Internet Group Management Protocol Version 3 (IGMPv3) / Multicast Listener Discovery Version 2 (MLDv2) and Multicast Routing Protocol Interaction
RFC 5186

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Network Working Group                                        B. Haberman
Request for Comments: 5186                      Johns Hopkins University
Category: Informational                                        J. Martin
                                                           Woven Systems
                                                                May 2008

        Internet Group Management Protocol Version 3 (IGMPv3) /
          Multicast Listener Discovery Version 2 (MLDv2) and
                 Multicast Routing Protocol Interaction

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Abstract

   The definitions of the Internet Group Management Protocol Version 3
   (IGMPv3) and Multicast Listener Discovery Version 2 (MLDv2) require
   new behavior within the multicast routing protocols.  The additional
   source information contained in IGMPv3 and MLDv2 messages
   necessitates that multicast routing protocols manage and utilize the
   information.  This document describes how multicast routing protocols
   will interact with these source-filtering group management protocols.

1.  Introduction

   The definitions of IGMPv3 [IGMP3] and MLDv2 [MLDv2] require new
   behavior within the multicast routing protocols.  The additional
   source information contained in IGMPv3 and MLDv2 messages
   necessitates that multicast routing protocols manage and utilize the
   information.  This document will describe how multicast routing
   protocols will interpret information learned from these source-
   filtering group management protocols.

2.  Multicast Forwarding State

   Existing multicast routing protocols utilize the group management
   database in determining if local members exist for a particular
   multicast group.  With previous group management protocols, this
   database had one type of record indicating the group for which there
   was interest and the associated local interfaces.

Haberman & Martin            Informational                      [Page 1]
RFC 5186          IGMPv3/MLDv2 and Multicast Protocols          May 2008

   In the case of IGMPv3 and MLDv2, these routing protocols may now
   build multicast forwarding state based on the source filter
   information available for each multicast group that has local
   membership.  This requires that the group management database have
   four record types.  Only one record may exist for a given interface
   and a given multicast group.

      1. EXCLUDE <>
         The EXCLUDE <> record indicates interest in all sources
         destined to this group address for a set of local interfaces.
         It is equivalent to the single record type existing in previous
         versions of the group management protocols.

      2. INCLUDE <>
         The INCLUDE <> record indicates that there is no interest in
         any sources destined to this group address for a set of local
         interfaces.

      3. EXCLUDE <list>
         The EXCLUDE <list> record indicates that there is interest in
         all sources other than the specifically listed sources for a
         set of local interfaces.

      4. INCLUDE <list>
         The INCLUDE <list> record indicates that there is interest in
         only the specifically listed sources for a set of local
         interfaces.

   The records in the group management database should be utilized when
   generating forwarding state for a multicast group.  If the source
   address in the multicast packet exists in the database for the
   specified multicast group and is in an INCLUDE list or is not listed
   in an EXCLUDE list, the multicast routing protocol should add the
   interface to the list of downstream interfaces; otherwise, it should
   not be added based on local group membership.

3.  DVMRP Interaction

   The Distance Vector Multicast Routing Protocol (DVMRP) [DVMRP] does
   not incorporate any knowledge of the multicast group's senders.
   Therefore, DVMRP will act only on the multicast group address
   contained in an IGMPv3 or MLDv2 report.

   Future standardized versions of DVMRP may incorporate pruning and
   grafting messages similar to PIM-DM (discussed in Section 5).  The
   rules defined in Section 5 can be applied in this situation.

Haberman & Martin            Informational                      [Page 2]
RFC 5186          IGMPv3/MLDv2 and Multicast Protocols          May 2008

4.  MOSPF Interaction

   In Multicast Extensions to OSPF (MOSPF) [MOSPF], the consideration of
   source filter information in the group management database is limited
   to the building of forwarding state (discussed above).  This is due
   to the flooding of group-membership-LSAs within MOSPF.

5.  PIM-DM Interaction

   The PIM-DM protocol [PIMDM] interaction with a source-filtering group
   management protocol is important in two areas: multicast distribution