One document matched: draft-von-hugo-multimob-future-work-00.txt
MultiMob Working Group Dirk v. Hugo
Internet Draft Deutsche Telekom Laboratories
Intended Status: Informational
Expires: April 22, 2010 October 19, 2009
Evaluation of further issues on Multicast Mobility:
Potential future work for WG MultiMob
<draft-von-hugo-multimob-future-work-00.txt>
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Abstract
This document discusses potential future extensions on the current
work plan of recently approved WG MultiMob (Multicast Mobility).
MultiMob charter explicitly states that scope of work will be limited
to mobility protocols Proxy Mobile IPv6, and multicast group
management in terms of IGMPv3/MLDv2 protocols. Furthermore only
listener mobility will be dealt with and any modification to these
existing protocols and to multicast routing protocols are out of
scope.
From an operational point of view, however, though such a basic
solution is essential, there challenges with efficient resource
utilization and user perceived service quality still persist. As
these issues may prevent large scale deployments of mobile multicast
applications this document attempts to identify topics for future
extension of work for WG MultiMob such as
o modifying base PMIPv6 and MLD/IGMP for optimal multicast support
o extending to and modifying of MIPv4/v6 and DSMIP
o sender (source) mobility
o consideration of Handover optimization
o multiple flows
o multi-hop transmission
o any other different issues
Intention of this document is to start and prepare for discussion on
potential re-chartering after scheduled work.
Introduction
Recently chartered WG MultiMob focusses on documentation of proper
configuaration 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 either the employed remote subscription aproach or
a traditional bidirectional tunneling will not be resource efficient
nor grant the service quality expected by the end user.
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Such a solution would resolve the problem to ensure multicast
reception in PMIPv6-enabled [1] 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 [6]. 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 are described to enable current PMIP6 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).
+------+ +------+
| MN | =====> | MN |
+------+ +------+
| .
| .
+-------+ +-------+
| MAG 1 | | MAG 2 |
+-------+ +-------+
| |
*** *** *** ***
* ** ** ** *
* *
* Internet Subnet *
* *
* ** ** ** *
*** *** *** ***
| |
+-------+ +-------+
| LMA 1 | | LMA 2 |
+-------+ +-------+
| |
*** *** *** ***
* ** ** ** *
* *
* Fixed Internet *
* *
* ** ** ** *
*** *** *** ***
|
+------+
| CN |
+------+
Figure 1: MultiMob Scenario for chartered PMIP6 issue
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These issues of an extended optimiyed multicast mobility solution are
sketched in Fig. 2:
+------+ +------+ +------+
| MN | =====> | MN | ====> | MN |
+------+ +------+ +------+
| . .
| . .
| . .
+-------+ +-------+ +-------+ +-------+
| MAG 1 | | MAG 2 | | AR 1 | | AR 2 |
+-------+ +-------+ +-------+ +-------+
\ / | |
*** *** *** *** *** *** *** ***
* ** *** ** * * ** *** ** *
* * * *
* 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 as shown in Fig. 1 the future work will
extend the scenario to 'Multi-hop, -homed, -flow' client mobility
(see Fig. 2).
Potential extension of the basic solution could cover issues as
o Modifation of base PMIPv6 and MLD/IGMP for optimal multicast
support
o Extension to and modifying of MIPv4/v6 and DSMIP
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o Consideration of sender (source) mobility
o consideration of Handover optimization
o Support of multiple flows
o Multi-hop transmission
o any other different issues
2. Problem Description
The general issues if multicast mobility are extensively discussed
and described in [6]. To reduce the complexity of the pleothera of
requirements listed in [6] 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 to be provided as a first outcome
of MultiMob WG as e.g. proposal [7], [8], or [9].
3. Issues for Modification of Future Multicast Mobility Protocols
3.1 Modification of base PMIPv6 and MLD/IGMP for optimal multicast
support
3.1.1 Modification of PMIPv6
Solutions proposed within this section are either agent-based, rely
on additional encapsulation or may be of a hybrid approach.
Since other functional enhancements of PMIPv6 are currently under way
in WG NETEXT 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.
3.1.2 Modification of MLD/IGMP
Potential approaches for enhancement of group management as
specified e.g. by MLDv2 [2] 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.
3.2 Extension to and modifying of MIPv4/v6 and DSMIP
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
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based specifications.
This section addresses the compatibility of PMIPv6-based multicast
solutions with MIPv6 [5], 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. DSMIP (RFC 5454, [3]) deals with multicast group
membership control messages such as MLD or MLDv2 [2], but does not
specify how to achieve group management and data forwarding unless
the Home Agent (HA) is a fully functional IPv6 multicast router.
3.3 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 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 [6] 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.
3.4 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 focussing on
intra-technology handover). Reusing multicast specific protocol
extensions exceeding IGMP/MLD modifications shall further decrease
the impact of group management induced delay.
3.5 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.
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3.6 Multi-hop transmission
This scenario adds another level of complexity to Multicast Mobility
and is of interest e.g. in nested NEMO (Network Mobility, RFC 3963
[4]) scenarios, for MANETs (Mobile Adhoc NETworks) where also
mechanisms for multicast forwarding are dicussed, e.g. in terms of
Simplified Multicast Forwarding (SMF, [9]) or for infrastructure mesh
networks.
4. Security Considerations
This document summarizes discussion of multicast extensions to
mobility. New methods or procedures have not been proposed.
Relevant issues for security and security have already been mentioned
exhaustively in [6].
5. Summary and Future Steps
This document shall provide a future extension of the scope of
Multicast Mobility within the framework of IETF WG with focus on
deployable and operational solutions.
6. IANA Considerations
There are no IANA considerations introduced by this draft.
7. References
Normative References
[1] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B.
Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[2] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2
(MLDv2) for IPv6", RFC 3810, June 2004.
[3] Tsirtsis, G., Park, V., and Soliman, H., "Dual-Stack Mobile IPv4",
RFC 5454, March 2009
[4] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005.
[5] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004.
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Informative References
[6] Schmidt, T.C., Waehlisch, M., and Fairhurst, G., "Multicast
Mobility in MIPv6: Problem Statement and Brief Survey",
draft-irtf-mobopts-mmcastv6-ps-08.txt, (work in progress), August
2009.
[7] Jeon, S., Kim, Y., and Lee, J., "Mobile Multicasting Support in
Proxy Mobile IPv6", draft-sijeon-multimob-mms-pmip6-00.txt, (work
in progress), July 2009.
[8] Schmidt, T.C., Waehlisch, M., Sarikaya, B., and Krishnan, S., "A
Minimal Deployment Option for Multicast Listeners in PMIPv6
Domains", draft-schmidt-multimob-pmipv6-mcast-deployment-01.txt,
(work in progress), June 2009.
[9] Macker, J., et al., "Simplified Multicast Forwarding",
draft-ietf-manet-smf-09, (work in progress), July 2009
[10] Krishnan, S., Sarikaya, B., and Schmidt, T.C., "Proxy Mobile IPv6
Basic Multicast Support Solution", draft-krishnan-multimob-
pmip6basicmcast-solution-00, (work in progress), July 2009.
Acknowledgments
The authors would thank all active mebers of MultiMob WG for
providing continuous support, especially for Thomas Schmidt, Matthias
Waehlisch, and Gorry Fairhurst for their fundamental document, Jouni
Korhonen and Behcet Sarikaya for helpful comments and review.
Authors' Addresses
Dirk v. Hugo
Deutsche Telekom AG Laboratories
Deutsche-Telekom-Allee 7
D-64295 Darmstadt, Germany
Email: Dirk.von-Hugo@Telekom.de
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