OPTIMAL NODE SELECTION AND ALARM EXCHANGE TECHNIQUE FOR REDUCING THE SECURITY COST IN MANET Jayashree S Patil 1 and Dr.K.V.N.Sunitha 2 I. INTRODUCTION 1.1 Mobile Ad-hoc Network (MANET) A MANET is a type of network with mobile nodes. Each node in this mobile adhoc network works as a router. The moving capability of nodes, wireless facility, and best connectivity with other moving nodes of the network makes MANETs very attractive. These facilities made the need for MANETS increase enormously. The areas where moving nodes are desirable wish to use this type of network. When all the nodes in a network are in motion, many nodes are added and many gets discarded from the network for various reasons [1].In MANET, there are numerous member nodes and each node link with the other nodes through radio waves. During network communication, the nodes which are within the transmission range of each other, communicate directly. But when the nodes are not within the transmission range, then the intermediate nodes forward and route the packets towards the destination. In MANET, every node communicates wirelessly and in a distributed manner [2]. 1.2 Characteristics of MANET MANET has many features which is critical to its network performance. Some of the important characteristics of MANET are: 1. Distributed Network Operation 2. Multihop Routing 3. Autonomous Terminal 4. Shared physical medium 5. Dynamic topology 6. Light weight terminals [2] 1 CSE Dept G Narayanamma Institute of Technology and Sciences Shaikpet Hyderabad Telangana India 2 BVRIT Hyderabad College of Engineering for Women, Nizampet Hyderabad Telangana, India International Journal of Latest Trends in Engineering and Technology IJLTET Special Issue- ICRACSC-2016 , pp.072-077 e-ISSN: 2278-621X Abstract: Mobile Ad-hoc Network (MANET) is a wireless network consisting of numerous nodes which are move every minute and are highly mobile. Basically, MANET is a self configuring network where nodes can enter the network and also leave the network in a random manner without prior notification to the network. This allows the malicious nodes to enter the network and attack other legitimate node. Hence, to ensure security in the network it is necessary to detect attacks or malicious nodes and notify the network. In this paper, we have proposed an Optimal Node Selection and Alarm Exchange Technique for Reducing the Security Cost and False Positives in MANET. This technique raises an alarm if any node detects its neighbour to be malicious and then it is validated to check for false alarm. In this way, network performance is enhanced by utilizing the nodes with lesser security costs for further traffic handling. Keywords: Optimal Node, Alarm exchange, Security Cost, False Positives