BGP Extended Communities Attribute
draft-ietf-idr-rfc4360-bis-01

IDR Working Group                                              S. Sangli
Internet-Draft                                          Juniper Networks
Obsoletes: 4360 (if approved)                                N. Kao, Ed.
Intended status: Standards Track                  Individual Contributor
Expires: 17 March 2026                                 13 September 2025

                   BGP Extended Communities Attribute
                     draft-ietf-idr-rfc4360-bis-01

Abstract

   This document describes the "extended community" BGP-4 attribute.
   This attribute provides a mechanism for labeling information carried
   in BGP-4.  These labels can be used to control the distribution of
   this information, or for other applications.

   This document obsoletes [RFC4360].

Status of This Memo

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Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  BGP Extended Communities Attribute  . . . . . . . . . . . . .   3
   3.  Defined BGP Extended Community Types  . . . . . . . . . . . .   5
     3.1.  Two-Octet AS-Specific Extended Community  . . . . . . . .   5
     3.2.  IPv4-Address-Specific Extended Community  . . . . . . . .   5
     3.3.  Opaque Extended Community . . . . . . . . . . . . . . . .   6
   4.  Route Target Community  . . . . . . . . . . . . . . . . . . .   7
   5.  Route Origin Community  . . . . . . . . . . . . . . . . . . .   7
   6.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Error Handling  . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  14
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     12.2.  Informative References . . . . . . . . . . . . . . . . .  16
   Appendix A.  Comparison with RFC4360  . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

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1.  Introduction

   The Extended Community Attribute provides a mechanism for labeling
   information carried in BGP-4 [BGP-4].  It provides two important
   enhancements over the existing BGP Community Attribute [RFC1997]:

   *  An extended range, ensuring that communities can be assigned for a
      plethora of uses, without fear of overlap.

   *  The addition of a Type field provides structure for the community
      space.

   The addition of structure allows the usage of policy based on the
   application for which the community value will be used.  For example,
   one can filter out all communities of a particular type, or allow
   only certain values for a particular type of community.  It also
   allows one to specify whether a particular community is transitive or
   non-transitive across an Autonomous System (AS) boundary.  Without
   structure, this can only be accomplished by explicitly enumerating
   all community values that will be denied or allowed and passed to BGP
   speakers in neighboring ASes based on the transitive property.

1.1.  Requirements Language

   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.

2.  BGP Extended Communities Attribute

   The Extended Communities Attribute is a transitive optional BGP
   attribute, with the Type Code 16.  The attribute consists of a set of
   "extended communities".  All routes with the Extended Communities
   attribute belong to the communities listed in the attribute.

   Each Extended Community is encoded as an 8-octet quantity, as
   follows:
      - Type Field  : 1 or 2 octets
      - Value Field : Remaining octets

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Type high    |  Type low(*)  |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+          Value                |
      |                                                               |

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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      (*) Present for Extended Types only, used for the Value field
          otherwise.

      Type Field:
         Two classes of Type Field are introduced: Regular Type and
         Extended Type.

         The size of Type Field for Regular Types is 1 octet, and the
         size of the Type Field for Extended Types is 2 octets.

         The value of the high-order octet of the Type Field determines
         if an extended community is a Regular Type or an Extended Type.
         The class of a type (Regular or Extended) is not encoded in the
         structure of the type itself.  The class of a type is specified
         in the document that defines the type and the IANA registry.

         The high-order octet of the Type Field is as shown below:
             0 1 2 3 4 5 6 7
            +-+-+-+-+-+-+-+-+
            |I|T|           |
            +-+-+-+-+-+-+-+-+

            I - IANA authority bit
               Value 0:  IANA-assignable type using the "First Come
                  First Serve" policy

               Value 1:  Part of this Type Field space is for IANA
                  assignable types using either the Standard Action or
                  the Early IANA Allocation policy.  The rest of this
                  Type Field space is for Experimental use.

            T - Transitive bit
               Value 0:  The community is transitive across ASes

               Value 1:  The community is non-transitive across ASes

            Remaining 6 bits:
               Indicates the structure of the community

      Value Field:
         The encoding of the Value Field is dependent on the "type" of
         the community as specified by the Type Field.

   Two extended communities are declared equal only when all 8 octets of
   the community are equal.

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   The two members in the tuple <Type, Value> should be enumerated to
   specify any community value.  The remaining octets of the community
   interpreted based on the value of the Type field.

3.  Defined BGP Extended Community Types

   This section introduces a few extended types and defines the format
   of the Value Field for those types.  The types introduced here
   provide "templates", where each template is identified by the high-
   order octet of the extended community Type field, and the lower-order
   octet (sub-type) is used to indicate a particular type of extended
   community.

3.1.  Two-Octet AS-Specific Extended Community

   This is an extended type with Type Field composed of 2 octets and
   Value Field composed of 6 octets.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | 0x00 or 0x40  |   Sub-Type    |    Global Administrator       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Local Administrator                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The value of the high-order octet of this extended type is either
   0x00 or 0x40.  The low-order octet of this extended type is used to
   indicate sub-types.

   The Value Field consists of two sub-fields:
      Global Administrator sub-field: 2 octets
         This sub-field contains an Autonomous System number assigned by
         IANA.

      Local Administrator sub-field: 4 octets
         The organization identified by Autonomous System number in the
         Global Administrator sub-field can encode any information in
         this sub-field.  The format and meaning of the value encoded in
         this sub-field should be defined by the sub-type of the
         community.

3.2.  IPv4-Address-Specific Extended Community

   This is an extended type with Type Field composed of 2 octets and
   Value Field composed of 6 octets.

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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | 0x01 or 0x41  |   Sub-Type    |    Global Administrator       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Global Administrator (cont.)  |    Local Administrator        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The value of the high-order octet of this extended type is either
   0x01 or 0x41.  The low-order octet of this extended type is used to
   indicate sub-types.

   The Value field consists of two sub-fields:
      Global Administrator sub-field: 4 octets
         This sub-field contains an IPv4 unicast address assigned by one
         of the Internet registries.

      Local Administrator sub-field: 2 octets
         The organization that has been assigned the IPv4 address in the
         Global Administrator sub-field can encode any information in
         this sub-field.  The format and meaning of this value encoded
         in this sub-field should be defined by the sub-type of the
         community.

3.3.  Opaque Extended Community

   This is an extended type with Type Field composed of 2 octets and
   Value Field composed of 6 octets.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | 0x03 or 0x43  |   Sub-Type    |                Value          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Value (cont.)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The value of the high-order octet of this extended type is either
   0x03 or 0x43.  The low-order octet of this extended type is used to
   indicate sub-types.

   This is a generic community of extended type.  The value of the sub-
   type that should define the Value Field is to be assigned by IANA.

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4.  Route Target Community

   The Route Target Community identifies one or more routers that may
   receive a set of routes (that carry this Community) carried by BGP.
   This is transitive across the Autonomous System boundary.

   The Route Target Community is of an extended type.

   The value of the high-order octet of the Type field for the Route
   Target Community can be 0x00 (as defined in Section 3.1), 0x01 (as
   defined in Section 3.2), or 0x02 (as defined in [RFC5668]).  The
   value of the low-order octet of the Type field for this community is
   0x02.

   When the value of the high-order octet of the Type field is 0x00 or
   0x02, the Local Administrator sub-field contains a number from a
   numbering space that is administered by the organization to which the
   Autonomous System number carried in the Global Administrator sub-
   field has been assigned by an appropriate authority.

   When the value of the high-order octet of the Type field is 0x01, the
   Local Administrator sub-field contains a number from a numbering
   space that is administered by the organization to which the IP
   address carried in the Global Administrator sub-field has been
   assigned by an appropriate authority.

   One possible use of the Route Target Community is specified in
   [RFC4364].

5.  Route Origin Community

   The Route Origin Community identifies one or more routers that inject
   a set of routes (that carry this Community) into BGP.  This is
   transitive across the Autonomous System boundary.

   The Route Origin Community is of an extended type.

   The value of the high-order octet of the Type field for the Route
   Origin Community can be 0x00 (as defined in Section 3.1), 0x01 (as
   defined in Section 3.2), or 0x02 (as defined in [RFC5668]).  The
   value of the low-order octet of the Type field for this community is
   0x03.

   When the value of the high-order octet of the Type field is 0x00 or
   0x02, the Local Administrator sub-field contains a number from a
   numbering space that is administered by the organization to which the
   Autonomous System number carried in the Global Administrator sub-
   field has been assigned by an appropriate authority.

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   When the value of the high-order octet of the Type field is 0x01, the
   Local Administrator sub-field contains a number from a numbering
   space that is administered by the organization to which the IP
   address carried in the Global Administrator sub-field has been
   assigned by an appropriate authority.

   One possible use of the Route Origin Community is specified in
   [RFC4364].

6.  Operations

   A BGP speaker may use the Extended Communities attribute to control
   which routing information it accepts or distributes to its peers.

   The Extended Community attribute MUST NOT be used to modify the BGP
   best path selection algorithm in a way that leads to forwarding
   loops.

   A BGP speaker receiving a route that doesn't have the Extended
   Communities attribute MAY append this attribute to the route when
   propagating it to its peers.

   A BGP speaker receiving a route with the Extended Communities
   attribute MAY modify this attribute according to the local policy.

   By default if a range of routes is to be aggregated and the resultant
   aggregates path attributes do not carry the ATOMIC_AGGREGATE
   attribute, then the resulting aggregate should have an Extended
   Communities path attribute that contains the set union of all the
   Extended Communities from all of the aggregated routes.  The default
   behavior could be overridden via local configuration, in which case
   handling the Extended Communities attribute in the presence of route
   aggregation becomes a matter of the local policy of the BGP speaker
   that performs the aggregation.

   A route may carry both the BGP Communities attribute, as defined in
   [RFC1997]), and the Extended BGP Communities attribute.  In this
   case, the BGP Communities attribute is handled as specified in
   [RFC1997], and the Extended BGP Communities attribute is handled as
   specified in this document.

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   If a route has non-transitive extended communities, those communities
   SHOULD NOT be propagated across an Autonomous System boundary and
   SHOULD be removed from the route.  However, non-transitive extended
   communities SHOULD NOT be removed when advertising the route within
   the same BGP AS Confederation(as defined in [RFC5065]).  As part of
   configuration or BGP protocol extensions, BGP speakers MAY attach
   non-transitive extended communities to routes advertised across
   Autonomous System boundaries.

   By default, when a BGP speaker receives routes with non-transitive
   extended communities across Autonomous System or Confederation
   Member-AS boundaries, it SHOULD NOT remove these extended
   communities.  The behavior MAY be configurable.  The BGP speaker
   SHOULD also allow local policies to match against or remove these
   extended communities.

7.  Error Handling

   [RFC7606], Section 7.14, defines the error handling procedure for the
   Extended Community attribute.

8.  IANA Considerations

   All the BGP Extended Communities contain a Type field.

   The Type could be either regular or extended.  For a Regular Type,
   the IANA allocates an 8-bit value; for an Extended Type, the IANA
   allocates a 16-bit value.

   The value allocated for a Regular Type MUST NOT be reused as the
   value of the high-order octet when allocating an Extended Type.  The
   value of the high-order octet allocated for an Extended Type MUST NOT
   be reused when allocating a Regular Type.

   The Type field indicates whether the Extended Community is transitive
   or not.  Future requests for assignment of a Type value must specify
   whether the Type value is intended for a transitive or a non-
   transitive Extended Community.

   The IANA has created two registries entitled "BGP Transitive Extended
   Community Types" [IANA-BGP-EC-TRANS] and "BGP Non-Transitive Extended
   Community Types" [IANA-BGP-EC-NONTRANS].  The IANA will maintain
   these registries.  The assignments of these registries consist of the
   name and the value.

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   Future assignments are to be made using either the Standards Action
   process defined in [RFC8126], the Early IANA Allocation process
   defined in [RFC7120], or the "First Come First Served" policy defined
   in [RFC8126].

   Further definitions of sub-type registries, along with their
   allocation policies, can be found in [RFC7153].

   Should the conditions be met, early creations of sub-type registries
   can be done and tracked using the Early Registry Creation process
   defined in [I-D.baber-ianabis-early-registries].

   The following table summarizes the ranges for the assignment of the
   "BGP Transitive Extended Community Types" registry
   [IANA-BGP-EC-TRANS]:

      +==================+=========================================+
      | TYPE VALUE RANGE | REGISTRATION PROCEDURES                 |
      +==================+=========================================+
      | 0x00-0x3F        | First Come First Served                 |
      +------------------+-----------------------------------------+
      | 0x80-0x8F        | First Come First Served or Experimental |
      |                  | Use (see [RFC3692] and [RFC9184])       |
      +------------------+-----------------------------------------+
      | 0x90-0xBF        | Standards Action                        |
      +------------------+-----------------------------------------+

                                 Table 1

   This document makes the following assignments in the "BGP Transitive
   Extended Community Types" registry [IANA-BGP-EC-TRANS]:

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      +=======+=====================================================+
      | TYPE  | NAME                                                |
      | VALUE |                                                     |
      +=======+=====================================================+
      | 0x00  | Transitive Two-Octet AS-Specific Extended Community |
      |       | (Sub-Types are defined in the "Transitive Two-Octet |
      |       | AS-Specific Extended Community Sub-Types" registry  |
      |       | [IANA-BGP-EC-TRANS-TWO-OCTET-AS])                   |
      +-------+-----------------------------------------------------+
      | 0x01  | Transitive IPv4-Address-Specific Extended Community |
      |       | (Sub-Types are defined in the "Transitive IPv4-     |
      |       | Address-Specific Extended Community Sub-Types"      |
      |       | registry [IANA-BGP-EC-TRANS-IPV4])                  |
      +-------+-----------------------------------------------------+
      | 0x03  | Transitive Opaque Extended Community (Sub-Types are |
      |       | defined in the "Transitive Opaque Extended          |
      |       | Community Sub-Types" registry                       |
      |       | [IANA-BGP-EC-TRANS-OPAQUE])                         |
      +-------+-----------------------------------------------------+

                                  Table 2

   The following table summarizes the ranges for the assignment of the
   "BGP Non-Transitive Extended Community Types" registry:

          +==================+==================================+
          | TYPE VALUE RANGE | REGISTRATION PROCEDURES          |
          +==================+==================================+
          | 0x40-0x7F        | First Come First Served          |
          +------------------+----------------------------------+
          | 0xC0-0xCF        | Experimental Use (see [RFC3692]) |
          +------------------+----------------------------------+
          | 0xD0-0xFF        | Standards Action                 |
          +------------------+----------------------------------+

                                  Table 3

   This document makes the following assignments in the "BGP Non-
   Transitive Extended Community Types" [IANA-BGP-EC-TRANS] registry:

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    +=======+=========================================================+
    | TYPE  | NAME                                                    |
    | VALUE |                                                         |
    +=======+=========================================================+
    | 0x40  | Non-Transitive Two-Octet AS-Specific Extended Community |
    |       | (Sub-Types are defined in the "Non-Transitive Two-Octet |
    |       | AS-Specific Extended Community Sub-Types" registry      |
    |       | [IANA-BGP-EC-NONTRANS-TWO-OCTET-AS])                    |
    +-------+---------------------------------------------------------+
    | 0x41  | Non-Transitive IPv4-Address-Specific Extended Community |
    |       | (Sub-Types are defined in the "Non-Transitive IPv4-     |
    |       | Address-Specific Extended Community Sub-Types" registry |
    |       | [IANA-BGP-EC-NONTRANS-IPV4])                            |
    +-------+---------------------------------------------------------+
    | 0x43  | Non-Transitive Opaque Extended Community (Sub-Types are |
    |       | defined in the "Non-Transitive Opaque Extended          |
    |       | Community Sub-Types" registry                           |
    |       | [IANA-BGP-EC-NONTRANS-OPAQUE])                          |
    +-------+---------------------------------------------------------+

                                  Table 4

   This document defines a class of extended communities called Two-
   Octet AS-Specific Extended Community for which the IANA is to create
   and maintain two registries entitled "Transitive Two-Octet AS-
   Specific Extended Community Sub-Types"
   [IANA-BGP-EC-TRANS-TWO-OCTET-AS] and "Non-Transitive Two-Octet AS-
   Specific Extended Community Sub-Types"
   [IANA-BGP-EC-NONTRANS-TWO-OCTET-AS].  All the communities in this
   class are of Extended Types.  Future assignments are to be made using
   the "First Come First Served" policy defined in [RFC8126].

   This document defines a class of extended communities called IPv4-
   Address-Specific Extended Community for which the IANA is to create
   and maintain two registries entitled "Transitive IPv4-Address-
   Specific Extended Community Sub-Types"
   [IANA-BGP-EC-TRANS-TWO-OCTET-AS] and "Non-Transitive IPv4-Address-
   Specific Extended Community Sub-Types"
   [IANA-BGP-EC-NONTRANS-TWO-OCTET-AS].  All the communities in this
   class are of extended Types.  Future assignments are to be made using
   the "First Come First Served" policy defined in [RFC8126].

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   This document defines a class of extended communities called Opaque
   Extended Community for which the IANA is to create and maintain two
   registries entitled "Transitive Opaque Extended Community Sub-Types"
   [IANA-BGP-EC-TRANS-OPAQUE] and "Non-Transitive Opaque Extended
   Community Sub-Types" [IANA-BGP-EC-NONTRANS-OPAQUE].  All the
   communities in this class are of extended Types.  Future assignments
   are to be made using the "First Come First Served" policy defined in
   [RFC8126].

   This document makes the following assignments in the "Transitive Two-
   Octet AS-Specific Extended Community Sub-Types" registry
   [IANA-BGP-EC-TRANS-TWO-OCTET-AS]:

                     +================+==============+
                     | SUB-TYPE VALUE | NAME         |
                     +================+==============+
                     | 0x02           | Route Target |
                     +----------------+--------------+
                     | 0x03           | Route Origin |
                     +----------------+--------------+

                                  Table 5

   This document makes the following assignments in the "Transitive
   IPv4-Address-Specific Extended Community Sub-Types" registry
   [IANA-BGP-EC-TRANS-IPV4]:

                     +================+==============+
                     | SUB-TYPE VALUE | NAME         |
                     +================+==============+
                     | 0x02           | Route Target |
                     +----------------+--------------+
                     | 0x03           | Route Origin |
                     +----------------+--------------+

                                  Table 6

   When requesting an allocation from more than one registry defined
   above, one may ask for allocating the same Type value from these
   registries.  If possible, the IANA should accommodate such requests.

9.  Security Considerations

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

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   This extension to BGP does not change the underlying security issues.
   Specifically, an operator who is relying on the information carried
   in BGP must have a transitive trust relationship back to the source
   of the information.  Specifying the mechanism(s) to provide such a
   relationship is beyond the scope of this document.

10.  Contributors

   Dan Tappan and Yakov Rekhter were the authors of [RFC4360] and,
   therefore, are contributing authors of this document.

11.  Acknowledgements

   We wish to thank John Hawkinson, Jeffrey Haas, Bruno Rijsman, Bill
   Fenner, and Alex Zinin for their suggestions and feedback on the
   original [RFC4360].

   We thank Yakov Rekhter and Alfred Hoenes for pointing out several
   errors in [RFC4360].

   We also wish to thank Bruno Decraene, Laurent Vanbever, and Pierre
   Francois for pointing out inconsistencies regarding the procedures
   for originating non-transitive extended communities in
   [I-D.decraene-idr-rfc4360-clarification].

   We also thank Jeffrey Haas, Robert Raszuk, Bruno Decraene, Linda
   Dunbar, Yingzhen Qu, Jie Dong and Lizhen Qiang for their suggestions
   and feedback on this document.

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,
              <https://www.rfc-editor.org/info/rfc1997>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3692]  Narten, T., "Assigning Experimental and Testing Numbers
              Considered Useful", BCP 82, RFC 3692,
              DOI 10.17487/RFC3692, January 2004,
              <https://www.rfc-editor.org/info/rfc3692>.

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   [BGP-4]    Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC5065]  Traina, P., McPherson, D., and J. Scudder, "Autonomous
              System Confederations for BGP", RFC 5065,
              DOI 10.17487/RFC5065, August 2007,
              <https://www.rfc-editor.org/info/rfc5065>.

   [RFC5668]  Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS
              Specific BGP Extended Community", RFC 5668,
              DOI 10.17487/RFC5668, October 2009,
              <https://www.rfc-editor.org/info/rfc5668>.

   [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code
              Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
              2014, <https://www.rfc-editor.org/info/rfc7120>.

   [RFC7153]  Rosen, E. and Y. Rekhter, "IANA Registries for BGP
              Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
              March 2014, <https://www.rfc-editor.org/info/rfc7153>.

   [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,
              <https://www.rfc-editor.org/info/rfc7606>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC9184]  Loibl, C., "BGP Extended Community Registries Update",
              RFC 9184, DOI 10.17487/RFC9184, January 2022,
              <https://www.rfc-editor.org/info/rfc9184>.

   [I-D.baber-ianabis-early-registries]
              Baber, A., "Early IANA Registry Creation", Work in
              Progress, Internet-Draft, draft-baber-ianabis-early-
              registries-00, 5 June 2025,
              <https://datatracker.ietf.org/doc/html/draft-baber-
              ianabis-early-registries-00>.

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   [IANA-BGP-EC-TRANS]
              IANA, "BGP Transitive Extended Community Types",
              <https://www.iana.org/assignments/bgp-extended-
              communities/bgp-extended-communities.xhtml#transitive>.

   [IANA-BGP-EC-NONTRANS]
              IANA, "BGP Non-Transitive Extended Community Types",
              <https://www.iana.org/assignments/bgp-extended-
              communities/bgp-extended-communities.xhtml#transitive>.

   [IANA-BGP-EC-TRANS-TWO-OCTET-AS]
              IANA, "Transitive Two-Octet AS-Specific Extended Community
              Sub-Types", <https://www.iana.org/assignments/bgp-
              extended-communities/bgp-extended-communities.xhtml#trans-
              two-octet-as>.

   [IANA-BGP-EC-NONTRANS-TWO-OCTET-AS]
              IANA, "Non-Transitive Two-Octet AS-Specific Extended
              Community Sub-Types", <https://www.iana.org/assignments/
              bgp-extended-communities/bgp-extended-
              communities.xhtml#non-trans-two-octet-as>.

   [IANA-BGP-EC-TRANS-IPV4]
              IANA, "Transitive IPv4-Address-Specific Extended Community
              Sub-Types", <https://www.iana.org/assignments/bgp-
              extended-communities/bgp-extended-communities.xhtml#trans-
              ipv4>.

   [IANA-BGP-EC-NONTRANS-IPV4]
              IANA, "Non-Transitive IPv4-Address-Specific Extended
              Community Sub-Types", <https://www.iana.org/assignments/
              bgp-extended-communities/bgp-extended-
              communities.xhtml#non-trans-ipv4>.

   [IANA-BGP-EC-TRANS-OPAQUE]
              IANA, "Transitive Opaque Extended Community Sub-Types",
              <https://www.iana.org/assignments/bgp-extended-
              communities/bgp-extended-communities.xhtml#trans-opaque>.

   [IANA-BGP-EC-NONTRANS-OPAQUE]
              IANA, "Non-Transitive Opaque Extended Community Sub-
              Types", <https://www.iana.org/assignments/bgp-extended-
              communities/bgp-extended-communities.xhtml#non-trans-
              opaque>.

12.2.  Informative References

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   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
              February 2006, <https://www.rfc-editor.org/info/rfc4360>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <https://www.rfc-editor.org/info/rfc4364>.

   [I-D.decraene-idr-rfc4360-clarification]
              Decraene, B., Vanbever, L., and P. Francois, "RFC 4360
              Clarification Request", Work in Progress, Internet-Draft,
              draft-decraene-idr-rfc4360-clarification-00, 19 October
              2009, <https://datatracker.ietf.org/doc/html/draft-
              decraene-idr-rfc4360-clarification-00>.

Appendix A.  Comparison with RFC4360

   The encodings and definitions of the extended communities are
   unchanged in this document.

   Besides addressing known errata in [RFC4360], this document updates
   the following:

   *  Section 6 clarifies the operations of non-transitive extended
      communities across Autonomous System or Confederation Member-AS
      boundaries.

   *  Section 7 is added to describe the error handling procedures.

   *  Section 8 is updated to reflect the current IANA registry status.
      The update splits the "BGP Extended Communities Type" registry
      into transitive and non-transitive registries.  This section also
      contains similar updates for the Sub-Types defined.

Authors' Addresses

   Srihari Sangli
   Juniper Networks
   Exora Business Park
   Bangalore, KA 560103
   India
   Email: ssangli@juniper.net

   Nat Kao (editor)
   Individual Contributor
   Email: pyxislx@gmail.com

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