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Versions: (draft-schmidt-multimob-fmipv6-pfmipv6-multicast) 00 01 02 03 04 05 06 07

MULTIMOB Group                                           T. Schmidt, Ed.
Internet-Draft                                               HAW Hamburg
Updates: 5568 (if approved)                                 M. Waehlisch
Intended status: Experimental                       link-lab & FU Berlin
Expires: September 20, 2014                                    R. Koodli
                                                                   Intel
                                                            G. Fairhurst
                                                  University of Aberdeen
                                                             Dapeng. Liu
                                                            China Mobile
                                                          March 19, 2014


   Multicast Listener Extensions for MIPv6 and PMIPv6 Fast Handovers
            draft-ietf-multimob-fmipv6-pfmipv6-multicast-05

Abstract

   Fast handover protocols for MIPv6 and PMIPv6 define mobility
   management procedures that support unicast communication at reduced
   handover latency.  Fast handover base operations do not affect
   multicast communication, and hence do not accelerate handover
   management for native multicast listeners.  Many multicast
   applications like IPTV or conferencing, though, comprise delay-
   sensitive real-time traffic and will benefit from fast handover
   completion.  This document specifies extension of the Mobile IPv6
   Fast Handovers (FMIPv6) and the Fast Handovers for Proxy Mobile IPv6
   (PFMIPv6) protocols to include multicast traffic management in fast
   handover operations.  This multicast support is provided first at the
   control plane by a management of rapid context transfer between
   access routers, second at the data plane by an optional fast traffic
   forwarding that may include buffering.  An FMIPv6 access router
   indicates support for multicast using an updated Proxy Router
   Advertisements message format.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any




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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 20, 2014.

Copyright Notice

   Copyright (c) 2014 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Use Cases and Deployment Scenarios  . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Protocol Overview . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Multicast Context Transfer between Access Routers . . . .   6
     3.2.  Protocol Operations Specific to FMIPv6  . . . . . . . . .   8
     3.3.  Protocol Operations Specific to PFMIPv6 . . . . . . . . .  10
   4.  Protocol Details  . . . . . . . . . . . . . . . . . . . . . .  13
     4.1.  Protocol Operations Specific to FMIPv6  . . . . . . . . .  14
       4.1.1.  Operations of the Mobile Node . . . . . . . . . . . .  14
       4.1.2.  Operations of the Previous Access Router  . . . . . .  14
       4.1.3.  Operations of the New Access Router . . . . . . . . .  15
       4.1.4.  Buffering Considerations  . . . . . . . . . . . . . .  16
     4.2.  Protocol Operations Specific to PFMIPv6 . . . . . . . . .  16
       4.2.1.  Operations of the Mobile Node . . . . . . . . . . . .  16
       4.2.2.  Operations of the Previous MAG  . . . . . . . . . . .  16
       4.2.3.  Operations of the New MAG . . . . . . . . . . . . . .  17
       4.2.4.  IPv4 Support Considerations . . . . . . . . . . . . .  18
   5.  Message Formats . . . . . . . . . . . . . . . . . . . . . . .  19
     5.1.  Multicast Indicator for Proxy Router Advertisement
           (PrRtAdv) . . . . . . . . . . . . . . . . . . . . . . . .  19
     5.2.  Extensions to Existing Mobility Header Messages . . . . .  19
     5.3.  New Multicast Mobility Option . . . . . . . . . . . . . .  20
     5.4.  New Multicast Acknowledgement Option  . . . . . . . . . .  22
     5.5.  Length Considerations: Number of Records and Addresses  .  23
     5.6.  MLD (IGMP) Compatibility Requirements . . . . . . . . . .  23



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   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  24
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  24
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  24
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  25
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  25
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  26
   Appendix A.  Considerations for Mobile Multicast Sources  . . . .  26
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

1.  Introduction

   Mobile IPv6 [RFC6275] defines a network layer mobility protocol
   involving participation by mobile nodes, while Proxy Mobile IPv6
   [RFC5213] provides a mechanism without requiring mobility protocol
   operations at a Mobile Node (MN).  Both protocols introduce traffic
   disruptions on handovers that may be intolerable in many real-time
   application scenarios such as gaming or conferencing.  Mobile IPv6
   Fast Handovers (FMIPv6) [RFC5568], and Fast Handovers for Proxy
   Mobile IPv6 (PFMIPv6) [RFC5949] improve the performance of these
   handover delays for unicast communication to the order of the maximum
   of the delays needed for link switching and signaling between Access
   Routers (ARs) or Mobile Access Gateways (MAGs) [FMIPv6-Analysis].

   No dedicated treatment of seamless multicast data service has been
   proposed by any of the above protocols.  MIPv6 only roughly defines
   multicast for Mobile Nodes using a remote subscription approach or a
   home subscription through bi-directional tunneling via the Home Agent
   (HA).  Multicast forwarding services have not been specified in
   [RFC5213], but are subject to current specification [RFC6224],
   [I-D.ietf-multimob-pmipv6-source].  It is assumed throughout this
   document that mechanisms and protocol operations are in place to
   transport multicast traffic to ARs.  These operations are referred to
   as 'JOIN/LEAVE' of an AR, while the explicit techniques to manage
   multicast transmission are beyond the scope of this document.

   Mobile multicast protocols need to support applications such as IPTV
   with high-volume content streams and allow distribution to
   potentially large numbers of receivers.  They should thus preserve
   the multicast nature of packet distribution and approximate optimal
   routing [RFC5757].  It is undesirable to rely on home tunneling for
   optimizing multicast.  Unencapsulated, native multicast transmission
   requires establishing forwarding state, which will not be transferred
   between access routers by the unicast fast handover protocols.  Thus
   multicast traffic will not experience expedited handover performance,
   but an MN - or its corresponding MAG in PMIPv6 - can perform remote
   subscriptions in each visited network.





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   This document specifies extensions to FMIPv6 and PFMIPv6 that include
   multicast traffic management for fast handover operations in the
   presence of any source or source specific multicast.  The protocol
   extensions were designed under the requirements that

   o  multicast context transfer shall be transparently included in
      unicast fast handover operations

   o  neither unicast mobility protocols nor multicast routing shall be
      modified or otherwise affected

   o  no active participation of MNs in PMIPv6 domains is defined.

   The solution common to both underlying unicast protocols defines the
   per-group or per channel transfer of multicast contexts between ARs
   or MAGs.  The protocol defines corresponding message extensions
   necessary for carrying (*,G) or (S,G) context information independent
   of the particular handover protocol.  ARs or MAGs are then enabled to
   treat multicast traffic according to fast unicast handovers and with
   similar performance.  No protocol changes are introduced that prevent
   a multicast unaware node from performing fast handovers with
   multicast aware ARs or MAGs.

   The specified mechanisms apply when a mobile node has joined and
   maintains one or several multicast group subscriptions prior to
   undergoing a fast handover.  It does not introduce any requirements
   on the multicast routing protocols in use, nor are the ARs or MAGs
   assumed to be multicast routers.  It assumes network conditions,
   though, that allow native multicast reception in both, the previous
   and new access network.  Methods to bridge regions without native
   multicast connectivity are beyond the scope of this document.

   Section 5.1 of this memo updates the Proxy Router Advertisements
   (PrRtAdv) message format defined in Section 6.1.2.  of [RFC5568] to
   allow an FMIPv6 AR to indicate support for multicast.

1.1.  Use Cases and Deployment Scenarios

   Multicast Extensions for Fast Handovers enable multicast services in
   those domains that operate any of the unicast fast handover protocols
   [RFC5568] or [RFC5949].  Typically, fast handover protocols are
   activated within an operator network or within a dedicated service
   installation.

   Multicast group communication has a variety of dominant use cases.
   One traditional application area is infotainment with voluminous
   multimedia streams delivered to a large number of receivers (e.g.,
   IPTV).  Other time-critical news items like stock-exchange prices are



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   commonly transmitted via multicast to support fair and fast updates.
   Both may be mobile and both largely benefit from fast handover
   operations.  Operators may enhance their operational quality or offer
   premium services by enabling fast handovers.

   Another traditional application area for multicast is conversational
   group communication in scenarios like conferencing or gaming, but
   also in dedicated collaborative environments or teams.  Machine-to-
   machine communication in the emerging Internet of Things is expected
   to generate various additional mobile use cases (e.g., among cars).
   High demands on transmission quality and rapidly moving parties may
   require fast handovers.

   Most of the deployment scenarios above are bound to a fixed
   infrastructure with consumer equipment at the edge.  Today, they are
   thus likely to follow an operator-centric approach like PFMIPv6.
   However, Internet technologies evolve for adoption in
   infrastructureless scenarios, at disaster recovery, rescue, crisis
   prevention and civil safety for example.  Mobile end-to-end
   communication in groups is needed in Public Protection and Disaster
   Relief (PPDR) scenarios, where mobile multicast communication needs
   to be supported between members of rescue teams, police officers,
   fire brigade teams, paramedic teams, command control offices in order
   to support the protection and health of citizens.  These use cases
   require fast and reliable mobile services which cannot rely on
   operator infrastructure.  They are thus predestined to running
   multicast with FMIPv6.

2.  Terminology

   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 [RFC2119].
   The use of the term, "silently ignore" is not defined in RFC 2119.
   However, the term is used in this document and can be similarly
   construed.

   This document uses the terminology of [RFC5568], [RFC5949],
   [RFC6275], and [RFC5213] for mobility entities.

3.  Protocol Overview

   This section provides an informative overview of the protocol
   mechanisms without normative specifications.

   The reference scenario for multicast fast handover is illustrated in
   Figure 1.  A Mobile Node is initially attached to the previous access
   network (P-AN) via the Previous Access Router (PAR) or Previous



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   Mobile Access Gateway (PMAG) and moves to the new access network
   (N-AN) connected via a New AR (NAR) or New MAG (NMAG).



                             ***  ***  ***  ***
                            *   **   **   **   *
                           *                    *
                            *  Multicast Cloud *
                           *                    *
                            *   **   **   **   *
                             ***  ***  ***  ***
                                  /      \
                                 /        \
                                /          \
                    +........../..+      +..\..........+
                    . +-------+-+ .______. +-+-------+ .
                    . |   PAR   |()_______)|   NAR   | .
                    . |  (PMAG) | .      . |  (NMAG) | .
                    . +----+----+ .      . +----+----+ .
                    .      |      .      .      |      .
                    .   ___|___   .      .   ___|___   .
                    .  /       \  .      .  /       \  .
                    . (  P-AN   ) .      . (  N-AN   ) .
                    .  \_______/  .      .  \_______/  .
                    .      |      .      .      |      .
                    .   +----+    .      .   +----+    .
                    .   | MN |  ---------->  | MN |    .
                    .   +----+    .      .   +----+    .
                    +.............+      +.............+

               Figure 1: Reference Network for Fast Handover

3.1.  Multicast Context Transfer between Access Routers

   In a fast handover scenario (cf. Figure 1), ARs/MAGs establish a
   mutual binding and provide the capability to exchange context
   information concerning the MN.  This context transfer will be
   triggered by detecting the forthcoming movement of an MN to a new AR
   and assists the MN to immediately resume communication on the new
   subnet using its previous IP address.  In contrast to unicast,
   multicast flow reception does not primarily depend on address and
   binding cache management, but requires distribution trees to adapt so
   that traffic follows the movement of the MN.  This process may be
   significantly slower than fast handover management [RFC5757].  To
   accelerate the handover, multicast listeners may offer the twofold
   advantage of including the multicast groups under subscription in the
   context transfer.  First, the NAR can proactively join the subscribed



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   groups as soon as it gains knowledge of them.  Second, multicast
   flows can be included in traffic forwarding via the tunnel
   established from the PAR to the NAR.

   There are two modes of operation in FMIPv6 and in PFMIPv6.  The
   predictive mode allows for AR-binding and context transfer prior to
   an MN handover, while in the reactive mode, these steps are executed
   after detection that the MN has re-attached to a NAR (NMAG).  Details
   of the signaling schemes differ between FMIPv6 and PFMIPv6 and are
   outlined in Section 3.2 and Section 3.3.

   In a predictive fast handover, the access router (i.e., PAR (PMAG) in
   Figure 1) learns about the impending movement of the MN and
   simultaneously about the multicast group context as specified in
   Section 3.2 and Section 3.3.  Thereafter, the PAR will initiate an
   AR-binding and context transfer by transmitting a HI message to NAR
   (NMAG).  The Handover Initiation (HI) message is extended by
   multicast group states carried in mobility header options as defined
   in Section 5.3.  On reception of the HI message, the NAR returns a
   multicast acknowledgement in its Handover Acknowledgement (HACK)
   answer that indicates its ability to support each requested group
   (see Section 5.4).  The NAR (NMAG) expresses its willingness to
   receive multicast traffic forwarded by the PAR using standard MLD
   signaling.  There are several reasons to waive forwarding, e.g., the
   NAR could already have a native subscription for the group(s), or
   capacity constraints can hinder decapsulation of additional streams.
   At the previous network, there may be policy of capacity constraints
   that make it undesirable to forward the multicast traffic.  The PAR
   can add the tunnel interface to its multicast forwarding database for
   those groups the MN wishes to receive, so that multicast flows can be
   forwarded in parallel to the unicast traffic.

   The NAR implements an MLD proxy [RFC4605] providing host-side
   behaviour towards the upstream PAR.  The proxy will submit an MLD
   report to the upstream tunnel interface to signal that it requests
   the groups/channels to be forwarded.  It will terminate multicast
   forwarding from the tunnel when the group is natively received.  In
   parallel, the NAR joins all groups that are not already under
   subscription using its native multicast upstream interface.  While
   the MN has not arrived at a downstream interface of the NAR,
   multicast subscriptions on behalf of the MN are associated with a
   downstream Loopback interface.  Reception of the Join at the NAR
   enables downstream native multicast forwarding of the subscribed
   group(s).

   In a reactive fast handover, the PAR will learn about the movement of
   the MN, after the latter has re-associated with the new access
   network.  Also from the new link, it will be informed about the



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   multicast context of the MN.  As group membership information is
   present at the new access network prior to context transfer, MLD join
   signaling can proceed in parallel to HI/HACK exchange.  Following the
   context transfer, multicast data can be forwarded to the new access
   network using the PAR-NAR tunnel of the fast handover protocol.
   Depending on the specific network topology multicast traffic for some
   groups may natively arrive before it is forwarded from PAR.

   In both modes of operation, it is the responsibility of the PAR
   (PMAG) to properly apply multicast state management when an MN leaves
   (i.e., to determine if it can prune the traffic for any unsubscribed
   group).  Depending on the link type and MLD parameter settings,
   methods for observing the departure of an MN need to be applied (cf.,
   [RFC5757]).  While considering subscriptions of the remaining nodes
   and from the tunnel interfaces, the PAR uses normal multicast
   forwarding rules to determine whether multicast traffic can be
   pruned.

   This method allows an MN to participate in multicast group
   communication with a handover performance that is comparable to
   unicast handover.

3.2.  Protocol Operations Specific to FMIPv6

   ARs that provide multicast support in FMIPv6 will advertise this
   general service by setting an indicator bit (M-bit) in its PrRtAdv
   message as defined in Section 5.1.  Additional details about the
   multicast service support, e.g., flavors and groups, will be
   exchanged within HI/HACK dialogs later at handover.

   An MN operating FMIPv6 will actively initiate the handover management
   by submitting a Fast Binding Update (FBU).  The MN, which is aware of
   the multicast groups it wishes to maintain, will attach mobility
   options containing its group states (see Section 5.3) to the FBU, and
   thereby inform ARs about its multicast context.  ARs will use these
   multicast context options for inter-AR context transfer.

   In predictive mode, the FBU is issued on the previous link and
   received by the PAR as displayed in Figure 2.  The PAR will extract
   the multicast context options and append them to its HI message.
   From the HACK message, PAR will redistribute the multicast
   acknowledgement by adding the corresponding mobility options to its
   Fast Binding ACK (FBACK) message.  From receiving the FBACK message,
   the MN will group-wise learn about the multicast support in the new
   access network.  If some groups or multicast service models are not
   supported, it can decide on taking actions to overcome the missing
   service (e.g., by tunneling).  Note that the proactive multicast




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   context transfer may proceed successfully, even if the MN misses the
   FBACK message on the previous link.


                  MN                    PAR                    NAR
                   |                     |                      |
                   |------RtSolPr------->|                      |
                   |<-----PrRtAdv--------|                      |
                   |                     |                      |
                   |                     |                      |
                   |---------FBU-------->|----------HI--------->|
                   | (Multicast MobOpt)  | (Multicast MobOpt)   |
                   |                     |                      |
                   |                     |<--------HAck---------|
                   |                     | (Multicast AckOpt)   |
                   |                     |                   Join to
                   |                     |                  Multicast
                   |                     |                   Groups
                   |                     |                      |
                   |       <-----FBack---|--FBack------>        |
                   |  (Multicast AckOpt) | (Multicast AckOpt)   |
                   |                     |                      |
                disconnect            optional                  |
                   |                   packet  ================>|
                   |                 forwarding                 |
                   |                     |                      |
                connect                  |                      |
                   |                     |                      |
                   |------------UNA --------------------------->|
                   |<=================================== deliver packets
                   |                                            |

            Figure 2: Predictive Multicast Handover for FMIPv6

   The flow diagram for reactive mode is depicted in Figure 3.  After
   attaching to the new access link and performing an unsolicited
   neighbor advertisement (UNA), the MN issues an FBU which the NAR
   forwards to the PAR without processing.  At this time, the MN is able
   to re-join all subscribed multicast groups without relying on AR
   assistance.  Nevertheless, multicast context options are exchanged in
   the HI/HACK dialog to facilitate intermediate forwarding of requested
   flows.  The multicast traffic could arrive from a MN subscription at
   the same time the NAR receives the HI message.  Such multicast flows
   may be transparently excluded from forwarding by setting an
   appropriate multicast acknowledge option.  In either case, the NAR
   MUST ensure that not more than one flow of the same group is
   forwarded to the MN.




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                  MN                    PAR                    NAR
                   |                     |                      |
                   |------RtSolPr------->|                      |
                   |<-----PrRtAdv--------|                      |
                   |                     |                      |
                disconnect               |                      |
                   |                     |                      |
                   |                     |                      |
                connect                  |                      |
                   |-------UNA-----------|--------------------->|
                   |-------FBU-----------|---------------------)|
                   | (Multicast MobOpt)  |<-------FBU----------)|
                   |                     |                      |
                Join to                  |                      |
               Multicast                 |                      |
                Groups                   |                      |
                   |                     |----------HI--------->|
                   |                     |  (Multicast MobOpt)  |
                   |                     |<-------HAck----------|
                   |                     |  (Multicast AckOpt)  |
                   |                     |                      |
                   |                     |(HI/HAck if necessary)|
                   |                     |                      |
                   |              FBack, optional               |
                   |              packet forwarding  ==========>|
                   |                     |                      |
                   |<=================================== deliver packets
                   |                                            |

             Figure 3: Reactive Multicast Handover for FMIPv6

3.3.  Protocol Operations Specific to PFMIPv6

   In a proxy mobile IPv6 environment, the MN remains agnostic of
   network layer changes, and fast handover procedures are operated by
   the access routers or MAGs to which MNs are connected via node-
   specific point-to-point links.  The handover initiation, or the re-
   association respectively are managed by the access networks.
   Consequently, access routers need to be aware of multicast membership
   state at the mobile node.  There are two ways to obtain the multicast
   membership of an MN.

   o  MAGs may perform explicit tracking (see [RFC4605], [RFC6224]) or
      extract membership status from forwarding states at node-specific
      links.

   o  routers can issue a general MLD query at handovers.  Both methods
      are equally applicable.  However, a router that does not operate



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      explicit tracking needs to query its downstream links after a
      handover.  The MLD membership information then allows the PMAG
      (PAR) to learn the multicast group/channel subscriptions of the
      MN.

   In predictive mode, the PMAG (PAR) will learn about the upcoming
   movement of the mobile node.  Without explicit tracking, it will
   immediately submit a general MLD query and receive MLD reports for
   the subscribed group(s).  As displayed in Figure 4, it will initiate
   binding and context transfer with the NMAG (NAR) by issuing a HI
   message that is augmented by multicast contexts in the mobility
   options defined in Section 5.3.  NAR will extract multicast context
   information and act as described in Section 3.1.






































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                                             PMAG          NMAG
           MN           P-AN       N-AN        (PAR)         (NAR)
           |             |          |            |             |
           |    Report   |          |            |             |
           |---(MN ID,-->|          |            |             |
           |  New AP ID) |          |            |             |
           |             |    HO Indication      |             |
           |             |--(MN ID, New AP ID)-->|             |
           |             |          |            |             |
           |             |          |         Optional:        |
           |             |          |         MLD Query        |
           |             |          |            |             |
           |             |          |            |------HI---->|
           |             |          |            |(Multicast MobOpt)
           |             |          |            |             |
           |             |          |            |<---HAck-----|
           |             |          |            |(Multicast AckOpt)
           |             |          |            |             |
           |             |          |            |          Join to
           |             |          |            |         Multicast
           |             |          |            |          Groups
           |             |          |            |             |
           |             |          |            |HI/HAck(optional)
           |             |          |            |<- - - - - ->|
           |             |          |            |             |
           |             |          |     optional packet      |
           |             |          |       forwarding =======>|
       disconnect        |          |            |             |
           |             |          |            |             |
        connect          |          |            |             |
           |    MN-AN connection    |    AN-MAG connection     |
           |<----establishment----->|<----establishment------->|
           |             |          |  (substitute for UNA)    |
           |             |          |            |             |
           |<========================================== deliver packets
           |             |          |            |             |


            Figure 4: Predictive Multicast Handover for PFMIPv6

   In reactive mode, the NMAG (NAR) will learn the attachment of the MN
   to the N-AN and establish connectivity using the PMIPv6 protocol
   operations.  However, it will have no knowledge about multicast state
   at the MN.  Triggered by a MN attachment, the NMAG will send a
   general MLD query and thereafter join the requested groups.  In the
   case of a reactive handover, the binding is initiated by the NMAG,
   and the HI/HACK message semantic is inverted (see [RFC5949]).  For
   multicast context transfer, the NMAG attaches to its HI message those



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   group identifiers it requests to be forwarded from PMAG.  Using the
   identical syntax in its multicast mobility option headers as defined
   in Section 5.4, the PMAG acknowledges the set of requested groups in
   a HACK answer, indicating the group(s) it is willing to forward.  The
   corresponding call flow is displayed in Figure 5.


                                             PMAG          NMAG
           MN         P-AN       N-AN        (PAR)         (NAR)
           |           |          |            |             |
       disconnect      |          |            |             |
           |           |          |            |             |
        connect        |          |            |             |
           |           |          |            |             |
           |   MN-AN connection   |    AN-MAG connection     |
           |<---establishment---->|<----establishment------->|
           |           |          |(substitute for UNA & FBU)|
           |           |          |            |             |
           |           |          |            |         MLD Query
           |           |          |            |             |
           |           |          |            |          Join to
           |           |          |            |         Multicast
           |           |          |            |          Groups
           |           |          |                          |
           |           |          |            |<------HI----|
           |           |          |            |(Multicast MobOpt)
           |           |          |            |             |
           |           |          |            |---HAck----->|
           |           |          |            |(Multicast AckOpt)
           |           |          |            |             |
           |           |          |            |             |
           |           |          |            |HI/HAck(optional)
           |           |          |            |<- - - - - ->|
           |           |          |            |             |
           |           |          |    optional packet       |
           |           |          |       forwarding =======>|
           |           |          |            |             |
           |<======================================== deliver packets
           |           |          |            |             |


             Figure 5: Reactive Multicast Handover for PFMIPv6

4.  Protocol Details

   In this section the protocol operations are defined in a normative
   way.




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4.1.  Protocol Operations Specific to FMIPv6

4.1.1.  Operations of the Mobile Node

   A Mobile Node willing to manage multicast traffic by fast handover
   operations MUST transfer its MLD listener state records within fast
   handover negotiations.

   When sensing a handover in predictive mode, an MN MUST build a
   Multicast Mobility Option as described in Section 5.3 that contains
   the MLD (IGMP) multicast listener state and append it to the Fast
   Binding Update (FBU) prior to signaling with PAR.

   It will receive the Multicast Acknowledgement Option(s) as part of
   the Fast Binding Acknowledge (FBACK) (see Section 5.4) and learn
   about unsupported or prohibited groups at the NAR.  The MN MAY take
   appropriate actions like home tunneling to receive groups/channels
   not available from NAR.  No multicast-specific operation is required
   by the MN when re-attaching in the new network besides standard
   FMIPv6 signaling.

   In reactive mode, the MN MUST append the identical Multicast Mobility
   Option to FBU sent after its reconnect.  In response, it will learn
   about the Multicast Acknowledgement Option(s) from FBACK and expect
   corresponding multicast data.  Concurrently it joins all subscribed
   multicast groups (channels) directly on its newly established access
   link.

4.1.2.  Operations of the Previous Access Router

   A PAR MUST advertise its support for multicast by setting the M-bit
   in PrRtAdv as specified in Section 5.1 of this document.  This
   indicator exclusively serves the purpose of informing MNs about the
   capability of the PAR to process and exchange Multicast Mobility
   Options during Fast Handover operations.

   In predictive mode, a PAR will receive the multicast listener state
   of an MN prior to handover from the Multicast Mobility Option
   appended to the FBU.  It forwards these records to NAR within HI
   messages and will expect Multicast Acknowledgement Option(s) in HACK,
   which itself is returned to the MN as an appendix to FBACK.  In
   performing multicast context exchange, the PAR is instructed to
   include the PAR-to-NAR tunnel obtained from unicast handover
   management in its multicast downstream interfaces and await MLD
   listener reports from the NAR.  In response to receiving multicast
   subscriptions, the PAR SHOULD forward group data acting as a regular
   multicast router or proxy.  However, the PAR MAY refuse to forward




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   some or all of the multicast flows (e.g., due to administrative
   configurations or load conditions).

   In reactive mode, the PAR will receive the FBU augmented by the
   Multicast Mobility Option from the new network, but continues with an
   identical multicast record exchange in the HI/HACK dialog.  As in the
   predictive case, it configures the PAR-to-NAR tunnel for the
   multicast downstream and forwards data according to MLD reports
   obtained from NAR, if capable of forwarding.

   In both modes, the PAR MUST interpret the first of the two events -
   the departure of the MN or the reception of the Multicast
   Acknowledgement Option(s) - as if the MN had sent a multicast LEAVE
   message and react according to the signaling scheme deployed in the
   access network (i.e., MLD querying, explicit tracking).

4.1.3.  Operations of the New Access Router

   A NAR MUST advertise its multicast support by setting the M-bit in
   PrRtAdv as specified in Section 5.1 of this document.  This indicator
   exclusively serves the purpose of informing MNs about the capability
   of the PAR to process and exchange Multicast Mobility Options during
   Fast Handover operations.

   In predictive mode, a NAR will receive the multicast listener state
   of an expected MN from the Multicast Mobility Option appended to the
   HI message.  It will extract the MLD/IGMP records from the message
   and intersect the request subscription with its multicast service
   offer.  Further on it will adjoin the supported groups (channels) to
   the MLD listener state using Loopback as downstream interface.  This
   will lead to suitable regular subscriptions on its native multicast
   upstream interface without additional forwarding.  Concurrently, the
   NAR builds a Multicast Acknowledgement Option(s) (see Section 5.4)
   listing those groups (channels) unsupported on the new access link
   and returns them within HACK.  As soon as the bidirectional tunnel
   from PAR to NAR is operational, the NAR joins the groups subscribed
   for forwarding on the tunnel link.

   In reactive mode, the NAR will learn about the multicast listener
   state of a new MN from the Multicast Mobility Option appended to a HI
   message at a time, when the MN has already performed local
   subscriptions of the multicast service.  Thus the NAR solely
   determines the intersection of requested and supported groups
   (channels) and issues the join requests for group forwarding on the
   PAR-NAR tunnel interface.

   In both modes, the NAR MUST send a LEAVE message to the tunnel after
   forwarding of a group (channel) becomes unneeded, e.g., after native



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   multicast traffic arrives or group membership of the MN terminates.
   Sending this immediately eliminates the need for PAR and NAR to
   process traffic that is not forwarded.

4.1.4.  Buffering Considerations

   Multicast packets may be lost during handover.  For example, in
   predictive mode as illustrated by figure 2, packets may be lost while
   the MN is - already or still - detached from the networks, even
   though they are forwarded to the NAR.  In reactive mode as
   illustrated by figure 3, the situation may be worse since there will
   be a delay for joining the multicast group after the MN re-attaches
   to the NAR.  Multicast packets cannot be delivered during this time.
   Buffering the multicast packets at the PAR can reduce the multicast
   packet loss, but may increase resource consumption and delay in
   packet transmission.  Implementors should balance the different
   requirements in the context of predominant application demands (e.g.,
   real-time requirements).

4.2.  Protocol Operations Specific to PFMIPv6

4.2.1.  Operations of the Mobile Node

   A Mobile Node willing to participate in multicast traffic will join,
   maintain and leave groups as if located in the fixed Internet.  It
   will cooperate in handover indication as specified in [RFC5949] and
   required by its access link-layer technology.  No multicast-specific
   mobility actions nor implementations are required at the MN in a
   PMIPv6 domain.

4.2.2.  Operations of the Previous MAG

   A MAG receiving a handover indication for one of its MNs follows the
   predictive fast handover mode as a PMAG.  It MUST issue an MLD
   General Query immediately on its corresponding link unless it
   performs an explicit tracking on that link.  After knowledge of the
   multicast subscriptions of the MN is acquired, the PMAG builds a
   Multicast Mobility Option as described in Section 5.3 that contains
   the MLD (IGMP) multicast listener state.  If not empty, this Mobility
   Option is appended to the regular fast handover HI messages, or - in
   the case of unicast HI message being submitted prior to multicast
   state detection - sent in an additional HI message to the NMAG.

   The PMAG then waits until it receives the Multicast Acknowledgement
   Option(s) with a HACK message (see Section 5.4) and the creation of
   the bidirectional tunnel with NMAG.  After the HACK message is
   received, the PMAG adds the tunnel to its downstream interfaces in
   the multicast forwarding database.  For those groups (channels)



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   reported in the Multicast Acknowledgement Option(s), i.e., not
   supported in the new access network, the PMAG normally takes
   appropriate actions (e.g., forwarding, termination) in concordance
   with the network policy.  It SHOULD start forwarding traffic down the
   tunnel interface for those groups for which an MLD listener report
   was received from NMAG.  However, it MAY deny forwarding for some or
   all groups included in the listener report.

   After the departure of the MN and on the reception of LEAVE messages
   for groups/channels, it is RECOMMENDED that the PMAG terminates
   forwarding of the specific groups and updates its multicast
   forwarding database.  Correspondingly it issues a group/channel LEAVE
   to its upstream link, if no more listeners are present on its
   downstream links.

   A MAG receiving a HI message with the Multicast Mobility Option for a
   currently attached node follows the reactive fast handover mode as a
   PMAG.  It will return Multicast Acknowledgement Option(s) (see
   Section 5.4) within a HACK message listing those groups/channels it
   does not support to forward to the NMAG.  It will add the
   bidirectional tunnel with NMAG to its downstream interfaces and will
   start forwarding multicast traffic for those groups it receives an
   MLD listener report message from the NMAG.  At the reception of LEAVE
   messages for groups (channels), the PMAG terminates forwarding of the
   specific groups and update its multicast forwarding database.
   According to its multicast forwarding state, it will need to issue a
   group/channel LEAVE to its upstream link, if no more listeners are
   present on its downstream links.

   In both modes, the PMAG will interpret the departure of the MN as a
   multicast LEAVE message of the MN and react according to the
   signaling scheme deployed in the access network (i.e., MLD querying,
   explicit tracking).

4.2.3.  Operations of the New MAG

   A MAG receiving a HI message with a Multicast Mobility Option for a
   currently unattached node follows the predictive fast handover mode
   as an NMAG.  It will decide on those multicast groups/channels it
   selects to be forwarded from the PMAG and builds a Multicast
   Acknowledgement Option (see Section 5.4) that enumerates only
   unwanted groups/channels.  This Mobility Option is appended to the
   regular fast handover HACK messages, or - in the case of a unicast
   HACK message being submitted prior to multicast state acknowledgement
   - sent in an additional HACK message to the PMAG.  Immediately
   thereafter, the NMAG SHOULD update its MLD membership state based on
   the report received in the Multicast Mobility Option.  Until the MN
   re-attaches, the NMAG uses its Loopback interface for downstream and



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   MUST NOT forward traffic to the potential link of the MN.  The NMAG
   SHOULD issue JOIN messages for those newly selected groups to its
   regular multicast upstream interface.  As soon as the bidirectional
   tunnel with PMAG is established, the NMAG additionally joins those
   groups/channels on the tunnel interface that it wants to receive
   forwarded from the PMAG.

   A MAG experiencing a connection request for an MN without prior
   reception of a corresponding Multicast Mobility Option is operating
   in the reactive fast handover mode as an NMAG.  Following the re-
   attachment, it SHOULD immediately issue an MLD General Query to learn
   about multicast subscriptions of the newly arrived MN.  Using
   standard multicast operations, the NMAG joins the missing groups
   (channels) on its regular multicast upstream interface.
   Concurrently, it selects groups (channels) for forwarding from PMAG
   and builds a Multicast Mobility Option as described in Section 5.3
   that contains the MLD (IGMP) multicast listener state.  If not empty,
   this Mobility Option is appended to the regular fast handover HI
   messages with the F flag set, or - in the case of unicast HI message
   being submitted prior to multicast state detection - sent in an
   additional HI message to the PMAG.  Upon reception of the Multicast
   Acknowledgement Option and establishment of the bidirectional tunnel,
   the NMAG additionally joins those groups/channels on the tunnel
   interface that it wants to receive by forwarding from the PMAG.  When
   multicast flows arrive, the NMAG forwards data to the appropriate
   downlink(s).

   In both modes, the NMAG MUST send a LEAVE message to the tunnel after
   forwarding of a group (channel) becomes unneeded, e.g., after native
   multicast traffic arrives or group membership of the MN terminates.
   Sending this immediately eliminates the need for PMAG and NMAG to
   process traffic that is not forwarded.

4.2.4.  IPv4 Support Considerations

   An MN in a PMIPv6 domain MAY use an IPv4 address transparently for
   communication as specified in [RFC5844].  For this purpose, LMAs can
   register IPv4-Proxy-CoAs in its Binding Caches and MAGs can provide
   IPv4 support in access networks.  Correspondingly, multicast
   membership management will be performed by the MN using IGMP.  For
   multi-protocol multicast support on the network side, IGMPv3 router
   functions are required at both MAGs (see Section 5.6 for
   compatibility considerations with previous IGMP versions).  Context
   transfer between MAGs can transparently proceed in the HI/HACK
   message exchanges by encapsulating IGMP multicast state records
   within Multicast Mobility Options (see Section 5.3 and Section 5.4
   for details on message formats).




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   The deployment of IPv4 multicast support SHOULD be homogeneous across
   a PMIP domain.  This avoids multicast service breaks during
   handovers.

   It is worth mentioning the scenarios of a dual-stack IPv4/IPv6 access
   network, and the use of GRE tunneling as specified in[RFC5845].
   Corresponding implications and operations are discussed in the PMIP
   Multicast Base Deployment document, see[RFC6224].

5.  Message Formats

5.1.  Multicast Indicator for Proxy Router Advertisement (PrRtAdv)

   This document updates the Proxy Router Advertisements (PrRtAdv)
   message format defined in Section 6.1.2. of [RFC5568].  The update
   assigns the first bit of the Reserved field, to carry the 'M' bit, as
   defined in Figure 6.  An FMIPv6 AR indicates support for multicast by
   assigning the setting 'M' bit to a value of 1.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Type     |      Code     |           Checksum            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Subtype    |M|  Reserved   |           Identifier          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Options ...
       +-+-+-+-+-+-+-+-+-+-+-+-

     Figure 6: Multicast Indicator Bit for Proxy Router Advertisement
                             (PrRtAdv) Message

   This document updates the reserved field to include the 'M' bit
   specified as follows.

      M = 1 indicates that the specifications of this document apply

      M = 0 indicates that the behaviour during Fast Handover proceeds
      according to [RFC5568].

   The default value (0) of this bit indicates a non-multicast capable
   service.

5.2.  Extensions to Existing Mobility Header Messages

   The fast handover protocols use an IPv6 header type called Mobility
   Header as defined in [RFC6275].  Mobility headers can carry variable
   Mobility Options.



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   The multicast listener context of an MN is transferred in fast
   handover operations from PAR/PMAG to NAR/NMAG within a new Multicast
   Mobility Option, and MUST be acknowledged by a corresponding
   Multicast Acknowledgement Option.  Depending on the specific handover
   scenario and protocol in use, the corresponding option is included
   within the mobility option list of HI/HACK only (PFMIPv6), or of FBU/
   FBACK/HI/HACK (FMIPv6).

5.3.  New Multicast Mobility Option

   This section defines the Multicast Mobility Option.  It contains the
   current listener state record of the MN obtained from the MLD Report
   message, and has the format displayed in Figure 7.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Type      |   Length      | Option-Code   |   Reserved    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                    MLD (IGMP) Report Payload                  +
       ~                                                               ~
       ~                                                               ~
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 7: Mobility Header Multicast Option

   RFC Editor note: IANA is requested to allocate the value XXX and
   remove this note prior to publication.

   Type: XXX

   Length: 8-bit unsigned integer.  The length in octets of this option,
   not including the Option Type and Option Length fields.

   Option-Code:

      1: IGMPv3 Payload Type

      2: MLDv2 Payload Type

      3: IGMPv3 Payload Type from IGMPv2 Compatibility Mode




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      4: MLDv2 Payload Type from MLDv1 Compatibility Mode

   Reserved: MUST be set to zero by the sender and MUST be ignored by
   the receiver.

   MLD (IGMP) Report Payload: this field is composed of the MLD (IGMP)
   Report message after stripping its ICMP header.  This Report Payload
   always contains an integer number of muticast records.  Corresponding
   message formats are defined for MLDv2 in [RFC3810], and for IGMPv3 in
   [RFC3376].  This field MUST always contain the first header line
   (reserved field and No of Mcast Address Records).

   Figure 8 shows the Report Payload for MLDv2, while the payload format
   for IGMPv3 is defined corresponding to the IGMPv3 payload format (see
   Section 5.2. of [RFC3810], or Section 4.2 of [RFC3376]) for the
   definition of Multicast Address Records).

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |           Reserved            |No of Mcast Address Records (M)|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |     .                                                               .
    .                  Multicast Address Record [1]                 .
    .                                                               .
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    .                                                               .
    .                  Multicast Address Record [2]                 .
    .                                                               .
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                               .                               |
    .                               .                               .
    |                               .                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    .                                                               .
    .                  Multicast Address Record [M]                 .
    .                                                               .
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 8: MLDv2 Report Payload






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5.4.  New Multicast Acknowledgement Option

   The Multicast Acknowledgement Option reports the status of the
   context transfer and contains the list of state records that could
   not be successfully transferred to the next access network.  It has
   the format displayed in Figure 9.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Type      |   Length      | Option-Code   |    Status     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +           MLD (IGMP) Unsupported Report Payload               +
       ~                                                               ~
       ~                                                               ~
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 9: Mobility Header Multicast Acknowledgement Option

   RFC Editor note: IANA is requested to allocate the value XXX and
   remove this note prior to publication.

   Type: XXX

   Length: 8-bit unsigned integer.  The length in octets of this option,
   not including the Option Type and Option Length fields.

   Option-Code: 0

   Status:

      1: Report Payload type unsupported

      2: Requested group service unsupported

      3: Requested group service administratively prohibited

   MLD (IGMP) Unsupported Report Payload: this field is syntactically
   identical to the MLD (IGMP) Report Payload field described in
   Section 5.3, but is only composed of those multicast address records
   that are not supported or prohibited in the new access network.  This
   field MUST always contain the first header line (reserved field and



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   No of Mcast Address Records), but MUST NOT contain any Mcast Address
   Records, if the status code equals 1.

   Note that group subscriptions to specific sources may be rejected at
   the destination network, and thus the composition of multicast
   address records may differ from initial requests within an MLD (IGMP)
   Report Payload option.

5.5.  Length Considerations: Number of Records and Addresses

   Mobility Header Messages exchanged in HI/HACK and FBU/FBACK dialogs
   impose length restrictions on multicast context records.  The maximal
   payload length available in FBU/FBACK messages is the PATH-MTU - 40
   octets (IPv6 Header) - 6 octets (Mobility Header) - 6 octets (FBU/
   FBACK Header).  For example, on an Ethernet link with an MTU of 1500
   octets, not more than 72 Multicast Address Records of minimal length
   (without source states) may be exchanged in one message pair.  In
   typical handover scenarios, this number reduces further according to
   unicast context and Binding Authorization data.  A larger number of
   MLD Reports that exceed the available payload size MAY be sent within
   multiple HI/HACK or FBU/FBACK message pairs.  In PFMIPv6, context
   information can be fragmented over several HI/HACK messages.
   However, a single MLDv2 Report Payload MUST NOT be fragmented.
   Hence, for a single Multicast Address Record on an Ethernet link, the
   number of source addresses (S,.) is limited to 89.

5.6.  MLD (IGMP) Compatibility Requirements

   Access routers (MAGs) MUST support MLDv2 (IGMPv3).  To enable
   multicast service for MLDv1 (IGMPv2) listeners, the routers MUST
   follow the interoperability rules defined in [RFC3810] ([RFC3376])
   and appropriately set the Multicast Address Compatibility Mode.

   When the Multicast Address Compatibility Mode is MLDv1 (IGMPv2), a
   router internally translates the following MLDv1 (IGMPv2) messages
   for that multicast address to their MLDv2 (IGMPv2) equivalents and
   uses these messages in the context transfer.  The current state of
   Compatibility Mode is translated into the code of the Multicast
   Mobility Option as defined in Section 5.3.  A NAR (nMAG) receiving a
   Multicast Mobility Option during handover will switch to the lowest
   level of MLD (IGMP) Compatibility Mode that it learned from its
   previous and new option values.  This minimal compatibility agreement
   is used to allow for continued operation.








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6.  Security Considerations

   Security vulnerabilities that exceed issues discussed in the base
   protocols of this document ([RFC5568], [RFC5949], [RFC3810],
   [RFC3376]) are identified as follows.

   Multicast context transfer at predictive handovers implements group
   states at remote access routers and may lead to group subscriptions
   without further validation of the multicast service requests.
   Thereby a NAR (nMAG) is requested to cooperate in potentially complex
   multicast re-routing and may receive large volumes of traffic.
   Malicious or inadvertent multicast context transfers may result in a
   significant burden of route establishment and traffic management onto
   the backbone infrastructure and the access router itself.  Rapid re-
   routing or traffic overload can be mitigated by a rate control at the
   AR that restricts the frequency of traffic redirects and the total
   number of subscriptions.  In addition, the wireless access network
   remains protected from multicast data injection until the requesting
   MN attaches to the new location.

7.  IANA Considerations

   This document defines two new mobility options which need allocation
   from the Mobility Header Type registry at http://www.iana.org/
   assignments/mobility-parameters.

      XXX Multicast Mobility Option, described in Section 5.3

      XXX Multicast Acknowledgement Option, described in Section 5.4

   RFC Editor note: The RFC Editor is requested to replace "XXX" by the
   IANA-assigned value prior to publication and may then remove this
   note.

8.  Acknowledgments

   Protocol extensions to support multicast in Fast Mobile IPv6 have
   been loosely discussed for several years.  Repeated attempts have
   been taken to define corresponding protocol extensions.  The first
   draft [fmcast-mip6] was presented by Suh, Kwon, Suh, and Park in
   2004.

   This work was stimulated by many fruitful discussions in the MobOpts
   research group.  We would like to thank all active members for
   constructive thoughts and contributions on the subject of multicast
   mobility.  The MULTIMOB working group has provided continuous
   feedback during the evolution of this work.  Comments, discussions
   and reviewing remarks have been contributed by (in alphabetical



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   order) Carlos J.  Bernardos, Luis M. Contreras, Hui Deng, Shuai Gao,
   Dirk von Hugo, Min Hui, Georgios Karagian, Marco Liebsch, Behcet
   Sarikaya, Stig Venaas and Juan Carlos Zuniga.

   Funding has been provided by the German Federal Ministry of Education
   and Research within the projects Mindstone, SKIMS and SAFEST, which
   is gratefully acknowledged.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
              in IPv6", RFC 6275, July 2011.

   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.

   [RFC5568]  Koodli, R., "Mobile IPv6 Fast Handovers", RFC 5568, July
              2009.

   [RFC5949]  Yokota, H., Chowdhury, K., Koodli, R., Patil, B., and F.
              Xia, "Fast Handovers for Proxy Mobile IPv6", RFC 5949,
              September 2010.

   [RFC1112]  Deering, S., "Host extensions for IP multicasting", STD 5,
              RFC 1112, August 1989.

   [RFC4605]  Fenner, B., He, H., Haberman, B., and H. Sandick,
              "Internet Group Management Protocol (IGMP) / Multicast
              Listener Discovery (MLD)-Based Multicast Forwarding ("IGMP
              /MLD Proxying")", RFC 4605, August 2006.

   [RFC3810]  Vida, R. and L. Costa, "Multicast Listener Discovery
              Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.

   [RFC3376]  Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
              Thyagarajan, "Internet Group Management Protocol, Version
              3", RFC 3376, October 2002.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.





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9.2.  Informative References

   [RFC5757]  Schmidt, T., Waehlisch, M., and G. Fairhurst, "Multicast
              Mobility in Mobile IP Version 6 (MIPv6): Problem Statement
              and Brief Survey", RFC 5757, February 2010.

   [fmcast-mip6]
              Suh, K., Kwon, D., Suh, Y., and Y. Park, "Fast Multicast
              Protocol for Mobile IPv6 in the fast handovers
              environments", draft-suh-mipshop-fmcast-mip6-00 (work in
              progress), July 2004.

   [FMIPv6-Analysis]
              Schmidt, TC. and M. Waehlisch, "Predictive versus Reactive
              - Analysis of Handover Performance and Its Implications on
              IPv6 and Multicast Mobility", Telecommunication Systems
              Vol 33, No. 1-3, pp. 131-154, November 2005.

   [RFC6224]  Schmidt, T., Waehlisch, M., and S. Krishnan, "Base
              Deployment for Multicast Listener Support in Proxy Mobile
              IPv6 (PMIPv6) Domains", RFC 6224, April 2011.

   [I-D.ietf-multimob-pmipv6-source]
              Schmidt, T., Gao, S., Zhang, H., and M. Waehlisch, "Mobile
              Multicast Sender Support in Proxy Mobile IPv6 (PMIPv6)
              Domains", draft-ietf-multimob-pmipv6-source-08 (work in
              progress), March 2014.

   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", RFC 5844, May 2010.

   [RFC5845]  Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung,
              "Generic Routing Encapsulation (GRE) Key Option for Proxy
              Mobile IPv6", RFC 5845, June 2010.

Appendix A.  Considerations for Mobile Multicast Sources

   This document specifies protocol operations for a fast handover of
   mobile listeners, only.  In this appendix, we briefly discuss aspects
   of supporting mobile multicast sources.

   In a multicast-enabled Proxy Mobile IPv6 domain, multicast sender
   support is likely to be enabled by any one of the mechanisms
   described in [I-D.ietf-multimob-pmipv6-source].  In this case,
   multicast data packets from an MN are transparently forwarded either
   to its associated LMA or to a multicast-enabled access network.  In
   any case, a mobile source can continue to transmit multicast packets
   after a handover from pMAG to nMAG without additional management



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   operations.  Packets (with a persistent source address) will continue
   to flow via the LMA or the access network into the previously
   established distribution system.

   In contrast, an MN will change its Care-of Address while performing
   FMIPv6 handovers.  Even though MNs are enabled to send packets via
   the reverse NAR-PAR tunnel using their previous Care-of Address for a
   limited time, Multicast sender support in such a Mobile IPv6 regime
   will most likely follow one of the basic mechanisms (1) bidirectional
   tunneling, (2) remote subscription, or (3) agent-based as described
   in Section 5.1 of [RFC5757].  A solution for multicast senders that
   is homogeneously deployed throughout the mobile access network can
   support seamless services during Fast Handovers, the details of which
   are beyond the scope of this document.

Authors' Addresses

   Thomas C. Schmidt (editor)
   HAW Hamburg
   Dept. Informatik
   Berliner Tor 7
   Hamburg  D-20099
   Germany

   Email: schmidt@informatik.haw-hamburg.de


   Matthias Waehlisch
   link-lab & FU Berlin
   Hoenower Str. 35
   Berlin  D-10318
   Germany

   Email: mw@link-lab.net


   Rajeev Koodli
   Intel
   3600 Juliette Lane
   Santa Clara,  CA 95054
   USA

   Email: rajeev.koodli@intel.com








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   Godred Fairhurst
   University of Aberdeen
   School of Engineering
   Aberdeen  AB24 3UE
   UK

   Email: gorry@erg.abdn.ac.uk


   Dapeng Liu
   China Mobile

   Phone: +86-123-456-7890
   Email: liudapeng@chinamobile.com





































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