– ASM Source Mobility

Mobile Group Communication

– Mobility & Multicast Status

– The Multicast Mobility Problem

– Listener Mobility

– ASM Source Mobility

– SSM Source Mobility

– Conclusions & Outlook

Where are we going Mobile today?

2 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

We need Multicast Services for …

– Public Content Broadcasting

– Voice and Video Conferencing

– Collaborative Environments

– Gaming

– Self Organisation of Distributed Systems

– …

All of this MOBILE!

Status: Where are we today?

o Internet Mobility

- Mobile IPv6 - RFC 3775 (June 2004, implemented)

o Real-Time Mobility

- FMIPv6, HMIPv6 – RFCs 4068, 4140 (August 2005, first implementations)

o Multicast Mobility

- Rough ideas in IETF … - Some proposals in IRTF

- First problem statement in Vancouver, Nov. 2005 o NGNs: DVB IP distribution services …

4 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Multicast:

What is the Problem?

o There is Any Source Multicast:

- Listeners harvest streams from any source - Sparse & dense mode routing

- Complex to deploy, Interdomain problem o There is Source Specific Multicast:

- Listeners subscribe to known sources - Immediate shortest path trees

- Easy to deploy, domain transparent

Multicast Receiver Mobility

6 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

o Multicast Routing is ‘Mobile’ :

- On handover listeners may re-subscribe to multicast group (ASM & SSM)

- Routing will construct delivery branch

o Problem: Multicast routing not seamless, but slow - Branch construction up to 30 s

- Real-time communication requirements:

handover below 100 ms!

Multicast Mobility Approaches

o Remote Subscription

- Show all movement by local multicast subscription

o Bi-directional Tunneling

- Hide all movement by tunneling via Home Agent

o Agent Based

- Compromise: Intermediate agents shield Mobile - Approaches: Extend unicast acceleration schemes

M-FMIPv6, M-HMIPv6, …

Fast Multicast Protocol for MIPv6

draft-suh-mipshop-fmcast-mip6-00

– Remote subscription with agent support

– Mobile multicast reception only

– Built on Fast Handovers for MIPv6 (FMIPv6)

– Predictive handovers based on L2 : L3 map

– Handled at access routers

– Extends signalling of FMIPv6 by multicast address option

8 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

M-FMIPv6: Prediction

M-FMIPv6: Forwarding

10 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

M-FMIPv6: Handover

M-FMIPv6: Completion

12 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Seamless Multicast Handover in a HMIPv6 Environment

draft-schmidt-waehlisch-mhmipv6-04

– Agent based: MAP as Multicast agent

– Mobile multicast reception and source

– Built on Hierarchical MIPv6 (HMIPv6)

– For mobile listeners:

– Micro mobile handovers hidden by MAP

– Reactive handovers between MAPs

– Unicast (tunnel) forwarding MN : MAP

– Change to remote subscription with MAP attendance

– Extends signalling of HMIPv6 by multicast advertisement flag

M-HMIPv6: Multicast Listener

14 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

M-HMIPv6: MAP-Local Handover

M-HMIPv6: Inter-MAP Handover

16 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

M-HMIPv6: Completion

Multicast Source Mobility Problem

18 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

o Distribution tree (somehow) rooted at source:

- Collapses after movement

- Reconstruction very slow (up to minutes) o Address Duality Problem:

- Source address is logical & topological ID o Source Activation Problem:

- New source to be discovered by interdomains o Decoupling Problem:

- Source has no feedback from receivers

Multicast Source Mobility Approaches

o Remote Subscription

- Show all movement by local multicast subscription

o Bi-directional Tunneling

- Hide all movement by tunneling via Home Agent

o Agent Based

- Use current Care-of-Address for Routing

- Use Home-Addres in Destination Option at Receiver

- “Tree Walking”

M-HMIPv6: Mobile Multicast Source

Mobile multicast sender anchored at MAP:

– Use Home Address Destination Option (CN must not verify BC on mcast)

– On handover:

– Initially tunnel through old MAP

– Initiate new tree by ‘pure IP packets’

– Handover on (protocol dependent) timeout

– On rapid Movement:

stay with established MAP

20 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

M-HMIPv6: Multicast Source

M-HMIPv6: MAP-Local Handover

22 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

M-HMIPv6: Inter-MAP Handover (1)

M-HMIPv6: Inter-MAP Handover (2)

24 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Multicast Source Mobility:

SSM Problems

o Receivers need to Subscribe to Source Address:

- HoA & current CoA needed at Receiver o Routers Maintain Source Specific States:

- HoA & current CoA needed at Routers o Decoupling: Source cannot Control Receiver

Updates:

- May loose receivers on handover

Multicast Source Mobility Approaches

26 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

o Remote Subscription

- Show all movement by local multicast subscription

o Bi-directional Tunneling

- Hide all movement by tunneling via Home Agent

o Agent Based

- Use current Care-of-Address for Routing

- Use Home-Addres in Destination Option at Receiver

- “Tree Walking”

Bi-Directional Tunneling

How good is BT?

Simulation: BT in ATT Network

28 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Internet with 154 Core Nodes

Internet with 1.540 Core Nodes

30 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Internet with 15.400 Core Nodes

What to do with Mobile SSM ?

Need to Change Routing:

– Logical (HoA) and topological (CoA) identifier needed at client and routing layer

Need to keep contact to clients after handover :

– Some mobility persistent entities?

Current Ideas:

– Re-introduce shared trees

– Re-use trees

What effect does mobility impose on SPTs?

32 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Analysis of ‘Moving’ Distribution Trees

– Multicast Distribution Trees subsequent under Mobility are highly correlated

– Previous and Next Tree overlap from receivers downward

– Coinciding subtrees: self-similar URT

– Results in frequent re-use of Mcast Routers

– Two characteristic measures

– ‘Step-Size’: pDR-to-nDR Distance

– Tree evolvement: Number of Receivers

34 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Simulation Study:

Tree Coincidence wrt. ‘Step-Size’

≈ 80 % Coincidence for 40 Receivers and

a mobility ‘step-size’ of 5

Simulation Study:

Tree Coincidence wrt. Tree Evolvement

> 80 % Coincidence for a mobility

‘step-size’ of 5 and

100 Receivers

Shared Tree Mobility

– Use Rendezvous Point as Mobility Anchor:

Mobility-aware Rendezvous Point (MRP)

– Need to Change Routing:

– Extend (*,G) states to (HoA, G, MRP-ID)

– Modify RPF-Check to identify CoA* sources with HoA

– Operate interdomain handovers via MRP-ID

36 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Source – Romdhani et al: Transparent Handover for Mobile Multicast Sources ,

In: Proceedings of the IEEE ICN'06, IEEE Press, April 2006

Mobility-aware Rendezvous Points

Source Specific Tree Modification

Need to Change Routing:

– Extend (CoA,G) states to (CoA,HoA,G)

Need to Preserve Previous Trees:

– Keep contact subsequent to handover

Idea: Morph Previous into Next Tree:

– Elongate root (modify RPF Check)

– Discover shortcuts

– Dismiss unneeded branches

38 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Source - Schmidt & Wählisch: Extending SSM to MIPv6 -- Problems Solutions and

Improvements, Computational Methods in Science and Technology, Vol. 11, No. 2,

pp. 147--152, Poznan:Scientific Publ. OWN --- Polish Academy of Sciences, Nov. 2005.

Tree Morphing

Root Elongation Phase

40 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

First Shortcut

42 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

Optimized Tree

Performance Snapshot

Conclusions & Outlook

44 Œ Prof. Dr. Thomas Schmidt Œ http:/www.informatik.haw-hamburg.de/~schmidt Œ

√ Mobile Multicast is Emerging Issue

√ Intricate Problem:

- Mobile Receivers on Good Way

- Mobile ASM Sources Difficult

- Mobile SSM Sources Hard

√ New Approach: Tree Morphing

- Seamless & free of encapsulation

- But requires change of SSM routing protocols

Future Development:

• Analysis & Simulations & Optimizations

• Detail out + Security Layer

Other Approaches

• Dynamically optimising agents

• Overlay Multicast

• XCast

References

• Romdhani, I., Kellil, M., Lach, H.-Y. et. al. "IP Mobile Multicast: Challenges and Solutions", IEEE Comm. Surveys, 6, 1, 2004.

• Schmidt, Wählisch: Multicast Mobility in MIPv6: Problem Statement , draft-irtf-mobopts-mmcastv6-ps-01.txt, 2006.

• Schmidt, Wählisch: “Morphing Distribution Trees - On the Evolution of Multicast

States under Mobility and an Adaptive Routing Scheme for Mobile SSM Sources ”,

Telecommunication Systems, Berlin Heidelberg:Springer, October 2006. (in press)