Multicast Mobility (multimob)

Last modified: 2014-12-01


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The Multicast mobility (multimob) working group provides guidance for supporting multicast in a mobile environment. The scope of work will be limited to Proxy Mobile IPv6, IGMPv3/MLDv2 protocols and listener mobility. The group will work on extensions of Proxy Mobile IPv6 to improve its capability to handle multicast efficiently. Work requiring modifications to IGMPv3/MLDv2 is out of scope in this stage of this working group, however, as are modifications to multicast routing protocols.

Specific goals for the group are:

  • A solution to the tunnel convergence problem by separating multicast routing from a mobility anchor. Possible techniques are using native infrastructure, using a dedicated mobility anchor etc.

  • Mechanisms to optimize multicast traffic during a handover. Such mechanisms may include context transfer functionality.

  • Mechanisms needed to support multicast source mobility. Both any source multicast and source specific multicast source mobility will be covered.

  • Document the configuration of IGMPv3/MLDv2 in mobile environments

The group shall primarily focus on Proxy Mobile IPv6 (PMIPv6) based networks when looking at the first three items. It is possible but not required that the solutions are applicable also for Mobile IPv6 (MIPv6) based networks.

For background, the PMIPv6 specification as defined in RFC 5213 does not describe how to support multicast. Some forms of multicast support can, however, be built in the involved nodes by using existing capabilities of multicast protocols and the underlying mobility protocols. The working group has already documented how existing mechanisms can be used to support multicast, without requiring any additions or changes to message types and parameters specified in RFC 5213, and assuming an unmodified mobile host. The current goals of the working group relate to improving the efficiency of this base solution.

IGMPv3/MLDv2 has been specified for wired networks with shared links. Mobile nodes have needs that are specific to wireless networks and mobility (e.g. entering a dormant mode to conserve battery power, minimizing the latency for joining and leaving a group in support of movement).

In performing its work, the working group will work closely with both the mobility community (NETEXT WG) and the multicast community (MBONED WG). The group will consider both source specific multicast and any source multicast multicast models.

Future work, subject to rechartering, may study/evaluate extensions to IGMPv3/MLDv2 to support better operation in mobile environments.

Goals and Milestones

Nov 2010
Initial version of a document on how to tune IGMPv3/MLDv2 for mobility
Apr 2011
Submit a document on how to tune IGMPv3/MLDv2 for mobility, for publication as either Informational or Best Current Practice
Jun 2011
Initial version of document on PMIPv6 routing optimizations to avoid tunnel convergence problem
Nov 2011
Initial version of document on PMIPv6 multicast source mobility solution
Nov 2011
Initial version of document on PMIPv6 handover optimizations
Jun 2012
Submit PMIPv6 routing optimizations document to IESG for publication as Internet Standard
Nov 2012
Submit PMIPv6 handover optimizations document to IESG for publication as Internet Standard
Nov 2012
Submit PMIPv6 multicast source mobility solution to IESG for publication as Internet Standard
Dec 2012
Decision to include additional optimization work involving extensions to IGMPv3 or MLDv2
Dec 2012
Recharter based on the above decisions (or close the group if no new work is needed)

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