[Idr] [Errata Held for Document Update] RFC4271 (5000)

RFC Errata System <rfc-editor@rfc-editor.org> Thu, 27 April 2017 13:44 UTC

Return-Path: <wwwrun@rfc-editor.org>
X-Original-To: idr@ietfa.amsl.com
Delivered-To: idr@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 099ED12951D; Thu, 27 Apr 2017 06:44:37 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.202
X-Spam-Level:
X-Spam-Status: No, score=-4.202 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RP_MATCHES_RCVD=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ZtgHV1IR1jug; Thu, 27 Apr 2017 06:44:35 -0700 (PDT)
Received: from rfc-editor.org (rfc-editor.org [4.31.198.49]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 9279B129519; Thu, 27 Apr 2017 06:44:35 -0700 (PDT)
Received: by rfc-editor.org (Postfix, from userid 30) id 621A4B81C7F; Thu, 27 Apr 2017 06:44:11 -0700 (PDT)
To: jgs@juniper.net, yakov@juniper.net, tony.li@tony.li, skh@nexthop.com
X-PHP-Originating-Script: 30:errata_mail_lib.php
From: RFC Errata System <rfc-editor@rfc-editor.org>
Cc: aretana@cisco.com, iesg@ietf.org, idr@ietf.org, rfc-editor@rfc-editor.org
Content-Type: text/plain; charset="UTF-8"
Message-Id: <20170427134411.621A4B81C7F@rfc-editor.org>
Date: Thu, 27 Apr 2017 06:44:11 -0700
Archived-At: <https://mailarchive.ietf.org/arch/msg/idr/hTtD5B7slvdHur54IuLQY_KVO1s>
Subject: [Idr] [Errata Held for Document Update] RFC4271 (5000)
X-BeenThere: idr@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Inter-Domain Routing <idr.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/idr>, <mailto:idr-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/idr/>
List-Post: <mailto:idr@ietf.org>
List-Help: <mailto:idr-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/idr>, <mailto:idr-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 27 Apr 2017 13:44:37 -0000

The following errata report has been held for document update 
for RFC4271, "A Border Gateway Protocol 4 (BGP-4)". 

--------------------------------------
You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=4271&eid=5000

--------------------------------------
Status: Held for Document Update
Type: Technical

Reported by: John Scudder <jgs@juniper.net>
Date Reported: 2017-04-19
Held by: Alvaro Retana (IESG)

Section: 9.1.1

Original Text
-------------
      If the route is learned from an external peer, then the local BGP
      speaker computes the degree of preference based on preconfigured
      policy information.  If the return value indicates the route is
      ineligible, the route MAY NOT serve as an input to the next phase
      of route selection; otherwise, the return value MUST be used as
      the LOCAL_PREF value in any IBGP readvertisement.


Corrected Text
--------------
      If the route is learned from an external peer, then the local BGP
      speaker computes the degree of preference based on preconfigured
      policy information.  If the return value indicates the route is
      ineligible, the route MUST NOT serve as an input to the next phase
      of route selection; otherwise, the return value MUST be used as
      the LOCAL_PREF value in any IBGP readvertisement.


Notes
-----
The original text uses "MAY NOT" capitalized as if it were an RFC 2119 keyword. However, RFC 2119 does not have any defined meaning for "MAY NOT". If a reader were to interpret this text as suggesting it is optional -- meaning, in effect, "the route MAY serve as an input to the next phase of route selection" -- that would be wrong and potentially problematic.

The minimal correction would be to use lower-case "may not", which makes the proper meaning reasonably clear. However, the English construct "may not" is notoriously ambiguous, therefore the proposed correction is "MUST NOT".

=====
After consultation with the idr WG, it was confirmed that the correct interpretation (based on implementation experience) is "MUST NOT".  --- Alvaro.

--------------------------------------
RFC4271 (draft-ietf-idr-bgp4-26)
--------------------------------------
Title               : A Border Gateway Protocol 4 (BGP-4)
Publication Date    : January 2006
Author(s)           : Y. Rekhter, Ed., T. Li, Ed., S. Hares, Ed.
Category            : DRAFT STANDARD
Source              : Inter-Domain Routing
Area                : Routing
Stream              : IETF
Verifying Party     : IESG