Skip to main content

Shepherd writeup

RFC 4858, template date: 1 November 2019.

(1) Type of RFC: Proposed standard
Why appropriate:  Proposing handling of a new AFI/SAFI along with new Wide
Communities atoms.  These changes modify BGP Update Packets by introducing new

(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:
It is hard to adjust traffic and optimize traffic paths in a
   traditional IP network from time to time through manual
   configurations.  It is desirable to have a mechanism for setting up
   routing policies, which adjusts traffic and optimizes traffic paths
   automatically.  This document describes BGP Extensions for Routing
   Policy Distribution (BGP RPD) to support this.

It is difficult to optimize traffic paths in a traditional IP network
   because of the following:

   *  Complex.  Traffic can only be adjusted device by device.  The
      configurations on all the routers that the traffic traverses need
      to be changed or added.  There are already lots of policies
      configured on the routers in an operational network.  There are
      different types of policies, which include security, management
      and control policies.  These policies are relatively stable.
      However, the policies for adjusting traffic are dynamic.  Whenever
      the traffic through a route is not expected, the policies to
      adjust the traffic for that route are configured on the related
      routers.  It is complex to dynamically add or change the policies
      to the existing policies on the special routers to adjust the
      traffic.  Some people would like to separate the stable route
      policies from the dynamic ones even though they have configuration
      automation systems (including YANG models).

   *  Difficult maintenance.  The routing policies used to adjust
      network traffic are dynamic, posing difficulties to subsequent
      maintenance.  High maintenance skills are required.

   *  Slow.  Adding or changing some route policies on some routers
      through a configuration automation system for adjusting some
      traffic to avoid congestions may be slow.

   It is desirable to have an automatic mechanism for setting up routing
   policies, which can simplify routing policy configuration and be
   fast.  This document describes extensions to BGP for Routing Policy
   Distribution to resolve these issues.

Working Group Summary:
There has been a good discussion on draft coverage. The WGLC is completed.

WG process.
The WGLC is closed by WG chairs in August 2021.

Document Quality:
The document quality is in good shape.

Are there existing implementations of the protocol? Have a significant number
of vendors indicated their plan to implement the specification? Are there any
reviewers that merit special mention as having done a thorough review, e.g.,
one that resulted in important changes or a conclusion that the document had no
substantive issues? If there was a MIB Doctor, YANG Doctor, Media Type or other
expert review, what was its course (briefly)? In the case of a Media Type
review, on what date was the request posted?


Who is the Document Shepherd?
Keyur Patel

Who is the 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.

This document is well written and easy to understand. It defines a new AFI/SAFI
to encode and announce route policy.

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

None at the present.

(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. However, there is a grow wg draft AS Path Prepending that
suggests imposing a limit of number of number of ASes that can be prepend. A
Grow and IDE wg call is going to soliciting input for need to referencing the
document. The wg call can be found at:

(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. None

(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?

Lizhenbin <>

Ou Liang <>

luoyuj <>

"jasonlu(陆素建)" <>

Huaimo Chen <> -

Zhuangshunwan <>

"Wanghaibo (Rainsword)" <

(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?

WGLC Consensus: - Rough to Good, ASPrepend Consensus: - Good, Single
Implementation Consensus: - Rough.

(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.

(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. Few ID nits

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews. The document
does not define new MIB/Yang models. That is expected to be covered in a
separate 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? No

(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). The IANA AFI/SAFI Codepoints has already been assigned for this

(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. None

(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. None.

(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? N/A