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rfc:rfc7028

Internet Engineering Task Force (IETF) JC. Zuniga Request for Comments: 7028 InterDigital Communications, LLC Category: Experimental LM. Contreras ISSN: 2070-1721 Telefonica I+D

                                                         CJ. Bernardos
                                                                  UC3M
                                                               S. Jeon
                                         Instituto de Telecomunicacoes
                                                                Y. Kim
                                                   Soongsil University
                                                        September 2013
   Multicast Mobility Routing Optimizations for Proxy Mobile IPv6

Abstract

 This document proposes some experimental enhancements to the base
 solution to support IP multicasting in a Proxy Mobile IPv6 (PMIPv6)
 domain.  These enhancements include the use of a multicast tree
 mobility anchor as the topological anchor point for multicast
 traffic, as well as a direct routing option where the Mobile Access
 Gateway can provide access to multicast content in the local network.
 The goal of these enhancements is to provide benefits such as
 reducing multicast traffic replication and supporting different
 PMIPv6 deployment scenarios.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for examination, experimental implementation, and
 evaluation.
 This document defines an Experimental Protocol for the Internet
 community.  This document is a product of the Internet Engineering
 Task Force (IETF).  It represents the consensus of the IETF
 community.  It has received public review and has been approved for
 publication by the Internet Engineering Steering Group (IESG).  Not
 all documents approved by the IESG are a candidate for any level of
 Internet Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7028.

Zuniga, et al. Experimental [Page 1] RFC 7028 Multicast Mobility Routing Optimizations September 2013

Copyright Notice

 Copyright (c) 2013 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
 2. Terminology .....................................................4
 3. Overview ........................................................5
    3.1. MTMA/Direct Routing Mode Selection .........................5
    3.2. Multicast Tree Mobility Anchor (Subscription via MTMA) .....5
    3.3. Direct Routing (Subscription via Direct Routing) ...........7
 4. Mobile Access Gateway Operation .................................9
    4.1. Extensions to Binding Update List Data Structure ...........9
    4.2. MAG as MLD Proxy ...........................................9
         4.2.1. MTMA Mode (Subscription via MTMA) ...................9
         4.2.2. Direct Routing Mode (Subscription via
                Direct Routing) ....................................11
 5. Local Mobility Anchor Operation ................................14
    5.1. Dynamic IP Multicast Selector Option ......................14
         5.1.1. Option Application Rules ...........................14
         5.1.2. Option Format ......................................14
 6. Multicast Tree Mobility Anchor Operation .......................16
    6.1. Conceptual Data Structures ................................17
 7. Mobile Node Operation ..........................................17
 8. IPv4 Support ...................................................17
 9. IANA Considerations ............................................18
 10. Security Considerations .......................................18
 11. Contributors ..................................................19
 12. References ....................................................20
    12.1. Normative References .....................................20
    12.2. Informative References ...................................21
 Appendix A. MTMA Deployment Use Cases .............................22
   A.1. PMIPv6 Domain with Ratio 1:1 ...............................22
   A.2. PMIPv6 Domain with Ratio N:1 ...............................22
   A.3. PMIPv6 Domain with Ratio 1:N ...............................24
   A.4. PMIPv6 Domain with H-LMA ...................................26

Zuniga, et al. Experimental [Page 2] RFC 7028 Multicast Mobility Routing Optimizations September 2013

1. Introduction

 Proxy Mobile IPv6 [RFC5213] is a network-based approach to solving
 the IP mobility problem.  In a Proxy Mobile IPv6 (PMIPv6) domain, the
 Mobile Access Gateway (MAG) behaves as a proxy mobility agent in the
 network and performs the mobility management on behalf of the Mobile
 Node (MN).  The Local Mobility Anchor (LMA) is the home agent for the
 MN and the topological anchor point.  PMIPv6 was originally designed
 for unicast traffic.  However, a PMIPv6 domain may handle data from
 both unicast and multicast sources.
 The Internet Group Management Protocol (IGMPv3) [RFC3376] is used by
 IPv4 hosts to report their IP multicast group memberships to
 neighboring multicast routers.  Multicast Listener Discovery Version
 2 (MLDv2) [RFC3810] is used in a similar way by IPv6 routers to
 discover the presence of IPv6 multicast hosts.  Also, the IGMP/MLD
 proxy specification [RFC4605] allows an intermediate (i.e., edge)
 node to appear as a multicast router to downstream hosts and as a
 host to upstream multicast routers.  IGMP- and MLD-related protocols
 however were not originally designed to address the IP mobility of
 multicast listeners (i.e., IGMP and MLD protocols were originally
 designed for fixed networks).
 A base solution to support both IPv4 and IPv6 multicast listener
 mobility in a PMIPv6 domain is specified in [RFC6224], which
 describes deployment options without modifying mobility and multicast
 protocol standards.  PMIPv6 allows a mobile access gateway to
 establish multiple PMIPv6 tunnels with different local mobility
 anchors, e.g., up to one per mobile node.  In the presence of
 multicast traffic, multiple instances of the same traffic can
 converge to the same MAG.  Hence, when IP multicasting is applied
 into PMIPv6, it may lead to redundant traffic at a MAG.  This is the
 tunnel convergence problem.
 In order to address this issue, this document proposes an
 experimental solution, consisting of two complementary enhancements:
 multicast anchor and direct routing.  The first enhancement makes use
 of a Multicast Tree Mobility Anchor (MTMA) as the topological anchor
 point for remotely delivering multicast traffic, while the second
 enhancement uses direct routing taking advantage of local multicast
 source availability, allowing a mobile access gateway to connect
 directly to a multicast router for simple access to local content.
 Neither of the two schemes has any impact on the mobile node to
 support IPv4 and IPv6 multicast listener mobility, nor on the wider
 Internet, as they only affect the PMIPv6 domains where they are
 deployed.  Although references to "MLD proxy" are used in the
 document, it should be understood to also include "IGMP/MLD proxy"
 functionality (see Section 8 for details).  The status of this

Zuniga, et al. Experimental [Page 3] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 proposal is Experimental.  The status of this proposal may be
 reconsidered in the future, once more implementation feedback and
 deployment experience is gathered, reporting on the performance of
 the two proposed schemes as well as operational feedback on scheme
 selection.

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 [RFC2119].
 This document uses the terminology defined in [RFC5213], [RFC6275],
 and [RFC3810].  Specifically, the definition of PMIPv6 domain is
 reused from [RFC5213] and reproduced here for completeness.
 Proxy Mobile IPv6 Domain (PMIPv6-Domain):  Proxy Mobile IPv6 domain
    refers to the network where the mobility management of a mobile
    node is handled using the Proxy Mobile IPv6 protocol as defined in
    [RFC5213].  The Proxy Mobile IPv6 domain includes local mobility
    anchors and mobile access gateways between which security
    associations can be set up and authorization for sending proxy
    binding updates on behalf of the mobile nodes can be ensured.
 In this document we refine the definition from the point of view of
 the kind of traffic served to the MN in the following way:
 PMIPv6 unicast domain:  PMIPv6 unicast domain refers to the network
    covered by one LMA for unicast service.  This service supports
    mobility as the MN moves from one MAG to another one, both
    associated with the same LMA regarding the MN unicast traffic.
 PMIPv6 multicast domain:  PMIPv6 multicast domain refers to the
    network covered by one network element named MTMA (defined below)
    for multicast service in such a way that an MN using that service
    is not aware of mobility as it moves from one MAG to another.
 From the definitions above, it can be stated that a PMIPv6 domain can
 have several PMIPv6 unicast domains and PMIPv6 multicast domains.
 Additionally, some other definitions are introduced, as follows.
 MTMA or multicast tree mobility anchor:  An entity working as
    topological anchor point for multicast traffic.  It manages the
    multicast groups subscribed by all (or a subset of) the MAGs in a
    PMIPv6 multicast domain, on behalf of the MNs attached to them.
    Hence, an MTMA performs the functions of either a designated
    multicast router or an MLD proxy.

Zuniga, et al. Experimental [Page 4] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 H-LMA or Hybrid-LMA:  An entity that is dedicated to both unicast and
    multicast services and able to work as both LMA and MTMA
    simultaneously.
 Direct routing:  This scheme uses the native multicast infrastructure
    for retrieving multicast data.  For an operator having its own
    local content, this technique also includes the case where the
    content source is directly connected to the MAG.
 Subscription via MTMA:  Multicast subscription mode in which the
    content is retrieved from the remote (or home) MTMA.
 Subscription via direct routing:  Multicast subscription mode in
    which the content is retrieved using direct routing from the local
    domain.

3. Overview

3.1. MTMA/Direct Routing Mode Selection

 This specification describes two complementary operational modes that
 can be used to deliver multicast traffic in a PMIPv6 domain:
 multicast tree mobility anchor and direct routing.  There are
 different approaches that can be followed to perform this operational
 mode selection, depending on the operator's preferences and PMIPv6
 deployment characteristics.  For example, the mode can be manually
 configured at the mobile access gateway, according to the multicast
 tree deployment in the PMIPv6 domain, following operator's
 configuration of the multicast distribution on it.  Another option is
 the use of dynamic policies, conveyed in the PBU (Proxy Binding
 Update) / PBA (Proxy Binding Acknowledgement) signaling using the
 Dynamic IP Multicast Selector option described in Section 5.1.  Next,
 each of the two operational modes is introduced.

3.2. Multicast Tree Mobility Anchor (Subscription via MTMA)

 A multicast tree mobility anchor is used to serve as the mobility
 anchor for multicast traffic.  The MTMA is either a designated
 multicast router or an MLD proxy.  Typically, the MTMA will be used
 to get access to remote multicast content.
 The multicast tree mobility anchor connects to the mobile access
 gateway, as described in [RFC6224], and it can reuse native PMIPv6
 features such as tunnel establishment and security [RFC5213],
 heartbeat [RFC5847], etc.  Unicast traffic will go normally to the
 local mobility anchors in the PMIPv6 domain as described in
 [RFC5213].  A MAG connecting to the MTMA acts as an MLD proxy.

Zuniga, et al. Experimental [Page 5] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 This section describes how the MTMA works in scenarios of MN
 attachment and multicast mobility.  It concentrates on the case of
 both LMA and MTMA defining a unique PMIPv6 domain.  Some other
 deployment scenarios are presented in Appendix A.
 Figure 1 shows an example of a PMIPv6 domain supporting multicast
 mobility.  The local mobility anchor is dedicated to unicast traffic,
 and the multicast tree mobility anchor is dedicated to multicast
 traffic.  The MTMA can be considered to be a form of upstream
 multicast router with tunnel interfaces allowing subscription via
 MTMA for the MNs.
 As shown in Figure 1, MAG1 may connect to both unicast (LMA) and
 multicast (MTMA) entities.  Thus, a given MN may simultaneously
 receive both unicast and multicast traffic.  In Figure 1, MN1 and MN2
 receive unicast traffic, multicast traffic, or both, whereas MN3
 receives multicast traffic only.

Zuniga, et al. Experimental [Page 6] RFC 7028 Multicast Mobility Routing Optimizations September 2013

                                 +--------------+
                                 |Content Source|   || - PMIPv6 Tunnel
                                 +--------------+   |  - Multicast
                                        |                Data Path
                                        |
       ***  ***  ***  ***      ***  ***  ***  ***
      *   **   **   **   *    *   **   **   **    *
     *                    *  *                     *
     *  Unicast Traffic   *  *  Multicast Traffic  *
     *                    *  *                     *
      *   **   **   **   *    *   **   **   **   *
       ***  ***  ***  **       ***  ***  ***  ***
               |                       |
               |                       |
               |                       |
            +-----+                 +------+
   Unicast  | LMA |                 | MTMA |     Multicast
    Anchor  +-----+                 +------+      Anchor
                \\                    // ||
                 \\                  //  ||
                  \\                //   ||
                   \\              //    ||
                    \\            //     ||
                     \\          //      ||
                      \\        //       ||
                       \\      //        ||
                        \\    //         ||
                        +------+      +------+
                        | MAG1 |      | MAG2 |   MLD Proxy
                        +------+      +------+
                        |     |          |
                        |     |          |
                      {MN1} {MN2}      {MN3}
    Figure 1: Architecture of Multicast Tree Mobility Anchor (MTMA)

3.3. Direct Routing (Subscription via Direct Routing)

 Direct routing uses a native multicast infrastructure, allowing a
 mobile access gateway to directly connect to a multicast router (as
 next hop) in the PMIPv6 domain.  A MAG acts as an MLD proxy.
 The main purpose of direct routing is to provide optimal connectivity
 for local content.  As a consequence, it replaces the MTMA of the
 channel management and data delivery of locally available content.
 Unicast traffic will go as normally to the LMAs in the PMIPv6 domain.

Zuniga, et al. Experimental [Page 7] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 This section describes how the direct routing works in scenarios of
 MN attachment and multicast mobility.
                         Multicast Tree
                                :
                                :         || - PMIPv6 Tunnel
     +----------+         +----------+    |  - Multicast Data Path
     |   LMA    |         |    MR    |
     +----------+         +----------+
          ||  \\           /     |
          ||   \\         /      |
          ||    \\       /       |
          ||     \\     /        |
          ||      \\   /         |
          ||       \\ /          |
          ||        \\           |
          ||        /\\          |
          ||       /  \\         |
          ||      /    \\        |
          ||     /      \\       |
          ||    /        \\      |
       +--------+        +--------+
       |  MAG1  |        |  MAG2  |    MLD proxy
       +--------+        +--------+
          :                   :
      +------+             +------+
      |  MN1 |   ----->    |  MN1 |
      +------+             +------+
  Figure 2: Architecture for Direct-Routing-Based PMIPv6 Multicasting
 Figure 2 shows the architecture for the local routing case using
 native multicasting infrastructure [PMIP6-REQ].
 The local mobility anchor is dedicated to unicast traffic, and the
 multicast traffic is obtained from an upstream multicast router
 present in the PMIPv6 domain.  Note that there can be multiple LMAs
 for unicast traffic (not shown in Figure 1 for simplicity) in a given
 PMIPv6 domain.
 As shown in Figure 2, a mobile access gateway may connect to both
 unicast (LMA) and multicast routers (MRs).  Thus, a given mobile node
 may simultaneously receive both unicast and multicast traffic.
 As seen in Figure 2, each MAG has a direct connection (i.e., not
 using the PMIPv6 tunnel interface) with a multicast router.
 Depending on the multicast support on the visited network, different
 schemas can be used to provide this direct connection between the

Zuniga, et al. Experimental [Page 8] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 MAGs and the multicast router(s), e.g., being connected to the same
 shared link or using a tunneling approach, such as Generic Routing
 Encapsulation (GRE) tunnels [RFC2784] or Automatic Multicast
 Tunneling (AMT) [AUTO].  To facilitate IGMP/MLD signaling and
 multicast traffic forwarding, an MLD proxy function defined in
 [RFC4605] SHOULD be implemented in the MAG.  There SHOULD be direct
 connectivity between the MAG and the local multicast router (or
 additional MLD proxy).

4. Mobile Access Gateway Operation

 This section describes the operation of the mobile access gateway,
 considering that the MAG incorporates MLD proxy functions as per
 [RFC4605].

4.1. Extensions to Binding Update List Data Structure

 A Binding Update List (BUL) at the MAG, like the one specified in
 [RFC5213], MUST be maintained to handle the relationship between the
 serving entities (e.g., MTMA and LMA) and the mobile nodes for both
 unicast and multicast traffic.

4.2. MAG as MLD Proxy

4.2.1. MTMA Mode (Subscription via MTMA)

 In case of subscription via MTMA, all MAGs that are connected to the
 MTMA must support the MLD proxy function [RFC4605].  Specifically in
 Figure 1, each of the MAG1-MTMA and MAG2-MTMA tunnel interfaces
 define an MLD proxy domain.  The mobile nodes are considered to be on
 the downstream interface of the MLD proxy (of the MAG), and the MTMA
 is considered to be on the upstream interface (of the MAG) as per
 [RFC4605].  Note that the mobile access gateway could also be an IGMP
 proxy.
 Figure 3 shows the procedure when MN1 attaches to a MAG, and
 establishes associations with the LMA (unicast) and the MTMA
 (multicast).

Zuniga, et al. Experimental [Page 9] RFC 7028 Multicast Mobility Routing Optimizations September 2013

         MN1                  MAG1       LMA        MTMA
         |                (MLD proxy) (Unicast) (Multicast)
         MN1 attaches to MAG1  |          |          |
         |                     |          |          |
         |----Rtr Sol--------->|          |          |
         |                     |--PBU---->|          |
         |                     |          |          |
         |                     |<----PBA--|          |
         |                     |          |          |
         |                     |=Unicast==|          |
         |                     |  Tunnel  |          |
         |<---------Rtr Adv----|          |          |
         |                     |          |          |
         |< ------ Unicast Traffic------->|          |
         |                     |          |          |
         |                     |==Multicast Tunnel===|
         |                     |          |          |
         |<-------MLD Query----|          |          |
         |                     |          |          |
         MN1 requires          |          |          |
         multicast services    |          |          |
         |                     |          |          |
         |----MLD Report (G)-->|          |          |
         |                     |          |          |
         |                     |----Aggregated------>|
         |                     |   MLD Report (G)    |
         |                     |          |          |
         |                     |          |          |
         |<-----------Multicast Traffic------------->|
         |                     |          |          |
 Figure 3: MN Attachment and Multicast Service Establishment for MTMA
 In Figure 3, the MAG first establishes the PMIPv6 tunnel with LMA for
 unicast traffic as defined in [RFC5213] after being triggered by the
 Router Solicitation message from MN1.  Unicast traffic will then flow
 between MN1 and LMA.
 For multicast traffic, a multicast tunnel may have been pre-
 configured between MAG and MTMA, or may be dynamically established
 when the first MN appears at the MAG.
 MN1 sends the MLD report message (when required by its upper-layer
 applications) as defined in [RFC3810] in response to an MLD Query
 from MAG (generated as defined by [RFC6224] upon handover).  The MAG,
 acting as an MLD proxy defined in [RFC4605], will then send an
 Aggregated MLD Report to the multicast anchor, MTMA (assuming that
 this is a new multicast group that the MAG had not previously

Zuniga, et al. Experimental [Page 10] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 subscribed to).  Multicast traffic will then flow from the MTMA
 towards MN1.  The MTMA acts as an MLD Querier, so it will
 periodically query each mobile access gateway about the subscriptions
 it maintains (not shown in Figure 3).
 We next consider a mobility scenario in which MN1 with an ongoing
 multicast subscription moves from one MAG to another MAG.  According
 to the baseline solution signaling method described in [RFC6224],
 after MN1 mobility, the new mobile access gateway acting in its role
 of MLD proxy will send an MLD Query to the newly observed mobile node
 on its downlink.  Assuming that the subsequent MLD Report from MN1
 requests membership for a new multicast group (from the new MAG's
 point of view), this will then result in an Aggregated MLD Report
 being sent to the MTMA from the new mobile access gateway.  This
 message will be sent through a multicast tunnel between the new MAG
 and MTMA (pre-established or dynamically established).
 When MN1 detaches, the old MAG may keep the multicast tunnel with the
 multicast MTMA if there are still other MNs using the multicast
 tunnel.  Even if there are no mobile nodes currently on the multicast
 tunnel, the old MAG may decide to keep the multicast tunnel
 temporarily for potential future use.
 As discussed above, existing MLD (and MLD proxy) signaling will
 handle a large part of the multicast mobility management for the
 mobile node.

4.2.2. Direct Routing Mode (Subscription via Direct Routing)

 In this case, the MLD proxy instance is configured to obtain the
 multicast traffic locally.  Figure 4 shows an example of multicast
 service establishment.  The mobile access gateway first establishes
 the PMIPv6 tunnel with the local mobility anchor for unicast traffic
 as defined in [RFC5213] after being triggered by the Router
 Solicitation message from the mobile node.  Unicast traffic will then
 flow between the MN and LMA.
 For multicast traffic, it is assumed that the upstream interface of
 the MLD proxy instance has been configured pointing to a multicast
 router internal to the PMIPv6 domain (or towards an additional MLD
 proxy node in the domain), for all the multicast channels (which, in
 consequence, have to be local).  There should be direct connectivity
 between the MAG and the local multicast router (or additional MLD
 proxy).

Zuniga, et al. Experimental [Page 11] RFC 7028 Multicast Mobility Routing Optimizations September 2013

      MN1                   MAG1          LMA            MR
       |                (MLD proxy)    (Unicast)    (Multicast)
  MN1 attaches to MAG1       |             |             |
       |                     |             |             |
       |----Rtr Sol--------->|             |             |
       |                     |--PBU------->|             |
       |                     |             |             |
       |                     |<-------PBA--|             |
       |                     |             |             |
       |                     |===Unicast===|             |
       |                     |   Tunnel    |             |
       |<---------Rtr Adv----|             |             |
       |                     |             |             |
       |<--------Unicast Traffic---------->|             |
       |                     |             |             |
       |                     |             |             |
       |<-------MLD Query----|<-------------MLD Query----|
       |                     |             |             |
   MN1 requires              |             |             |
   multicast services        |             |             |
       |                     |             |             |
       |--MLD Report (G)---->|             |             |
       |                     |             |             |
       |                     |----Aggregated------------>|
       |                     |   MLD Report (G)          |
       |                     |             |             |
       |                     |             |             |
       |<-------------Multicast Traffic----------------->|
       |                     |             |             |
     Figure 4: Multicast Service Establishment for Direct Routing
 Upon detecting node attachment from an incoming interface, the MAG
 adds each downstream interface to the MLD proxy instance with an
 upstream link to an MR according to the standard MLD proxy operations
 [RFC4605] and sends an MLD Query message towards the MN.  The mobile
 node sends the MLD report message (when required by its upper-layer
 applications) in response to an MLD Query from the MAG.  Upon
 receiving the MLD Report message from each incoming interface, the
 MAG checks the MLD proxy instance associated with the downstream
 interface and then the MLD Report messages will be aggregated and
 forwarded to the upstream link associated with the MR (assuming that
 this is a new multicast group that the MAG had not previously
 subscribed to).  Multicast traffic will then flow from the local
 multicast router towards the mobile node.

Zuniga, et al. Experimental [Page 12] RFC 7028 Multicast Mobility Routing Optimizations September 2013

       MN1          P-MAG       N-MAG        LMA        MR
        |             |           |           |          |
        |             |           |           |          |
        |<------------|<-- Multicast Data----------------|
        |             |       .   |           |          |
        |             |       .   |           |          |
        |             |       .   |           |          |
     Link         Handover        |           |          |
  Disconnected    Detection       |           |          |
        |             |           |           |          |
        |             |           |           |          |
        |             |    MN Attachment      |          |
        |             |           |           |          |
        |             |           |           |          |
        |----Rtr Sol------------->|           |          |
        |             |           |           |          |
        |             |           |--PBU----->|          |
        |             |           |           |          |
        |             |           |<-----PBA--|          |
        |             |           |           |          |
        |<-----------MLD Query----|           |          |
        |             |           |           |          |
        |----MLD Report---------->|           |          |
        |             |           |           |          |
        |             |           |----Aggregated------->|
        |             |           |    MLD Report        |
        |             |           |           |          |
        |<------------------------|<---Multicast Data----|
        |             |           |           |          |
       Figure 5: Multicast Mobility Signaling for Direct Routing
 Figure 5 shows the handover operation procedure for the direct
 routing operation mode.  When MN1 hands off to the next MAG (N-MAG)
 from the previous MAG (P-MAG), the N-MAG detects the newly arrived
 attached mobile node and performs binding update procedure by
 exchanging PBU/PBA signaling messages with LMA.  At the same time, an
 MLD proxy instance detecting MN1 transmits an MLD query message to
 the mobile node.  After receiving the MLD query message, MN1 sends an
 MLD report message that includes the multicast group information.
 The N-MAG then sends an aggregated MLD report message to the upstream
 link associated with the MR.  An upstream interface of MLD proxy
 instance is chosen towards certain multicast router.  The upstream
 interface selection can be done according to dynamic policies
 conveyed in the Dynamic IP Multicast Selector option (as described in
 Section 5.1) or according to manually configured policies.  Note that
 in the base solution defined in [RFC6224], the interface selection is
 determined for each MN based on the Binding Update List.  When the

Zuniga, et al. Experimental [Page 13] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 N-MAG receives the multicast packets from the MR, it then simply
 forwards them without tunnel encapsulation.  The N-MAG updates MN1's
 location information to the LMA by exchanging PBU/PBA signaling
 messages.

5. Local Mobility Anchor Operation

 This section includes a new mobility option to support dynamic
 policies on subscription via MTMA/direct routing based on the local
 mobility anchor conveying the required info to the mobile access
 gateway in the proxy binding acknowledgement message.

5.1. Dynamic IP Multicast Selector Option

5.1.1. Option Application Rules

 A new TLV-encoded mobility option, the Dynamic IP Multicast Selector
 option, is defined for use with the proxy binding acknowledgement
 message exchanged between an LMA and a MAG to convey dynamic policies
 on subscription via MTMA/direct routing.  This option is used for
 exchanging the IP addresses of both the group subscribed to by the
 MN, and the source(s) delivering it, as well as the applicable filter
 mode.  This information is carried by using directly the Multicast
 Address Record format defined in [RFC3810].  There can be multiple
 "Dynamic IP Multicast Selector" options present in the message, up to
 one for each active subscription maintained by the MN.

5.1.2. Option Format

 The format of this new option is as follows:

Zuniga, et al. Experimental [Page 14] RFC 7028 Multicast Mobility Routing Optimizations September 2013

  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    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |     Protocol    |M| Reserved  |Nr of Mcast Address Records (N)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 +                  Multicast Address Record [1]                 +
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 +                  Multicast Address Record [2]                 +
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                               .                               |
 |                               .                               |
 |                               .                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 +                  Multicast Address Record [N]                 +
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Type:
    54
 Length:
    8-bit unsigned integer indicating the length of the option in
    octets, excluding the type and length fields.
 Protocol:
    Field used to identify the multicast membership protocol in use,
    and the corresponding format of the next Multicast Address Record.
    This field maps the type codification used in the original MLD
    specifications for the Report message, namely for MLDv2 [RFC3810]
    the Protocol value MUST be 143, whereas for MLDv1 [RFC2710] the
    Protocol value MUST be 131.
 Dynamic IP Multicast Selector Mode Flag (M-bit):
    This field indicates the subscription via MTMA/direct routing
    mode.  If the (M) flag value is set to a value of (1), it is an
    indication that the IP multicast traffic associated with the
    multicast group(s) identified by the Multicast Address Record(s)

Zuniga, et al. Experimental [Page 15] RFC 7028 Multicast Mobility Routing Optimizations September 2013

    in this mobility option SHOULD be routed locally (subscription via
    direct routing mode).  If the (M) flag value is set to a value of
    (0), it is an indication that IP multicast traffic associated with
    the multicast group(s) identified by the Multicast Address Record
    in this mobility option(s) SHOULD be routed to the home network,
    via the MTMA (subscription via MTMA mode).  The mobile access
    gateway MAY also choose to use static pre-established policies
    instead of following the indications provided by the local
    mobility anchor.  All other IP traffic associated with the mobile
    node is managed according to a default policy configured at the
    PMIPv6 multicast domain.
 Reserved:
    This field is unused for now.  The value MUST be initialized to 0
    by the sender and MUST be ignored by the receiver.
 Nr of Mcast Address Records (N)
    16-bit unsigned integer indicating the number of Mcast Address
    Records (N) present in this option.
 Multicast Address Record:
    Multicast subscription information corresponding to a single
    multicast address as defined in [RFC3810], or as defined in
    [RFC2710] for MLDv1.

6. Multicast Tree Mobility Anchor Operation

 The MTMA provides connectivity to the multicast infrastructure out of
 the PMIPv6 domain.  The MTMA itself either could act as an additional
 MLD proxy (only in the case where all the connected mobile access
 gateways act also as MLD proxies), reporting to a further node an
 aggregated view of the subscriptions in a PMIPv6 multicast domain, or
 can act as a designated multicast router for all the MAGs in a PMIPv6
 multicast domain.  The multicast tree mobility anchor will then
 request the multicast content on behalf of the MAGs (and mobile nodes
 behind them).  In addition, the MTMA will create and maintain the
 corresponding multicast forwarding states per each tunnel interface
 towards the MAGs.  Whatever the role played, when the MAGs act as MLD
 proxy, the MTMA becomes the MLD querier of the MLD proxy instance
 located in each MAG.

Zuniga, et al. Experimental [Page 16] RFC 7028 Multicast Mobility Routing Optimizations September 2013

6.1. Conceptual Data Structures

 The multicast tree mobility anchor does not directly interact with
 the mobile nodes attached to any of the mobile access gateways.  The
 MTMA only manages the multicast groups subscribed per MAG on behalf
 of the MNs attached to it.  Having this in mind, the relevant
 information to be stored in the MTMA should be the tunnel interface
 identifier (tunnel-if-id) of the bidirectional tunnel for multicast
 between the MTMA and every MAG (e.g., similar to what is stated in
 [RFC5213] for the unicast case), the IP addresses of the multicast
 group delivered per tunnel to each of the MAGs, and the IP addresses
 of the sources injecting the multicast traffic per tunnel to the
 multicast domain defined by the MTMA.

7. Mobile Node Operation

 The mobile node operation is not impacted by the existence of an MTMA
 as anchor for the multicast traffic being subscribed or the use of
 direct routing.  The MN will act according to the stated operations
 in [RFC5213] and [RFC6224].
 This document considers that every mobile node requesting multicast-
 only services is previously registered in a PMIPv6 unicast domain to
 get a unicast IP address.  The registration can also be required for
 several purposes such as remote management, billing, multicast
 configuration, etc.
 A given mobile node's policy profile information must be updated to
 be able to store the IPv6 addresses of both the local mobility anchor
 and multicast tree mobility anchor, the later for the subscription
 via MTMA case.

8. IPv4 Support

 This document does not introduce any IPv4-specific issue regarding
 [RFC5844].  In order for the solution to support IPv4, all the
 described network elements (i.e., MAG, MTMA, and MR) must support
 IGMP.  In this case, the functionalities of the MAG and MTMA would be
 as described in [RFC6224], with the MTMA replicating the requirements
 described for the LMA.  For the case of the MR, it must also be dual-
 stack (i.e., IPv6/IPv4) enabled.
 Although references to "MLD proxy" have been used in the document, it
 should be understood to also include "IGMP/MLD proxy" functionality.
 Regarding the Dynamic IP Multicast Selector Option format, it SHOULD
 consider IPv4 compatibility in the following way:

Zuniga, et al. Experimental [Page 17] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 Protocol field:
    For IPv4, this field maps the type codification used in the
    original IGMP specifications for the Report message, in the
    following way:
    It MUST be 0x12 in case of using IGMPv1.
    It MUST be 0x16 in case of using IGMPv2.
    It MUST be 0x22 in case of using IGMPv3.
 Multicast Address Record field:
    This field takes different formats depending on the IGMP version
    being used by the MN, as follows:
  • For IGMPv1, it takes the format given by the Group Address in

[RFC1112].

  • For IGMPv2, it takes the format given by the Group Address in

[RFC2236].

  • For IGMPv3, it takes the format given by the Group Record in

[RFC3376].

9. IANA Considerations

 This document defines a new mobility option, the Dynamic IP Multicast
 Selector, which has been assigned the Type 54 by IANA.  The Type
 value for these options has been assigned from the same numbering
 space as allocated for the other mobility options, as defined in
 [RFC6275]: http://www.iana.org/assignments/mobility-parameters.

10. Security Considerations

 This document describes two complementary operational modes that can
 be used to deliver multicast traffic in a PMIPv6 domain: multicast
 anchor and direct routing.  Different approaches are described in the
 document to decide which operational mode is selected: i) the use of
 pre-configured/pre-provisioned policies at the mobile access gateway,
 or ii) the use of dynamic policies.  Approach ii) could introduce a
 potential security issue if the protocol signaling is not properly
 secured.  The use of the Dynamic IP Multicast Selector option
 described in the document requires message integrity protection and
 source authentication.  Hence, the IPsec security mechanism

Zuniga, et al. Experimental [Page 18] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 recommended by Proxy Mobile IPv6 [RFC5213] MUST be used to secure the
 Dynamic IP Multicast Selector option conveyed in the PBA (Proxy
 Binding Acknowledgement).
 This document does not introduce any additional security threats
 beyond the current security considerations of PMIPv6 [RFC5213], MLD
 [RFC3810], IGMP [RFC3376], and IGMP/MLD Proxying [RFC4605].

11. Contributors

 The following individuals made significant contributions to this
 document.
 Akbar Rahman
 InterDigital Communications, LLC
 EMail: akbar.rahman@interdigital.com
 Ignacio Soto
 Universidad Carlos III de Madrid
 EMail: isoto@it.uc3m.es

Zuniga, et al. Experimental [Page 19] RFC 7028 Multicast Mobility Routing Optimizations September 2013

12. References

12.1. Normative References

 [RFC1112]    Deering, S., "Host extensions for IP multicasting",
              STD 5, RFC 1112, August 1989.
 [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2236]    Fenner, W., "Internet Group Management Protocol, Version
              2", RFC 2236, November 1997.
 [RFC2710]    Deering, S., Fenner, W., and B. Haberman, "Multicast
              Listener Discovery (MLD) for IPv6", RFC 2710,
              October 1999.
 [RFC2784]    Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
              March 2000.
 [RFC3376]    Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
              Thyagarajan, "Internet Group Management Protocol,
              Version 3", RFC 3376, October 2002.
 [RFC3810]    Vida, R. and L. Costa, "Multicast Listener Discovery
              Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
 [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.
 [RFC5213]    Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury,
              K., and B. Patil, "Proxy Mobile IPv6", RFC 5213,
              August 2008.
 [RFC5844]    Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", RFC 5844, May 2010.
 [RFC5847]    Devarapalli, V., Koodli, R., Lim, H., Kant, N.,
              Krishnan, S., and J. Laganier, "Heartbeat Mechanism for
              Proxy Mobile IPv6", RFC 5847, June 2010.
 [RFC6275]    Perkins, C., Johnson, D., and J. Arkko, "Mobility
              Support in IPv6", RFC 6275, July 2011.

Zuniga, et al. Experimental [Page 20] RFC 7028 Multicast Mobility Routing Optimizations September 2013

12.2. Informative References

 [AUTO]       Bumgardner, G., "Automatic Multicast Tunneling", Work in
              Progress, July 2013.
 [MLDPROXY]   Asaeda, H. and S. Jeon, "Multiple Upstream Interface
              Support for IGMP/MLD Proxy", Work in Progress,
              February 2013.
 [MUIIMP]     Zhang, H. and T. Schmidt, "Multi-Upstream Interfaces
              IGMP/MLD Proxy", Work in Progress, July 2013.
 [MULTIMOB]   Schmidt, T., Gao, S., Zhang, H., and M. Waehlisch,
              "Mobile Multicast Sender Support in Proxy Mobile IPv6
              (PMIPv6) Domains", Work in Progress, July 2013.
 [PMIP6-REQ]  Deng, H., Chen, G., Schmidt, T., Seite, P., and P. Yang,
              "Multicast Support Requirements for Proxy Mobile IPv6",
              Work in Progress, July 2009.
 [RFC6224]    Schmidt, T., Waehlisch, M., and S. Krishnan, "Base
              Deployment for Multicast Listener Support in Proxy
              Mobile IPv6 (PMIPv6) Domains", RFC 6224, April 2011.
 [UPSTREAM]   Contreras, LM., Bernardos, CJ., and JC. Zuniga,
              "Extension of the MLD proxy functionality to support
              multiple upstream interfaces", Work in Progress,
              February 2013.

Zuniga, et al. Experimental [Page 21] RFC 7028 Multicast Mobility Routing Optimizations September 2013

Appendix A. MTMA Deployment Use Cases

 This informative appendix describes, from the network architecture
 point of view, several deployment options considering the MTMA.
 These options can be distinguished in terms of the number of LMAs and
 MTMAs present in a PMIPv6 domain and the service relationship that a
 set of MNs gets from them, in the form of a "LMA : MTMA" ratio.
 According to that, it is possible to differentiate the following
 approaches:
 o  A set of MNs is served in a PMIPv6 domain by two entities, one
    MTMA for multicast service, and one LMA for unicast, in such a way
    that the ratio is 1:1 (one common PMIPv6 unicast and multicast
    domain).
 o  A set of MNs is served in a PMIPv6 domain by several entities, one
    MTMA for multicast service, while the others (LMAs) for unicast,
    in such a way that the ratio is N:1 (N PMIPv6 unicast domains
    coexist with a unique multicast domain).
 o  A set of MNs is served in a PMIPv6 domain by several entities, one
    LMA for unicast, while the others (MTMAs) are devoted to multicast
    service, in such a way that the ratio is 1:N (one single PMIPv6
    unicast domain coexists with multiple multicast domains).
 Scenarios with an N:M ratio are considered to be a combination of the
 previous ones.

A.1. PMIPv6 Domain with Ratio 1:1

 This approach refers to the architecture presented in Figure 1.
 Within this approach, a common set of MNs is served by a couple of
 entities, one LMA for unicast and one MTMA for multicast.  All the
 MNs of the set are served by these two elements as they move in the
 PMIPv6 domain.

A.2. PMIPv6 Domain with Ratio N:1

 This approach refers to the situation where a common set of MNs is
 served by a unique MTMA for multicast service, but simultaneously
 there are subsets from that group of MNs that are served by distinct
 LMAs for unicast service as they move in the PMIPv6 domain.  Each
 particular MN association with the LMAs (unicast) and MTMA
 (multicast) remains always the same as it moves in the PMIPv6 domain.
 Figure 6 shows the scenario here described.

Zuniga, et al. Experimental [Page 22] RFC 7028 Multicast Mobility Routing Optimizations September 2013

          +----------------+       +----------------+
          |Content Source A|       |Content Source B|
          +----------------+       +----------------+
                 |                      |
                 |                      |
       ***  ***  ***  ***  ***  ***  ***  *** *** *** ***
      *   **   **   **   **  **   **   **   **   **  **  *
     *                                                    *
     *                 Fixed Internet                     *
     *        (Unicast & Multicast Traffic)               *
      *   **   **   **   **  **   **   **   **   **  **  *
       ***  ***  ***  *** *** ***  ***  ***  ***  ***  ***
         |                     |                      |
         |                     |                      |
         |                     |                      |
      +------+        +-----------------+          +------+
      | LMA1 |        |       MTMA2     |          | LMA3 |
      +------+        +-----------------+          +------+
        || \\        oo    oo      oo   oo          //  ||
        ||  \\      oo     oo      oo    oo        //   ||
        ||   \\    oo      oo      oo     oo      //    ||
        ||    \\  oo       oo      oo      oo    //     ||
        ||     \\oo        oo      oo       oo  //      ||
        ||      \\         oo      oo        oo//       ||
        ||     oo\\        oo      oo         //        ||
        ||    oo  \\       oo      oo        //oo       ||
        ||   oo    \\      oo      oo       //  oo      ||
        ||  oo      \\     oo      oo      //    oo     ||
      +------+      +--------+     +--------+     +--------+
      | MAG1 |      |  MAG2  |     |  MAG3  |     |  MAG4  |
      +------+      +--------+     +--------+     +--------+
      |      |       |      |       |      |       |      |
      |      |       |      |       |      |       |      |
   {MN10}  {MN11}  {MN20} {MN21}  {MN30} {MN31} {MN40} {MN41}
                Figure 6: PMIPv6 Domain with Ratio N:1
 Figure 6 proposes an architecture where there are two entities acting
 as LMAs, LMA1 and LMA3, while there is another one, named MTMA2,
 working as multicast tree mobility anchor.  LMA1 and LMA3 constitute
 two distinct unicast domains, whereas MTMA2 forms a single multicast
 domain.  The tunnels among MAGs and LMAs represented by lines ("||")
 indicate a tunnel transporting unicast traffic, while the tunnels
 among MAGs and MTMA2 depicted with circles ("o") show a tunnel
 transporting multicast traffic.
 In the figure, it can be observed that all the MNs are served by
 MTMA2 for the incoming multicast traffic from sources A or B.

Zuniga, et al. Experimental [Page 23] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 However, there are different subsets regarding unicast traffic, which
 maintain distinct associations within the PMIPv6 domain.  For
 instance, the subset formed by MN10, MN11, MN20, and MN21 is served
 by LMA1 for unicast, and the rest of MNs are served by LMA3.  For the
 scenario described above, the association between each MN and the
 corresponding LMA and MTMA is permanently maintained.

A.3. PMIPv6 Domain with Ratio 1:N

 This approach is related to a scenario where a common group of MNs is
 served by a unique LMA for unicast service, but simultaneously there
 are subsets from that group of MNs that are served by distinct MTMAs
 for multicast service as they move in the PMIPv6 domain.  Different
 MTMAs might be associated with serving different multicast groups.
 These associations remain the same even if the MNs move within the
 PMIPv6 domain.
 Figure 7 shows the scenario here described.

Zuniga, et al. Experimental [Page 24] RFC 7028 Multicast Mobility Routing Optimizations September 2013

   +----------------+                    +----------------+
   |Content Source A|                    |Content Source B|
   +----------------+                    +----------------+
          |                                       |
          |          ********************         |
         ( )        *                    *       ( )
        (   )      *    Fixed Internet    *     (   )
       (     )     *   (Unicast Traffic)  *    (     )
        (   )       *                    *      (   )
         ( )         ********************        ( )
          |                   |                   |
          |                   |                   |
       +------+       +--------------+      +------+
       | MTMA1|       |     LMA2     |      | MTMA3|
       +------+       +--------------+      +------+
       oo      oo           // \\          ^^     ^^
        oo       oo        //   \\       ^^      ^^
         oo        oo     //     \\    ^^       ^^
          oo         oo  //       \\ ^^        ^^
           oo          oo/         ^^         ^^
            oo         //oo      ^^ \\       ^^
             oo       //   oo  ^^    \\     ^^
              oo     //      oo       \\   ^^
               oo   //      ^^ oo      \\ ^^
                oo //     ^^     oo     \^^
             +-------------+     +-------------+
             |   \      /  |     |  \     |    |
             |   ~o~~~~o~  |     |  ~o~~~~o~   |
             |  ( MLD w  ) |     | (  MLD w )  |
             |  ( multip ) |     | ( multip )  |
             |  (  i/f   ) |     | (  i/f   )  |
             |   ~~~~~~~~  |     |  ~~~~~~~~   |
             |             |     |             |
             |     MAG1    |     |     MAG2    |
            /+-------------+     +-------------+\
           |       |       |     |        |      |
           |       |       |     |        |      |
        {MN10}   {MN11} {MN12}  {MN20}  {MN21} {MN22}
                Figure 7: PMIPv6 Domain with Ratio 1:N
 Figure 7 proposes an architecture where the LMA2 is the unique LMA
 for a certain group of MNs, while there are two other entities, MTMA1
 and MTMA3, acting as MTMAs for different subsets of multicast
 content.  MTMA1 and MTMA3 constitute two distinct multicast domains,
 whereas LMA2 forms a single unicast domain.  Each MTMA could be
 devoted to carry on a different content (for instance, MTMA1 for
 source A and MTMA3 for source B).  Looking at the figure, all MNs are

Zuniga, et al. Experimental [Page 25] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 served by LMA2 for unicast, while they might be simultaneously served
 by MTMA1 and MTMA3, depending on the multicast content.  For the
 scenario described above, the association between multicast content
 and MTMA is permanently maintained.  Note that this scenario would
 require support for MLD proxy with multiple interfaces [MULTIMOB],
 [UPSTREAM], [MLDPROXY], [MUIIMP] at the MAGs.

A.4. PMIPv6 Domain with H-LMA

 The H-LMA is defined as an entity that simultaneously transports
 unicast and multicast service, that is, it simultaneously works as
 LMA and MTMA.  In the context of the MTMA solution, an H-LMA can play
 the role of MTMA for an entire group of MNs in a PMIPv6 domain, while
 acting simultaneously as LMA for a subset of them.  Figure 8 adapts
 the PMIPv6 domain with ratio N:1 scenario of Figure 6 to the case
 where MTMA2 is an H-LMA, which serves multicast traffic to all the
 MNs in the picture, and simultaneously, it is able to serve unicast
 traffic to the subset formed by MN21 and MN30.

Zuniga, et al. Experimental [Page 26] RFC 7028 Multicast Mobility Routing Optimizations September 2013

          +----------------+       +----------------+
          |Content Source A|       |Content Source B|
          +----------------+       +----------------+
                 |                      |
                 |                      |
       ***  ***  ***  ***  ***  ***  ***  *** *** *** ***
      *   **   **   **   **  **   **   **   **   **  **  *
     *                                                    *
     *                 Fixed Internet                     *
     *        (Unicast & Multicast Traffic)               *
      *   **   **   **   **  **   **   **   **   **  **  *
       ***  ***  ***  *** *** ***  ***  ***  ***  ***  ***
         |                     |                      |
         |                     |                      |
         |                     |                      |
      +------+        +-----------------+          +------+
      | LMA1 |        |       H-LMA     |          | LMA3 |
      +------+        +-----------------+          +------+
        || \\        oo    db      db   oo          //  ||
        ||  \\      oo     db      db    oo        //   ||
        ||   \\    oo      db      db     oo      //    ||
        ||    \\  oo       db      db      oo    //     ||
        ||     \\oo        db      db       oo  //      ||
        ||      \\         db      db        oo//       ||
        ||     oo\\        db      db         //        ||
        ||    oo  \\       db      db        //oo       ||
        ||   oo    \\      db      db       //  oo      ||
        ||  oo      \\     db      db      //    oo     ||
      +------+      +--------+     +--------+     +--------+
      | MAG1 |      |  MAG2  |     |  MAG3  |     |  MAG4  |
      +------+      +--------+     +--------+     +--------+
      |      |       |      |       |      |       |      |
      |      |       |      |       |      |       |      |
   {MN10}  {MN11}  {MN20} {MN21}  {MN30} {MN31} {MN40} {MN41}
                  Figure 8: PMIPv6 Domain with H-LMA
 Figure 8 presents a PMIPv6 network where there are two pure unicast
 LMAs, LMA1, and LMA3, and a hybrid LMA, labeled as H-LMA in the
 figure.  The H-LMA is an MTMA from the perspective of MAG1 and MAG4.
 The tunnels among MAGs and LMAs represented by lines ("||") indicate
 a tunnel transporting exclusively unicast traffic, the tunnels
 depicted with circles ("o") show a tunnel transporting exclusively
 multicast traffic, and the tunnels with mixed lines and circles
 ("db") describe a tunnel transporting both types of traffic
 simultaneously.

Zuniga, et al. Experimental [Page 27] RFC 7028 Multicast Mobility Routing Optimizations September 2013

 All of the MNs in the figure receive the multicast traffic from H-LMA
 (one single multicast domain), but it is possible to distinguish
 three subsets from the unicast service perspective (that is, three
 unicast domains).  The first subset is the one formed by MN10, MN11,
 and MN20, which receives unicast traffic from LMA1.  A second subset
 is the one formed by MN21 and MN30, which receives unicast traffic
 from H-LMA.  And finally, a third subset is built on MN31, MN40, and
 MN41, which receives unicast traffic from LMA3.  For the scenario
 described above, the association between each MN and the
 corresponding LMA and H-LMA is permanently maintained.

Zuniga, et al. Experimental [Page 28] RFC 7028 Multicast Mobility Routing Optimizations September 2013

Authors' Addresses

 Juan Carlos Zuniga
 InterDigital Communications, LLC
 1000 Sherbrooke Street West, 10th floor
 Montreal, Quebec  H3A 3G4
 Canada
 EMail: JuanCarlos.Zuniga@InterDigital.com
 URI:   http://www.InterDigital.com/
 Luis M. Contreras
 Telefonica I+D
 Don Ramon de la Cruz, 82-84
 Madrid  28006
 Spain
 EMail: lmcm@tid.es
 Carlos J. Bernardos
 Universidad Carlos III de Madrid
 Av. Universidad, 30
 Leganes, Madrid  28911
 Spain
 Phone: +34 91624 6236
 EMail: cjbc@it.uc3m.es
 URI:   http://www.it.uc3m.es/cjbc/
 Seil Jeon
 Instituto de Telecomunicacoes
 Campus Universitario de Santiago
 Aveiro  3810-193
 Portugal
 EMail: seiljeon@av.it.pt
 URI:   https://atnog.av.it.pt/~sjeon/
 Younghan Kim
 Soongsil University
 Sangdo-dong, Dongjak-gu
 Seoul  511
 Republic of Korea
 EMail: yhkim@dcn.ssu.ac.kr
 URI:   http://dcnlab.ssu.ac.kr/

Zuniga, et al. Experimental [Page 29]

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