1. Forwarding Group Multicast Protocol (FGMP) for Multihop, Mobile Wireless Networks Speaker : Wilson Lai Date : 91.09.17 Ching-Chuan Chiang, Mario Gerla and Lixia Zhang UCLA to appear at CLUSTER COMPUTING (1998)

2. Outline Introduction DVMRP FGMP Simulation and evaluation Conclusion Future work

3. Motivation nMultihop, Mobile Wireless Networks  rapid deployment & dynamic reconfiguration nMulticast:  minimize link bandwidth consumption of transmitting data from multiple senders to multiple receivers nWireless Multicast challenges:  limited channel bandwidth  changing topology  diverse wireless channel

4. DVMRP Distance Vector Multicast Routing Protocol Per-Source Multicast A Proactive Protocol Extension of DVMRP for fixed networks Each sender uses “floods” multicast packets to all nodes within a specified range. They use reverse shortest path forwarding scheme. Periodically non-member leaf nodes and nodes without any downstream members send prune messages to prune off branches. They become alive again after a timeout.

5. Problems of DVMRP in Ad-Hoc Networks  Leaf Node Detection ACK The overhead is ACK traffic and delay. Neighbors’s routing tables The overhead is the all neighbors’s routing tables  Flooding overhead for Grafting/Pruning  Reverse shortest Path Forwarding (RPF) does not work due to mobility. Scalability Very poor. Adaptive Reverse shortest Path Forwarding.

6. Adaptive Reverse Shortest Path Forwarding

7. Shared Tree Multicast Another Proactive Protocol Based on the concept of a rendezvous point (RP) Sender Messages send multicast packets to the RP. Join requests are also sent to the RP Multicast packets are forwarded to receiver members along the multicast forwarding tree, either in the unicast mode or multicast mode.

8. Forwarding Group Multicast Protocol (FGMP) nForwarding Group (FG) : a set of nodes which are in charge of forwarding multicast packets forwarding flag & timer soft state (refresh & timeout) nKey advantages: lLow storage & channel overhead nFG maintenance lFG nodes are discovered/activated by tracing shortest path between senders and receivers Sender advertising (FGMP-SA)/Receiver advertising (FGMP- RA) S S S R R R

10. Sender = {12} 2 11 22 15 21 16 7 6 17 18 9 24 10 1 3 5 8 13 14 19 20 23 26 Receivers = {3,5,15,18,27} FG = {4,12,16,22,25} Forwarding Table of Node 22: Receivers Next hop 3 5 15 18 27 4 4 16 22 Receivers Next hop 27 25 27 Forwarding Table of Node 12: Forwarding Tables path 12 4 25 Example of FGMP-RA 22 16 4 25

11. Network Infrastructure  Clustered multihop networks  MAC : Clusterhead- controlled Token (polling) 1 2 3 4 5 6 7 8 9 10 11 12 13 1617 18 19 21 23 37 1 4 6 11 3 5 7 13 16 19 21 23 12

12. Simulation Environments nParallel simulation language : Maisie/PARSEC nArea of movement : 1000x1000 meter square nRadio transmission range : 120 meters nChannel bandwidth : 2 Mbps nPacket size: ldata : 10K bits lrouting table : 2K bits lcontrol : 500 bits ntraffic assumption : heavy/light npacket loss due to buffer overflow or no route

13. Type 1. 1 sender and 9 receiver members. Type 2. 10 members is both sender and receiver.

14. Throughput & Efficiency

15. Forwarding Group Size

16. Channel Overhead

17. Light Load Traffic Performance

18. Storage Overhead

19. Conclusion nAdvantage of FGMP over Tree Multicast  Low storage overhead one timer & one flag for each group  Better channel efficiency reduce redundant flooding  Higher connectivity than tree  Less sensitive to mobility nLimitation of FGMP  Need of global routing infrastructure  Inefficient with high mobility, sparse requirement, large number of nodes

20. Future Work  Comparison study of Ad Hoc wireless multicast protocol.  Efficiency and effectiveness protocol.