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Internet Engineering Task Force (IETF)                          E. RosenRequest for Comments: 7902                        Juniper Networks, Inc.Updates:6514                                                   T. MorinCategory: Standards Track                                         OrangeISSN: 2070-1721                                                June 2016Registry and Extensions forP-Multicast Service Interface Tunnel Attribute FlagsAbstract   The BGP-based control procedures for Multicast Virtual Private   Networks (MVPNs) 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 "P-Multicast Service Interface (PMSI)   Tunnel" attribute.  This document updatesRFC 6514.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available inSection 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7902.Rosen & Morin                Standards Track                    [Page 1]

RFC 7902               PMSI Tunnel Attribute Flags             June 2016Copyright Notice   Copyright (c) 2016 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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.Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .22.  Extending the "PMSI Tunnel" Attribute "Flags" Field . . . . .33.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .54.  Security Considerations . . . . . . . . . . . . . . . . . . .65.  Normative References  . . . . . . . . . . . . . . . . . . . .6   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .7   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .71.  Introduction   A BGP attribute, "P-Multicast Service Interface (PMSI) Tunnel"   attribute is defined in [RFC6514].  This attribute, referred to as   the "PMSI Tunnel" attribute in this document, 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].Rosen & Morin                Standards Track                    [Page 2]

RFC 7902               PMSI Tunnel Attribute Flags             June 20162.  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.   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 one-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.Rosen & Morin                Standards Track                    [Page 3]

RFC 7902               PMSI Tunnel Attribute Flags             June 2016   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   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, 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.Rosen & Morin                Standards Track                    [Page 4]

RFC 7902               PMSI Tunnel Attribute Flags             June 20163.  IANA Considerations   IANA has created a new registry called "P-Multicast Service Interface   (PMSI) Tunnel Attribute Flags" in the "Border Gateway Protocol (BGP)   Parameters" registry.   PerSection 5 of [RFC6514], 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 has initialized the   registry as follows:       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)RFC 6514                       "PMSI Tunnel" Attribute Flags   The registration procedure for this registry is Standards Action.   IANA has also assigned the codepoint 0x07 from the "First Come, First   Served" range of the "Transitive Opaque Extended Community Sub-Types"   registry for "Additional PMSI Tunnel Attribute Flags".   IANA has established a registry for the bit flags carried in the   "Additional PMSI Tunnel Attribute Flags" Extended Community.  The   bits are numbered 0-47, with 0 being the most significant bit and 47   being the least significant bit.  The registration policy for this   registry is "Standards Action".   The initial registry should be as follows:                   Bit Flag          Name          Reference                    0-47            Unassigned                 Additional "PMSI Tunnel" Attribute FlagsRosen & Morin                Standards Track                    [Page 5]

RFC 7902               PMSI Tunnel Attribute Flags             June 20164.  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 a "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.5.  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>.Rosen & Morin                Standards Track                    [Page 6]

RFC 7902               PMSI Tunnel Attribute Flags             June 2016Acknowledgments   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.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.comRosen & Morin                Standards Track                    [Page 7]