International Journal of Emerging Technology and Advanced Engineering Website: (ISSN , Volume 2, Issue 9, September 2012)

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1 Cross Layer Design for P2P Overlay Network over MANET Prof. Rekha Patil 1, Ashwini.D 2 1 Professor, 2 M.Tech (CS), PDA College Of Engineering, Gulbarga Abstract - Peer-to-peer (p2p) network is an alternative of client/server system for sharing resources, e.g. files. P2P network is a robust, distributed and fault tolerant architecture. We consider the scenario of p2p network over MANET where all nodes are the members of p2p network and one of the node acts as p2p server which maintains the file list available to the nodes. The mobility of nodes constantly changes the file chunks availability in the peer which raises the demand for a comprehensive framework that can lucidly overlay p2p network on MANET. The p2p node is configured as server (peer). In p2p network, since nodes are peer they provide a large portion of shared files that can be accessed. A node decides to publish its files and update the server with the files. The server before sending the route request message, it forms a cluster. In this cluster one of the nodes is selected as cluster head based on maximum connectivity. We use an ad hoc on-demand routing protocol (AODV) through delay measurement to propose a p2p overlay network. In this work, we use simulation to determine the impact on the performance of the protocol. Simulation results show that the proposed protocol performs better. Keyword - AODV, MANET, P2P Overlay Network, Peer. I. INTRODUCTION Mobile ad hoc network (MANET) is an autonomous system of mobile nodes connected via wireless links. Each node operates not only as an end system, but also as a router to forward packets. The nodes are free to move about and organize themselves into a network. These nodes change position frequently. P2P network is an overlay network for distributed object store, search and sharing [1]. P2P is a class of applications that take advantage of resources storage, cycles, content, human presence available at the edges of the internet. P2P is a special distributed system on the application layer, where each pair of peers can communicate each other through the routing protocol in p2p layers. A general p2p network is pictured in figure I. Each node (peer) keeps an object (such as file, etc.) database. Each peer can query its wanted object from other peers through the logical connection on p2p layer. Object DB Client/Server (Peer) Figure 1: General P2P Model [15] P2P overlay networks are distributed systems in nature, without any hierarchical organization or centralized control. P2P protocol provides a good mechanism for conventional MANET. But conventional MANET routing protocol do not seamlessly support ad hoc protocols. Therefore in this work, we overlay p2p protocol over MANET by integrating p2p application protocols with that off MANET routing protocols at same time using delay. The objective of this work is to integrate p2p protocol with MANET and at same time ensuring that file availability could be retained on such overlays. A peer-to-peer (p2p) overlay network consists of a dynamically changing set of nodes connected via the internet. A mobile ad hoc network consists of mobile nodes communicating with each other using multi-hop wireless links. Here promising research direction in networking is to exploit the synergy between p2p overlay and MANET routing protocols to design better routing protocols for MANETs. As a supporting example, the work applies recent advancement in p2p overlay networks, i.e., topology-aware structured p2p overlay routing protocols, to routing in MANETs [14]. 212

2 Since topology-aware structured p2p overlay routing protocols, it is clear that we cannot combine p2p overlay network over MANET. Since the existing system does not combine the p2p overlay network over MANET, the proposed system overcomes this situation by combining p2p overlay network over MANET. In this work, there is a definite need for overlay/p2p networking in a MANET, for the following reasons: (a) the MANET routing layer is often inadequate to provide the services needed by sophisticated mobile applications, and; (b) the unpredictability of the radio channel combined with the mobility of the users can pose major challenges to routing, requiring upper layer intervention. Both MANETs and P2P networks follow a P2P paradigm characterized by the lack of a central node or peer acting as a managing server, all participants having therefore to collaborate in order for the whole system to work. II. RELATED WORK The rapid growth of wireless communication and mobile computing technologies has led to the appearance of a new networking concept-mobile Ad hoc Networks (MANETs) [1]. A mobile ad-hoc network (MANET) is characterized by a set of mobile devices that communicate among themselves using wireless links. This communication is done in a completely decentralized, selforganised manner and without requiring any pre-existing fixed communications infrastructure. AODV (Ad hoc On demand routing protocol) a novel algorithm for the operation of Ad hoc networks this protocol is an excellent choice for ad hoc network establishment is proposed in the phases involved in AODV are Path Discovery, Route Table Management, Path Maintenance, (RREQ, RREP, RRER) are the control messages used for establishing paths in MANET [2]. Cross Layer violates the OSI layered architecture but keep the impact of design violations as small as possible. There are various cross layer design methods available. A simple and effective design of the cross layer architecture has been chosen to improve the performance of lot of services in ad hoc networks. In our paper, we are using upward information flow [3]. On-demand protocols such as AODV typically pick the shortest path route during the route discovery process, and then sticks to this route until it breaks. Continuous use of the route may drain the nodes of battery power. We take a two-step approach to design the adaptive energy-aware protocol. First, the nodes are classified according to their remaining battery energy. 213 Depending on their classification the nodes react differently to the routing protocol dynamics. Second, a new cost function is used as routing metric taking into consideration both the hop-wise distance and the battery levels of the nodes [4]. A fundamental problem that confronts peer-to-peer applications is to efficiently locate the node that stores a particular data item. This presents Chord, a distributed lookup protocol that addresses this problem. Chord locates the node that stores a particular data item [5]. This presents the design and evaluation of Pastry, a scalable, distributed object location and routing substrate for wide-area peer-topeer applications. Pastry performs application-level routing and object location in a potentially very large overlay network of nodes connected via the Internet. It can be used to support a variety of peer-to-peer applications, including global data storage, data sharing, group communication and naming [6]. In these systems, files are stored at the end user machines (peers) rather than at a central server and, as opposed to the traditional client-server model, files are transferred directly between peers. CANs resemble a hash table; the basic operations performed on a CAN are the insertion, lookup and deletion of (key, value) pairs. Hash tables which map keys onto values are an essential building block in modern software systems. In this, we introduce the concept of a Content-Addressable Network (CAN) as a distributed infrastructure that provides hash table-like functionality on Internet-like scales [7]. Mobile Ad-Hoc Networks (MANETs) and Peer-to- Peer (P2P) applications are emerging technologies based on the same paradigm: the Peer-to-Peer paradigm. In this model, nodes have equivalent functionalities and provision capabilities and, as a consequence, are called peer entities. Every peer is able to send and reply to request messages originated from another one. This shows the dual interface of these peers, since they might play the role of servers and clients simultaneously [8]. Peer-to-peer (P2P) systems, in which peer nodes form a cooperative network and share their resources (storage, CPU, bandwidth), have attracted a lot of interest lately. Therefore, they are particularly attractive for systems with limited resources, where the cost of sending a message is non-negligible (e.g., in terms of energy) and flooding is considered prohibitive [9]. Peer-to-peer (P2P) file sharing in mobile ad hoc networks has continuously gained popularity due to its strong adaptability in many practical applications. In this, we restrict logical peers, i.e., nodes exchanging file pieces, to physical neighbors, yet data is propagated through the (overlay) network of peers of common interest, which is the basic concept of operation of P2P file sharing systems.

3 In this it is used to maintain enough connectivity among peers with low overhead, such that users can download files in less time than existing protocols [10]. III. PROPOSED WORK A mobile ad hoc network (MANET) is a collection of mobile nodes that dynamically self organize in a wireless network without using any pre-existing infrastructure. In a MANET, the applications are typically peer-to-peer rather than client-server. Moreover, a MANET is often built to support a specific application, thus the networking is application-driven. For these reasons, we often refer to the ad hoc networking done in a MANET as peer-to-peer (P2P) networking. In the Internet, a P2P network is basically an overlay network justified by the need for specialized functions that are not possible in the IP layer. There is a definite need for overlay/p2p networking in a MANET, for the following reasons: (a) the MANET routing layer is often inadequate to provide the services needed by sophisticated mobile applications, and; (b) the unpredictability of the radio channel combined with the mobility of the users can pose major challenges to routing, requiring upper layer intervention. The leading strategy today is to keep MANET routing and transport protocols simple (mainly for ease of standardization), and; to complement them when necessary with upper layer functions via overlays and P2P networking. MANETs and P2P networks share a good number of key characteristics, such as the lack of a central infrastructure, a highly dynamic network topology, and the need for selforganization. Hence, when designing distributed network applications for MANETs, it would be intuitive to consider the building blocks that have proven themselves appropriate in P2P systems. Both MANETs and P2P networks follow a P2P paradigm characterized by the lack of a central node or peer acting as a managing server, all participants having therefore to collaborate in order for the whole system to work. A key issue in both networks is the process of discovering the requested data or route efficiently in a decentralized manner. MANETs and P2P networks also have a highly dynamic topology: nodes are constantly moving in and out of radio coverage of neighboring nodes in the former and peers are continuously joining or leaving the network in the latter. Information (or data) sharing is an application layer task that allows different devices to share data in order to carry out distributed computations and satisfy user needs. 214 Data sharing is considered of fundamental importance for mobile ad hoc networks, since they have been proposed to enable data access for mobile devices in the absence of an infrastructure. In the proposed system, the p2p node is configured as server (peer). In this all nodes are the members of p2p network. In p2p network, since nodes are peer they provide a large portion of shared files that can be accessed. A node decides to publish its files and update the server with the files. The server before sending the RREQ message it forms a cluster. In this cluster one of the nodes is selected as cluster head based on maximum connectivity. In this, the cluster head calculation starts and will store all the cluster head and also nodes that have joined the cluster. It finds if the node with maximum cluster is already a cluster head or not. In the cluster if the node has maximum neighbors, then select it as cluster head and also stores neighbors of it. Now it makes its neighbors to join the cluster and if it is already a cluster head, it will not select it. This is particularly true if one or more nodes are on other routes as well. Note that each message transmission and reception drains battery power. We take a two-step approach to design the adaptive energy-aware protocol. First, the nodes are classified according to their remaining battery energy. Depending on their classification the nodes react differently to the routing protocol dynamics. Second, a new cost function is used as routing metric taking into consideration both the hop-wise distance and the battery levels of the nodes. C i energy is calculated as follows: C i energy=d i /E i remain C i energy is a function depending of the distance and remaining energy of node i, d i is the distance of the node provided by the physical layer and E i remain is the current remaining energy of the node provided by the physical layer. More remaining energy and shorter distance indicate less C i energy [11]. IV. SYSTEM DESIGN AND IMPLEMENTATION This paper has been implemented to combine p2p overlay network on Manet using AODV routing protocol along with delay measurement. In this work, nodes search the files and locate in the database. Information (or data) sharing is an application layer task that allows different devices to share data in order to carry out computations and satisfy user needs. In fig II, When any node has data packets to send the node first checks the routes to the destination in the route cache are present or not. If routes are already present it sends the packets on those paths. If routes are not present then it floods the RREQ message to all its neighboring nodes.

4 When the RREQ message is received by any intermediate node then first it checks if route to destination is known if so forward else generates RREQ packet. Using find node we can search a node in the routing table. The delay value is appended along with the RREQ packet, when RREQ reaches the destination the incoming paths are put in the cache. RREP is generated and if node is part of RREP, it must update its value. The delay value is calculated and data is sent to the nodes. Start Generate RREQ Delay<0.5 NO YES Forward RREQ Generate RREP destination Data Packet Sent at Intermediate Node Calculate Delay= Pkt Received Time - Pkt sent time V. SIMULATION To study the performance of our proposed algorithm simulation was conducted using OMNeT++ [15] which supports complete physical, data link and MAC layer models for simulating wireless ad hoc networks. OMNeT++ is a freely distributed, object-oriented, modular, discrete-event simulator written in C++. It is designed for general-purpose discrete-event simulation, and provides model libraries for communication protocols and network systems. We simulated network of mobile nodes placed randomly in an area of 5000x5000 square meters, with mobile nodes ranging from10 to 50. A source and a destination is selected randomly Mobility pattern of the mobile nodes is generated using Random waypoint model [12]. A mobile selects another node in the network and constantly moves towards it at a given velocity. Once it reaches there, it waits for some pause time and selects another node and again starts moving. By observing the performance of the network under mobility we can test the stability of the design in real time scenario. Speed of a mobile node is assigned a value between 0 to 5 meters/sec. Initially all the mobiles would be given some initial energy (10000). As the packets re to be transmitted through the nodes, they would loose some energy. It is assumed from previous research [13] (as the size of each packet is constant), that the radio interference, when powered on, consumes 1.2W while actually receiving a packet and 1.6W while transmitting a packet. As the communication in MANET is normally a cross layered approach, upward information flow model is very efficient in designing and modeling the network. The performance parameters studied for simulation study are throughput, latency, packet delivery ratio and energy left by varying the Packet rate and simulation time. A. Result Send RREP Send data Stop Figure 2: Flow Chart Figure3: Packet Delivery Ratio Vs Simtime 215

5 Figure III shows the packet delivery ratio (PDR) of proposed and present system. We can observe that packet delivery ratio of proposed system is better than present system along with simulation time. Increasing simtime does not affect the packet delivery ratio. Figure 6: Energyleft Vs Packetrate The graph shows the remaining energy of the nodes in the network of both proposed and present system. The energy left varies along with packet rate. Figure 4: Latency Vs Simtime The graph shows that latency of proposed system is lesser than the latency of present system. There may be slight variation in the latency of proposed system. Figure 5: Throughput Vs Packetrate The throughput is better in proposed system when compared with the present system. In this there may be slight increase or decrease along the packet rate of proposed system but the throughput is high when compared to present system. VI. CONCLUSION AND FUTURE WORK We presented a new technique for simulation study for sharing data and files within a small area network but most popular file sharing protocol like p2p are supported by such a network. We consider the scenarios of P2P network over MANET where all nodes are the members of P2P network and one of the node acts as p2p server which maintains the file list available to the nodes. The mobility of nodes constantly changes the file chunks availability in the peer which raises the demand for a comprehensive framework that can lucidly overlay p2p network on MANET. A discrete-event C++ based simulator OMNET++ can efficiently simulate a p2p overlay network on Manet. From the simulation results we can conclude that the throughput and PDR are significantly improved in the proposed work. There is however slight increase in the latency which is attributed by more packet delivery. The remaining energy is also given for all nodes. The algorithm does not take into account of changes in the cluster head or the server. The System can be further modified to handle the issues of cluster head alteration due to mobility or link failure. More optimization schemes can be adopted to improve the performance of the system under mobility. 216

6 REFERENCES [1 ] S. Jochen, Mobile Communications. Boston, MA, USA: Addison- Wesley Longman Publishing Co., Inc., [2 ] Charles E. Perkins, Elizabeth M. Royer, Samir R. Das and Mahesh K. Performance Comparison of Two On-Demand Routing Protocols for Ad Hoc Networks, IEEE Personal Communications, Feb 2001,pp [3 ] [Vineet Srivastava, Mehul Motani, Cross-Layer Design: A Survey and the Road Ahead, IEEE Communications Magazine, December [4 ] Nishant Gupta and Samir R. Das, Energy-Aware On-Demand Routing for Mobile Ad Hoc Networks, Computer Science Department, USA. [5 ] Stoica, R. Morris, D. Karger, M.F. Kaashoek, and H. Balakrishnan, Chord: A scalable peer-to-peer lookup service for internet applications, in Proceedings of the ACM SIGCOMM 01 Conference, San Diego, California, USA, August [6 ] A. Rowstron and P. Druschel, Pastry: Scalable, decentralized object location and routing for large-scale peer-to-peer systems, IFIP/ACM International Conference on Distributed Systems Platforms (Middleware), Germany, November [7 ] Sylvia Ratnasamy, Paul Francis, Mark Handley, Richard Karp, Scott Shenker, A Scalable Content-Addressable Network, In Proceeding SIGCOMM 01, August 27-31, 2001, San Diego, California, USA. [8 ] Leonardo B. Oliveira, I.G. Siqueira, A.F. Loureiro, On the performance of ad hoc routing protocols under a peer-to-peer application, Journal of Parallel and Distributed Computing Volume 65, Issue 11, November 2005, Pages [9 ] Raphal Kummer, Peter Kropf, Pascal Felber: Distributed Lookup in Structured Peer-to-Peer Ad-Hoc Networks. In Proceeding of the OTM Conferences (2) 2006: [10 ] U. Lee, J.S Park, S.H Lee, W. W. Ro, G. Pau, M. Gerla, Efficient Peer-to-peer File Sharing using Network Coding in MANET, Journal of Communications and Networks (JCN), November [11 ] K. Akkaya, M. Younis, An energy-aware QoS routing protocol for wireless networks, Proceedings of International Conference on Distributed Computing Systems Workshops [12 ] FanBai, Ahmed Helmy, A survey of mobility models in wireless Ad Hoc Networks, University of Southern California, U. S. A. [13 ] L. M. Feeney, An energy consumption model for performance analysis of routing protocols for mobile ad hoc networks, ACM J. of Mobile Networks and Applications, vol. 6 issue 3, June 2001, pages [14 ] Hu, Y. Charlie; Das, Saumitra M.; and Pucha, Himabindu, "Exploiting the Synergy between Peer-to-Peer and Mobile Ad Hoc Networks" (2002). ECE Technical Reports. Paper 167. [15 ] Chonggang Wang and Bo Li, Peer-to-Peer Overlay Networks: A Survey, Department of Computer Science, the Hong Kong University of Science and Technology, Hong Kong April 20, [16 ] Andras Varga, OMNeT++, 217