Mobile Group Communication

Transcription

1 Mobile Group Communication Mobility & Multicast Status The Multicast Mobility Problem Listener Mobility ASM Source Mobility SSM Source Mobility Conclusions & Outlook 1 Prof. Dr. Thomas Schmidt

2 Where are we going Mobile today? 2 Prof. Dr. Thomas Schmidt

3 We need Multicast Services for Public Content Broadcasting Voice and Video Conferencing Collaborative Environments Gaming Self Organisation of Distributed Systems All of this MOBILE! 3 Prof. Dr. Thomas Schmidt

4 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 o NGNs: DVB IP distribution services 4 Prof. Dr. Thomas Schmidt

5 Multicast: What is the Problem? othere is Any Source Multicast: - Listeners harvest streams from any source - Sparse & dense mode routing - Complex to deploy, Interdomain problem othere is Source Specific Multicast: - Listeners subscribe to known sources - Immediate shortest path trees - Easy to deploy, domain transparent 5 Prof. Dr. Thomas Schmidt

6 Multicast Receiver Mobility 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! 6 Prof. Dr. Thomas Schmidt

7 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, 7 Prof. Dr. Thomas Schmidt

8 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 Prof. Dr. Thomas Schmidt

9 M-FMIPv6: Prediction 9 Prof. Dr. Thomas Schmidt

10 M-FMIPv6: Forwarding 10 Prof. Dr. Thomas Schmidt

11 M-FMIPv6: Handover 11 Prof. Dr. Thomas Schmidt

12 M-FMIPv6: Completion 12 Prof. Dr. Thomas Schmidt

13 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 13 Prof. Dr. Thomas Schmidt

14 M-HMIPv6: Multicast Listener 14 Prof. Dr. Thomas Schmidt

15 M-HMIPv6: MAP-Local Handover 15 Prof. Dr. Thomas Schmidt

16 M-HMIPv6: Inter-MAP Handover 16 Prof. Dr. Thomas Schmidt

17 M-HMIPv6: Completion 17 Prof. Dr. Thomas Schmidt

18 Multicast Source Mobility Problem 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 18 Prof. Dr. Thomas Schmidt

19 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 19 Prof. Dr. Thomas Schmidt

20 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 Prof. Dr. Thomas Schmidt

21 M-HMIPv6: Multicast Source 21 Prof. Dr. Thomas Schmidt

22 M-HMIPv6: MAP-Local Handover 22 Prof. Dr. Thomas Schmidt

23 M-HMIPv6: Inter-MAP Handover (1) 23 Prof. Dr. Thomas Schmidt

24 M-HMIPv6: Inter-MAP Handover (2) 24 Prof. Dr. Thomas Schmidt

25 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 25 Prof. Dr. Thomas Schmidt

26 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 26 Prof. Dr. Thomas Schmidt

27 Bi-Directional Tunneling 27 Prof. Dr. Thomas Schmidt How good is BT?

28 Simulation: BT in ATT Network 28 Prof. Dr. Thomas Schmidt

29 Internet with 154 Core Nodes 29 Prof. Dr. Thomas Schmidt

30 Internet with Core Nodes 30 Prof. Dr. Thomas Schmidt

31 Internet with Core Nodes 31 Prof. Dr. Thomas Schmidt

32 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 Prof. Dr. Thomas Schmidt

33 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 33 Prof. Dr. Thomas Schmidt

34 Simulation Study: Tree Coincidence wrt. Step-Size 80 % Coincidence for 40 Receivers and a mobility step-size of 5 34 Prof. Dr. Thomas Schmidt

35 Simulation Study: Tree Coincidence wrt. Tree Evolvement > 80 % Coincidence for a mobility step-size of 5 and 100 Receivers 35 Prof. Dr. Thomas Schmidt

36 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 Source Romdhani et al: Transparent Handover for Mobile Multicast Sources, In: Proceedings of the IEEE ICN'06, IEEE Press, April Prof. Dr. Thomas Schmidt

37 Mobility-aware Rendezvous Points 37 Prof. Dr. Thomas Schmidt

38 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 Source - Schmidt & Wählisch: Extending SSM to MIPv6 -- Problems Solutions and Improvements, Computational Methods in Science and Technology, Vol. 11, No. 2, 38 Prof. Dr. Thomas Schmidt pp , Poznan:Scientific Publ. OWN --- Polish Academy of Sciences, Nov

39 Tree Morphing 39 Prof. Dr. Thomas Schmidt

40 Root Elongation Phase 40 Prof. Dr. Thomas Schmidt

41 First Shortcut 41 Prof. Dr. Thomas Schmidt

42 Optimized Tree 42 Prof. Dr. Thomas Schmidt

43 Performance Snapshot 43 Prof. Dr. Thomas Schmidt

44 Conclusions & Outlook 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 44 Prof. Dr. Thomas Schmidt

45 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, Schmidt, Wählisch: Multicast Mobility in MIPv6: Problem Statement, draft-irtf-mobopts-mmcastv6-ps-01.txt, 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 (in press) 45 Prof. Dr. Thomas Schmidt