Network Working Group                                         Y. Rekhter
Request for Comments: 5701                              Juniper Networks
Category: Standards Track                                  November 2009


         IPv6 Address Specific BGP Extended Community Attribute

Abstract

   Current specifications of BGP Extended Communities (RFC 4360) support
   the IPv4 Address Specific Extended Community, but do not support an
   IPv6 Address Specific Extended Community.  The lack of an IPv6
   Address Specific Extended Community may be a problem when an
   application uses the IPv4 Address Specific Extended Community, and
   one wants to use this application in a pure IPv6 environment.  This
   document defines a new BGP attribute, the IPv6 Address Specific
   Extended Community, that addresses this problem.  The IPv6 Address
   Specific Extended Community is similar to the IPv4 Address Specific
   Extended Community, except that it carries an IPv6 address rather
   than an IPv4 address.

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

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1.  Introduction

   Current specifications of BGP Extended Communities [RFC4360] support
   the IPv4 Address Specific Extended Community, but do not support an
   IPv6 Address Specific Extended Community.  The lack of an IPv6
   Address Specific Extended Community may be a problem when an
   application uses IPv4 Address Specific Extended Community and one
   wants to use this application in a pure IPv6 environment.

   Because the BGP Extended Community attribute defines each BGP
   Extended Community as being 8 octets long, it is not possible to
   define the IPv6 Specific Extended Community using the existing BGP
   Extended Community attribute [RFC4360].  Therefore, this document
   defines a new BGP attribute, the IPv6 Address Specific Extended
   Community, that has a structure similar to the IPv4 Address Specific
   Extended Community, and thus could be used in a pure IPv6 environment
   as a replacement of the IPv4 Address Specific Extended Community.

2.  IPv6 Address Specific BGP Extended Community Attribute

   The IPv6 Address Specific Extended Community Attribute is a
   transitive, optional BGP attribute [BGP-4].  The attribute consists
   of a set of "IPv6 Address Specific extended communities".  All routes
   with the IPv6 Address Specific Extended Community attribute belong to
   the communities listed in the attribute.

   Just like all other BGP Extended Communities, the IPv6 Address
   Specific Extended Community supports multiple sub-types.

   Each IPv6 Address Specific extended community is encoded as a
   20-octet quantity, as follows:

    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       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Global Administrator (cont.)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Global Administrator (cont.)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Global Administrator (cont.)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Global Administrator (cont.)  |    Local Administrator        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The first high-order octet indicates whether a particular sub-type of
   this community is transitive across Autonomous Systems (ASes) (0x00),
   or not (0x40).  The second high-order octet of this extended type is
   used to indicate sub-types.  The sub-types are the same as for the
   IPv4 Address Specific Extended Community.

   Global Administrator field: 16 octets

      This field contains an IPv6 unicast address assigned by one of the
      Internet registries.

   Local Administrator field: 2 octets

      The organization that has been assigned the IPv6 address in the
      Global Administrator field can encode any information in this
      field.  The format and meaning of the value encoded in this field
      should be defined by the sub-type of the community.

3.  IANA Considerations

   This document defines a new BGP attribute, called the IPv6 Address
   Specific Extended Community (value 25).

   This document defines a class of extended communities, called the
   IPv6 Address Specific Extended Community, for which the IANA has
   created and will maintain a registry entitled "IPv6 Address Specific
   Extended Community".  Future assignments are to be made using the
   "First Come First Served" policy defined in [RFC5226].  The Type
   values for the transitive communities of the IPv6 Address Specific
   Extended Community class are 0x0000-0x00ff; for the non-transitive
   communities of that class, they are 0x4000-0x40ff.  Assignments
   consist of a name and the value.

   This document makes the following assignments for the IPv6 Address
   Specific extended community types:

      Name                                     Type Value
      ----                                     --------------
      IPv6 address specific Route Target       0x0002
      IPv6 address specific Route Origin       0x0003

4.  Security Considerations

   This document does not add new security issues.  All the security
   considerations for BGP Extended Communities apply here.  At the time
   that this document was written, there were significant efforts
   underway to improve the security properties of BGP.  For examples of
   documents that have been produced up to this time of publication, see
   [RFC4593] and [SIDR].

   There is a potential serious issue if a malformed, optional,
   transitive attribute is received.  This issue and the steps to avoid
   it are discussed in [OPT_TRANS].

5.  Acknowledgements

   Many thanks to Michael Lundberg and Emre Ertekin for their review and
   comments.

6.  References

6.1.  Normative References

   [BGP-4]      Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
                Border Gateway Protocol 4 (BGP-4)", RFC 4271, January
                2006.

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

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

6.2.  Informative References

   [OPT_TRANS]  Scudder, J. and E. Chen, "Error Handling for Optional
                Transitive BGP Attributes", Work in Progress, April
                2009.

   [RFC4593]    Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
                Routing Protocols", RFC 4593, October 2006.

   [SIDR]       Lepinski, M. and S. Kent, "An Infrastructure to Support
                Secure Internet Routing", Work in Progress, July 2009.

Author's Address

   Yakov Rekhter
   Juniper Networks, Inc.
   EMail: yakov@juniper.net