1. 1 http://www.realmv6.org http://www.realmv6.org Towards Seamless Handovers in SSM Source Mobility – An Evaluation of the Tree Morphing Protocol Olaf Christ, Thomas C. Schmidt, Matthias Wählisch christ_o@informatik.haw-hamburg.de {t.schmidt, waehlisch@ieee.org} HAW Hamburg & link-lab

2. 2 http://www.realmv6.org http://www.realmv6.org Agenda  Mobile SSM Sources: What is the problem?  Tree Morphing: Routing for mobile SSM Sources  Design of the Tree Morphing Protocol  Simulation & Evaluation  Conclusion & Outlook

3. 3 http://www.realmv6.org http://www.realmv6.org Source Specific Multicast Listeners subscribe to source-specific (S,G) channels Typically used for real-time applications WebTV / IPTV VoIP / VCoIP Collaborative applications Massive Multiplayer Games Immediate shortest path trees Routing simplified (in contrast to ASM) Easy to deploy, domain transparent

4. 4 http://www.realmv6.org http://www.realmv6.org Problem: Mobile SSM Sources Real-time constraints (50 – 100 ms) SSM was designed for known, fixed sources On source handover, the delivery tree rooting at the source invalidates Address duality: Source filtering in routers and receivers Logical Group Identifier: Home Address Topological Tree Locator: Care-of Address Decoupling: Source cannot Control Receiver Initiated Updates May loose receivers on handover

5. 5 http://www.realmv6.org http://www.realmv6.org Solutions Statically Rooted Distribution Trees Handover compliant to Mobile IPv6 Packets are tunneled via the Home Agent Additional undesired latencies Single Source of Failure Reconstruction of Distribution Trees Separate multicast control tree with information about source address changes or Bicasting data into an old and a new tree via anchor points (APs) Tree Modification Schemes Attempt to re-use established states

6. 6 http://www.realmv6.org http://www.realmv6.org Multicast Forwarding States: Change of Distribution Trees under Mobility 75 – 95 % Coincidence for a mobility ‘step-size’ of 5 and 100 Receivers

7. 7 http://www.realmv6.org http://www.realmv6.org Tree Morphing: Routing for mobile SSM sources Preserve previous trees: Keep contact subsequent to handover Idea: Morph previous into next tree: Elongate root (modify RPF-Check) Send packets to previous root of delivery tree Discover shortcuts, but re-use common parts of trees Dismiss unneeded branches A new SPT is generated Need to change routing Extend (CoA,G) states to (CoA,G,HoA)

8. Mobile Source Specific Multicast: Tree Morphing Protocol

9. Root Elongation Phase

10. First Shortcut

11. Optimized Tree

12. 12 http://www.realmv6.org http://www.realmv6.org Design of the Tree Morphing Protocol State update - necessary information Group context (HoA, G) Tree topology (nCoA, G) “Piggy-backing” of update information Eliminates additional update packets Minimum extension to existing mobility messages Re-use of existing headers (see next slides) Security and robustness of updates

13. 13 http://www.realmv6.org http://www.realmv6.org Tree Morphing: State Update Message Combination of a Binding Update with CGA headers, a Router Alert Option and a Routing Header Routing Header directs packets from nDR to pDR (source routing) Router Alert Option instructs routers, to further inspect the packet (RFC 2711) CGA authenticates these updates

14. 14 http://www.realmv6.org http://www.realmv6.org Benefits of Tree Morphing Protocol Signaling of updates by combining existing IPv6 headers Router Alert Option is slight addition to existing Mobile IPv6 Binding Update Packet processing is well-defined and already well tested Inserting the update message into the data stream does not introduce additional packets

15. 15 http://www.realmv6.org http://www.realmv6.org Simulation OMNeT++ IPv6Suite

16. 16 http://www.realmv6.org http://www.realmv6.org First Step: Test Topologies Net 1Net 2

17. 17 http://www.realmv6.org http://www.realmv6.org Delay Stretch Net 1Net 2

18. 18 http://www.realmv6.org http://www.realmv6.org Convergence Time

19. 19 http://www.realmv6.org http://www.realmv6.org Packet Loss

20. 20 http://www.realmv6.org http://www.realmv6.org Second Step: Real-world Topologies SCAN + Lucent (1.540 Core Routers)

21. 21 http://www.realmv6.org http://www.realmv6.org Conclusion & Outlook Benefits of Tree Morphing Algorithm enables smooth source handover with state re-use Protocol signaling realized as compact combination with Mobile IPv6 headers Evaluation: Full protocol implementation on OMNeT++ Test topologies reveal strengths and weaknesses Real-world topologies smoothly mix effects Packet loss too high Current work and outlook Protocol improvement: decouple signaling, eleminate source routing Heals performance deficits (loss in particular) Optimized versions for Fast MIPv6 & Multihoming

22. 22 http://www.realmv6.org http://www.realmv6.org Thank you very much for your attention! Do you have any questions?