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Versions: 02 03 04 05 rfc5186                              Informational
   MAGMA Working Group                                         B. Haberman
   Internet Draft                                         Caspian Networks
   draft-ietf-magma-igmpv3-and-routing-05.txt                    J. Martin
   October 2003                                                Netzwert AG
   Expires April 2004


        IGMPv3/MLDv2 and Multicast Routing Protocol Interaction


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026 [RFC 2026].

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that
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   The list of current Internet-Drafts can be accessed at
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   The list of Internet-Draft Shadow Directories can be accessed at
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Abstract

   The definitions of IGMPv3 and MLDv2 require new behavior within the
   multicast routing protocols.  The additional source information
   contained in IGMPv3 and MLDv2 messages necessitates multicast
   routing protocols to 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 multicast routing protocols to 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


Haberman, Martin                                                     1


Internet Draft   IGMPv3/MLDv2 and Multicast Protocols     October 2003

   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.

   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 the group management database to 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
        only 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 DVMRP protocol[DVMRP] interaction with a source-filtering group
   management protocol is important in two areas: multicast
   distribution tree pruning and multicast distribution tree grafting.
   The following sections will describe the behavior needed in DVMRP to
   interoperate with IGMPv3 and MLDv2.


  3.1  DVMRP Prunes



Haberman, Martin                                                     2


Internet Draft   IGMPv3/MLDv2 and Multicast Protocols     October 2003

   DVMRP prune messages are initiated when a DVMRP router determines
   that there are no entities interested in the data flowing on the
   (S,G) forwarding state.  If the multicast router is running IGMPv3
   or MLDv2, this is determined by the source S being in EXCLUDE state
   in the source filter for the destination G or all interest in G
   being terminated for an existing (S,G) forwarding entry.

  3.2  DVMRP Grafts

   DVMRP graft messages are sent in order to override an existing DVMRP
   prune.  In the case of IGMPv3 or MLDv2, this occurs when prune state
   exists for (S,G) and a state change occurs in which the source
   filter state for S changes to INCLUDE for the specified G.


4. MOSPF Interaction

   In 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

   Like DVMRP, PIM-DM[PIMDM] must utilize the source filter information
   when generating Prune and Graft messages.  The following sections
   describe the creation of these message types.


  5.1  PIM-DM Prunes

   PIM-DM prune messages are initiated when a PIM-DM router determines
   that there are no entities interested in the data flowing on the
   (S,G) forwarding state.  If the multicast router is running IGMPv3
   or MLDv2, this is determined by the source S being in EXCLUDE state
   in the source filter for the destination G or all interest in G
   being terminated for an existing (S,G) forwarding entry.


  5.2  PIM-DM Grafts

   PIM-DM graft messages are sent in order to override an existing PIM-
   DM prune.  In the case of IGMPv3 or MLDv2, this occurs when prune
   state exists for (S,G) and a state change occurs in which the source
   filter state for S changes to INCLUDE for the specified G.


6. PIM-SM Interaction

   A PIM-SM interaction takes place when a PM-SM[PIMSM] router receives
   an IGMP or MLD message regarding a group address that is in the Any

Haberman, Martin                                                     3


Internet Draft   IGMPv3/MLDv2 and Multicast Protocols     October 2003

   Source Multicast (ASM) range. This range is defined as the entire
   multicast address space excluding the global SSM range [SSM] and any
   locally defined Source Specific space.


  6.1  PIM-SM Joins (ASM Behavior)

   PIM-SM join messages are initiated when a PIM-SM router determines
   that there are entities interested in a specific group or a specific
   source sending to the group. If this is due to a IGMPv3 or MLDv2
   report with a zero-length EXCLUDE list, then the join is sent as a
   (*,G) join towards the RP.

   If the join is triggered by an IGMPv3 or MLDv2 state change that
   affects source information, the PIM-SM join is sent as a (S,G) join
   towards the specific source. This behavior optimizes the join
   process, as well as facilitates the adoption of the SSM model. The
   generation of this (S,G) join can cause failures in architectures
   where leaf routers do not have global reachability, and thus, can be
   overridden by local policy. If this is the case, then all triggered
   joins are sent towards the RP as (*,G) joins. The router sending the
   (*,G) join is responsible for filtering the data as per the IGMPv3
   database before forwarding.


  6.2  PIM-SM Prunes (ASM Behavior)

   PIM-SM prune messages are initiated when a PIM-SM router determines
   that there are no entities interested in a specific group, or a
   specific source sending to the group. If this is triggered by either
   receiving a report with an EXCLUDE or if a specific Source/Group
   times out, then an (S,G) prune is sent towards the upstream router.
   If all of the IGMPv3 or MLDv2 derived requests for a group time out,
   then (S,G) and (*,G) prunes are sent upstream as needed to stop all
   flow of traffic for that group.


7. PIM-SSM Interaction

   A PIM-SSM interaction takes place when a PIM-SM router receives an
   IGMPv3 or MLDv2 message regarding a group address that is in the
   Source Specific Multicast range. This behavior is not defined in
   this document, but rather in [PIMSM].


8. Security Considerations

   This document does not introduce any additional security issues
   above and beyond those already discussed in [PIMSM], [IGMP3], and
   [MLDv2].



Haberman, Martin                                                     4


Internet Draft   IGMPv3/MLDv2 and Multicast Protocols     October 2003

9. Acknowledgements

   The authors would like to thank Murali Brahmadesam, Leonard
   Giuliano, and Hal Sandick for their feedback and suggestions.


10. Authors' Addresses

   Brian Haberman
   Caspian Networks
   753 Bridgewater Drive
   Sykesville, MD  21784

   brian@innovationslab.net
   +1-410-552-1421


   Jim Martin
   Netzwert AG
   An den Treptowers 1
   D-12435 Berlin

   jim@Netzwert.AG
   +49.30/5 900 800-180


11. References
  11.1 Normative References
   [IGMP3] B. Cain, et al, "Internet Group Management Protocol, Version
           3", RFC 3376, October 2002.

   [MLDv2] R. Vida, et al., “Multicast Listener Discovery Version 2
           (MLDv2) for IPv6”, work in progress.

   [DVMRP] T. Pusateri, "Distance Vector Multicast Routing Protocol",
           work in progress.

   [MOSPF] J. Moy, "Multicast Extensions to OSPF", RFC 1584, March
           1994.

   [PIMDM] A. Adams, et al, "Protocol Independent Multicast - Dense
           Mode: Protocol Specification (Revised)", work in progress.

   [PIMSM] B.Fenner, et al, "Protocol Independent Multicast -Sparse
           Mode (PIM-SM): Protocol Specification (Revised)", work in
           progress.

   [SSM]   H. Holbrook, et al, "Source-Specific Multicast for IP", work
           in progress.




Haberman, Martin                                                     5


Internet Draft   IGMPv3/MLDv2 and Multicast Protocols     October 2003

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   This document expires in April, 2004.








Haberman, Martin                                                     6