Policy Behavior for Well-Known BGP Communities
RFC 8642

Document Type RFC - Proposed Standard (August 2019; No errata)
Updates RFC 1997
Last updated 2019-08-07
Replaces draft-ymbk-grow-wkc-behavior
Stream IETF
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Stream WG state Submitted to IESG for Publication
Document shepherd Job Snijders
Shepherd write-up Show (last changed 2019-04-17)
IESG IESG state RFC 8642 (Proposed Standard)
Consensus Boilerplate Yes
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Send notices to Job Snijders <job@ntt.net>
IANA IANA review state IANA OK - Actions Needed
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Internet Engineering Task Force (IETF)                    J. Borkenhagen
Request for Comments: 8642                                          AT&T
Updates: 1997                                                    R. Bush
Category: Standards Track                                   IIJ & Arrcus
ISSN: 2070-1721                                                R. Bonica
                                                        Juniper Networks
                                                            S. Bayraktar
                                                           Cisco Systems
                                                             August 2019

             Policy Behavior for Well-Known BGP Communities

Abstract

   Well-known BGP communities are manipulated differently across various
   current implementations, resulting in difficulties for operators.
   Network operators should deploy consistent community handling across
   their networks while taking the inconsistent behaviors from the
   various BGP implementations into consideration.  This document
   recommends specific actions to limit future inconsistency: namely,
   BGP implementors must not create further inconsistencies from this
   point forward.  These behavioral changes, though subtle, actually
   update RFC 1997.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8642.

Borkenhagen, et al.          Standards Track                    [Page 1]
RFC 8642     Policy Behavior for Well-Known BGP Communities  August 2019

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Manipulation of Communities by Policy . . . . . . . . . . . .   3
   3.  Community Manipulation Policy Differences . . . . . . . . . .   3
   4.  Documentation of Vendor Implementations . . . . . . . . . . .   4
     4.1.  Note on an Inconsistency  . . . . . . . . . . . . . . . .   5
   5.  Note for Those Writing RFCs for New Community-Like Attributes   5
   6.  Action Items  . . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   The BGP Communities attribute was specified in [RFC1997], which
   introduced the concept of well-known communities.  In hindsight,
   [RFC1997] did not prescribe as fully as it should have how well-known
   communities may be manipulated by policies applied by operators.
   Currently, implementations differ in this regard, and these
   differences can result in inconsistent behaviors that operators find
   difficult to identify and resolve.

   This document describes the current behavioral differences in order
   to assist operators in generating consistent community-manipulation
   policies in a multi-vendor environment and to prevent the
   introduction of additional divergence in implementations.

   This document recommends specific actions to limit future
   inconsistency: namely, BGP implementors MUST NOT create further
   inconsistencies from this point forward.

Borkenhagen, et al.          Standards Track                    [Page 2]
RFC 8642     Policy Behavior for Well-Known BGP Communities  August 2019

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.
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