Assigned BGP extended communities

Document Type Active Internet-Draft (idr WG)
Last updated 2016-07-07
Replaces draft-decraene-idr-reserved-extended-communities
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Network Working Group                                        B. Decraene
Internet-Draft                                                    Orange
Intended status: Standards Track                             P. Francois
Expires: January 8, 2017                             Cisco Systems, Inc.
                                                            July 7, 2016

                   Assigned BGP extended communities


   This document defines an IANA registry in order to assign non-
   transitive extended communities from.  These are similar to the
   existing well-known BGP communities defined in RFC 1997 but provide a
   control over inter-AS community advertisement as, per RFC RFC 4360,
   they are not transitive across Autonomous System boundaries.

   For that purpose, this document defines the use of the reserved
   Autonomous System number 0.65535 in the non-transitive generic four-
   octet AS specific extended community type.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 8, 2017.

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Internet-Draft        Assigned extended communities            July 2016

Copyright Notice

   Copyright (c) 2016 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
   ( 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.

1.  Introduction

   [RFC1997] defines the BGP community attribute and some BGP well-known
   communities whose meaning SHALL be understood by all compliant
   implementations.  New communities can be registered in the IANA "BGP
   Well-known Communities" registry but it can't be assumed anymore that
   they will be known by all BGP implementations.  Implementations or
   BGP policies which recognize them will behave as specified in the
   IANA registry.  Implementations which do not recognize those new IANA
   assigned communities will propagate them from BGP neighbor to BGP
   neighbor and from AS to AS with an unlimited scope.

   There is currently no agreed way to register a non-transitive well-
   known community.

   On one hand, [RFC1997] defines BGP Well-known communities with no
   structure to set their transitiveness across ASes.  Without
   structure, communities can only be filtered by explicitly enumerating
   all community values that will be denied or allowed to BGP speakers
   in neighboring ASes.  This is not satisfactory as this would require
   upgrading all border routers to understand this community before its
   first usage.

   On the other hand, [RFC4360] defines the BGP extended community
   attribute with a structure including a type and a transitive bit "T".
   This transitive bit, when set, allows to restrict the scope of the
   community within an AS.  But there is no IANA registry to allocate
   one well-known extended community.  [RFC4360] defines IANA registries
   to allocate BGP Extended Communities types.  Each type is able to
   encode 2^48 or 2^56 values depending on the type being extended or
   regular.  Therefore, one needing to reserve a single non-transitive
   extended community would need to reserve an extended subtype which
   represents 2^48 communities, while a single value is used.  This

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