Shepherd writeup
draft-ietf-lsvr-bgp-spf-11

As required by RFC 4858, this is the current template for the Document 
Shepherd Write-Up. Changes are expected over time. 

This version is dated 1 November 2019.

(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? 

Proposed Standard

(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:

Many Massively Scaled Data Centers (MSDCs) have converged on simplified layer 3 routing.  Furthermore, requirements for operational simplicity have led many of these MSDCs to converge on BGP as their single routing protocol for both their fabric routing and their Data Center Interconnect (DCI) routing.  This draft describes a solution which leverages BGP Link-State distribution and the Shortest Path First (SPF) algorithm like Internal Gateway Protocols (IGPs) such as OSPF.
How is this done?
This document augments BGP-LS [RFC7752] by replacing its use of the existing Decision Process.  Rather than reusing the BGP-LS SAFI, the BGP-LS-SPF SAFI is introduced to insure backward compatibility.  The BGP Phase 1 and 2 decision functions of the Decision Process are replaced with the Shortest Path First (SPF) algorithm also known as the Dijkstra algorithm.  The BGP Phase 3 decision function is also simplified since it is no longer dependent on the previous phases.  This solution avails the benefits of both BGP and SPF-based IGPs.  These include TCP based flow-control, no periodic link-state refresh, and completely incremental NLRI advertisement.  These advantages can reduce the overhead in MSDCs where there is a high degree of Equal Cost Multi-Path (ECMPs) and the topology is very stable.  Additionally, using an SPF-based computation can support fast convergence and the computation of Loop-Free Alternatives (LFAs) [RFC5286] in the event of link failures.  Furthermore, a BGP based solution lends itself to multiple peering models including those incorporating route-reflectors [RFC4456] or controllers.


Working Group Summary:

The LSVR WG enjoyed a turbulent startup period. The IDR WG and LSR WG handle routing for interdomain and intradomain. LSVR is using foundational technology from both BGP and SPF based routing protocols. The IETF face-2-face meetings included IDR and LSR WG participants to voice the depths of their experience and technology authority. This contributed to develop and provide feedback upon the draft draft-ietf-lsvr-bgp-spf.
The draft went through few iterations of volunteer review cycles that have been tracked within the WG email list. In addition, the draft went through early directorate reviews. The OPSDIR review executed upon an early version went well (state: READY), while RTGDIR (state: HAS ISSUES) review caused additional technology discussion resulting in the draft to be updated upon the feedback provided (See: https://mailarchive.ietf.org/arch/msg/lsvr/9z_KGdwqHlmhnzD5HWrarmlSroU/ ).
In addition, the LSVR chairs asked expert reviewers to provide feedback on the document, and those have been included and discussed on the WG mailing list.

The document went through two cycles of WGLC to finally result into current documentation status:

WGLC#1 on draft-ietf-lsvr-bgp-spf-03
	Date: 3 December 208 to 17 December 2018
	Reference: https://mailarchive.ietf.org/arch/msg/lsvr/-7zKGZ-PIXCNnpmxfEjHVSEUqXc/
WGLC#2 on draft-ietf-lsvr-bgp-spf-05
	Date: 23 September 2019 – 7 October 2019
	Reference: https://mailarchive.ietf.org/arch/msg/lsvr/A066U6av_6--WDo7BRFswOtMea4/


Document Quality:

Arrcus (March 2019): https://mailarchive.ietf.org/arch/msg/lsvr/OPB6pO_aKU8ty0A3PspSBTQyqXg/
FRR (Plans to support): https://mailarchive.ietf.org/arch/msg/lsvr/wCXxSObjSy0Vih5SRS2PPbfacz8/


Personnel:

Document Shepherd: Gunter Van de Velde
Responsible Area Director: 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. 

Document went through few iterations of review. This 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? 

Review cycle was contributed by experts, and working implementation exists.

(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. 

No specific concerns

(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, all authors responded on the list about IPR ( there is no IPR awareness.
No other WG member responded with any IPRdisclosure when WGLC was initiated.

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

No

(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? 

Document went through 2 WGLCs
Document has been presented at each IETF LSVr WG meeting to inform about updates and changes
Feedback has been promptly incorporated by the document authors

(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 threatening for an appeal on this document

(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. 

When going trough the idnit check 12 missing document references were found.
However, those references for proposed standard are referenced in the informational section of the draft
One informational draft [Missing Reference: 'I-D.ietf-lsvr-applicability'] is progressed in parallel with this draft and describe how to apply the technology in a network environment.

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

No such components included.
YANG is to progressed in a separate LSVR WG document

(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? 

Yes, the draft [ietf-idr-bgpls-segment-routing-epe]

(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 8126). 

IANA section document the request of IANA code points
no indications for code-point have been provided

(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. 

Request IANA to assign the BGP-LS/BGP-LS-SPF (AFI 16388 / SAFI TBD1) as described in [RFC4760].
From safi range [1-63] standards action: https://www.iana.org/assignments/safi-namespace/safi-namespace.xhtml
When this registry is modified, the YANG module [iana-routing-types] must be updated as defined in [RFC8294].

This draft also defines five attribute TLVs for BGP-LS NLRI from the "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs" Registry
Expert review suggested by IANA:

https://www.iana.org/assignments/bgp-ls-parameters/bgp-ls-parameters.xhtml
The draft request IANA to assign types for the

  * SPF capability TLV
  * Sequence Number TLV
  * IPv4 Link Prefix-Length TLV
  * IPv6 Link Prefix-Length TLV
  * SPF Status TLV.

(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.

YANG definition is to be defined in a seperate LSVR WG document.
This work has not been initiated by the LSVR WG.

(20) If the document contains a YANG module, has the module been checked with any of the recommended validation tools (https://trac.ietf.org/trac/ops/wiki/yang-review-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?

No YANG module included
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