1. 1 Data Overhead Impact of Multipath Routing for Multicast in Wireless Mesh Networks Yi Zheng, Uyen Trang Nguyen and Hoang Lan Nguyen Department of Computer Science & Engineering York University, Toronto, Canada

2. 2 Outline of the Talk Introduction to wireless mesh networks (WMNs) Motivation and contributions Experiment parameters Experimental results Conclusion and future work

3. 3 Introduction to WMNs Mesh routers provide multi-hop wireless connectivity  from one host to another  from a host to the Internet Applications  Internet access in rural areas  security surveillance  disaster recovery

4. 4 Motivation Multipath routing has been proved to be effective for mobile adhoc networks (MANETs) to deal with node mobility [1, 2].  improves data delivery reliability in case of link/node failures. In WMNs, routers are typically static.  traffic carried by the backup paths may adversely impact other flows and the multicast group itself.  contention, collisions, congestion This impact was unknown before this work.

5. 5 Contributions We study the impact of data overhead of multipath routing for multicast in WMNs.  single path routing (Dijkstra's algorithm): SPT (shortest path tree)  multipath routing (Zhao et al. [3, 4]): MDM (minimum disjoint mesh) Using QualNet simulation software Meaningful and useful metrics  average packet delivery ratios (PDR) of multicast group  average PDR of background unicast flows  average end-to-end delay of multicast packets

6. 6 Experiment Parameters

7. 7 Varying Group size 10-60 receivers, multicast rate 60 pkts/s, 20 unicast flows, 2 pkts/s per flow

8. 8 Varying Multicast Source Rate 40 receivers, multicast rate 10-80 pkts/s, 20 unicast flows, 2 pkts/s per flow

9. 9 Varying Background Traffic Load 20 receivers, multicast rate 50 pkts/s, 40 unicast flows, 1 to 4.5 pkts/s per flow

10. 10 Conclusion MDM offers comparable performance to SPT only when the group size is small or the traffic load is very light. In other cases, MDM trees suffer from  lower PDRs (by up to 8%)  higher end-to-end delay (up to 165% higher),  more packet loss to the background unicast flows than SPTs (by up to 13%). Suggestion: an algorithm similar to Cisco’s Interior Gateway Routing Protocol  dual paths run a single stream of traffic in a round-robin fashion  automatic switchover to the remaining path if one path fails  more complex implementation Future work: multicast multipath routing in WMNs for improved throughput, load balancing, and quality of service provisioning.

11. 11 References [1] A. Sriniva and E. Modiano, “Minimum energy disjoint pathrouting in wireless ad hoc networks,” in Proc. ACM MobiCom, pp. 122-133, Sept. 2003. [2] L. R. Reddy and S. V. Raghavan, “SMORT: scalable multipath on-demand routing for mobile ad hoc networks,” Ad Hoc Networks, vol. 5, no. 2, pp. 162-188, Mar. 2007. [3] X. Zhao, C. T. Chou, J. Guo, S. Jha, “Protecting multicast sessions in wireless mesh networks”, in Proc. IEEE LCN, pp. 467- 474, Nov. 2006. [4] X. Zhao, C. T. Chou, J. Guo, S. Jha, “A Scheme for Probabilistically Reliable Multicast Routing in Wireless Mesh Networks,” in Proc. IEEE LCN, pp. 213-214, Oct. 2007.

12. 12 Thank you! Q & A