1. A Preferred Link Based Multicast Protocol for Wireless Mobile Ad hoc Networks R. S. Sisodia, Karthigeyan. I, B. S. Manoj, and C. Siva Ram Murthy ICC 2003

2. Outline • Introduction • Multicast Tree • Preferred Link Based Algorithm • Tree Maintenance • Performance • Conclusions

3. Introduction • Existing multicast routing protocols can be broadly classified into two categories • Tree based protocols • Mesh based protocol • Mesh based protocols have high packet delivery ratio compared to tree based protocols • More control overhead • JoinQuerypackets

4. Introduction (cont.) • This paper propose an efficient protocol • Preferred Link Based Multicast protocol (PLBM) • Uses a preferred link approach for forwarding JoinQuerypackets • Restricts the flooding of JQ packets • Preferred link based algorithm • Preferred nodes • Locally repairs broken links • The local two hop network topology

5. Multicast Tree • Tree nodes • Multicast source • Connected member nodes • Forwarding nodes • Neighbors Neighbors Table (NNT) • Connect Table (CT)

6. Multicast Tree (cont.)

7. Preferred node E C Preferred Link Based Algorithm • The PLBA • Preferred links (nodes) • Utilizes the two hop topology information • NNT E C D B A

8. Preferred Link Based Algorithm (cont.) • Condition 1 • The current forwarding node excludes all its neighbors that have already forwarded JQ D E B C JQ A

9. Preferred Link Based Algorithm (cont.) • Condition 2 • The current forwarding node is prevented from forwarding JQ to those neighbors that are shared by the nodes D B C A

10. Preferred Link Based Algorithm (cont.) • Condition 3 • Prevents broadcast to those nodes that are neighbors of nodes in the traversed path of JQ D D B C A

11. Preferred Link Based Algorithm (cont.) • Example

12. Preferred Link Based Algorithm (cont.) • Example

13. Tree Maintenance PACKET_AWAIT_TIMER

14. Performance • GloMoSim • Simulation Area 1000X1000 m • The simulation is run for 600 seconds • Transmission Rage 250m • Nodes 50 • PACKET_AWAIT_TIMER 1 sec

15. Performance (cont.) Group size 20

16. Performance (cont.) Mobility 9 m/s

17. Conclusions • An efficient receiver-initiated tree based multicast protocol • Preferred link based approach • Dominating set