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Versions: 00 01 02 03 04 05 06 RFC 5790

MBONED Working Group                                              H. Liu
Internet-Draft                                                    W. Cao
Expires: June, 2007                        Huawei Technologies Co., Ltd.
                                                               H. Asaeda
                                                         Keio University
                                                       December 19, 2006


                 Lightweight IGMPv3 and MLDv2 Protocols
          <draft-ietf-mboned-lightweight-igmpv3-mldv2-00.txt>

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
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Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document describes lightweight IGMPv3 and MLDv2 protocols (LW-
   IGMPv3 and LW-MLDv2), which simplify the standard (full) versions of
   IGMPv3 and MLDv2.  The interoperability with the full versions and
   the previous versions of IGMP and MLD is also taken into account.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
   NOT","SHOULD", "SHOULD NOT", "RECOMMENDED","MAY", and "OPTIONAL" in
   this document are to be interpreted as described in RFC 2119



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   [KEYWORDS].



Table of Contents

   1. Introduction ................................................... 2
   2. Simplification Method Overview ................................. 4
      2.1. Behavior of Group Members ................................. 4
      2.2. Behavior of Multicast Routers ............................. 4
   3. LW-IGMPv3 Protocol for Group Members ........................... 5
      3.1. Action on Change of Interface State ....................... 5
      3.2. Action on Reception of a Query ............................ 6
      3.3. Applicable Group Record Types ............................. 7
   4. LW-IGMPv3 Protocol for Multicast Routers ....................... 8
      4.1. Group Timers and Source Timers
           in the Lightweight Version ................................ 8
      4.2. Source-Specific Forwarding Rules .......................... 9
      4.3. Reception of Current-State Records ....................... 10
      4.4. Reception of Source-List-Change and
           Filter-Mode-Change Records ............................... 11
   5. Interoperability .............................................. 12
      5.1. Interoperation with the Full Version of IGMPv3 ........... 12
      5.2. Interoperation with IGMPv1/IGMPv2 ........................ 13
         5.2.1. Behavior of Group Members ........................... 13
         5.2.2. Behavior of Multicast Routers ....................... 13
   6. Implementation Considerations ................................. 13
      6.1. Implementation of Source-Specific Multicast .............. 14
      6.2. Implementation of Multicast Source Filter (MSF) APIs ..... 14
   7. Security Considerations ....................................... 14
   8. Normative References .......................................... 14
   9. Informative References ........................................ 15
   Intellectual Property Statement .................................. 16
   Disclaimer of Validity ........................................... 16
   Copyright Statement .............................................. 16
   Acknowledgment ................................................... 16



1. Introduction

   IGMP version 3 [IGMPv3] and MLD version 2 [MLDv2] implement source
   filtering capability that is not suported by their earlier versions
   IGMPv2 [IGMPv2] and MLDv1 [MLDv1].  An IGMPv3 or MLDv2 capable host
   can tell which group it would like to join to its upstream router
   with specifying which sources it does or does not intend to receive
   multicast traffic from.  IGMPv3 and MLDv2 add the capability for a
   multicast router to also learn which sources are of interest to



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   neighboring systems, for packets sent to any particular multicast
   address.

   The filter-modes are defined for the host and router parts of the
   protocols respectively to support the source filtering function.  If
   a receiver host wants to receive from specific sources, it sends an
   IGMPv3 or MLDv2 report with filter-mode set to INCLUDE.  If the host
   does not want to receive from some sources, it sends the report with
   filter-mode set to EXCLUDE.  A source list for the given sources
   shall be included in the report message.

   INCLUDE and EXCLUDE filter modes are also defined in a multicast
   router to process the IGMPv3 or MLDv2 reports.  When a multicast
   router receives the report messages from its downstream hosts, it
   forwards the corresponding multicast traffic by managing requested
   group and source addresses.  Group timer and source timer are used to
   maintain forwarding state of desired group and source.  A multicast
   router decides its filter-mode, type, and value of the timers and
   forwarding methods according to the specific rules when a group
   report message arrives or the timer expires.  The router then has to
   switch its filter-mode under certain conditions.  With all above
   factors correlating with each other, the determination rule becomes
   relatively complex as the interface states could be frequently
   changed.

   The multicast filter-mode improves the expressing ability of the
   multicast receiver.  It is useful to support Source-Specific
   Multicast (SSM) [SSM] by specifying interesting source addresses with
   INCLUDE mode.  However, practical applications do not use EXCLUDE
   mode to block sources so often, because a user or application usually
   wants to specify desired source addresses, not undesired source
   addresses to not receive from them.  Even if a user wants to
   explicitly refuse traffic from some sources in a group, when other
   users in the same shared network have interest in these sources, the
   corresponding multicast traffic is forwarded to the network after
   all.

   This document aims to propose the simplified IGMPv3 and MLDv2, being
   named Lightweight IGMPv3 and Lightweight MLDv2 (or LW-IGMPv3 and LW-
   MLDv2), in which EXCLUDE filter-mode that supports to exclude data
   come from specified sources is eliminated.  Not only LW-IGMPv3 and
   LW-MLDv2 are compatible with the standard IGMPv3 and MLDv2, but also
   the protocol operations made by data receiver hosts and routers or
   switches (performing IGMPv3/MLDv2 snooping) are simplified in the
   lightweight protocol and complicated operations are hence effectively
   reduced.  Since LW-IGMPv3 and LW-MLDv2 are fully compatible with the
   full version of these protocols (i.e. the standard IGMPv3 and MLDv2),
   hosts or routers that have implemented the full version do not need



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   to implement or modify anything to cooperate with LW-IGMPv3/LW-MLDv2
   hosts or routers.


2. Simplification Method Overview

   The principle is to simplify the host and router parts as much as
   possible to improve efficiency, while guaranteeing the
   interoperability with the full versions, and introducing no side
   effects on the applications.

   For convenience, this document mainly discusses IGMPv3 since MLDv2
   inherits the same source filtering mechanism, but additionally shows
   MLDv2's unique specifications when needed.

2.1. Behavior of Group Members

   In the LW-IGMPv3, the same service interface model as that of IGMPv3
   is inherited:

      IPMulticastListen ( socket, interface, multicast-address,
                          filter-mode, source-list )

   In the lightweight protocol, EXCLUDE mode on the host part is
   preserved only for EXCLUDE (*,G) join, which denotes non-source-
   specific group report (as known as (*,G) join) and is equivalent to
   the group membership join triggered by IGMPv2/IGMPv1/MLDv1.  The
   detailed host operation of LW-IGMPv3/LW-MLDv2 is described in section
   3.

2.2. Behavior of Multicast Routers

   According to [IGMPv3], router filter-mode is defined to optimize the
   state description of a group.  As a rule, once a member report is in
   EXCLUDE mode, the router filter-mode for the group will be set to
   EXCLUDE.  When all systems cease sending EXCLUDE mode reports, the
   filter-mode for that group may transit back to INCLUDE mode.  Group
   timer is used to identify such transition.

   In LW-IGMPv3, member reports carry mainly the INCLUDE mode
   information with only one exception for EXCLUDE (*,G), which means
   including all sources and can also be interpreted as INCLUDE mode.
   Without EXCLUDE mode report information, it is unnecessary for the
   router to maintain the EXCLUDE filter-mode, and the state model for
   multicast router can be simplified as:

      (multicast address, group timer, (source records))




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   Here group timer is kept to represent (*,G) group join.  Its basic
   behavior is: when a router receives a (*,G) group join, it will set
   its group timer, and the source list for the source-specific group
   will be kept.  As the group timer expires, the router may change to
   the reception for the listed sources.

   The elimination of the filter-mode will greatly simplify the router
   behavior, e.g. the action on reception of reports and the setting of
   the timers.  The detailed operation of router operation is described
   in section 4.


3. LW-IGMPv3 Protocol for Group Members

   LW-IGMPv3 uses two sets of messages, i.e., Query and Report messages,
   being the same as the full version protocols.  Although most of these
   message types and corresponding group records are inherited from the
   full version protocols, an operation that triggers EXCLUDE (S,G) join
   is omitted and the corresponding record types of the Report are
   modified on the lightweight protocols.

   There are three Group Record Types defined in the full IGMPv3:
   Current-State Record noted by MODE_IS_INCLUDE (referred to as IS_IN)
   or MODE_IS_EXCLUDE (IS_EX), Filter-Mode-Change Record noted by
   CHANGE_TO_INCLUDE_MODE (TO_IN) or CHANGE_TO_EXCLUDE_MODE (TO_EX), and
   Source-List-Change Record noted by ALLOW_NEW_SOURCES (ALLOW) or
   BLOCK_OLD_SOURCES (BLOCK).

3.1. Action on Change of Interface State

   When an interface state of a group member host is changed, a State-
   Change Report for that interface is immediately transmitted from that
   interface.  The type and contents of the Group Record(s) in that
   Report are determined by comparing the filter mode and source list
   for the affected multicast address before and after the change.
   While the requirements are the same as the full version for the
   computation, in the lightweight version host, the interface state
   change rules are simplified due to the reduction of message types.
   The contents of the new transmitted report are calculated as follows
   (Group Record Types are described in section 3.3):

       Old State        New State        State-Change Record Sent
       -----------      -----------      ------------------------

       INCLUDE (A)      INCLUDE (B)      ALLOW(B-A), BLOCK(A-B)

       INCLUDE (A)      EXCLUDE ()       IS_EX()




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       INCLUDE ()       EXCLUDE ()       IS_EX()

       EXCLUDE ()       INCLUDE (B)      TO_IN(B)

   To cover the possibility of the State-Change Report being missed by
   one or more multicast routers, it is retransmitted [Robustness
   Variable]-1 more times, at intervals chosen at random from the range
   (0, [Unsolicited Report Interval]).  (These values are defined in
   [IGMPv3, MLDv2].)

   In the full version of IGMPv3, as was done with the first report, the
   interface state for the affected group before and after the latest
   change is compared, and the report records expressing the difference
   are built and merged with the contents of the pending report, to
   create the new State-Change report.  However, it is optional that a
   LW-IGMPv3 host merges with the contents of the pending report.  If
   the LW-IGMPv3 host does not merge with the contents of the pending
   report, it transmits each report sequentially.  Doing so can greatly
   simplified the operation for scheduling the reports.

3.2. Action on Reception of a Query

   When a lightweight version host receives a Query, it does not respond
   immediately.  Instead, it delays its response by a random amount of
   time, bounded by the Max Resp Time value derived from the Max Resp
   Code in the received Query message [IGMPv3, MLDv2].  The system may
   receive a variety of Queries on different interfaces and of different
   kinds (e.g., General Queries, Group-Specific Queries, and Group-and-
   Source-Specific Queries), each of which may require its own delayed
   response.

   Before scheduling a response to a Query, the system must first
   consider previously scheduled pending responses and in many cases
   schedule a combined response.  Therefore, the lightweight version
   host must be able to maintain the following state:

   o A timer per interface for scheduling responses to General Queries.

   o A per-group and interface timer for scheduling responses to Group-
     Specific and Group-and-Source-Specific Queries.

   o A per-group and interface list of sources to be reported in the
     response to a Group-and-Source-Specific Query.

   LW-IGMPv3 inherits most of the rules that are used to determine if a
   Report needs to be scheduled from the full version.  The different
   point is regarding the simplification of EXCLUDE filter-mode and the
   type of Report to schedule as detailed in section 3.3.



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   While it is optional that a LW-IGMPv3 host merges with the contents
   of the pending report for unsolicited report (i.e. State-Change
   report) as mentioned in the previous section, if the received Query
   is a Group-and-Source-Specific Query and there is a pending response
   for this group with a non-empty source-list, then the group source
   list is augmented to contain the list of sources in the new Query and
   a single response is scheduled using the group timer as with the full
   version host.  The new response is then scheduled to be sent at the
   earliest of the remaining time for the pending report and the
   selected delay.

3.3. Applicable Group Record Types

   Among Group Record Types defined in the full IGMPv3, several record
   types are not used in LW-IGMPv3 as some of the processes related to
   the filter mode change to the EXCLUDE mode are eliminated and some of
   the report messages are converged with a record having null source
   address list.  All of the record types of report messages used by the
   full and lightweight version protocols are shown as follows:

      IGMPv3      LW-IGMPv3    Comments
      --------    ---------    -------------------------------------

      IS_EX()      IS_EX()     Query response for (*,G) join

      IS_EX(x)     N/A         Query response for EXCLUDE (x,G) join

      IS_IN(x)     ALLOW(x)    Query response for INCLUDE (x,G) join

      ALLOW(x)     ALLOW(x)    INCLUDE (x,G) join

      BLOCK(x)     BLOCK(x)    INCLUDE (x,G) leave

      TO_IN(x)     TO_IN(x)    Change to INCLUDE (x,G) join

      TO_IN()      TO_IN()     (*,G) leave

      TO_EX(x)     N/A         Change to EXCLUDE (x,G) join

      TO_EX()      IS_EX()     (*,G) join

   where "x" represents non-null source address list and "()" represents
   null source address list.  For instance, IS_EX() means a report whose
   record type is IS_EX with null source address list.  "N/A" represents
   not applicable (or no use) because the corresponding operation should
   not occur in the lightweight version protocols.

   LW-IGMPv3 does not use EXCLUDE filter-mode with non-null source



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   address list.  And a multicast router creates the same state when it
   receives a report message containing either of IS_EX or TO_EX record
   types.  Therefore, LW-IGMPv3 integrates the TO_EX operation to the
   IS_EX operation.

   When a LW-IGMPv3 host needs to make a query response for the state of
   INCLUDE (x,G) join, the host makes the response whose message type is
   expressed with ALLOW(x), instead of using IS_IN record type, for
   router's processing of the two messages are completely the same, the
   IS_IN(x) type is eliminated for simplification.

   A LW-IGMPv3 host does not use EXCLUDE mode, while TO_IN record is
   used with the following situation: the host firstly launches an
   application (AP1) that requests INCLUDE (x,G) join, and it sends
   ALLOW(x).  Then the host launches another application (AP2) that
   joins (*,G), and it sends IS_EX().  In this condition, when AP2
   terminates but AP1 keeps working on the lightweight version host, the
   host sends a report with TO_IN(x) record type for [Robustness
   Variable] times.


4. LW-IGMPv3 Protocol for Multicast Routers

   The major difference between the full and lightweight version
   protocol on the router is that filter-mode is discarded for the
   lightweight version, as section 2.2 mentioned.  Then the IGMP state
   maintained by the router for each attached network can be simplified
   as:

      (multicast address, group timer, (source records))

   where the source record includes pairs of source address and its
   corresponding source timer.  In this model, the filter-mode is
   omitted and the meaning of the group timer is redefined to implement
   simplified processing.

4.1. Group Timers and Source Timers in the Lightweight Version

   The source timer is kept for each source record and it is updated
   when the source is present in a received report.  It indicates the
   validity of the sources and needs to be referred when the router
   takes its forwarding decision.

   The group timer being used in the full version of IGMPv3 as a
   mechanism for transitioning the router's filter-mode from EXCLUDE to
   INCLUDE, is now redefined for the identification of the non-source-
   specific receiving states, i.e., (*,G)join.  Once a group record of
   IS_EX() is received, the group timer is used to represent this (*,G)



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   group join.  The expiration of the group timer indicates that there
   are no listeners on the attached network for this (*,G) group.  Then
   if at this moment there are unexpired sources (whose source timers
   are greater than zero), the router will change to receiving for those
   sources.  The role of the group timer can be summarized as follows:

       Group Timer Value      Actions/Comments
       ------------------     --------------------------------------

       G_Timer > 0            All members in this group.

       G_Timer == 0           No more listeners to this (*,G) group.
                              If all source timers have expired then
                              delete group record.  If there are
                              still source record timers running,
                              use those source records with running
                              timers as the source record state.

   The operation related to the group and source timers has some
   difference compared with the full IGMPv3.  In the full version, if a
   source timer expires under the EXCLUDE router filter-mode, its
   corresponding source record is not deleted until the group timer
   expires.  They are kept for indicating undesired sources.  In the
   lightweight version, since there is no need to keep such records for
   blocking specific sources, if a source timer expires, its source
   record should be deleted immediately, not waiting for the time-out of
   the group timer.

4.2. Source-Specific Forwarding Rules

   A multicast router needs to consult IGMPv3 state information when it
   makes decisions on forwarding a datagram from a source to its
   attached network. In the full IGMPv3, the router filter-mode and
   source timer are taken as the necessary judging conditions.  In LW-
   IGMPv3, because of the absence of the router filter-mode, the group
   timer and source timer could be used for such decisions.  The
   forwarding suggestion made by LW-IGMPv3 to the routing protocols can
   be summarized as follows:

       Group Timer    Source Timer          Action
       ------------   ------------------    -----------------------

       G_Timer == 0   S_TIMER > 0           Suggest to forward
                                            traffic from source

       G_Timer == 0   S_TIMER == 0          Suggest to stop
                                            forwarding traffic from
                                            source and remove



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                                            source record.  If there
                                            are no more source
                                            records for the group,
                                            delete group record

       G_Timer == 0   No Source Elements    Suggest not to forward
                                            traffic from the source

       G_Timer > 0    S_TIMER >= 0          Suggest to forward
                                            traffic from source

       G_Timer > 0    No Source Elements    Suggest to forward
                                            traffic from source

4.3. Reception of Current-State Records

   When receiving Current-State Records, the LW-IGMPv3 router resets its
   group or source timers and updates its source list within the group.
   For source-specific group reception state (G_Timer==0), the source
   list includes sources to be forwarded by the router, while in non-
   source-specific group reception (G_Timer>0) the source list remembers
   the sources to be forwarded after toggling to source-specific
   reception state.

   The following table describes the action taken by a multicast router
   after receiving Current-State Records.  The notations have the same
   meaning as that in the full IGMPv3.

                      Old                     New
                      Source                  Source
       Group Timer    List     Report Rec'd   List     Actions
       ------------   ------   ------------   ------   -----------

       G_Timer == 0     A       IS_IN(B)       A+B     (B)=GMI

       G_Timer == 0     A       IS_EX()         A      G_Timer=GMI

       G_Timer > 0      A       IS_IN(B)       A+B     (B)=GMI

       G_Timer > 0      A       IS_EX()         A      G_Timer=GMI

   And the above table could be further simplified for the processes
   that are completely same for the two values of the G_Timer:

       Old                      New
       Source                   Source
       List     Report Rec'd    List     Actions
       ------   ------------    ------   -----------



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         A       IS_IN(B)        A+B     (B)=GMI

         A       IS_EX()          A      G_Timer=GMI

   Without EXCLUDE filter-mode, a router's process on receiving Current-
   State Record is simple: when a router receives an IS_IN report, it
   appends the reported source addresses to the previous source list
   with their source timers set to GMI.  Upon receiving an IS_EX()
   report, the router sets the non-source-specific receiving states with
   GMI group timer value and keeps the previous source list without
   modification.

4.4. Reception of Source-List-Change and Filter-Mode-Change Records

   On receiving Source-List-Change and Filter-Mode-Change Records, the
   LW-IGMPv3 router needs to reset its group and source timers, update
   its source list within the group, or trigger group queries.  The
   queries are sent by the router for the sources that are requested to
   be no longer forwarded to a group.  The table below describes the
   state change and the actions that should be taken.

                      Old                     New
                      Source                  Source
       Group Timer    List     Report Rec'd   List     Actions
       ------------   ------   ------------   ------   -------------

       G_Timer == 0     A       ALLOW(B)       A+B     (B)=GMI

       G_Timer == 0     A       BLOCK(B)        A      Send Q(G,A*B)

       G_Timer == 0     A       TO_IN(B)       A+B     (B)=GMI
                                                       Send Q(G,A-B)

       G_Timer > 0      A       ALLOW(B)       A+B     (B)=GMI

       G_Timer > 0      A       BLOCK(B)        A      Send Q(G,A*B)

       G_Timer > 0      A       TO_IN(B)       A+B     (B)=GMI
                                                       SendQ(G,A-B)
                                                       Send Q(G)

   The table could be further simplified by merging duplicate lines:

       Old                     New
       Source                  Source
       List     Report Rec'd   List     Actions
       ------   ------------   ------   ----------------------




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         A       ALLOW(B)       A+B     (B)=GMI

         A       BLOCK(B)        A      Send Q(G,A*B)

         A       TO_IN(B)       A+B     (B)=GMI
                                        Send Q(G,A-B)
                                        If G_Timer>0 Send Q(G)


5. Interoperability

   LW-IGMPv3/LW-MLDv2 hosts and routers should interoperate gracefully
   with the full version protocols [IGMPv3, MLDv2].  Also, LW-IGMPv3/LW-
   MLDv2 hosts and routers should interoperate gracefully with hosts and
   routers running IGMPv1/v2 or MLDv1.

5.1. Interoperation with the Full Version of IGMPv3

   Eliminating EXCLUDE filter-mode from the full version protocols
   simplifies the processes inside the host and router.  On the other
   hand, LW-IGMPv3 does not introduce any change on the message format
   of the group query and report messages the full version protocols
   use.  Therefore, the group member sends a subset of IGMPv3 report
   messages, which can be recognized by a multicast router running the
   full or the lightweight IGMPv3 protocol on the same LAN.

   A LW-IGMPv3 router translates IS_EX(x) and TO_EX(x) records that are
   used with the full IGMPv3 but not used with LW-IGMPv3. When a LW-
   IGMPv3 router receives these report messages from the full version
   host, it translates them to IS_EX() records and makes the
   corresponding behavior.  All possible record types are compared as
   follows:

       IGMPv3 Report         LW-IGMPv3 Equivalent
       -------------         --------------------

          IS_IN(x)                 IS_IN(x)

          IS_EX(x)                 IS_EX()

          TO_IN(x)                 TO_IN(x)

          TO_EX(x)                 IS_EX()

          ALLOW(x)                 ALLOW(x)

          BLOCK(x)                 BLOCK(x)




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5.2. Interoperation with IGMPv1/IGMPv2

   The LW-IGMPv3 protocol basically adopts the same Host/Group
   Compatibility Mode and keeps Querier Present timers for IGMPv1 and
   IGMPv2.  Their definition and processing is the same as that of
   IGMPv3.

5.2.1. Behavior of Group Members

   A host's compatibility mode is determined from the Host Compatibility
   Mode variable which can be in one of three states: IGMPv1, IGMPv2 or
   IGMPv3.  The Host Compatibility Mode of an interface is set to IGMPv2
   and IGMPv2 Querier Present is set to Older Version Querier Present
   Timeout second (defined in [IGMPv3]) whenever an IGMPv2 General Query
   is received on that interface.  The Host Compatibility Mode of an
   interface is set to IGMPv1 and IGMPv1 Querier Present is set to Older
   Version Querier Present Timeout second whenever an IGMPv1 Membership
   Query is received on that interface.  Based on the Host Compatibility
   Mode variable, a host acts using the IGMPv3, IGMPv2, or IGMPv1
   protocol on that interface

   While above manner is inherited from the definition of [IGMPv3], LW-
   IGMPv3 may enable to configure the Host Compatibility Mode variable
   by other means: when a LW-IGMPv3 host is placed on a link where there
   are IGMPv1/IGMPv2 hosts, a host may allow its IGMPv3 report message
   to be suppressed by an IGMPv1 or IGMPv2 report message.

5.2.2. Behavior of Multicast Routers

   When Group Compatibility mode is IGMPv2 or IGMPv1, a LW-IGMPv3 router
   translates the following IGMPv2 or IGMPv1 messages for that group to
   their IGMPv2 or IGMPv1 equivalents:

       IGMP Message          LW-IGMPv3 Equivalent
       -------------         --------------------

         v1 Report                 IS_EX()

         v2 Report                 IS_EX()

         v2 Leave                  TO_IN()


6. Implementation Considerations

   The lightweight protocols requires no additional burden on the
   implementation of the related protocols or systems, e.g. IGMP/MLD
   snooping, multicast routing protocol, and operation of application



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   sockets, while the processing loads on the switches and routers that
   running IGMPv3 (snooping) and multicast routing protocols could be
   greatly decreased.

   In the following sections, the implementation related topics are
   described for the lightweight version protocols.

6.1. Implementation of Source-Specific Multicast

   [IGMP-SSM] illustrates the requirements of implementation of Source-
   Specific Multicast (SSM) on IGMPv3/MLDv2 hosts and routers.  The
   lightweight protocol does not impose any bad influences on an SSM
   application.  The requirements of LW-IGMPv3/LW-MLDv2 for supporting
   SSM are illustrated below.

   A LW-IGMPv3/LW-MLDv2 host should not send a non-source-specific join,
   i.e. IS_EX(), and IGMPv2 Leave and MLDv1 Done messages for the
   application whose multicast address is in the SSM address range.  The
   reception of a non-source-specific join with an SSM group address
   should indicate an error to the application.  The SSM-aware router
   will ignore IS_EX() reports with SSM addresses.  Other types of
   Reports should be processed normally.

6.2. Implementation of Multicast Source Filter (MSF) APIs

   Multicast Source Filter (MSF) APIs [MSF] defines (1) IPv4 Basic MSF
   API, (2) IPv4 Advanced MSF API, (3) Protocol-Independent Basic MSF
   API, and (4) Protocol-Independent Advanced MSF API.

   According to the MSF APIs definition, a LW-IGMPv3 host should
   implement at least one of IPv4 Basic MSF API and Protocol-Independent
   Basic MSF API, and a LW-MLDv2 host should implement Protocol-
   Independent Basic MSF API.  Other APIs, IPv4 Advanced MSF API and
   Protocol-Independent Advanced MSF API, are optional to implement in
   LW-IGMPv3/LW-MLDv2 host.


7. Security Considerations

   The security consideration is the same as that of the full version of
   IGMPv3/MLDv2.


8 Normative References

   [KEYWORDS] Bradner, S., "Key words for use in RFCs to indicate
       requirement levels," RFC 2119, March 1997.




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   [IGMPv3] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and
       Thyagarajan, A., "Internet Group Management Protocol, Version3,"
       RFC 3376, October 2002.

   [MLDv2] Vida, R. and Costa, L., "Multicast Listener Discovery Version
       2 (MLDv2) for IPv6," RFC 3810, June 2004.


9 Informative References

   [SSM] Holbrook, H. and Cain, B., "Source-Specific Multicast for IP,"
       RFC 4607, August 2006.

   [IGMPv2] Fenner, W., "Internet Group Management Protocol, Version 2,"
       RFC 2236, November 1997.

   [MLDv1] Deering, S., Fenner, W., and Haberman, B., "Multicast
       Listener Discovery (MLD) for IPv6," RFC 2710, October 1999.

   [IGMP-SSM] Holbrook, H., Cain, B., and Haberman, B., "Using Internet
       Group Management Protocol Version 3 (IGMPv3) and Multicast
       Listener Discovery Protocol Version 2 (MLDv2) for Source-Specific
       Multicast," RFC 4604, August 2006.

   [MSF] Thaler, D., Fenner, B., and Quinn, B., "Socket Interface
       Extensions for Multicast Source Filters," RFC 3678, January 2004.


Author's Addressess

   Hui Liu
   Huawei Technologies Co., Ltd.
   Huawei Bld., No.3 Xinxi Rd.,
   Shang-Di Information Industry Base,
   Hai-Dian Distinct, Beijing 100085,
   China

   Email: Liuhui47967@huawei.com


   Wei Cao
   Huawei Technologies Co., Ltd.
   Huawei Bld., No.3 Xinxi Rd.,
   Shang-Di Information Industry Base,
   Hai-Dian Distinct, Beijing 100085,
   China

   Email: caowayne@huawei.com



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   Hitoshi Asaeda
   Graduate School of Media and Governance
   Keio University
   5322 Endo, Fujisawa, Kanagawa 252-8520,
   Japan

   Email: asaeda@wide.ad.jp


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Copyright Statement

   Copyright (C) The Internet Society (2006).



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   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.


Acknowledgment

   The author would like to thank magma and mboned mailing lists for
   discussion and contribution for the ideas.










































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