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Network Working Group                                        B. HabermanRequest for Comments: 5186                      Johns Hopkins UniversityCategory: Informational                                        J. Martin                                                           Woven Systems                                                                May 2008Internet Group Management Protocol Version 3 (IGMPv3) /Multicast Listener Discovery Version 2 (MLDv2) andMulticast Routing Protocol InteractionStatus 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 inSection 5).  The   rules defined inSection 5 can be applied in this situation.Haberman & Martin            Informational                      [Page 2]

RFC 5186          IGMPv3/MLDv2 and Multicast Protocols          May 20084.  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   tree pruning and multicast distribution tree grafting.  The following   sections will describe the behavior needed in PIM-DM to interoperate   with IGMPv3 and MLDv2.5.1.  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   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.Haberman & Martin            Informational                      [Page 3]

RFC 5186          IGMPv3/MLDv2 and Multicast Protocols          May 20086.1.  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 an 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 [PIMDM], [PIMSM], [IGMP3], and   [MLDv2].9.  Acknowledgements   The authors would like to thank Murali Brahmadesam, Leonard Giuliano,   and Hal Sandick for their feedback and suggestions.Haberman & Martin            Informational                      [Page 4]

RFC 5186          IGMPv3/MLDv2 and Multicast Protocols          May 200810.  Normative References   [IGMP3] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.           Thyagarajan, "Internet Group Management Protocol, Version 3",RFC 3376, October 2002.   [MLDv2] Vida, R., Ed., and L. Costa, Ed., "Multicast Listener           Discovery Version 2 (MLDv2) for IPv6",RFC 3810, June 2004.   [DVMRP] Waitzman, D., Partridge, C., and S. Deering, "Distance Vector           Multicast Routing Protocol",RFC 1075, November 1988.   [MOSPF] Moy, J., "Multicast Extensions to OSPF",RFC 1584, March           1994.   [PIMDM] Adams, A., Nicholas, J., and W. Siadak, "Protocol Independent           Multicast - Dense Mode (PIM-DM): Protocol Specification           (Revised)",RFC 3973, January 2005.   [PIMSM] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,           "Protocol Independent Multicast - Sparse Mode (PIM-SM):           Protocol Specification (Revised)",RFC 4601, August 2006.   [SSM]   Holbrook, H. and B. Cain, "Source-Specific Multicast for IP",RFC 4607, August 2006.Authors' Addresses   Brian Haberman   The Johns Hopkins University Applied Physics Laboratory   11100 Johns Hopkins Road   Laurel, MD  20723-6099   US   Phone: +1 443 778 1319   EMail: brian@innovationslab.net   Jim Martin   Woven Systems   2455 Augustine Drive, Suite 211   Santa Clara, CA  95054   US   Phone: +1 408 654-8143   EMail: jim@wovensystems.comHaberman & Martin            Informational                      [Page 5]

RFC 5186          IGMPv3/MLDv2 and Multicast Protocols          May 2008Full Copyright Statement   Copyright (C) The IETF Trust (2008).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Haberman & Martin            Informational                      [Page 6]