09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 1 Lookup Service for Peer-to-Peer Systems in Mobile Ad-hoc Networks M. Tech Project Presentation By, Kalpesh Patel Guided By, Dr. Sridhar Iyer, Dr. Krishna Paul.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 2 Outline Introduction Motivation Problem Definition Related Work RINGS : Lookup Service Analysis and Comparison Simulation Results Directions for Future Work and Conclusion

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 3 Introduction Peer-to-Peer Systems Nodes share files and services among other nodes in P2P network. Mostly focuse on wired network. Mobile Ad-hoc Networks MANET is an autonomous system for mobile hosts over wireless links. Multi-hop scenario. Mobility.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 4 Motivation Why P2P in MANET? What happens if existing P2P protocols are deployed in MANET? –Neighbours at application layer may not necessarily be neighbours at network layer. Problems with existing MANET protocols

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 5 Problem Definition The overall objective is to efficiently deploy P2P applications in Mobile Ad-hoc Networks. Specifically, need of a network layer protocol which optimizes query lookup service.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 6 Related Work Mobile Peer-to-Peer Protocol (MPP) : Recent work on P2P in mobile environment. Reference : Rudiger Schollmeier, Ingo Gruber, Michael Finkenzeller, Protocol for Peer-to-Peer Networking in Mobile Environments. The problem is, MPP still relies on flooding at network layer.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 7 RINGS : Lookup Service Basic Protocol - Advertisement Network layer gets index from application layer. Node broadcasts its data index into the network. Every K-hop nodes keep index for a given node. This process is followed by every node in the network. Basic Protocol – Query lookup Node forwards the query to its neighbors. Due to equal distribution of indices throughout the network, query is answered within K/2 hops. So, Upper bound for query lookup is K/2 hops.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 8 RINGS : Cont… Basic protocol makes a set of imaginary circles for a given source node as shown in Fig.1. Fig. 2 shows an example of 2-hop (K=2) scenario.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 9 RINGS : Cont… Route Maintenance –Advertise packet maintains route to the source node. –This is accomplished by maintaining reverse route on the path. –A node, which stores the index, keeps this route along with other information. –If a query comes to this node, it responds with query result as well as route to the source. –An optimal route.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 10 RINGS : Cont… Mobility –Mobility has none or little impact on the performance of the protocol. –In average, number of neighbors per node in mobile network can be taken as log(N). –So, even if as much as log(N) -1 nodes moves away from the network, node gets at least one node for query result. –Thus, a node gets at least one node which can satisfy its query even if L number of nodes from nearest circle leave the network, where L is, Where K = 2, 4, 6, …

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 11 RINGS : Cont… Optimization –Data Updates Updates are sent to only those nodes which have stored indices for the source node. –Node Joining Whenever a new node joins the network, it gets some share of indices from its neighbors.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 12 RINGS : Cont… Node Deletion –Neighbors of leaving node search for an alternative route. –After getting alternative route, indices are reallocated according to index-hop (K) value.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 13 Analysis Goal Count the ‘actual’ query lookup cost for P2P protocol like ‘Chord’ in MANET. The average distance d between any two nodes at the network layer can be taken as, Now, query lookup cost for Chord in application layer is log(N). Actual cost = App. Layer cost + Network layer cost. So, effective lookup cost L chord for chord protocol is,

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 14 Analysis (Cont…) For RINGS, –Query lookup cost at first hop is, In turn, each of these log(N) nodes forwards query to its neighbors. Continuing this way, query lookup cost at the nearest K-hop is,

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 15 Simulation Results An important measure is, how average number of remote indices stored per node increases as the value of K increases. Result indicates that, as value of K increases, average number of remote indices per node increases very fast. Value K = 4 balances both the metrics.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 16 Simulation Results (Cont…) Graph shows comparison between query lookup costs L chord and L RINGS For the value of K = 4, RINGS performs better than Chord in terms of query lookup cost. For the value of K = 6, as the number of nodes increases beyond a certain number, RINGS performs better than Chord.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 17 Comparison Why RINGS? –Most recent work still relies on network layer flooding for query lookup. –Most adopted MANET protocols like AODV, DSR uses broadcast technique, results in flooding the whole network every-time when a search for a node requires. –P2P protocols Gnutella uses broadcast. Chord assigns every node a virtual identifier independent of actual locations, which is not preferable at network layer.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 18 Directions for Future Work RINGS assumes enough storage space available at the node. There is a scope of improvement to reduce this overhead. Effective mobility handling. Practical applications.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 19 Conclusion There is a need to combine P2P applications and Ad-hoc systems to share data among mobile users. Current P2P protocols fail to perform well with this combination. An initial step to this problem is RINGS, which focuses on query lookup cost optimization.

09/07/2004Peer-to-Peer Systems in Mobile Ad-hoc Networks 20 Thank You