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. 

Document Quality:

There are existing implementations of the document.


 Document Shepherd: Acee Lindem
 Responsible AD: Alvaro Retana

(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 other than one reference. 

(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 procedure.


(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 stage.

(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.

Both the "IS-IS Sub-Sub-TLVs for Flexible Algorithm Definition Sub-TLV" and "OSPF Flexible Algorithm Definition TLV sub-TLV" 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 RFC8342?


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