Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address
RFC 3956

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Network Working Group                                          P. Savola
Request for Comments: 3956                                     CSC/FUNET
Updates: 3306                                                B. Haberman
Category: Standards Track                                        JHU APL
                                                           November 2004

              Embedding the Rendezvous Point (RP) Address
                      in an IPv6 Multicast 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.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This memo defines an address allocation policy in which the address
   of the Rendezvous Point (RP) is encoded in an IPv6 multicast group
   address.  For Protocol Independent Multicast - Sparse Mode (PIM-SM),
   this can be seen as a specification of a group-to-RP mapping
   mechanism.  This allows an easy deployment of scalable inter-domain
   multicast and simplifies the intra-domain multicast configuration as
   well.  This memo updates the addressing format presented in RFC 3306.

Table of Contents

   1.  Introduction  ...............................................   2
       1.1.  Background ............................................   2
       1.2.  Solution  .............................................   2
       1.3.  Assumptions and Scope .................................   3
       1.4.  Terminology  ..........................................   4
       1.5.  Abbreviations  ........................................   4
   2.  Unicast-Prefix-based Address Format  ........................   4
   3.  Modified Unicast-Prefix-based Address Format  ...............   5
   4.  Embedding the Address of the RP in the Multicast Address  ...   5
   5.  Examples  ...................................................   7
       5.1.  Example 1  ............................................   7
       5.2.  Example 2  ............................................   7
       5.3.  Example 3  ............................................   8
       5.4.  Example 4  ............................................   8

Savola & Haberman           Standards Track                     [Page 1]
RFC 3956        The RP Address in IPv6 Multicast Address   November 2004

   6.  Operational Considerations  .................................   8
       6.1.  RP Redundancy .........................................   8
       6.2.  RP Deployment  ........................................   9
       6.3.  Guidelines for Assigning IPv6 Addresses to RPs ........   9
       6.4.  Use as a Substitute for BSR ...........................   9
       6.5.  Controlling the Use of RPs ............................   9
   7.  The Embedded-RP Group-to-RP Mapping Mechanism  ..............  10
       7.1.  PIM-SM Group-to-RP Mapping ............................  10
       7.2.  Overview of the Model .................................  11
   8.  Scalability Analysis  .......................................  12
   9.  Acknowledgements  ...........................................  13
   10. Security Considerations .....................................  13
   11. References ..................................................  15
       11.1. Normative References ..................................  15
       11.2. Informative References ................................  15
   A.  Discussion about Design Tradeoffs ...........................  16
   Authors' Addresses ..............................................  17
   Full Copyright Statement ......................................... 18

1.  Introduction

1.1.  Background

   As has been noticed [V6MISSUES], there exists a deployment problem
   with global, interdomain IPv6 multicast: PIM-SM [PIM-SM] RPs have no
   way of communicating the information about (active) multicast sources
   to other multicast domains, as Multicast Source Discovery Protocol
   (MSDP) [MSDP] has deliberately not been specified for IPv6.
   Therefore the whole interdomain Any Source Multicast (ASM) model is
   rendered unusable; Source-Specific Multicast (SSM) [SSM] avoids these
   problems but is not a complete solution for several reasons, as noted
   below.

   Further, it has been noted that there are some problems with the
   support and deployment of mechanisms SSM would require [V6MISSUES]:
   it seems unlikely that SSM could be usable as the only interdomain
   multicast routing mechanism in the short term.

1.2.  Solution

   This memo describes a multicast address allocation policy in which
   the address of the RP is encoded in the IPv6 multicast group address,
   and specifies a PIM-SM group-to-RP mapping to use the encoding,