IDR                                                        J. Heitz, Ed.
Internet-Draft                                                     Cisco
Intended status: Standards Track                        J. Snijders, Ed.
Expires: May 3, 17, 2017                                                NTT
                                                                K. Patel
                                                             I. Bagdonas
                                                              A. Simpson
                                                             N. Hilliard
                                                        October 30,
                                                       November 13, 2016


                         BGP Large Communities


   This document describes the Large BGP Large Communities attribute, an
   extension to BGP-4.  This attribute provides a mechanism to signal
   opaque information within separate namespaces to aid in routing
   management.  The attribute is suitable for use with four-octet ASNs.
   Autonomous System Numbers.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [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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   This Internet-Draft will expire on May 3, 17, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   ( in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Large  BGP Large Communities Attribute . . . . . . . . . . . . . . .   3
   3.  Aggregation . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Canonical Representation  . . . . . . . . . . . . . . . . . .   4
   5.  Reserved Large BGP Large Community values . . . . . . . . . . . . .   4
   6.  Error Handling  . . . . . . . . . . . . . . . . . . . . . . .   4   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION   5
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   6
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6   7
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   7
     12.2.  Informative References . . . . . . . . . . . . . . . . .   7   8
     12.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   BGP implementations typically support a routing policy language to
   control the distribution of routing information.  Network operators
   attach BGP communities to routes to identify intrinsic associate particular properties of
   with these routes.  These properties may include information such as
   the route origin location, or specification of a routing policy
   action to be taken, or one that has been taken, and may apply to an individual
   route or is applied to all
   routes contained in a group of routes. BGP Update Message where the Communities
   Attribute is included.  Because BGP communities are optional
   transitive BGP attributes, BGP communities may be acted upon or
   otherwise used by routing policies in other Autonomous Systems (ASes)
   on the Internet.


   BGP Communities attributes are a variable length attribute consisting
   of a set of one or more four-octet values, each of which specify a
   community [RFC1997].  Common use of the individual values of this
   attribute type split this single 32-bit value into two two-octet words. 16-bit values.
   The most significant word is interpreted as an Autonomous System
   Number (ASN) and the least significant word is a locally defined
   value whose meaning is assigned by the operator of the Autonomous
   System in the most significant word.

   Since the adoption of four-octet ASNs [RFC6793], the BGP Communities
   attribute can no longer accommodate the above encoding, as a two-
   octet word cannot fit a four-octet ASN.  The BGP Extended Communities
   attribute [RFC4360] is also unsuitable, as the protocol limit unsuitable.  The six-octet length of six
   octets cannot accommodate both a four-octet Global Administrator the
   Extended Community value and a four-octet Local Administrator value, which precludes the common operational practice practise of
   encoding a target ASN four-octet ASNs in both the Global Administrator and the
   Local Administrator field. sub-fields.

   To address these shortcomings, this document defines a Large BGP Large
   Communities attribute encoded as an unordered set of one or more
   twelve-octet values, each consisting of a four-octet Global
   Administrator field and two four-octet operator-defined fields, each
   of which can be used to denote properties or actions significant to
   the operator of the Autonomous System assigning the values.

2.  Large  BGP Large Communities Attribute

   This document creates defines the Large BGP Large Communities attribute as an
   optional transitive path attribute of variable length.  All routes
   with the Large BGP Large Communities attribute belong to the community communities
   specified in the attribute.

   The attribute consists of one or more twelve-octet values.

   twelve-octet Large BGP Communities Large Community value represents three four-octet
   values, is encoded as a 12-octet quantity, as

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   |                      Global Administrator                     |
   |                       Local Data Part 1                       |
   |                       Local Data Part 2                       |

   Global Administrator:  A four-octet namespace identifier.  This
      SHOULD be an Autonomous System Number.

   Local Data Part 1:  A four-octet operator-defined value.

   Local Data Part 2:  A four-octet operator-defined value.

   The Global Administrator field is intended to allow different
   Autonomous Systems to define Large BGP Large Communities without collision.
   Implementations MUST allow
   This field SHOULD be either one of the operator reserved values as defined
   below, or an Autonomous System Number (ASN).  If it is a reserved
   value, then the Local Data Parts are as defined by the reserved
   value.  If it is an ASN then the Local Data Parts are to specify any value for be
   interpreted as defined by the
   Global Administrator field. owner of the ASN.

   There is no significance to the order in which twelve-octet Large BGP Communities
   Community Attribute values are encoded in the BGP path attribute payload. a Large Communities
   attribute, A BGP speaker can transmit them in any order.

   Duplicate Large BGP Communities Large Community values SHOULD NOT be transmitted.  A
   receiving speaker SHOULD silently remove duplicate Large BGP
   Communities Large
   Community values from a BGP UPDATE message. Large Community attribute.

3.  Aggregation

   If a range of routes is aggregated, then the resulting aggregate
   should have a Large BGP Large Communities attribute which contains all of
   the Large BGP Large Communities attributes from all of the aggregated

4.  Canonical Representation


   The canonical representation of BGP Large Communities MUST be represented as is three
   separate unsigned integers in decimal notation in the following
   order: Global Administrator, Local Data 1, Local Data 2.  Numbers
   MUST NOT contain leading zeros; a zero value MUST be represented with
   a single zero.  Each number is separated from the next by a single
   colon.  For example: 64496:4294967295:2, 64496:0:0, or (64496, 111, 222). 64496:0:0.

   BGP Large Communities SHOULD be represented in the canonical

5.  Reserved Large BGP Large Community values

   The following Global Administrator values are reserved: 0 (the first
   ASN) [RFC7607], 65535 (UINT16_MAX) and 4294967295 (the last ASN)
   [RFC7300]. 0, 65535, and
   4294967295.  Operators SHOULD NOT use these Global Administrator

   Although this document does not define any Special-Use Large BGP Large
   Communities, the Global Administrator values specified above could be
   used if there is a future need for them.

6.  Error Handling

   The error handling of Large BGP Large Communities is as follows:

   o  A Large BGP Large Communities attribute SHALL be considered malformed if
      the length of the BGP Large Communities Attribute value, expressed
      in octets, is not a non-zero multiple of 12.

   o  A BGP UPDATE message with a malformed Large BGP Large Communities
      attribute SHALL be handled using the approach of "treat-as-
      withdraw" as described in section 2 [RFC7606].

   The Large BGP Large Communities Global Administrator field may MAY contain any
   value, and a Large BGP Large Communities attribute MUST NOT be considered
   malformed if the Global Administrator field contains an unallocated,
   unassigned or reserved ASN or is set to one of the reserved Large BGP Large
   Community values defined in Section 5.

7.  Security Considerations

   This extension to BGP has similar security implications as BGP
   Communities [RFC1997].

   This document does not change any underlying security issues
   associated with any other BGP Communities mechanism.  Specifically,
   an AS relying on the Large BGP Large Communities attribute carried in BGP
   must have trust in every other AS in the path, as any intermediate
   Autonomous System in the path may have added, deleted, or altered the
   BGP Large Communities attribute.  Specifying the mechanism to provide
   such trust is beyond the scope of this document.

   BGP Large Communities do not protect the integrity of each community
   value.  Operators should be aware that it is possible for a BGP
   speaker to alter BGP Large Community Attribute values in a BGP Update
   Message.  Protecting the integrity of the transitive handling of BGP
   Large Community attributes in a manner consistent with the intent of
   expressed BGP routing policies falls within the broader scope of
   securing BGP, and is not specifically addressed here.

   Network administrators should note the recommendations in Section 11
   of BGP Operations and Security [RFC7454].


   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC7942].
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may

   As of today these vendors have produced an implementation of Large BGP
   Large Communities:

   o  Cisco IOS XR

   o  ExaBGP

   o  GoBGP

   o  BIRD

   o  OpenBGPD

   o  pmacct

   o  Quagga

   The latest implementation news is tracked at [1].

9.  IANA Considerations

   IANA has made an Early Allocation of the value 32 (LARGE_COMMUNITY)
   in the "BGP Path Attributes" registry under the "Border Gateway
   Protocol (BGP) Parameters" group and is now asked to make that

10.  Contributors

   The following people contributed significantly to the content of the

   John Heasley
   NTT Communications

   Adam Simpson

11.  Acknowledgments

   The authors would like to thank Ruediger Volk, Russ White, Acee
   Lindem, Shyam Sethuram, Jared Mauch, Joel M.  Halpern, Jeffrey Haas,
   Gunter van de Velde, Marco Marzetti, Eduardo Ascenco Reis, Mark
   Schouten, Paul Hoogsteder, Martijn Schmidt, Greg Hankins, Bertrand
   Duvivier, Barry O'Donovan, Grzegorz Janoszka, Linda Dunbar, Marco
   Davids, Gaurab Raj Upadhaya, Jeff Tantsura, Teun Vink, Adam
   Davenport, Theodore Baschak, Pier Carlo Chiodi, Nabeel Cocker, Ian
   Dickinson, Jan Baggen, Duncan Lockwood, David Farmer, Randy Bush, Wim
   Henderickx, Stefan Plug, Kay Rechthien, Rob Shakir, Warren Kumari,
   Gert Doering, Thomas King, Mikael Abrahamsson, Wesley Steehouwer,
   Sander Steffann, Brad Dreisbach, Martin Millnert, Christopher Morrow,
   Jay Borkenhagen, Arnold Nipper, Joe Provo, Niels Bakker, Bill Fenner,
   Tom Daly, Ben Maddison, Alexander Azimov, Brian Dickson, Peter van
   Dijk, Julian Seifert, Tom Petch, Tom Scholl, Arjen Zonneveld, Remco
   van Mook, Adam Chappell, Jussi Peltola, Kristian Larsson, Markus
   Hauschild, Richard Steenbergen, David Freedman, Richard Hartmann Hartmann,
   Geoff Huston and Mach Chen for their support, insightful review and

12.  References

12.1.  Normative References

   [RFC1997]  Chandra, R., Traina, P., and T. Li, "BGP Communities
              Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC6793]  Vohra, Q. and E. Chen, "BGP Support for Four-Octet
              Autonomous System (AS) Number Space", RFC 6793,
              DOI 10.17487/RFC6793, December 2012,

   [RFC7606]  Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
              Patel, "Revised Error Handling for BGP UPDATE Messages",
              RFC 7606, DOI 10.17487/RFC7606, August 2015,

12.2.  Informative References

   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
              February 2006, <>.

   [RFC7300]  Haas, J. and J. Mitchell, "Reservation of Last Autonomous
              System (AS) Numbers", BCP 6, RFC 7300,
              DOI 10.17487/RFC7300, July 2014,

   [RFC7454]  Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
              and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
              February 2015, <>.

   [RFC7607]  Kumari, W., Bush, R., Schiller, H., and K. Patel,
              "Codification of AS 0 Processing", RFC 7607,
              DOI 10.17487/RFC7607, August 2015,

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,

12.3.  URIs


Authors' Addresses

   Jakob Heitz (editor)
   170 West Tasman Drive
   San Jose, CA  95054


   Job Snijders (editor)
   NTT Communications
   Theodorus Majofskistraat 100
   Amsterdam  1065 SZ
   The Netherlands


   Keyur Patel
   Arrcus, Inc

   Ignas Bagdonas

   Adam Simpson
   600 March Road
   Ottawa  Ontario K2K 2E6


   Nick Hilliard
   4027 Kingswood Road
   Dublin  24