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Versions: (draft-decraene-idr-reserved-extended-communities) 00 01 02 03 04 05 06 07 08 09

Network Working Group                                        B. Decraene
Internet-Draft                                   France Telecom - Orange
Intended status: Standards Track                             P. Francois
Expires: June 7, 2012                                     IMDEA Networks
                                                            Dec 05, 2011


                   Assigned BGP extended communities
            draft-ietf-idr-reserved-extended-communities-02

Abstract

   This document defines two IANA registries in order to assign
   transitive and non-transitive extended communities from.  These are
   similar to the existing well-known BGP communities defined in RFC
   1997 but provide an easier control of inter-AS community
   advertisement as a community could be chosen as transitive or non-
   transitive across ASes.

   For that purpose, this document defines the use of the reserved AS
   number 0 for the transitive and non-transitive generic four-octet AS
   specific extended community types.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 7, 2012.

Copyright Notice




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   Copyright (c) 2011 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.


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.
   Implementations which do not recognize those new reserved 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 their 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
   would both waste the resources and disable the ability to define



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   global policies on reserved communities, such as to accept them or to
   filter them out.


   To address this limitation, this document defines two IANA registries
   in order to allow the registration of transitive and non-transitive
   extended communities.  These are similar to the existing Well-known
   BGP communities defined in [RFC1997] but provides a control on
   inter-AS community advertisement as a community could be chosen as
   transitive or non-transitive across ASes.


2.  Assigned extended communities

   [I-D.ietf-idr-as4octet-extcomm-generic-subtype] defines a generic
   sub-type for the four-octet AS specific extended community.  The
   value of the four-octets Global Administrator sub-field contains a
   four-octet Autonomous System number.  The value of their two-octet
   Local Administrator sub-field has semantics defined by the Autonomous
   System set in the Global Administrator sub-field.

   This document updates [I-D.ietf-idr-as4octet-extcomm-generic-subtype]
   and defines the use of the Local Administrator sub-field when the AS
   number encoded in the Global Administrator sub-field has the reserved
   value 0.

   When the AS number encoded in the Global Administrator sub-field has
   the reserved value 0, the communities have global significance.  The
   lists of those communities are maintained by the IANA in the
   registries "Assigned transitive extended communities" for the
   "transitive generic four-octet AS specific" extended community type
   and "Assigned non-transitive extended communities" for the "non-
   transitive generic four-octet AS specific" extended community type.

   Note that this use of the reserved AS number 0 in the AS field of the
   communities is similar to the one defined by [RFC1997] for the BGP
   Well-Known communities.


3.  IANA Considerations

   The IANA is requested to create and maintain a registry entitled
   "Assigned transitive extended communities" with the following
   registration procedure:







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    Registry Name: Assigned transitive extended communities

       Range              Registration Procedures
       -----------        -------------------------
       0x0000-8000        First Come First Served
       0x8001-FFFF        Standards Action/Early IANA Allocation



   The IANA is requested to create and maintain a registry entitled
   "Assigned non-transitive extended communities" with the following
   registration procedure:


    Registry Name: Assigned non-transitive extended communities

       Range              Registration Procedures
       -----------        -------------------------
       0x0000-8000        First Come First Served
       0x8001-FFFF        Standards Action/Early IANA Allocation



   An application may need both a transitive and a non-transitive
   community and it may be beneficial to have the same value for both
   communities.  (Note that both extended communities will still be
   different as they will differ from their T bit).  The IANA SHOULD try
   to accommodate such request to get both a transitive and non-
   transitive assigned community with the same value for both.


4.  Security Considerations

   This document defines IANA actions.  In itself, it has no impact on
   the security of the BGP protocol.


5.  Normative References

   [I-D.ietf-idr-as4octet-extcomm-generic-subtype]
              Rao, D., Mohapatra, P., and J. Haas, "Generic Subtype for
              BGP Four-octet AS specific extended community",
              draft-ietf-idr-as4octet-extcomm-generic-subtype-04 (work
              in progress), July 2011.

   [RFC1997]  Chandrasekeran, R., Traina, P., and T. Li, "BGP
              Communities Attribute", RFC 1997, August 1996.




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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, February 2006.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.


Authors' Addresses

   Bruno Decraene
   France Telecom - Orange
   38 rue du General Leclerc
   Issy Moulineaux cedex 9  92794
   France

   Email: bruno.decraene@orange.com


   Pierre Francois
   IMDEA Networks
   Avda. del Mar Mediterraneo, 22
   Leganese  28918
   ES

   Email: pierre.francois@imdea.org






















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