Presentation on theme: "Ranveer Chandra Ramasubramanian Venugopalan Ken Birman"— Presentation transcript:
1Anonymous Gossip Improving Multicast Reliability in Mobile Ad Hoc Networks Ranveer ChandraRamasubramanian VenugopalanKen BirmanDept. of Computer Science,Cornell University.
2Introduction Mobile ad hoc network Harsh working conditions wireless mobile devices capable of direct peer to peer communication.deployable without fixed infrastructure.Harsh working conditionslow bandwidth connections.restricted power supply.
3Multicast in Ad Hoc Networks Applications of ad hoc networks.disaster relief and rescue missions.military coordination.sensor networks.Multicast is inevitable!On demand multicast routing protocols.MAODV, AMRIS. (tree based)ODMRP, MCEDAR. (mesh based)
4Reliable Multicast!Messages not delivered to some members of the group.mobility and congestion.transient partitions.maintenance of multicast structure.No attempt to recover lost messages.
5Classical Gossip + = Works in background with multicast protocol. ProbabilisticReliability=Works in background with multicast protocol.Members “gossip” randomly with other members to recover lost messages.Probabilistic reliability guarantees.see “Epidemic Algorithms…”, Demers et al.see “Bimodal Multicast…”, Birman et al.
7Classical Gossip Anonymous Gossip Members should have complete or partial knowledge of other group members.Impracticable in ad-hoc networks.no organized hierarchies.increased volatility in membership.Anonymous GossipOur Protocol
8Anonymous Gossip No knowledge of group membership is necessary. Uses underlying multicast structure to direct gossip requests.Each node chooses a random neighbor to forward gossip requests.Gossip replies are sent back directly.
10Optimization I: Informed Gossip Circuitous gossip paths discovered.Multicast structure may be broken.Gossip with members discovered in earlier rounds of anonymous gossip.Unicast gossip requests as well as replies.Gossip across virtual partitions.
12Optimization II: Gossip with Locality Gossip with nearer members.receive gossip replies faster.reduce traffic overhead.Gossip with distant members.recover from regional losses.High probability: gossip with nearer members.Low probability: gossip with distant members.
13AG: The Complete Protocol AnonymousGossipInformedGossiplocalityMulticast Protocol
14Simulation MAODV: underlying multicast protocol. GloMoSim: network simulator.Random waypoint: mobility model.Every third node is a group member.Node 1 sends 2201 packets over 440s.10 runs with different seeds.
19Analysis Increases packet delivery of MAODV. Smoothens variation in packet delivery at different nodes.Scalable with size of network.Can work with unidirectional links.Extra message overhead.Latency in recovering lost messages.
20Conclusions AG improves performance significantly. Can be applied to tree based and mesh based on-demand multicast protocols.Can be applied in wire line networks.