Use of BGP Large Communities
RFC 8195

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Internet Engineering Task Force (IETF)                       J. Snijders
Request for Comments: 8195                                    J. Heasley
Category: Informational                                              NTT
ISSN: 2070-1721                                               M. Schmidt
                                                                 i3D.net
                                                               June 2017

                      Use of BGP Large Communities

Abstract

   This document presents examples and inspiration for operator
   application of BGP Large Communities.  Based on operational
   experience with BGP Communities, this document suggests logical
   categories of BGP Large Communities and demonstrates an orderly
   manner of organizing community values within them to achieve typical
   goals in routing policy.  Any operator can consider using the
   concepts presented as the basis for their own BGP Large Communities
   repertoire.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see 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
   http://www.rfc-editor.org/info/rfc8195.

Snijders, et al.              Informational                     [Page 1]
RFC 8195              Use of BGP Large Communities             June 2017

Copyright Notice

   Copyright (c) 2017 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
   (http://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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  The Design Overview . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Informational Communities . . . . . . . . . . . . . . . .   4
     2.2.  Action Communities  . . . . . . . . . . . . . . . . . . .   5
   3.  Examples of Informational Communities . . . . . . . . . . . .   5
     3.1.  Location  . . . . . . . . . . . . . . . . . . . . . . . .   5
       3.1.1.  An ISO 3166-1 Numeric Function  . . . . . . . . . . .   6
       3.1.2.  A UN M.49 Region Function . . . . . . . . . . . . . .   6
     3.2.  Relation Function . . . . . . . . . . . . . . . . . . . .   7
     3.3.  Combining Informational Communities . . . . . . . . . . .   7
   4.  Examples of Action Communities  . . . . . . . . . . . . . . .   7
     4.1.  Selective NO_EXPORT . . . . . . . . . . . . . . . . . . .   7
       4.1.1.  ASN-Based Selective NO_EXPORT . . . . . . . . . . . .   8
       4.1.2.  Location-Based Selective NO_EXPORT  . . . . . . . . .   8
     4.2.  Selective AS_PATH Prepending  . . . . . . . . . . . . . .   9
       4.2.1.  ASN-Based Selective AS_PATH Prepending  . . . . . . .   9
       4.2.2.  Location-Based Selective AS_PATH Prepending . . . . .  10
     4.3.  Manipulation of the LOCAL_PREF Attribute  . . . . . . . .  10
       4.3.1.  Global Manipulation of LOCAL_PREF . . . . . . . . . .  11
       4.3.2.  Region-Based Manipulation of LOCAL_PREF . . . . . . .  11
       4.3.3.  Note of Caution for LOCAL_PREF Functions  . . . . . .  12
     4.4.  Route Server Prefix Distribution Control  . . . . . . . .  12
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

Snijders, et al.              Informational                     [Page 2]
RFC 8195              Use of BGP Large Communities             June 2017

1.  Introduction

   BGP Large Communities [RFC8092] provide a mechanism to signal opaque
   information between and within Autonomous Systems (ASes).  In very
   much the same way that [RFC1998] provides a concrete real-world