RFC 6516

IPv6 Multicast VPN (MVPN) Support Using PIM Control Plane and Selective Provider Multicast Service Interface (S-PMSI) Join Messages

📅 published February 2012, from ietf

RFC 6516 💖

Okay bestie, this is RFC 6516 🎀, an IETF doc from February 2012. The authors are Y. Cai, E. Rosen (Ed.), and IJ. Wijnands, all from Cisco Systems. It's Standards Track 🦋 with ISSN 2070-1721. It doesn't list anything it obsoletes or updates, but it does extend RFC 6513 (the MVPN spec) ✨.

Title: IPv6 Multicast VPN (MVPN) Support Using PIM Control Plane and Selective Provider Multicast Service Interface (S-PMSI) Join Messages 🌈

Abstract ✨

okay so the MVPN spec has an option to use PIM as the control protocol between provider edge routers 🌸. It also has an option where UDP-based messages, called S-PMSI Join messages, bind particular customer multicast flows to particular tunnels through a service provider's network 💅. This doc extends RFC 6513 so both options work when the customer multicast flows are IPv6 🦋.

Status of This Memo 📜

This is an Internet Standards Track document 💜.

It's a product of the Internet Engineering Task Force (IETF) 🌸. It represents the consensus of the IETF community, got public review, and was approved for publication by the Internet Engineering Steering Group (IESG) 👑. More info on Internet Standards is in Section 2 of RFC 5741 🍓.

For the current status, any errata, and how to give feedback, go to http://www.rfc-editor.org/info/rfc6516 🔥.

Copyright Notice 🌈

This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as in effect on the publication date. Please read these carefully, because they describe your rights and restrictions for this document 🫶. Code Components extracted from this document has to include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Simplified BSD License 💀.

Table of Contents 🗺️

1. Introduction ....................................................2
2. Specification of Requirements ...................................3
3. S-PMSI Joins Binding IPv6 Flows to GRE/IPv4 P-Tunnels ...........3
   3.1. Encoding ...................................................3
   3.2. Encapsulation of S-PMSI Joins in UDP Datagrams .............4
4. PE-PE PIM/IPv6 over an IPv4 P-Tunnel ............................4
5. IANA Considerations .............................................5
6. Security Considerations .........................................5
7. Acknowledgments .................................................5
8. Normative References ............................................5

1. Introduction 🌸

okay so the MVPN spec [RFC6513] defines the notion of a "PMSI" (Provider Multicast Service Interface) and explains how a PMSI can be built by different kinds of tunnels through a service provider's network, called "P-tunnels" 🧚. It also lays out the procedures for using PIM (Protocol Independent Multicast [RFC4601]) as the control protocol between Provider Edge (PE) routers 💅. When PIM is the control protocol, PIM messages get sent through a P-tunnel from one PE in an MVPN to the others in that same MVPN ✨. These PIM messages carry customer multicast routing information 🦋. The tea though: [RFC6513] doesn't 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 spec [RFC6513] also specifies "S-PMSI (Selective PMSI) Join" messages 🎀. They're optionally used to bind particular customer multicast flows to particular P-tunnels 🫶. But the spec doesn't cover the case where the customer flows are IPv6 flows 🙈.

So this doc extends [RFC6513] by adding the spec 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 👑. It also explains how to send multiple S-PMSI Join messages in a single UDP datagram 🌈.

This doc uses terminology defined in [RFC6513]: C-source, C-group, C-flow, P-group, and (C-S,C-G) 💜.

2. 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 in Section 7.4.2.2 of [RFC6513] ✨. These messages have a type field, and [RFC6513] only defines 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's created by PIM/IPv4 🦋. To send data or control packets over that P-tunnel, the packets get encapsulated in GRE (Generic Routing Encapsulation) within IPv4, as specified in Section 12 of [RFC6513] 🌸.

In this doc, 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's 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                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Here's the breakdown 🧁:

Type (8 bits): 4
Length (16 bits): 40. This is the length in octets of the entire S-PMSI Join message, including the Type, Length, Reserved, C-source, C-group, and P-group fields 💜.
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] that matches the IPv4 address the originating PE router uses as its source address in the PIM instance that creates 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 one 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 a router processes a received UDP datagram that contains one or more S-PMSI Joins, it 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 on an IPv4 infrastructure (meaning it uses an IPv4-based control protocol to build 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] that matches the IPv4 address the originating PE router uses as its source address in the PIM instance that creates the specified P-tunnel 🦋. If the IPv6 Destination Address field is the multicast address ALL-PIM-ROUTERS, the IPv6 form of that address (ff02::d) is used 🍓. These IPv6 PIM control messages are, of course, not sent natively over the service provider's network. They get encapsulated in GRE/IPv4 instead 💜.

5. 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] 🔥. Still, don't skip [RFC6513]'s security section, because it's the whole story here 🙈.

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 👑.

Authors' 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.com

📦 where this page comes from

ietf: rfc6516 2012-02
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