M-HBH Efficient Mobility Management in Multicast

1. M-HBHEfficient Mobility Management in Multicast Rolland Vida, Luis Costa, Serge Fdida Laboratoire d’Informatique de Paris 6 – LIP6 Université Pierre et Marie Curie, Paris NGC ‘02, October 23-25, Boston, MA

2. Outline • The mobility problem in a multicast group • Traditional solutions • Bi-directional tunneling • Remote subscription • The original HBH protocol • Mobility handling in M-HBH • Performance analysis • Conclusion 2

3. The problem • More and more emerging mobile devices • Mobility handling became an important service requirement • The multicast service: • a multicast group, identified by a multicast address G • a source S that sends data to G • a receiver r that listens to packets sent to G • How to assure multicast data delivery if … • the source S is mobile or • the receiver r is mobile 3

4. Traditional solutions (1) • Proposed by Mobile IP [Perkins, RFC 3220] • Bi-directional tunneling (BT) • tunnel between the home and the foreign location of the MN • Source mobility: data is tunneled to the home network, and then retransmitted on the old tree • Receiver mobility: data is delivered on the old tree, and then tunneled to the MN • Drawbacks: • triangular routing • encapsulation/decapsulation of data • tunnel convergence (receiver mobility) 4

5. Example S’ S HA R1 R2 R3 R4 R5 r1 r3 r4 r2 5

6. Traditional solutions (2) • Remote subscription (RS) • reconfiguration of the multicast tree according to the new location of the MN • Source mobility: receivers redirect their Join messages towards the new location of the source • Receiver mobility: the MN joins the tree from its new location • Drawbacks: • Source mobility: • the entire tree must be reconstructed • reconstruction is costly, not efficient for a highly mobile source • Receiver Mobility • cost is lower, only a branch has to be added 6

7. Example S’ S R6 R1 R7 R2 R3 R4 R5 r1 r3 r4 r2 7

8. Example S’ S S R6 R1 R1 R7 R2 R3 R4 R5 r1 r3 r4 r2 8

9. Hybrid solutions • Switch between the two techniques, based on specific criteria • Mobile Multicast Protocol (MoM) [Harrison et al., Mobicom ’97] • Range-Based MoM [Lin et al., Infocom ’00] • Hierarchical Multicast Architecture [Wang et al., ACM Mobile Networks and Applications, 2001] 9

10. HBH multicast • In traditional multicast, the group is a single unit, identified by the multicast address • Mobility of an individual member is hard to handle • Keep the unit (tree) + tunnel • Reconstruct the unit (tree) • HBH – Hop-By-Hop Multicast Routing [Costa et al., Sigcomm ’01] • Uses a recursive unicast addressing scheme to provide multicast • Data is not sent to the group, but to the next branching node • Nodes are handled as individuals, not as a group 10

11. Data delivery in HBH MFT S S H2 MCT H1 Relay Node H1 S H2 MFT H2 Branching Node S H3 H4 H2 MFT – Multicast Forwarding Table MFT MCT – Multicast Control Table MFT H3 H4 S r3 r4 S r1 r2 MCT H5 r1 S r2 r3 r4 r2 11

12. The M-HBH protocol • In HBH multicast, nodes are treated as individuals, not as a group • Mobility is easier to handle • Mobile Hop-By-Hop Multicast Routing Protocol • Extension of HBH • Handles both source and receiver mobility • Mobile Node • Multicast connectivity – M-HBH • Unicast connectivity – Mobile IP 12

13. Source mobility with M-HBH MFT MFT S’ S S/S H2 S/S’ H2 MCT U1 H1 S/S H2 U2 MFT S/S S/S’ H3 H4 H2 MFT MFT U Unicast Router H3 H4 S/S S/S’ r3 r4 S/S’ S/S r1 r2 MCT H5 r1 S/S S/S’ r2 r3 r4 r2 13

14. Receiver mobility with M-HBH MFT S S H1 r3 MFT H1 MCT H2 S r1 r2/r2’ r2 S r3 MCT r3 r1 H3 S r2 Multicast Data U Join (r2/r2’) MCT HA Home Agent H4 S r2 r2 r2 HA r2’ 14

15. Advantages of M-HBH • Reduces triangular routing • Better delivery path • No encapsulation, no tunneling • Transparent handling of mobility • Preserves the advantages of HBH • Passes through unicast-only clouds • Takes into account asymmetric routes, data is forwarded on direct shortest path • Limits tree reconstruction … 15

16. The M-HBH tradeoff • M-HBH represents a trade-off between: • Shortest path delivery • Tree reconstruction • M-HBH shortcuts routing triangles, but… • Passing through the first (or the last) branching node does not assure shortest path delivery • Periodical tree reconfiguration can be considered • Reconfiguration frequency is limited 16

17. Routing triangle First branching node F yS Last branching node L S’ S S xS zS L F z r x r y r 17

18. Performance analysis • Mathematical models • K-ary trees • Self-similar trees • Simulation • Realistic Internet-like generated topology 18

19. Simulation results (multicast tree shape) • Average length of Xs vs. Xr 19

20. Simulation results (source mobility) • A) Average delivery delay M-HBH vs. BT vs. RS • B) Relative gains in average delivery delay, for M-HBH over BT, proportional to the average length of Xs 20

21. Simulation results (receiver mobility) • A) Average delivery delay M-HBH vs. BT vs. RS • B) Relative gains in average delivery delay, for M-HBH over BT, proportional to the average length of Xr 21

22. Conclusion • Traditional solutions have drawbacks: • Triangular routing, encapsulation (BT) • Frequent tree reconstruction (RS) • M-HBH uses a recursive unicast addressing scheme • Reduces routing triangles • eliminates tunneling • limits tree reconstruction • Simple, transparent, incrementally deployable • Simulations show important performance gains • Further details and analysis: hhtp://www-rp.lip6.fr/~vida/mhbh_techrep.pdf 22

23. Questions? 23

24. Mobile multicast source • Shared Multicast Tree (CBT, PIM-SM) • S sends data in unicast to the core (RP) • data is retransmitted on the shared tree • if S moves in a new network, it still can send unicast packets to the core (RP). Data is delivered to receivers. • Source-Specific Multicast Tree (PIM-SSM) • the multicast tree is rooted in the home network of S • S moves in a new network and obtains a new address (S’): • Multicast packets sent by S’ are dropped if … • no multicast router in the visited network • no multicast routing state in the router 24