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PIM Group-to-Rendezvous-Point Mapping
RFC 6226

Internet Engineering Task Force (IETF)                          B. Joshi
Request for Comments: 6226                     Infosys Technologies Ltd.
Updates: 4601                                                 A. Kessler
Category: Standards Track                            Cisco Systems, Inc.
ISSN: 2070-1721                                              D. McWalter
                                                                May 2011

                 PIM Group-to-Rendezvous-Point Mapping

Abstract

   Each Protocol Independent Multicast - Sparse Mode (PIM-SM) router in
   a PIM domain that supports Any Source Multicast (ASM) maintains
   Group-to-RP mappings that are used to identify a Rendezvous Point
   (RP) for a specific multicast group.  PIM-SM has defined an algorithm
   to choose a RP from the Group-to-RP mappings learned using various
   mechanisms.  This algorithm does not consider the PIM mode and the
   mechanism through which a Group-to-RP mapping was learned.

   This document defines a standard algorithm to deterministically
   choose between several Group-to-RP mappings for a specific group.
   This document first explains the requirements to extend the Group-to-
   RP mapping algorithm and then proposes the new algorithm.

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 in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6226.

Joshi, et al.                Standards Track                    [Page 1]
RFC 6226                 PIM Group-to-RP Mapping                May 2011

Copyright Notice

   Copyright (c) 2011 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
   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. Terminology .....................................................3
   3. Existing Algorithm ..............................................4
   4. Assumptions .....................................................5
   5. Common Use Cases ................................................5
   6. Proposed Algorithm ..............................................6
   7. Interpretation of MIB Objects ...................................8
   8. Clarification for MIB Objects ...................................8
   9. Use of Dynamic Group-to-RP Mapping Protocols ....................9
   10. Considerations for Bidirectional-PIM and BSR Hash ..............9
   11. Filtering Group-to-RP Mappings at Domain Boundaries ............9
   12. Security Considerations .......................................10
   13. Acknowledgements ..............................................10
   14. Normative References ..........................................10

1.  Introduction

   Multiple mechanisms exist today to create and distribute Group-to-RP
   mappings.  Each PIM-SM router may learn Group-to-RP mappings through
   various mechanisms, as described in Section 4.

   It is critical that each router select the same 'RP' for a specific
   multicast group address; otherwise, full multicast connectivity will
   not be established.  This is true even when using an Anycast RP to
   provide redundancy.  This RP address may correspond to a different
   physical router, but it is one logical RP address and must be
   consistent across the PIM domain.  This is usually achieved by using
   the same algorithm to select the RP in all the PIM routers in a
   domain.

Joshi, et al.                Standards Track                    [Page 2]
RFC 6226                 PIM Group-to-RP Mapping                May 2011

   PIM-SM [RFC4601] has defined an algorithm to select a 'RP' for a
   given multicast group address, but it is not flexible enough for an
   administrator to apply various policies.  Please refer to Section 3

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