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Internet Engineering Task Force (IETF)                            Y. CaiRequest for Comments: 6516                                 E. Rosen, Ed.Category: Standards Track                                   IJ. WijnandsISSN: 2070-1721                                            Cisco Systems                                                           February 2012IPv6 Multicast VPN (MVPN) Support Using PIM Control Planeand Selective Provider Multicast Service Interface (S-PMSI)Join MessagesAbstract   The specification for Multicast Virtual Private Networks (MVPNs)   contains an option that allows the use of PIM as the control protocol   between provider edge routers.  It also contains an option that   allows UDP-based messages, known as Selective Provider Multicast   Service Interface (S-PMSI) Join messages, to be used to bind   particular customer multicast flows to particular tunnels through a   service provider's network.  This document extends the MVPN   specification (RFC 6513) so that these options can be used when the   customer multicast flows are IPv6 flows.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 5741.   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/rfc6516.Copyright Notice   Copyright (c) 2012 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 respectCai, et al.                  Standards Track                    [Page 1]

RFC 6516                    IPv6 MVPN Support              February 2012   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. Specification of Requirements ...................................33. S-PMSI Joins Binding IPv6 Flows to GRE/IPv4 P-Tunnels ...........33.1. Encoding ...................................................33.2. Encapsulation of S-PMSI Joins in UDP Datagrams .............44. PE-PE PIM/IPv6 over an IPv4 P-Tunnel ............................45. IANA Considerations .............................................56. Security Considerations .........................................57. Acknowledgments .................................................58. Normative References ............................................51.  Introduction   The Multicast Virtual Private Network (MVPN) specification [RFC6513]   defines the notion of a "PMSI" (Provider Multicast Service Interface)   and specifies how a PMSI can be instantiated by various kinds of   tunnels through a service provider's network ("P-tunnels").  It also   specifies the procedures for using PIM (Protocol Independent   Multicast [RFC4601]) as the control protocol between Provider Edge   (PE) routers.  When PIM is used as the control protocol, PIM messages   are sent through a P-tunnel from one PE in an MVPN to others in the   same MVPN.  These PIM messages carry customer multicast routing   information.  However, [RFC6513] does not cover the case where the   customer is using IPv6, but the service provider is using P-tunnels   created by PIM over an IPv4 infrastructure.   The MVPN specification [RFC6513] also specifies "S-PMSI (Selective   PMSI) Join" messages, which are optionally used to bind particular   customer multicast flows to particular P-tunnels.  However, the   specification does not cover the case where the customer flows are   IPv6 flows.   This document extends [RFC6513] by adding the specification for   handling customer IPv6 multicast flows when a service provider is   using PE-PE PIM and/or S-PMSI Join messages over an IPv4   infrastructure.  This document also specifies how to send multiple   S-PMSI Join messages in a single UDP datagram.   This document uses terminology defined in [RFC6513]: C-source,   C-group, C-flow, P-group, and (C-S,C-G).Cai, et al.                  Standards Track                    [Page 2]

RFC 6516                    IPv6 MVPN Support              February 20122.  Specification of Requirements   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].3.  S-PMSI Joins Binding IPv6 Flows to GRE/IPv4 P-Tunnels   The S-PMSI Join message is defined inSection 7.4.2.2 of [RFC6513].   These messages contain a type field, and [RFC6513] defines only Type   1 S-PMSI Joins.  A Type 1 S-PMSI Join may be used to assign a   customer IPv4 (C-S,C-G) flow to a P-tunnel that is created by   PIM/IPv4.  To transmit data or control packets over such a P-tunnel,   the packets are encapsulated in GRE (Generic Routing Encapsulation)   within IPv4, as specified inSection 12 of [RFC6513].   In this document, we define the Type 4 S-PMSI Join.  A Type 4 S-PMSI   Join may be used to assign a customer IPv6 (C-S,C-G) flow to a   P-tunnel that is created by PIM/IPv4.  GRE/IPv4 encapsulation is used   to send data or control packets on the P-tunnel.3.1.  Encoding     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      |           Length            |    Reserved     |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                                                               |    |                           C-source                            |    |                                                               |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                                                               |    |                           C-group                             |    |                                                               |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                           P-group                             |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   Type (8 bits): 4   Length (16 bits): 40, the length in octets of the entire S-PMSI Join   message, including the Type, Length, Reserved, C-source, C-group, and   P-group fields.Cai, et al.                  Standards Track                    [Page 3]

RFC 6516                    IPv6 MVPN Support              February 2012   Reserved (8 bits):  this field SHOULD be zero when transmitted and   MUST be ignored when received.   C-source (128 bits): the IPv6 address of the traffic source in the   VPN.   C-group (128 bits): the IPv6 group address of the multicast traffic.   P-group (32 bits): the IPv4 group address identifying the P-tunnel.   Data packets sent on this tunnel are encapsulated in IPv4 GRE packets   with this group address in the IP destination address field of the   outer header.3.2.  Encapsulation of S-PMSI Joins in UDP Datagrams   All S-PMSI Joins are encapsulated in UDP datagrams [RFC768].  A Type   4 S-PMSI Join MUST be encapsulated in an IPv6 UDP datagram.  The IPv6   source address field of these datagrams SHOULD be the IPv4-mapped   IPv6 address [RFC4291] corresponding to the IPv4 address that the   originating PE router uses as its source address in the instance of   PIM that is used to create the specified P-tunnel.   A single UDP datagram MAY carry multiple S-PMSI Join messages, as   many as can fit entirely within it.  If there are multiple S-PMSI   Joins in a UDP datagram, they MUST be of the same S-PMSI Join type.   The end of the last S-PMSI Join (as determined by the S-PMSI Join   length field) MUST coincide with the end of the UDP datagram, as   determined by the UDP length field.  When processing a received UDP   datagram that contains one or more S-PMSI Joins, a router MUST   process all the S-PMSI Joins that fit into the datagram.4.  PE-PE PIM/IPv6 over an IPv4 P-Tunnel   If a VPN customer is using PIM over IPv6, but the SP (service   provider) is using an IPv4 infrastructure (i.e., is using an   IPv4-based control protocol to construct its P-tunnels), then the PE   routers will need to originate IPv6 PIM control messages.  The IPv6   Source Address field of any such IPv6 PIM control message SHOULD be   the IPv4-mapped IPv6 address [RFC4291] corresponding to the IPv4   address that the originating PE router uses as its source address in   the instance of PIM that is used to create the specified P-tunnel.   If the IPv6 Destination Address field is the multicast address ALL-   PIM-ROUTERS, the IPv6 form of the address (ff02::d) is used.  These   IPv6 PIM control messages are, of course, not transmitted natively   over the service provider's network but rather are encapsulated in   GRE/IPv4.Cai, et al.                  Standards Track                    [Page 4]

RFC 6516                    IPv6 MVPN Support              February 20125.  IANA Considerations   [RFC6513] created an IANA registry for the "S-PMSI Join Message Type   Field".  This document registers a new value in that registry:      Value: 4      Description: GRE S-PMSI for IPv6 traffic (unaggregated)6.  Security Considerations   There are no additional security considerations beyond those of   [RFC6513].7.  Acknowledgments   The authors wish to thank DP Ayyadevara, Arjen Boers, Rayen Mohanty,   Rajesh Sharma, and Karthik Subramanian.8.  Normative References   [RFC768]  Postel, J., "User Datagram Protocol", STD 6,RFC 768,             August 1980.   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate             Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing             Architecture",RFC 4291, February 2006.   [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,             "Protocol Independent Multicast - Sparse Mode (PIM-SM):             Protocol Specification (Revised)",RFC 4601, August 2006.   [RFC6513] Rosen, E., Ed., and R. Aggarwal, Ed., "Multicast in             MPLS/BGP IP VPNs",RFC 6513, February 2012.Cai, et al.                  Standards Track                    [Page 5]

RFC 6516                    IPv6 MVPN Support              February 2012Authors' Addresses   Yiqun Cai   Cisco Systems, Inc.   170 Tasman Drive   San Jose, CA  95134   EMail: ycai@cisco.com   Eric C. Rosen (editor)   Cisco Systems, Inc.   1414 Massachusetts Avenue   Boxborough, MA  01719   EMail: erosen@cisco.com   IJsbrand Wijnands   Cisco Systems, Inc.   De kleetlaan 6a Diegem 1831   Belgium   EMail: ice@cisco.comCai, et al.                  Standards Track                    [Page 6]