Shepherd writeup

Shepherd Write-up: per RFC 4858, template: 2/24/2012
last updated 2/11/2019. 
(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?

Standards RFC - additions to RFC7752 (BGP-LS) in the 
BGP-LS NLRI in order to pass segment routing (SR) information 
for IGPS in the BGP-LS NLRI.  Extension to RFC7752 to add this 
information includes: 
a) Node NLRI within the BGP-LS NLRI that passes  
SR identifiers (SID), SR capabilities, SR algorithm, SR local 
block range, and SR mapping server preference.
b) The Link NLRI within BGP-LS NLRI  that passes 
SIDs for adjacency, LAN  adjaency SID, L2 Bundle TLV.
c) prefix NLRI within BGP-LS NLRI that passes: 
Prefix SID, Prefix attribute (OSPFv2, OSPFv3, ISISflags),
Range of prefixes. 

(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
   Segment Routing (SR) allows for a flexible definition of end-to-end
   paths by encoding paths as sequences of topological sub-paths, called
   "segments".  These segments are advertised by routing protocols e.g.
   by the link state routing protocols (IS-IS, OSPFv2 and OSPFv3) within
   IGP topologies.

   This draft defines extensions to the BGP Link-state address-family 
   defined in RFC7752 in order to carry segment routing information
   for IGPs in BGP.   Extensions include additions to SR routing 
   identifiers (SIDs) for IGP nodes, link adjacencies, and prefixes
   as well as passing information on SR capabilities,  algorithms and 
   mapping servers.

Working Group Summary

The WG has reviewed the BGP-LS segment
routing drafts for 3-5 years in coordination with the 
SPRING, MPLS, and BESS working groups. 
Please read the RFC 8402 and
draft-ietf-spring-segement-routing-central-epe-15 to 
understand the architecture construct.  

This draft is one of a family of BGP additions for BGP-LS 
segment routing (SR) and and BGP Traffic 
Engineering (TE) that IDR is standardizing after receiving 
reports of 2 independent implementations.
Other drafts for segment routing reading for standardization 
include: draft-ietf-idr-bgp-prefix-sid and
Other drafts for BGP-LS based TE include:  
draft-ietf-idr-bgp-ls-node-admin-tag-extension and
Document Quality

1) technical quality: 
Existing implementations of the protocol: 2 from Cisco 
Plans: Huawei has indicated plans to implement. 
Careful reviews: 
Jeff Haas (via comments on list) - resulted in -06
John Scudder's  follow-up

Aijun Wang
(Note: Aijun Wang is part of the operational community 
 as operator of a network in China). 
RTG-DIR QA reviewer: Victoria Pritchard (\

OPS-DIR QA Reviewer: Joel Jaeggli

Shepherd's comments on RTG-DIR QA review responses:

Shepherd's additional comments on security: 
see thread:

OPS Comments from Grow  WG- sent to grow WG, but no comments received.
AD is welcome to ping WG chairs again. 

Summary for IESG of the security thread: 
The inclusion of the reference in the security consideration
in -10.txt of a specific reference to RFC8402 (SR architecture)
and a clear statement that these BGP-LS extensions 
are to be operated in a trusted domain with
isolated BGP peers with filtering restrictions 
so that this information cannot go outside this peers. 
In this shepherd's understandings, these restrictions form
a web of trusted BGP peers.   

If these BGP peers operate in the SR-MPLS environment, 
the authors believe the security analysis provided  by RFC4381 should apply.   
The shepherd is concerned regarding this statement, but if the 
deployment is within a web of trusted BGP peers 
then it is the web of trusted BGP peers (each validated 
by configuration and other means) to the web. 

These security restrictions are in addition to the 
RFC7752  security restrictions.  Since RFC7752 does not provide require 
a trusted domain or BGP-LS isolation these additional restrictions are important. 

  Document Shepherd: Susan Hares 
  Responsible AD:  Alvaro Retana 
  RTG-DIR QA reviewer: Victoria Pritchard (
  OPS-DIR: QA reviewer: Joel Jaeggli 
  Key onlist reviewers: Jeff Haas, Aijun Wang

(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.

Reviewer went through draft aligning it with other Spring and IDR work. 
Reviwer went through the following key reviews: 
1) WG LC - Jeff Haas, Aijun Wang 
2) Requested QA Reviews 

  RTG-DIR reviewer: Victoria Pritchard (

  RTG-DIR QA reviewer:

3) Requested Grow WG to review these two drafts for operational usefulness 

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


No nits. 

(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 additional review. 

(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.

Robert Raszuk (and Tony Li's agreement) WG LC is worth reviewing here: 

Robert Rasuk and Tony Li feel that BGP-LS (RFC7752) was unwise direction for 
BGP, and expanding it is a greater error.   The BGP-LS proponents suggested
that BGP-LS was simply a way to get IGP data (OSPFv2/v3, ISIS) out of a
network for processing.  

These segment routing additions take the BGP-LS 
work beyond its initial description of providing information to 
manage network into the realm of supporting  a centralized SDN controller which creates
Segment Routing infrastructure. 

The IESG should consider whether this general application of 
BGP-LS into creating routing infrastructure is important. 
If it is, approve this document for publication and the 
WG chairs and AD will note this decision point. 
If it is not, then reject this document for publication with the 
a clear statement that this expansion of work is not appropriate. 

(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.

Stefano Previdi

Ketan Talaulikar

Clarence Filsfils

Hannes Gredler

Mach Chen

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

No 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?   

WG in this area tends to be strong pushing toward the draft, but
there are concerns raised by the Robert Raszuk, Tony LI, and others
regarding this use of BGP as a transport for information. 

(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 threats of an appeal. 

(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

No nits 

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

(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?

Non-RFC normative 
draft-ietf-idr-te-pm-bgp 0- approved for RFC 
draft-ietf-isis-segment-routing-extensions - approved for publication 
draft-ietf-ospf-ospfv3-segment-routing-extensions-15.txt = approved for publication 
(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. 
te the aut
-Not as I understand RFC3967

(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. These are additions to RFC7752.  

(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).

AFAIK - this draft followed early allocation procedures correctly.
I have sent a request for a IANA QA review, and 
received an "OK" from IANA. 
Please do a re-check of the last version. 

(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.


(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.

None needed