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Shepherd writeup

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 15 February 2022.

(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:

1. 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
intra-fabric routing, inter-fabric routing and 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.

2. Review and Consensus
The LSVR WG enjoyed a turbulent startup period. The IDR WG and LSR WG handle
routing for interdomain and intradomain, while LSVR is using foundational
technology of both BGP and SPF based routing protocols. The IETF face-2-face
meetings avoided timing overlap to allow 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 original (2019) 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: ).  The
document was re-reviewed in June 2021 with some additional concerns for
consideration before publication.  These issues identified in the RTGDIR were
addressed in the most recent version of publication. The document went through
a third WGLC in 2021 (May – June) and completed on June 17, 2021.

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 three cycles of WGLC to finally result into current
documentation status:

WGLC#1 on draft-ietf-lsvr-bgp-spf-03
        Date: 3 December 2018 to 17 December 2018
WGLC#2 on draft-ietf-lsvr-bgp-spf-05
        Date: 23 September 2019 – 7 October 2019
WGLC#3 on draft-ietf-lsvr-bgp-spf-13
        Date: 20 May 2021 – 17 June 2021
Current Implementations: •     
 Arrcus (March 2019): •      
FRR Plans (June 2020):

3. Intellectual Property
During the WGLC IPR calls were performed. No claims for IPR awareness were
mentioned by WG members and neither by any of the participating document

4. Other Points
No downward references
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: 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: 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.

WG Yang draft in progress found here -

5. Checklist
•       This applicability for bgp-spf
( draft is progressed in
parallel with 'I-D.ietf-lsvr-applicability'