Lookup Service for Peer-to-Peer Systems in Mobile Ad-hoc Networks

1. M. Tech Project Presentation By, Kalpesh Patel 02329027 Guided By, Dr. Sridhar Iyer, Dr. Krishna Paul. Lookup Service for Peer-to-Peer Systems in Mobile Ad-hoc Networks Peer-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 Peer-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. Peer-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 Peer-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. Peer-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. Peer-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. Peer-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. Peer-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. Peer-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, … Peer-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. Peer-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. Peer-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 Lchord for chord protocol is, Peer-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, Peer-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. Peer-to-Peer Systems in Mobile Ad-hoc Networks

16. Simulation Results (Cont…) • Graph shows comparison between query lookup costs Lchord and LRINGS • 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. Peer-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. Peer-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. Peer-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. Peer-to-Peer Systems in Mobile Ad-hoc Networks

20. Thank You Peer-to-Peer Systems in Mobile Ad-hoc Networks