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Versions: (draft-rosen-bess-pta-flags) 00 01 02 03 RFC 7902

BESS Working Group                                              E. Rosen
Internet-Draft                                    Juniper Networks, Inc.
Updates: 6514 (if approved)                                     T. Morin
Intended status: Standards Track                                  Orange
Expires: November 4, 2016                                    May 3, 2016


                      Registry and Extensions for
          P-Multicast Service Interface Tunnel Attribute Flags
                    draft-ietf-bess-pta-flags-03.txt

Abstract

   The BGP-based control procedures for Multicast Virtual Private
   Networks make use of a BGP attribute known as the "P-Multicast
   Service Interface (PMSI) Tunnel" attribute.  The attribute contains a
   one-octet "Flags" field.  The purpose of this document is to
   establish an IANA registry for the assignment of the bits in this
   field.  Since the Flags field contains only eight bits, this document
   also defines a new BGP Extended Community, "Additional PMSI Tunnel
   Attribute Flags", that can be used to carry additional flags for the
   PMSI Tunnel attribute.  This document updates RFC 6514.

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
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   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 November 4, 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
   (http://trustee.ietf.org/license-info) in effect on the date of



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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Extending the PMSI Tunnel Attribute Flags Field . . . . . . .   2
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   4.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   A BGP attribute known as the "P-Multicast Service Interface (PMSI)
   Tunnel" attribute is defined in [RFC6514].  This attribute contains a
   one-octet "Flags" field.  Only one flag is defined in that RFC, but
   there is now a need to define additional flags.  However, that RFC
   did not create an IANA registry for the assignment of bits in the
   "Flags" field.  This document creates a registry for that purpose.
   In addition, there may be a need to define more than eight flags.
   Therefore this document defines a new BGP Extended Community,
   "Additional PMSI Tunnel Attribute Flags", that can be used to carry
   additional flags for the PMSI Tunnel attribute.  A registry is also
   created for this Extended Community, allowing IANA to assign flag
   bits from the Extended Community's six-octet value field.

   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 [RFC2119].

2.  Extending the PMSI Tunnel Attribute Flags Field

   In [RFC6514], only a single octet in the "PMSI Tunnel" attribute is
   defined to carry bit flags.  This allows eight flags, which is
   unlikely to be sufficient for all future applications.

   This document defines a new Transitive Opaque Extended Community
   ([RFC4360], [RFC7153]), "Additional PMSI Tunnel Attribute Flags".  It
   also defines a new bit flag in the "PMSI Tunnel" attribute Flags
   field, called the "Extension" flag.





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   The "Additional PMSI Tunnel Attribute Flags" Extended Community MUST
   NOT be carried by a given BGP UPDATE message unless the following
   conditions both hold:

   o  the given BGP UPDATE message is also carrying a "PMSI Tunnel"
      attribute, and

   o  the "Extension" flag of that "PMSI Tunnel" attribute's "Flags"
      field is set.

   The six-octet value field of the "Additional PMSI Tunnel Attribute
   Flags" Extended Community is considered to be a string of 48 bit
   flags.  As shown in Figure 1, the leftmost bit (the most significant
   bit of the most significant octet) is bit 0, and the rightmost bit
   (the least significant bit of the least significant octet) is bit 47.


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               |               |               |               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      3               4
      2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               |               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 1: Value Field of the Additional PMSI Tunnel Attribute Flags
                            Extended Community

   A BGP speaker MUST NOT attach more than one "Additional PMSI Tunnel
   Attribute Flags" Extended Community to a given BGP UPDATE.  If a
   given BGP UPDATE already contains an "Additional PMSI Tunnel
   Attribute Flags" Extended Community, a BGP speaker MUST NOT attach
   any additional such Extended Communities.

   If a BGP speaker receives a BGP UPDATE with more than one "Additional
   PMSI Tunnel Attribute Flags" Extended Communities attached, only the
   flag settings in first occurrence of the Extended Community are
   significant.  Flag settings in subsequent occurrences of the Extended
   Community MUST be ignored.  When propagating the UPDATE, all
   instances of the Extended Community other than the first SHOULD be
   removed.

   Suppose a BGP speaker receives an UPDATE message that contains a
   "PMSI Tunnel" attribute, but does not contain an "Additional PMSI



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   Tunnel Attribute Flags" Extended Community.  If the "Extension" flag
   of the "PMSI Tunnel" attribute is set, the UPDATE is considered to be
   malformed, and the "treat-as-withdraw" procedure of [RFC7606] MUST be
   applied.

   If a BGP speaker receives an UPDATE message that contains one or more
   "Additional PMSI Tunnel Attribute Flags" Extended Communities, but
   either (a) that UPDATE message does not contain a PMSI Tunnel
   attribute, or (b) the Extension flag of the PMSI Tunnel attribute is
   not set, then the Extended Community(ies) SHOULD be removed and
   SHOULD NOT be redistributed.  The BGP UPDATE message MUST be
   processed (and if necessary, redistributed) as if the Extended
   Community(ies) had not been present.

   A BGP speaker that supports the current document, but does not
   recognize a particular flag (either in the" PMSI Tunnel" attribute
   "Flags" field or in the "Additional PMSI Tunnel Attribute Flags"
   Extended Community) MUST simply ignore that flag.  If the BGP speaker
   propagates either the PMSI Tunnel attribute or the "Additional PMSI
   Tunnel Attribute Flags" Extended Community or both along with the
   UPDATE message, it SHOULD leave the setting of the flag unchanged.

   It is possible that a particular application will require all members
   of a particular set of BGP speakers to support a particular flag.
   How it is determined whether all such BGP speakers support that flag
   is outside the scope of this document.

   In some situations, a BGP speaker may need to modify or replace the
   "PMSI Tunnel" attribute before propagating an UPDATE.  If the
   "Extension" flag of the "PMSI Tunnel" attribute was set before the
   attribute is modified or replaced, but that flag is no longer set
   after the attribute is modified or replaced, any "Additional PMSI
   Tunnel Attribute Flags" Extended Communities MUST be removed before
   the UPDATE is propagated.  If the PMSI Tunnel attribute is removed
   entirely before an UPDATE is propagated, the "Additional PMSI Tunnel
   Attribute Flags" Extended Communities (if any) MUST also be removed.

3.  IANA Considerations

   IANA is requested to create a new registry called "P-Multicast
   Service Interface (PMSI) Tunnel Attribute Flags" in the "Border
   Gateway Protocol (BGP) Parameters" registry.

   Per [RFC6514] section 5, a "PMSI Tunnel" attribute contains a "Flags"
   octet.  The Flags field is a single octet, with bits numbered, left-
   to-right, from 0 to 7.  IANA is requested to initialize the registry
   as follows:




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       Bit Position      Description                      Reference
       (left to right)
            0            unassigned
            1            Extension                        This document
            2            unassigned
            3            unassigned
            4            unassigned
            5            unassigned
            6            unassigned
            7            Leaf Information Required (L)    RFC6514


                        PMSI Tunnel Attribute Flags

   The registration procedure for this registry is Standards Action.

   IANA is also requested to assign a codepoint, from the "First Come,
   First Served" range of the Transitive Opaque Extended Community Sub-
   Types registry, for "Additional PMSI Tunnel Attribute Flags".
   [TO BE REMOVED: This registration should take place at the following
   location: http://www.iana.org/assignments/bgp-extended-communities
   /bgp-extended-communities.xhtml#trans-opaque]

   IANA is further requested to establish a registry for the bit flags
   carried in the "Additional PMSI Tunnel Attribute Flags" Extended
   Community.  The bits shall be numbered 0-47, with 0 being the most
   significant bit and 47 being the least significant bit.  The
   registration policy for this registry shall be "Standards Action".
   [TO BE REMOVED: The creation of the registry should take place at the
   following location: http://www.iana.org/assignments/bgp-extended-
   communities/bgp-extended-communities.xhtml]
   The initial registry should be as follows:


       Bit Flag          Name          Reference

        0-47            unassigned


                  Additional PMSI Tunnel Attribute Flags

4.  Acknowledgments

   The authors wish to thank Martin Vigoureux for his review of this
   document.  We also thank Christian Huitema and Alexey Melnikov for
   their review and comments.





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5.  Security Considerations

   This document establishes an IANA registry, and defines a new
   Transitive Opaque Extended Community ([RFC4360], [RFC7153]).

   Establishment of an IANA registry does not raise any security
   considerations.

   While this document defines a new Extended Community for carrying bit
   flags, it does not define any of the bit flags in that Extended
   Community.  Therefore no security considerations are raised.

   This document defines a new flag, the "Extension" flag, in the "PMSI
   Tunnel" attribute.  If a particular UPDATE contains "PMSI Tunnel"
   attribute with this flag set, but the UPDATE does not contain an
   "Additional PMSI Tunnel Attribute Flags" Extended Community, then the
   UPDATE is considered to be malformed, and the "treat-as-withdraw"
   procedure of [RFC7606] is invoked.  Thus one can cause an UPDATE to
   be treated as a withdrawal by incorrectly setting this bit.

6.  Normative References

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

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

   [RFC6514]  Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
              Encodings and Procedures for Multicast in MPLS/BGP IP
              VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
              <http://www.rfc-editor.org/info/rfc6514>.

   [RFC7153]  Rosen, E. and Y. Rekhter, "IANA Registries for BGP
              Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
              March 2014, <http://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,
              <http://www.rfc-editor.org/info/rfc7606>.







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Authors' Addresses

   Eric C. Rosen
   Juniper Networks, Inc.
   10 Technology Park Drive
   Westford, Massachusetts  01886
   United States

   Email: erosen@juniper.net


   Thomas Morin
   Orange
   2, avenue Pierre-Marzin
   22307 Lannion Cedex
   France

   Email: thomas.morin@orange.com

































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