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Shepherd writeup

(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 Proposed Standard.

Yes - Proposed Standard. This document level is required for protocol extension
and interoperability.

(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 provides extensions to OSPF and IS-IS to use different algorithms
to compute the paths to different prefixes. Since not all nodes in the
computation domain (i.e., an OSPF or IS-IS area) may support every algorithm SR
or SRv6 is used to between nodes.

Working Group Summary:

The was good collaboration on the document. The only controversy came at the
tail end of the process when there was some discussion as to whether RFC 8919
/RFC 8920 Application Specific Link Attributes (ASLAs) should be used for
alternate metrics or whether the advetisements used for RSVP TE could also be
used. The consensus was to allow RFC 8919/RFC 8920 attributes to be required.

Discussion and implementation uncovered that some additional OSPF encodings
were needed for ASBR routes. This resulted in updates and second WG Last Call.
During the second WG Last Call, the discussion of the application specific
attributes resulted in Errata to both RFC 8919 and 8920:

Document Quality:

The document is of high quality with vendors and operators reviewing.
There are existing implementations of the document and three other WG documents
that augment the base document:


 Document Shepherd: Acee Lindem
 Responsible AD: John Scudder

(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 reviewed the document multiple times and provided
editorial and consistency comments.  The shepherd's review is acknowledged in
the draft.

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


(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.


(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.


(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?


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


(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 strong consensus behind the document and it is considered a bulding
block for other functionality including network slicing. Several network
operators have reviewed and commented on the draft.

(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.)


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

The nits have been all fixed.

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

None of these are applicable. The YANG model augmentations will be added in a
separate draft.

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


(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?

Yes - the OSPFv3 SRv6 enhancements is behind this document and will block
publication until published. This document will be advanced soon after the
IS-IS SRv6 extensions complete WG last call.

(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


(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.


(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 8126).

This document has IANA registrations. However, the document has gone through
the early allocation process and has going through extensive reviews by
designated experts and the Working Group. The only comment that came up was
whether 1/2 of the IGP algorithm space should be devoted to flexible
algorithms. As document shepherd, I have reviewed the IANA requirements at each

(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.

The "IS-IS Sub-Sub-TLVs for Flexible Algorithm Definition Sub-TLV", "OSPF
Flexible Algorithm Definition TLV sub-TLV", "OSPFv2 Extended Inter-Area ASBR
TLVs", "OSPFv2 Extended Inter-Area ASBR Sub-TLVs", and "OSPF Flex-Algorithm
Prefix Metric Bits" registries are created by this document. The allocation
policy is designated as Expert Review. Designated experts should be drawn from
the WG membership and will most likely be different for IS-IS and OSPF.

(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, YANG modules, etc.


(20) If the document contains a YANG module, has 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