MULTIMOB Working Group D. von Hugo
Internet-Draft Deutsche Telekom Laboratories
Intended status: Informational H. Asaeda
Expires: August 26, 2010 Keio University
B. Sarikaya
Huawei USA
P. Seite
France Telecom - Orange
February 22, 2010
Evaluation of further issues on Multicast Mobility: Potential future
work for WG MultiMob
<draft-von-hugo-multimob-future-work-01.txt>
Abstract
The WG MultiMob aims at defining a basic mobile multicast solution
leveraging on network localized mobility management, i.e. Proxy
Mobile IPv6 protocol. The solution would be basically based on
multicast group management, i.e. IGMP/MLD, proxying at the access
gateway. If such a basic solution is essential from an operational
point of view, challenges with efficient resource utilization and
user perceived service quality still persist. These issues may
prevent large scale deployments of mobile multicast applications.
This document attempts to identify topics for future extension of
work such as modifying base PMIPv6 and MLD/IGMP for optimal multicast
support, extending to and modifying of MIPv4/v6 and DSMIP, sender
(source) mobility, consideration of Handover optimization, multiple
flows with multihoming and any other different issues.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. IGMP/MLD Proxy Architecture . . . . . . . . . . . . . . . . . 7
4. Problem Description . . . . . . . . . . . . . . . . . . . . . 8
4.1. Modification of base PMIPv6 for optimal multicast
support . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Modification of MLD/IGMP for optimal multicast support . . 8
4.3. Extensions to and modifying of MIPv4/v6 and DSMIPv6 . . . 9
4.4. Consideration of sender (source) mobility . . . . . . . . 9
4.5. Consideration of Handover Optimization . . . . . . . . . . 9
4.6. Support of multiple flows . . . . . . . . . . . . . . . . 10
4.7. Support of multi-hop transmission . . . . . . . . . . . . 10
4.8. Mobility agnosticity . . . . . . . . . . . . . . . . . . . 10
4.9. Local routing . . . . . . . . . . . . . . . . . . . . . . 10
5. Requirements on Solutions . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
Recently chartered WG MultiMob focuses on documentation of proper
configuration and usage of existing (specified standard) protocols
within both mobility and multicast related areas to enable and
support mobility for multicast services and vice versa. Although the
final recommendation is not yet available it is expected that such a
solution following the remote subscription aproach will not be
resource efficient nor grant the service quality expected by the end
user.
Such a solution would resolve the problem to ensure multicast
reception in PMIPv6-enabled [RFC5213] networks without appropriate
multicast support. However it would neither automatically minimize
multicast forwarding delay to provide seamless and fast handovers for
real-time services nor minimize packet loss and reordering that
result from multicast handover management as stated in
[I-D.irtf-mobopts-mmcastv6-ps]. Also Route Optimization is out of
scope of the basic solution - an issue for reducing amount of
transport resource usage and transmission delay. Thus possible
enhancements and issues for solutions beyond a basic solution need to
be described to enable current PMIPv6 protocols to fully support
efficient mobile multicast services. Such extensions may include
protocol modifications for both mobility and multicast related
protocols to achieve optimizations for resource efficient and
performance increasing multimob approaches. The document includes
the case of mobile multicast senders using Any Source Multicast (ASM)
and Source Specific Multicast (SSM) [RFC4607].
Figure 1 illustrates the key components of the foreseen basic
Multimob solution. The extended multicast mobility scenario, leading
to above issues, is sketched in Figure 2.
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+------+ +------+
| MN | =====> | MN |
+------+ +------+
| .
| .
+--------+ +--------+
| MAG 1 | | MAG 2 |
|IGMP/MLD| |IGMP/MLD|
|Proxy | |Proxy |
+--------+ +--------+
| |
*** *** *** ***
* ** ** ** *
* *
* Internet Subnet *
* *
* ** ** ** *
*** *** *** ***
| |
+-------+ +-------+
| LMA 1 | | LMA 2 |
+-------+ +-------+
| |
*** *** *** ***
* ** ** ** *
* *
* Fixed Internet *
* *
* ** ** ** *
*** *** *** ***
|
+------+
| CN |
+------+
Figure 1: MultiMob Scenario for chartered PMIP6 issue
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+------+ +------+ +------+
| MN | =====> | MN | ====> | MN |
+------+ +------+ +------+
| . .
| . .
| . .
+-------+ +-------+ +-------+ +-------+
| MAG 1 | | MAG 2 | | AR 1 | | AR 2 |
|IGMP/MLD| |IGMP/MLD| |IGMP/MLD| |IGMP/MLD|
|Proxy | |Proxy | |Proxy | |Proxy |
+-------+ +-------+ +-------+ +-------+
\ / | |
*** *** *** *** *** *** *** ***
* ** *** ** * * ** *** ** *
* * * *
* Internet Subnet 1 * * Internet Subnet 2 *
* * * *
* ** *** ** * * ** *** ** *
*** *** *** *** *** *** *** ***
| | |
+-------+ +-------+ |
| LMA 1 | | LMA 2 | /
+-------+ +-------+ /
\ | /
*** *** *** *** / *** *** *** ***
* ** ** ** * / * ** *** ** *
* * * *
* Fixed Internet * * Internet Subnet 3 *
* *_____* *
* ** ** ** * * ** *** ** *
*** *** *** *** *** .*** *** ***
| .
+-------+ +-------+
| CN | ====> | CN |
+-------+ +-------+
Figure 2: MultiMob scenario for extended MultiMob issues
In summary additional to a 'Single hop, link, flow' Proxy MIP
mobility for listening MNs (scenario shown in Figure 1), the future
work will focus on optimization of performances and extend the
scenario to 'Multi-hop, -homed, -flow' client mobility, thus also
including optimizations for MIPv6 [RFC3775]. The following is the
proposed work items to be covered in the MultiMob continuation: (see
Figure 2).
o Modification of base PMIPv6 and MLD/IGMP for optimal multicast
support.
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o Extension to and modifying of MIPv4/v6 and DSMIP using IGMP/MLD
Proxy and the Foreign Agent/ Access Router.
o Consideration of sender (source) mobility.
o Consideration of Handover optimization.
o Support of multiple flows on multihomed mobile nodes.
o Multi-hop transmission.
o Fixed mobile convergence support.
o Consideration of earlier versions of IGMP and MLD in the
solutions.
o Consideration of locally available multicast without remote
subscription.
o Improve host mobility agnoticity
o Routing optimization
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 BCP 14 [RFC2119].
This document uses the terminology defined in [RFC3775], [RFC3376],
[RFC3810], [RFC5213], [I-D.irtf-mobopts-mmcastv6-ps].
3. IGMP/MLD Proxy Architecture
Multimob basic solution is based on IGMPv3/MLDv2 Proxy support at the
mobile access gateway (MAG) of Proxy Mobile IPv6 as shown in
Figure 1. IGMPv3/MLDv2 proxy keeps multicast state on the
subscriptions of the mobile nodes and only an aggregate state is kept
at the local mobility anchor (LMA). When LMA receives multicast data
it can forward it to the MAG without duplication because MAG takes of
the packet duplication. This leads to solving the avalanche problem.
By keeping multicast state locally, IGMPv3/MLDv2 Proxy introduces
mobility related problems such as possible packet loss when a mobile
node does a handover to another MAG and its multicast state is not
modified fast enough at the LMA.
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IGMPv3/MLDv2 introduces tunnel convergence problem which occurs when
a given MAG serves MNs that belong to different LMAs and MNs
subscribe to the same multicast group. In that case MNs receive
duplicate multicast data forwarded from more than one LMA.
It can be foreseen that mobile access gateways will serve both mobile
and fixed terminals concurrently. The tuning of multicast-related
protocol parameters based on the terminal characteristics is needed.
Parameters only applicable to mobile users need to be distinguished
from the parameters applicable to fixed users. It should be also
possible to distinguish between slow and fast movement and handover
frequency to form corresponding tunnels for mobile users.
Based on the above observations we will state the problems next and
then list the requirements on possible solutions.
4. Problem Description
The general issues of multicast mobility are extensively discussed
and described in [I-D.irtf-mobopts-mmcastv6-ps]. To reduce the
complexity of the pleothera of requirements listed in
[I-D.irtf-mobopts-mmcastv6-ps] and in
[I-D.deng-multimob-pmip6-requirement] this document tries to propose
lightweight solutions for multicast mobility which allow for easy
deployment within realistic scenarios and architectures, and which
build directly on basic MultiMob solution which is based on IGMP/MLD
Proxy at the mobile access gateway.
4.1. Modification of base PMIPv6 for optimal multicast support
There would be potential solutions proposed for multicast
optimization for PMIPv6 such as
[I-D.asaeda-multimob-pmip6-extension], agent-based reling on
additional encapsulation, and a hybrid approach. Since other
functional enhancements of PMIPv6 are currently under way in NETEXT
WG, both the impact of new features on Mobile Multicast as well as a
potential Multicast-initiated proposal for PMIPv6 modification have
to be considered in a continuous exchange process between both WGs.
4.2. Modification of MLD/IGMP for optimal multicast support
Potential approaches for enhancement of group management as specified
e.g. by MLDv2 [RFC3810] include default timer value modification,
specific query message introduction, and standard (query) reaction
suppression, beside introducing multicast router attendance control
in terms of e.g. specification of a Listener Hold message as proposed
in [I-D.asaeda-multimob-igmp-mld-mobility-extensions].
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4.3. Extensions to and modifying of MIPv4/v6 and DSMIPv6
Operational interest clearly focusses on network-based mobility
approaches, but in the framework of multiple technologies serving a
mobile user there will be demand to include also other non-PMIPv6
based specifications.
This section addresses the compatibility of PMIPv6-based multicast
solutions with MIPv6 [RFC3775], i.e. handover between network-based
and client mobility support as well as interoperabiliy between IPv4
and IPv6 mechanisms (e.g. FA handling, IPv4/v4-tunneling) with
mobile multicast. DSMIPv6 [RFC5555] has a basic support for
multicast which is based on remote subscription and bi-directional
tunneling, but does not specify how to achieve group management and
data forwarding unless the mobility anchor (i.e. Home Agent) is a
fully functional IPv6 multicast router.
4.4. Consideration of sender (source) mobility
We see future demand for such a feature in terms of applications such
as 'Push to talk over wireless technologies' (packet based point-to-
multipoint (P2MP) group voice) like 3GPP or WiMAX, 'Multi-party
mobile audio/video conferencing', 'mobile multi-player gaming' etc,
where due to real-time constraints a solution based on a central
server might add too much delay.
According to [I-D.irtf-mobopts-mmcastv6-ps] generally (i.e. for ASM)
a mobile multicast source must provide address transparency at
Routing - for Reverse Path Forwarding (RPF) checks - as well as on
Transport layer - to coincide with packet source address at receiver
side. Further issues are temporal handover constraints, possible
packet loss and multicast scoping, and enhanced complexity of inter-
domain multicasting. Additional challenges arise for SSM (Source
Specific Multicast) due to the principle of multicast decoupling
between sender and receivers.
4.5. Consideration of Handover Optimization
This work item would deal with reduction of delay, packet loss, and
packet reordering effort. In case these degradations are induced due
to terminal movement it will be discussed how to make use of MIPSHOP
approaches such as HMIP, FMIP etc. (predominantly focusing on intra-
technology handover). Reusing multicast specific protocol extensions
exceeding IGMP/MLD modifications shall further decrease the impact of
group management induced delay.
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4.6. Support of multiple flows
Considering a per-flow handover for parallel multicast sessions
allows to treat different services requirements and labels of flows
independently. This would improve user perceived service performance
as well as allow for more efficient usage of network resources
because of the enabled flexibility.
4.7. Support of multi-hop transmission
This scenario adds another level of complexity to Multicast Mobility
and is of interest e.g. in nested NEMO (Network Mobility, [RFC3963])
scenarios, for MANETs (Mobile Adhoc NETworks) where also mechanisms
for multicast forwarding are dicussed, e.g. in terms of Simplified
Multicast Forwarding (SMF, [I-D.ietf-manet-smf]) or for
infrastructure mesh networks. Here, more than the mobile and
temporary character of connections, it is the existence of (more or
less stable) multiple hops and multiple paths which is stressed.
4.8. Mobility agnosticity
In the idea of network based mobility management, the mobile node
should remain agnostic of the multicast mobility management when
roaming. In particular, the node MUST not be required to re-
subscribe to multicast group(s) after handoff. If the mobile node
does no re-resubscribes, the new MAG must be able to retrieve the
multicast states corresponding to the moving node.
4.9. Local routing
Short term deployment focuses on architecture where multicast traffic
is provided via the home network. However, depending on the network
topology, namely the location of the content delivery network, the
LMA may not be on the optimal multicast service delivery path. This
enables mobile nodes to access locally available multicast services
such as local channels.
Figure 3 illustrates the use-case for local routing.
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+----+
|LMA |
+----+
|
|
*** *** *** ***
* ** ** ** *
* * +-------------+
* Local Routing * _____ | Content |
* * | Delivery |
| Network |
* ** ** ** * +-------------+
*** *** *** ***
|| ||
+----+ +----+
|MAG1| |MAG2|
+----+ +----+
| | |
| | |
MN1 MN2 MN3
Figure 3: local Multicast routing
In such a case, the MAG should act as a multicast router to construct
the optimal multicast delivery path. If the MAG also supports MLD
proxy function issue raises up on the dual mode behaviour. In such a
case, a pragmatic approach could be to leverage only on multicast
routing at the MAG in the PMIP domain.
Whatever is the MAG operation mode, the multicast state is locally
kept at the access gateway, so unknown from the mobility anchor. In
other words, the multicast service is independent from the mobility
service that the mobile node is receiving from the network in the
form of PMIPv6 or DSMIPv6. However, handover support is still
desirable but cannot be provided by the mobility anchor (i.e. HA or
LMA). In such a case mobility support for locally available
multicast should be provided by extending multicast protocols of IGMP
or MLD.
5. Requirements on Solutions
This section tries to identify requirements from the issues discussed
in previous section.
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o Seamless handover (low latency and during the handover).
o Similar packet loss to unicast service.
o Multiple LMAs architecture.
o Agnostic mobile host re-subscription. So, MAGs must be able to
retrieve multicast contexts of the mobile nodes.
o Solution address IPv6, IPv4 only and dual stack nodes.
o Supports sender (source) mobility.
o Optimal local routing.
o To be completed...
6. Security Considerations
This draft introduces no additional messages. Compared to [RFC3376],
[RFC3810], and [RFC3775][RFC5213] there is no additional threats to
be introduced.
7. IANA Considerations
None.
8. Acknowledgements
The authors would thank all active mebers of MultiMob WG, especially
(in no specific order) Gorry Fairhurst, Jouni Korhonen, Thomas
Schmidt, Suresh Krishnan and Matthias Waehlisch for providing
continuous support and helpful comments.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3314] Wasserman, M., "Recommendations for IPv6 in Third
Generation Partnership Project (3GPP) Standards",
RFC 3314, September 2002.
[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version
3", RFC 3376, October 2002.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
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[RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery
Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
IP", RFC 4607, August 2006.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
Routers", RFC 5555, June 2009.
9.2. Informative References
[23246] "3GPP TS 23.246 V8.2.0, Multimedia Broadcast/Multicast
Service (MBMS); Architecture and functional description
(Release 8).", 2008.
[23401] "3GPP TS 23.401 V8.2.0, General Packet Radio Service
(GPRS) enhancements for Evolved Universal Terrestrial
Radio Access Network (E-UTRAN) access (Release 8).", 2008.
[23402] "3GPP TS 23.402 V8.4.1, Architecture enhancements for non-
3GPP accesses (Release 8).", 2009.
[I-D.asaeda-multimob-igmp-mld-mobility-extensions]
Asaeda, H. and T. Schmidt, "IGMP and MLD Hold and Release
Extensions for Mobility",
draft-asaeda-multimob-igmp-mld-mobility-extensions-03
(work in progress), July 2009.
[I-D.asaeda-multimob-igmp-mld-optimization]
Asaeda, H., "IGMP and MLD Optimization for Mobile Hosts
and Routers",
draft-asaeda-multimob-igmp-mld-optimization-01 (work in
progress), October 2009.
[I-D.asaeda-multimob-pmip6-extension]
Asaeda, H., Seite, P., and J. Xia, "PMIPv6 Extensions for
Multicast", draft-asaeda-multimob-pmip6-extension-02 (work
in progress), July 2009.
[I-D.deng-multimob-pmip6-requirement]
Deng, H., Chen, G., Schmidt, T., Seite, P., and P. Yang,
"Multicast Support Requirements for Proxy Mobile IPv6",
draft-deng-multimob-pmip6-requirement-02 (work in
progress), July 2009.
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[I-D.ietf-16ng-ipv4-over-802-dot-16-ipcs]
Madanapalli, S., Park, S., Chakrabarti, S., and G.
Montenegro, "Transmission of IPv4 packets over IEEE
802.16's IP Convergence Sublayer",
draft-ietf-16ng-ipv4-over-802-dot-16-ipcs-06 (work in
progress), June 2009.
[I-D.ietf-manet-smf]
Macker, J. and S. Team, "Simplified Multicast Forwarding",
draft-ietf-manet-smf-09 (work in progress), July 2009.
[I-D.irtf-mobopts-mmcastv6-ps]
Fairhurst, G., Schmidt, T., and M. Waehlisch, "Multicast
Mobility in MIPv6: Problem Statement and Brief Survey",
draft-irtf-mobopts-mmcastv6-ps-09 (work in progress),
October 2009.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, January 2005.
[RFC5121] Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S.
Madanapalli, "Transmission of IPv6 via the IPv6
Convergence Sublayer over IEEE 802.16 Networks", RFC 5121,
February 2008.
Authors' Addresses
Dirk von Hugo
Deutsche Telekom Laboratories
Deutsche-Telekom-Allee 7
64295 Darmstadt, Germany
Email: dirk.von-hugo@telekom.de
Hitoshi Asaeda
Keio University
Graduate School of Media and Governance
5322 Endo
Fujisawa, Kanagawa 252-8520
Japan
Email: asaeda@wide.ad.jp
URI: http://www.sfc.wide.ad.jp/~asaeda/
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Behcet Sarikaya
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX 75075
Email: sarikaya@ieee.org
Pierrick Seite
France Telecom - Orange
4, rue du Clos Courtel
BP 91226
Cesson-Sevigne, BZH 35512
France
Email: pierrick.seite@orange-ftgroup.com
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