MobOpts Research Group Thomas C. Schmidt
Internet Draft HAW Hamburg
Matthias Waehlisch
Expires: September 2007 link-lab
March 2007

Multicast Mobility in MIPv6: Problem Statement

IPR Statement

By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79 [1].

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This document is a submission of the IRTF MobOpts RG. Comments should
be directed to the MobOpts RG mailing list, mobopts@irtf.org.


In this document we discuss mobility extensions to current IP layer
multicast solutions. Problems arising from mobile group communication
in general, in the case of multicast listener mobility and for mobile
Any Source Multicast as well as Source Specific Multicast senders are
documented. Characteristic aspects of multicast routing and
deployment issues are summarized. The principal approaches to the
multicast mobility problems are outlined subsequently.

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Table of Contents

1. Introduction and Motivation....................................3

2. Problem Description............................................4
2.1 Generals...................................................4
2.2 Multicast Listener Mobility................................5
2.3 Multicast Source Mobility..................................6
2.3.1 Any Source Multicast Mobility.........................6
2.3.2 Source Specific Multicast Mobility....................7
2.4 Deployment Issues..........................................8

3. Characteristics of Multicast Routing Trees under Mobility......8

4. Solutions......................................................9
4.1 General Approaches.........................................9
4.2 Solutions for Multicast Listener Mobility.................10
4.3 Solutions for Multicast Source Mobility...................10
4.3.1 Any Source Multicast Mobility Approaches.............10
4.3.2 Source Specific Multicast Mobility Approaches........11

5. Security Considerations.......................................12

6. IANA Considerations...........................................12

Appendix A. Implicit Source Notification Options.................12

7. References....................................................13


Author's Addresses...............................................17

Intellectual Property Statement..................................18

Copyright Notice.................................................18

Disclaimer of Validity...........................................18


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1. Introduction and Motivation

Group communication forms an integral building block of a wide
variety of applications, ranging from public content distribution and
streaming over voice and video conferencing, collaborative
environments and gaming up to the self-organization of distributed
systems. Its support by network layer multicast will be needed,
whenever globally distributed, scalable, serverless or instantaneous
communication is required. As broadband media delivery more and more
emerges to be a typical mass scenario, scalability and bandwidth
efficiency of multicast routing continuously gains relevance. The
idea of Internet multicasting already arose in the early days [2],
its realization will be of particular importance to mobile
environments, where users commonly share frequency bands of limited
capacity. The rapidly increasing mobile reception of 'infotainment'
streams may soon require a wide deployment of mobile multicast
services. Multicast mobility consequently has been a concern for
about ten years [3] and led to innumerous proposals, but no generally
accepted solution.

The fundamental approach to deal with mobility in IPv6 [4] is stated
in the Mobile IPv6 RFCs [5,6]. MIPv6 [5] only roughly treats
multicast mobility, in a pure remote subscription approach or through
bi-directional tunneling via the Home Agent. Whereas the remote
subscription suffers from slow handovers, as it relies on multicast
routing to adapt to handovers, bi-directional tunneling introduces
inefficient overheads and delays due to triangular forwarding.
Therefore none of the approaches can be considered solutions for a
deployment on large scale. A mobile multicast service for a future
Internet should admit 'close to optimal' routing at predictable and
limited cost, robustness combined with a service quality compliant to
real-time media distribution.

Intricate multicast routing procedures, though, are not easily
extensible to comply with mobility requirements. Any client
subscribed to a group while in motion, requires delivery branches to
pursue its new location; any mobile source requests the entire
delivery tree to adapt to its changing positions. Significant effort
has already been invested in protocol designs for mobile multicast
receivers. Only limited work has been dedicated to multicast source
mobility, which poses the more delicate problem [35].

In multimedia conference scenarios each member commonly operates as
receiver and as sender for multicast based group communication. In
addition, real-time communication such as voice or video over IP
places severe temporal requirement on mobility protocols: Seamless
handover scenarios need to limit disruptions or delay to less than
100 ms. Jitter disturbances are not to exceed 50 ms. Note that 100 ms
is about the duration of a spoken syllable in real-time audio.

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It is the aim of this document, to specify the problem scope for a
multicast mobility management as to be refined in future work. The
attempt is made to subdivide the various challenges according to
their originating aspects and to present existing proposals for
solution, as well as major bibliographic references.

2. Problem Description

2.1 Generals

Multicast mobility must be considered as a generic term, which
subsumes a collection of quite distinct functions. At first,
multicast communication divides into Any Source Multicast (ASM) [7]
and Source Specific Multicast (SSM) [8,9]. At second, the roles of
senders and receivers are asymmetric and need distinction. Both may
individually be mobile. Their interaction is facilitated by a
multicast routing function such as DVMRP [10], PIM-SM/SSM [11,12],
Bi-directional PIM [13] or CBT [14] and the multicast listener
discovery protocol [15,16].

Any multicast mobility solution must account for all of these
functional blocks. It should enable seamless continuity of multicast
sessions when moving from one IPv6 subnet to another. It should
preserve the multicast nature of packet distribution and approximate
optimal routing. It should support per flow handover for multicast
traffic, as properties and designations of flows may be of distinct

Multicast routing dynamically adapts to session topologies, which
then may change under mobility. However, depending on the topology
and the protocol in use, routing convergence arrives at a time scale
close to seconds, or even minutes and is far too slow to support
seamless handovers for interactive or real-time media sessions. The
actual temporal behavior strongly depends on the routing protocol in
use and on the geometry of the current distribution tree. A mobility
scheme that arranges for adjustments, i.e., partial changes or full
reconstruction of multicast trees is forced to make provision for
time buffers sufficient for protocol convergence. Special attention
is needed with a possible rapid movement of the mobile node, as this
may occur at much higher rates than compatible with protocol

IP layer multicast packet distribution is an unreliable service,
which is bound to connectionless transport protocols. Packet loss
thus will not be handled in a predetermined fashion. Mobile multicast
handovers should not cause significant packet drops. Due to

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statelessness the bi-casting of multicast flows does not cause
foreseeable degradations of the transport layer.

Group addresses in general are location transparent, even though
there are proposals to embed unicast prefixes or Rendezvous Point
addresses [17]. Addresses of sources contributing to a multicast
session are interpreted by the routing infrastructure and by receiver
applications, which frequently are source address aware. Multicast
therefore inherits the mobility address duality problem for source
addresses, being a logical node identifier, i.e., the home address
(HoA) at the one hand and a topological locator, the care-of-address
(CoA) at the other.

Multicast sources in general operate decoupled from their receivers
in the following sense: A multicast source submits data to a group of
unknown receivers and thus operates without any feedback channel. It
neither has means to inquire on properties of its delivery trees, nor
will it be able to learn about the state of its receivers. In the
event of an inter-tree handover, a mobile multicast source therefore
is vulnerable to loosing receivers without taking notice. (Cf.
Appendix A for implicit source notification approaches). Applying a
mobility binding update or return routability procedure will likewise
break the semantic of a receiver group remaining unidentified by the
source and thus cannot be applied in unicast analogy.

2.2 Multicast Listener Mobility

A mobile multicast listener entering a new IP subnet faces the
problem of transferring the multicast membership context to its new
point of attachment. It thereby may encounter either one of the
following conditions: The new network may not be multicast enabled or
the specific multicast service in use may be unsupported or
prohibited. Alternatively, the requested multicast service may be
supported and enabled in the new network, but the multicast groups
under subscription may not be forwarded to it. Then current
distribution trees for the desired groups may reside at large routing
distance. It may as well occur that data of some or all groups under
subscription of the mobile node are received by one or several local
group members at the instance of arrival and that multicast streams
flow natively.

The problem of achieving seamless multicast listener handovers is
thus threefold:
o Ensure multicast reception even in visited networks without
appropriate multicast support.
o Expedite primary multicast forwarding to comply with a seamless
timescale at handovers.
o Realize native multicast forwarding whenever applicable to
preserve network resources and avoid data redundancy.

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Additional aspects related to infrastructure remain. In changing its
point of attachment a mobile receiver may not have enough time to
leave groups in the previous network. Also, packet duplication and
disorder may result from the change of topology.

2.3 Multicast Source Mobility

2.3.1 Any Source Multicast Mobility

A node submitting data to an ASM group either defines the root of a
source specific shortest path tree (SPT), distributing data towards a
rendezvous point or receivers, or it forwards data directly down a
shared tree, e.g., via encapsulated PIM register messages. Aside from
tunneling or shared trees, forwarding along source specific delivery
trees will be bound to a topological network address due to reverse
path forwarding (RPF) checks. A mobile multicast source moving away
is solely enabled to either inject data into a previously established
delivery tree, which may be a rendezvous point based shared tree, or
to (re-)define a multicast distribution tree compliant to its new
location. In pursuing the latter the mobile sender will have to
proceed without control of the new tree construction due to
decoupling of sender and receivers.

A mobile multicast source consequently must meet address transparency
at two layers: In order to comply with RPF checks, it has to use an
address within the IPv6 basic header's source field, which is in
topological concordance with the employed multicast distribution
tree. For application transparency the logical node identifier,
commonly the HoA, must be presented as packet's source address to the
socket layer at the receiver side.

Conforming to address transparency and temporal handover constraints
will be major problems for any route optimizing mobility solution.
Additional issues arrive from possible packet loss and from multicast
scoping. A mobile source away from home must attend scoping
restrictions, which arise from its home and its visited location [5].

Within intra-domain multicast routing the employment of shared trees
may considerably relax mobility related complexity. Relying upon a
static rendezvous point, a mobile source may continuously submit data
by encapsulating packets with its previous topologically correct or
home source address. Constraints even weaken, when bi-directional PIM
is used. Intra-domain mobility is transparently covered by bi-
directional shared trees, eliminating the need for tunneling data to
reach the rendezvous point.

However, issues arise in inter-domain multicast scenarios, whenever
notification of source addresses is required between distributed

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instances of shared trees. A new CoA acquired after a mobility
handover will necessarily be subject to inter-domain record exchange.
In presence of embedded rendezvous point addresses [17], e.g., for
inter-domain PIM-SM, the primary rendezvous point will be globally
appointed and the signaling requirements obsolete.

2.3.2 Source Specific Multicast Mobility

Fundamentally, Source Specific Multicast has been designed for static
addresses of multicast senders. Source addresses in client
subscription to SSM groups are directly used for route
identification. Any SSM subscriber is thus forced to know the
topological address of its group contributors. SSM source
identification invalidates, when source addresses change under
mobility. Hence client implementations of SSM source filtering MUST
be MIPv6 aware in the sense that a logical source identifier (HoA) is
correctly mapped to its current topological correspondent (CoA).

Consequently source mobility for SSM packet distribution requires a
dedicated conceptual treatment in addition to the problems of mobile
ASM. As a listener is subscribed to an (S,G) channel membership and
as routers have established an (S,G)-state shortest path tree rooted
at source S, any change of source addresses under mobility requests
for state updates at all routers and all receivers. On source
handover a new SPT needs to be established, which partly will
coincide with the previous SPT, e.g., at the receiver side. As the
principle multicast decoupling of a sender from its receivers
likewise holds for SSM, client updates needed for switching trees
turns into a severe problem.

An SSM listener subscribing to or excluding any specific multicast
source, may want to rely on the topological correctness of network
operations. The SSM design permits trust in equivalence to the
correctness of unicast routing tables. Any SSM mobility solution
should preserve this degree of confidence. Binding updates for SSM
sources thus should have to prove address correctness in the unicast
routing sense, which is equivalent to binding update security with a
correspondent node in MIPv6 [5].

All of the above severely add complexity to a robust SSM mobility
solution, which should converge to optimal routes and, for the sake
of efficiency, should avoid data encapsulation, as well. Like in ASM
handover delays are to be considered critical. The routing distance
between subsequent points of attachment, the ’step size’ of the
mobile from previous to next designated router, may serve as an
appropriate measure of complexity [43,47].

Finally, Source Specific Multicast has been designed as a light-
weight approach to group communication. In adding mobility

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management, it is desirable to preserve the principle leanness of SSM
by minimizing additional signaling overheads.

2.4 Deployment Issues

IP multicast deployment in general has been hesitant over the past 15
years, even though all major router vendors and operating systems
offer a wide variety of implementations to support multicast [44]. A
dispute arose on the appropriate layer, where group communication
service should reside, and the focus of the research community turned
towards application layer multicast. This debate on "efficiency
versus deployment complexity" now overlaps into the mobile multicast
domain [45]. Hereunto Garyfalos and Almeroth [24] derived from fairly
generic principles that when mobility is introduced the performance
gap between IP and application layer multicast widens in different
metrics up to a factor of four.

Therefore it is desirable that any solution to mobile multicast
should leave routing protocols unchanged. Mobility management in such
deployment-friendly schemes should preferably be handled at edge
nodes, preserving the routing infrastructure in mobility agnostic
condition. Facing the current state of proposals, the urge remains
open to search for such simple, infrastructure transparent solutions,
even though there are reasonable doubts, whether the desired can be
achieved in all cases.

Nevertheless, multicast services in mobile environments may soon
become indispensable, when multimedia distribution services such as
DVB will develop as a strong business case for IP portables. As IP
mobility will unfold dominance and as efficient link utilization will
show a larger impact in costly radio environments, the evolution of
multicast protocols will naturally follow mobility constraints.

3.Characteristics of Multicast Routing Trees under Mobility

Multicast distribution trees have been studied well under the focus
of network efficiency. Grounded on empirical observations Chuang and
Sirbu [38] proposed a scaling power-law for the total number of links
in a multicast shortest path tree with m receivers (prop. m^k). The
authors consistently identified the scale factor to attain the
independent constant k = 0.8. The validity of such universal, heavy-
tailed distribution suggests that multicast shortest path trees are
of self-similar nature with many nodes of small, but few of higher
degrees. Trees consequently would be shaped rather tall than wide.

Subsequent empirical and analytical work, cf. [39,40], debated the
applicability of the Chuang and Sirbu scaling law. Van Mieghem et al.
[39] proved that the proposed power law cannot hold for an increasing
Internet or very large multicast groups, but is indeed applicable for

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moderate receiver numbers and the current Internet size N = 10^5 core
nodes. Investigating on self-similarity Janic and Van Mieghem [42]
semi-empirically substantiated that multicast shortest path trees in
the Internet can be modeled with reasonable accuracy by uniform
recursive trees (URT) [41], provided m remains small compared to N.

The mobility perspective on shortest path trees focuses on their
alteration, i.e., the degree of topological changes induced by
movement. For receivers, and more interestingly for sources this may
serve as an outer measure for routing complexity. Source specific
multicast trees subsequently generated from mobility handover steps
are not independent, but highly correlated. They most likely branch
to the identical receivers at one or several intersection points. By
the self-similar nature, the persistent subtrees (of previous and
next distribution tree), rooted at any such intersection point,
exhibit again the scaling law behavior, are tall-shaped with nodes of
mainly low degree and thus likely to coincide. Tree alterations under
mobility have been studied in [43], both analytically and by
simulations. It was found that even in large networks and for
moderate receiver numbers more than 80 % of the multicast router
states remain invariant under a source handover.

4. Solutions

4.1 General Approaches

Three approaches to mobile Multicast are commonly around [36]:

o Bi-directional Tunnelling guides the mobile node to tunnel all
multicast data via its home agent. This principle multicast solution
hides all movement and results in static multicast trees. It may be
employed transparently by mobile multicast listeners and sources, on
the price of triangular routing and possibly significant performance
degradations due to widely spanned data tunnels.

o Remote Subscription forces the mobile node to re-initiate
multicast distribution subsequent to handover by submitting an MLD
listener report within the subnet it newly attached to. This approach
of tree discontinuation relies on multicast dynamics to adapt to
network changes. It not only results in rigorous service disruption,
but leads to mobility driven changes of source addresses, and thus
disregards session persistence under multicast source mobility.

o Agent-based solutions attempt to balance between the previous two
mechanisms. Static agents typically act as local tunnelling proxies,
allowing for some inter-agent handover while the mobile node moves
away. A decelerated inter-tree handover, i.e. tree walking, will be
the outcome of agent-based multicast mobility, where some extra

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effort is needed to sustain session persistence through address
transparency of mobile sources.

MIPv6 [5] introduces bi-directional tunnelling as well as remote
subscription as minimal standard solutions. Various publications
suggest utilizing remote subscription for listener mobility, only,
while advising bi-directional tunnelling as the solution for source
mobility. Such approach suffers from the drawback that multicast
communication roles are not explicitly known at the network layer and
may change or mix unexpectedly.

It should be noted that none of the above approaches address SSM
source mobility, except the bi-directional tunnelling.

4.2 Solutions for Multicast Listener Mobility

There are proposals of agent assisted handovers compliant to the
unicast real-time mobility infrastructure of Fast MIPv6 [18], the M-
FMIPv6 [19,20], and of Hierarchical MIPv6 [21], the M-HMIPv6 [22],
and to context transfer [23], which have been thoroughly analyzed in
[43,49]. A hybrid architecture of reactively operating proxy-gateways
located at the Internet edges is introduced in [24]. An approach
based on dynamically negotiated inter-agent handovers is presented in
[25]. Aside from IETF work countless publications present proposals
for seamless multicast listener mobility, cf. [35] for a
comprehensive overview.

4.3 Solutions for Multicast Source Mobility

4.3.1 Any Source Multicast Mobility Approaches

Solutions for the multicast source mobility problem can be sorted in
three categories:

o Statically Rooted Distribution Trees:

Following a shared tree approach, Romdhani et al. [26] propose to
employ Rendezvous Points of PIM-SM as mobility anchors. Mobile
senders tunnel their data to these "Mobility-aware Rendezvous Points"
(MRPs), whence in restriction to a single domain this scheme is
equivalent to the bi-directional tunneling. Focusing on interdomain
mobile multicast, the authors design a tunnel- or SSM-based backbone
distribution of packets between MRPs.

o Reconstruction of Distribution Trees:

Several authors propose to construct a completely new distribution
tree after the movement of a mobile source and thereby have to

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compensate routing delays. M-HMIPv6 [22] tunnels data into previously
established trees rooted at mobility anchor points to compensate for
routing delays until a protocol dependent timer expires. The RBMoM
protocol [27] introduces additional Multicast Agents (MA), which
advertise their service range. The mobile source registers with the
closest MA and tunnels its data through it. When moving out of the
previous service range, it will perform a MA discovery, a re-
registration and continue data tunneling with its newly established
Multicast Agent in its current vicinity.

o Tree Modification Schemes:

In the case of DVMRP routing, Chang and Yen [28] propose an algorithm
to extend the root of a given delivery tree for incorporating a new
source location in ASM. To fix DVMRP forwarding states and heal
reverse path forwarding (RPF) check failures, the authors rely on a
complex additional signaling protocol.

4.3.2 Source Specific Multicast Mobility Approaches

The shared tree approach of [26] has been extended to SSM mobility by
introducing the HoA address record to Mobility-aware Rendezvous
Points. These MRPs operate on extended multicast routing tables,
which simultaneously hold HoA and CoA and are thus enabled to
logically identify the appropriate distribution tree. Mobility thus
re-introduces rendezvous points to SSM routing.

Approaches of reconstructing SPTs in SSM have to rely on client
notification for initiating new router state establishment. At the
same time they need to preserve address transparency to the client.
To account for the latter, Thaler [29] proposes to employ binding
caches and to obtain source address transparency analogous to MIPv6
unicast communication. Initial session announcements and changes of
source addresses are to be distributed periodically to clients via an
additional multicast control tree based at the home agent. Source
tree handovers are then activated on listener requests.
Jelger and Noel [30] suggest handover improvements by employing
anchor points within the source network, supporting a continuous data
reception during client initiated handovers. Client updates are to be
triggered out of band, e.g. by SDR. Receiver oriented tree
construction in SSM thus remains unsynchronized with source

Addressing this synchronization problem at the routing layer, several
proposals concentrate on direct modification of distribution trees.
Based on a multicast Hop-by-Hop protocol, a recursive scheme of loose
unicast source routes with branch points, Vida et al [31] optimize
SPTs for moving sources on the path between source and first
branching point. O'Neill [32] suggests a scheme to overcome RPF check

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failures originating from multicast source address changes in a
rendezvous point scenario by introducing extended routing
information, which accompanies data in a Hop-by-Hop option "RPF
redirect" header. The Tree Morphing approach of Schmidt and Waehlisch
[33] uses source routing to extend the root of a previously
established SPT, thereby injecting router state updates in a Hop-by-
Hop option header. Using extended RPF checks the elongated tree
autonomously initiates shortcuts and smoothly reduces to a new SPT
rooted at the relocated source. Lee et al. [34] introduce a state
update mechanism for re-using major parts of established multicast
trees. The authors start from initially established distribution
states centered at the mobile source's home agent. A mobile leaving
its home network will signal a multicast forwarding state update on
the path to its home agent and, subsequently, distribution states
according to the mobile source's new CoA are implemented along the
previous distribution tree. Multicast data then is intended to
natively flow in triangular routes via the elongation and updated
tree centered at the home agent. Consequently this mechanism refrains
from using shortest path trees. Unfortunately the authors do not
address the problem of RPF check failures in their paper.

5. Security Considerations

This document discusses multicast extensions to mobility. Security
issues arise from source address binding updates, specifically in the
case of source specific multicast. Threats of hijacking unicast
sessions will result from any solution jointly operating binding
updates for unicast and multicast sessions. Admission control issues
may arise with new CoA source addresses being introduced to SSM
channels (cf. [37] for a comprehensive discussion). Future solutions
must address the security implications.

6. IANA Considerations

There are no IANA considerations introduced by this draft.

Appendix A. Implicit Source Notification Options

A multicast source will transmit data to a group of receivers without
any option of an explicit feedback channel. There are attempts though
to implicitly obtain information on listening group members. One
approach has been dedicated to inquire designated routers on the pure
existence of receivers. Based on an extension of IGMP, the Multicast
Source Notification of Interest Protocol (MSNIP) [48] was designed to
allow for the multicast source querying its designated router.
However, work on MSNIP has been terminated by IETF.

A majority of real-time applications employ RTP [50] as its
application layer transport protocol, which is accompanied by its

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control protocol RTCP. RTP is capable of multicast group distribution
and RTCP receiver reports are submitted to the same group in the
multicast case. Thus RTCP may be used to monitor, manage and control
multicast group operations, as it provides a fairly comprehensive
insight into group member statuses. However, RTCP information is
neither present at the network layer nor does multicast communication
presuppose the use of RTP.

7. References

Normative References

1 S. Bradner "Intellectual Property Rights in IETF Technology", BCP
79, RFC 3979, March 2005.

2 Aguilar, L. "Datagram Routing for Internet Multicasting", In ACM
SIGCOMM '84 Communications Architectures and Protocols, pp. 58-63,
ACM Press, June, 1984.

3 G. Xylomenos and G.C. Plyzos "IP Multicast for Mobile Hosts", IEEE
Communications Magazine, pp. 54-58, January 1997.

4 R. Hinden and S. Deering "Internet Protocol Version 6
Specification", RFC 2460, December 1998.

5 D.B. Johnson, C. Perkins and J. Arkko "Mobility Support in IPv6",
RFC 3775, June 2004.

6 J. Arkko, V. Devarapalli and F. Dupont "Using IPsec to Protect
Mobile IPv6 Signaling Between Mobile Nodes and Home Agents", RFC
3776, June 2004.

7 S. Deering "Host Extensions for IP Multicasting", RFC 1112, August

8 S. Bhattacharyya "An Overview of Source-Specific Multicast (SSM)",
RFC 3569, July 2003.

9 H. Holbrook, B. Cain "Source-Specific Multicast for IP", RFC 4607,
August 2006.

10 D. Waitzman, C. Partridge, S.E. Deering "Distance Vector Multicast
Routing Protocol", RFC 1075, November 1988.

11 D. Estrin, D. Farinacci, A. Helmy, D. Thaler, S. Deering, M.
Handley, V. Jacobson, C. Liu, P. Sharma, L. Wei "Protocol

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Independent Multicast-Sparse Mode (PIM-SM): Protocol
Specification", RFC 2362, June 1998.

12 B. Fenner, M. Handley, H. Holbrook, I. Kouvelas: "Protocol
Independent Multicast - Sparse Mode PIM-SM): Protocol
Specification (Revised)", RFC 4601, August 2006.

13 M. Handley, I. Kouvelas, T. Speakman, L. Vicisano "Bi-directional
Protocol Independent Multicast (BIDIR-PIM)", draft-ietf-pim-bidir-
09.txt, (work in progress), February 2007.

14 A. Ballardie "Core Based Trees (CBT version 2) Multicast Routing",
RFC 2189, September 1997.

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

16 R. Vida and L. Costa (Eds.) "Multicast Listener Discovery Version
2 (MLDv2) for IPv6", RFC3810, June 2004.

17 P. Savola, B. Haberman "Embedding the Rendezvous Point (RP)
Address in an IPv6 Multicast Address", RFC 3956, November 2004.

18 Koodli, R. "Fast Handovers for Mobile IPv6", RFC 4068, July 2004.

19 Suh, K., Kwon, D.-H., Suh, Y.-J. and Park, Y. "Fast Multicast
Protocol for Mobile IPv6 in the fast handovers environments",
Internet Draft - (work in progress, expired), February 2004.

20 Xia, F. and Sarikaya, B. "FMIPv6 extensions for Multicast
Handover", draft-xia-mipshop-fmip-multicast-00.txt, (work in
progress), September 2006.

21 Soliman, H., Castelluccia, C., El-Malki, K., Bellier, L.
"Hierarchical Mobile IPv6 mobility management", RFC 4140, August

22 Schmidt, T.C. and Waehlisch, M. "Seamless Multicast Handover in a
Hierarchical Mobile IPv6 Environment(M-HMIPv6)", draft-schmidt-
waehlisch-mhmipv6-04.txt, (work in progress, expired), December

23 Jonas, K. and Miloucheva, I. "Multicast Context Transfer in mobile
IPv6", draft-miloucheva-mldv2-mipv6-00.txt, (work in progress,
expired), June 2005.

Schmidt, Waehlisch Expires - September 2007 [Page 14]
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24 Garyfalos, A., Almeroth, K. "A Flexible Overlay Architecture for
Mobile IPv6 Multicast", IEEE Journ. on Selected Areas in Comm., 23
(11), pp. 2194-2205, November 2005.

25 Zhang, H. et al "Mobile IPv6 Multicast with Dynamic Multicast
Agent", draft-zhang-mipshop-multicast-dma-03.txt, (work in
progress), January 2007.

26 Romdhani, I., Bettahar, H. and Bouabdallah, A. "Transparent
handover for mobile multicast sources", in P. Lorenz and P. Dini,
eds, 'Proceedings of the IEEE ICN'06', IEEE Press, 2006.

27 Lin, C.R. et al., "Scalable Multicast Protocol in IP-Based Mobile
Networks", Wireless Networks and Applications, 5, pp. 259-271,

28 Chang, R.-S. and Yen, Y.-S. "A Multicast Routing Protocol with
Dynamic Tree Adjustment for Mobile IPv6", Journ. Information
Science and Engineering 20, 1109-1124, 2004.

29 Thaler, D. "Supporting Mobile SSM Sources for IPv6", Proceedings
of ietf meeting Dec. 2001, individual.
URL: www.ietf.org/proceedings/01dec/slides/magma-2.pdf

30 Jelger, C. and Noel, T. "Supporting Mobile SSM sources for IPv6
(MSSMSv6)", Internet Draft (work in progress, expired), January

31 Vida, R., Costa, L., Fdida, S. "M-HBH - Efficient Mobility
Management in Multicast", Proc. of NGC '02, pp. 105-112, ACM Press

32 O'Neill, A. "Mobility Management and IP Multicast", draft-oneill-
mip-multicast-01.txt, (work in progress, expired), July 2002.

33 Schmidt, T. C. and Waehlisch, M. "Extending SSM to MIPv6 -
Problems, Solutions and Improvements", Computational Methods in
Science and Technology 11(2), 147-152. Selected Papers from TERENA
Networking Conference, Poznan, May 2005.

34 Lee, H., Han, S. and Hong, J. "Efficient Mechanism for Source
Mobility in Source Specific Multicast", in K. Kawahara and I.
Chong, eds, "Proceedings of ICOIN2006", Vol. 3961 of LNCS, pp. 82-
91, Springer-Verlag, Berlin, Heidelberg, 2006.

Schmidt, Waehlisch Expires - September 2007 [Page 15]
MMCASTv6-PS March 2007

Informative References

35 Romdhani, I., Kellil, M., Lach, H.-Y. et. al. "IP Mobile
Multicast: Challenges and Solutions", IEEE Comm. Surveys, 6(1),

36 Jannetau, C., Tian, Y., Csaba, S. et al "Comparison of Three
Approaches Towards Mobile Multicast", IST Mobile Summit 2003,
Aveiro, Portugal, 16-18 June 2003, online http://www.comnets.rwth-

37 Kellil, M., Romdhani, I., Lach, H.-Y., Bouabdallah, A. and
Bettahar, H. "Multicast Receiver and Sender Access Control and its
Applicability to Mobile IP Environments: A Survey", IEEE Comm.
Surveys & Tutorials 7(2), pp. 46-70, 2005.

38 Chuang, J. and Sirbu, M. "Pricing Multicast Communication: A Cost-
Based Approach", Telecommunication Systems 17(3), 281-297, 2001.
Presented at the INET'98, Geneva, Switzerland, July 1998.

39 Van Mieghem, P., Hooghiemstra, G., Hofstad, R. "On the Efficiency
of Multicast", Transactions on Networking, 9, 6, pp. 719-732,
December 2001.

40 Chalmers, R.C. and Almeroth, K.C., "On the topology of multicast
trees", IEEE/ACM Trans. Netw. 11(1), 153-165, 2003.

41 Van Mieghem, P. "Performance Analysis of Communication Networks
and Systems", Cambridge University Press, 2006.

42 Janic, M. and Van Mieghem, P. "On properties of multicast routing
trees", Int. J. Commun. Syst. 19(1), pp. 95-114, 2006.

43 Schmidt, T.C. and Waehlisch, M. "Predictive versus Reactive -
Analysis of Handover Performance and Its Implications on IPv6 and
Multicast Mobility", Telecommunication Systems, 30(1-3), pp. 123-
142, November 2005.

44 Diot, C. et al. "Deployment Issues for the IP Multicast Service
and Architecture", IEEE Network Magazine, spec. issue on
Multicasting 14(1), pp. 78-88, 2000.

45 Garyfalos, A., Almeroth, K. and Sanzgiri, K. "Deployment
Complexity Versus Performance Efficiency in Mobile Multicast",
Intern. Workshop on Broadband Wireless Multimedia: Algorithms,
Architectures and Applications (BroadWiM), San Jose, California,
USA, October 2004. Online: http://imj.ucsb.edu/papers/BROADWIM-

Schmidt, Waehlisch Expires - September 2007 [Page 16]
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46 Jelger, C., Noel, T. "Multicast for Mobile Hosts in IP Networks:
Progress and Challenges", IEEE Wireless Comm., pp 58-64, Oct.

47 Schmidt, T.C. and Waehlisch, M. "Morphing Distribution Trees -
On the Evolution of Multicast States under Mobility and an
Adaptive Routing Scheme for Mobile SSM Sources", Telecommunication
Systems, Vol. 33, No. 1-3, pp. 131-154, Berlin Heidelberg:
Springer, December 2006.

48 Fenner, B. et al. "Multicast Source Notification of Interest
Protocol", draft-ietf-idmr-msnip-05.txt, (work in progress,
expired), March 2004.

49 Leoleis, G., Prezerakos, G., Venieris, I. "Seamless multicast
mobility support using fast MIPv6 extensions", Computer Comm. 29,
pp. 3745-3765, 2006.

50 Schulzrinne, H. et al. "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003.


The authors would like to thank Mark Palkow (DaViKo GmbH) and Hans L.
Cycon (FHTW Berlin) for valuable discussions and a joyful
collaboration. They also thank Stig Venaas (UNINETT) for many

Author's Addresses

Thomas C. Schmidt
HAW Hamburg, Dept. Informatik
Berliner Tor 7
D-20099 Hamburg, Germany
Phone: +49-40-42875-8157
Email: Schmidt@informatik.haw-hamburg.de

Matthias Waehlisch
Hönowerstr. 35
D-10318 Berlin, Germany
Email: mw@link-lab.net

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