? For example, perhaps he or she is
    uncomfortable with certain parts of the document, or has concerns
    whether there really is a need for it. In any event, if the WG has
    discussed those issues and has indicated that it still wishes to
    advance the document, detail those concerns here.

      None.

(7) Has each author confirmed that any and all appropriate IPR
    disclosures required for full conformance with the provisions of BCP
    78 and BCP 79 have already been filed. If not, explain why?

    Yes.

(8) Has an IPR disclosure been filed that references this document? If
    so, summarize any WG discussion and conclusion regarding the IPR
    disclosures.

      No - but one is expected from Huawei given the corresponding
      IS-IS draft has an IPR disclosure.

(9) How solid is the WG consensus behind this document? Does it
    represent the strong concurrence of a few individuals, with others
    being silent, or does the WG as a whole understand and agree with it?

      There is consensus from the WG and others outside the WG that
      this document can progress.

(10) Has anyone threatened an appeal or otherwise indicated extreme
    discontent?  If so, please summarise 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.

(11) Identify any ID nits the Document Shepherd has found in this
    document.  (See http://www.ietf.org/tools/idnits/ and the
    Internet-Drafts Checklist).  Boilerplate checks are not enough;
    this check needs to be thorough.

      Nits are all resolved - other than some confusion about the
      RFC 8174 reference.

(12) Describe how the document meets any required formal review
    criteria, such as the MIB Doctor, media type, and URI type reviews.

      Not applicable.

(13) Have all references within this document been identified as either
    normative or informative?

      Yes.

(14) Are there normative references to documents that are not ready for
    advancement or are otherwise in an unclear state? If such
    normative references exist, what is the plan for their completion?
 
      No. Publication for "IS-IS ELC" will be requested concurrently.

(15) Are there downward normative references references (see RFC 3967)?
    If so, list these downward references to support the Area Director
    in the Last Call procedure.

      No.

(16) Will publication of this document change the status of any existing
    RFCs?  Are those RFCs listed on the title page header, listed in
    the abstract, and discussed in the introduction? If the RFCs are
    not listed in the Abstract and Introduction, explain why, and point
    to the part of the document where the relationship of this document
    to the other RFCs is discussed. If this information is not in the
    document, explain why the WG considers it unnecessary.

      No.

(17) 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 protocol extensions that the
    document makes are associated with the appropriate reservations in
    IANA registries. Confirm that any referenced IANA registries have
    been clearly identified. Confirm that newly created IANA registries
    include a detailed specification of the initial contents for the
    registry, that allocations procedures for future registrations are
    defined, and a reasonable name for the new registry has been
    suggested (see RFC 5226).

    The IANA considerations section is clear and early allocations have
    been made for the requested code points.
 
    https://www.iana.org/assignments/ospfv2-parameters/ospfv2-parameters.xhtml#extended-prefix-tlv-flags
    https://www.iana.org/assignments/ospfv3-parameters/ospfv3-parameters.xhtml#ospfv3-parameters-4

(18) List any new IANA registries that require Expert Review for future
    allocations. Provide any public guidance that the IESG would find
    useful in selecting the IANA Experts for these new registries.

    No new registries are required.

(19) Describe reviews and automated checks performed by the Document
    Shepherd to validate sections of the document written in a formal
    language, such as XML code, BNF rules, MIB definitions, etc.

      Not applicable.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
    Standard, Informational, Experimental, or Historic)? Why is this the
    proper type of RFC? Is this type of RFC indicated in the title page
    header?

      A Standards Track RFC is being requested and is indicated in the
      title page header.

(2) The IESG approval announcement includes a Document Announcement
    Write-Up.  Please provide such a Document Announcement Write-Up.
    Recent examples can be found in the "Action" announcements for
    approved documents. The approval announcement contains the following
    sections:

Technical Summary:

      This document specifies extensions to OSPFv2/OSPFv3 Prefix
      advertisement to indicate whether or not a prefix is Entropy
      Label Capable (ELC), i.e., eligible for entropy label processing.
      Additionally, a new MSD type is defined to advertise the Entropy
      Readable Label Depth (ERLD). The ELRD will be advertised using the
      existing Maximum SID Depth (MSD) encodings defined in RFC 8476.
      Finally, the mapping of these extensions to existing BGP-LS encodigs
      is specified.

Working Group Summary:
   
    The draft went through multiple iterations due to a change in
    requirements. Originally, the ELC was a node-level attribute. However,
    a Service Provider (SP) use case relating to external prefix
    advertisement required per-prefix advertisement. A second change was
    required when the BGP-LS encodings specification was incorporated into
    the draft. Since this incorporation obviated the BGP-LS draft, a sixth
    author was added.
   

Document Quality:

      This document has been a WG document over 4 years. While it has gone
      through several iterations, we are now confident that it is ready
      for publication. There have also been several side meetings

Personnel:

      Acee Lindem is the Document Shepherd.
      Alvaro Retana is the Responsible Area Director.

(3) Briefly describe the review of this document that was performed by
    the Document Shepherd. If this version of the document is not ready
    for publication, please explain why the document is being forwarded
    to the IESG.

    The document shepherd has reviewed each revision of the document
    and followed the discussion on the OSPF mailing list. Additionally,
    the document shepherd provided editorial updates for consistency
    with other OSPF RFCs. The document shepherd fully believes that the
    document is ready for publication.


(4) Does the document Shepherd have any concerns about the depth or
    breadth of the reviews that have been performed?

      No.

(5) Do portions of the document need review from a particular or from
    broader perspective, e.g., security, operational complexity, AAA,
    DNS, DHCP, XML, or internationalization? If so, describe the review
    that took place.

      No.

(6) Describe any specific concerns or issues that the Document Shepherd
    has with this document that the Responsible Area Director and/or
    the IESG should be aware of? For example, perhaps he or she is
    uncomfortable with certain parts of the document, or has concerns
    whether there really is a need for it. In any event, if the WG has
    discussed those issues and has indicated that it still wishes to
    advance the document, detail those concerns here.

      None.

(7) Has each author confirmed that any and all appropriate IPR
    disclosures required for full conformance with the provisions of BCP
    78 and BCP 79 have already been filed. If not, explain why?

    Yes.

(8) Has an IPR disclosure been filed that references this document? If
    so, summarize any WG discussion and conclusion regarding the IPR
    disclosures.

      No - but one is expected from Huawei given the corresponding
      IS-IS draft has an IPR disclosure.

(9) How solid is the WG consensus behind this document? Does it
    represent the strong concurrence of a few individuals, with others
    being silent, or does the WG as a whole understand and agree with it?

      There is consensus from the WG and others outside the WG that
      this document can progress.

(10) Has anyone threatened an appeal or otherwise indicated extreme
    discontent?  If so, please summarise 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.

(11) Identify any ID nits the Document Shepherd has found in this
    document.  (See http://www.ietf.org/tools/idnits/ and the
    Internet-Drafts Checklist).  Boilerplate checks are not enough;
    this check needs to be thorough.

      Nits are all resolved - other than some confusion about the
      RFC 8174 reference.

(12) Describe how the document meets any required formal review
    criteria, such as the MIB Doctor, media type, and URI type reviews.

      Not applicable.

(13) Have all references within this document been identified as either
    normative or informative?

      Yes.

(14) Are there normative references to documents that are not ready for
    advancement or are otherwise in an unclear state? If such
    normative references exist, what is the plan for their completion?
 
      No. Publication for "IS-IS ELC" will be requested concurrently.

(15) Are there downward normative references references (see RFC 3967)?
    If so, list these downward references to support the Area Director
    in the Last Call procedure.

      No.

(16) Will publication of this document change the status of any existing
    RFCs?  Are those RFCs listed on the title page header, listed in
    the abstract, and discussed in the introduction? If the RFCs are
    not listed in the Abstract and Introduction, explain why, and point
    to the part of the document where the relationship of this document
    to the other RFCs is discussed. If this information is not in the
    document, explain why the WG considers it unnecessary.

      No.

(17) 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 protocol extensions that the
    document makes are associated with the appropriate reservations in
    IANA registries. Confirm that any referenced IANA registries have
    been clearly identified. Confirm that newly created IANA registries
    include a detailed specification of the initial contents for the
    registry, that allocations procedures for future registrations are
    defined, and a reasonable name for the new registry has been
    suggested (see RFC 5226).

    The IANA considerations section is clear and early allocations have
    been made for the requested code points.
 
    https://www.iana.org/assignments/ospfv2-parameters/ospfv2-parameters.xhtml#extended-prefix-tlv-flags
    https://www.iana.org/assignments/ospfv3-parameters/ospfv3-parameters.xhtml#ospfv3-parameters-4

(18) List any new IANA registries that require Expert Review for future
    allocations. Provide any public guidance that the IESG would find
    useful in selecting the IANA Experts for these new registries.

    No new registries are required.

(19) Describe reviews and automated checks performed by the Document
    Shepherd to validate sections of the document written in a formal
    language, such as XML code, BNF rules, MIB definitions, etc.

      Not applicable.