International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 03 | Mar-2016 www.irjet.net p-ISSN: 2395-0072 © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 191 Behavior of Jamming Attack in OLSR, GRP, TORA and improvement with PCF in TORA using OPNET tool Anupam Sharma, Deepinderjeet Kaur Desh Bhagat University Mandi Gobindgarh Punjab ------------------------------------------------------------------------------------------------------------------------------- Abstract- MANETs have distinguishing characteristics like dynamic topology, wireless radio medium, limited resources and lack of centralization; as a result, they are vulnerable to different types of malicious attacks in different layers of protocol stack. Each node in a MANET is capable of acting as a router. The necessity for a secure MANET networks is powerfully tied to the security and privacy features. This Jamming attacks are one of them. These occur by transmitting continuous radio ways to inhibit the transmission among sender and receiver. These attacks affect the network by decreasing the network performance. For our proposed work we will take the OLSR, TORA and GRP protocols. The proposed work includes a network with high mobility. Implementation of jamming attack and impact of jamming attack, and finally we will use the PCF technique so that we will reduce the jamming effect. Key Words: MANET, DOS Attack, Jamming Attack, Routing Protocols 1. Introduction: A mobile ad hoc network (MANET) is generally defined as a network that has many free or independent nodes, often composed of mobile devices or other mobile pieces that can arrange themselves in various ways and operate without firm top-down network administration. It uses decentralized approach. Ad-hoc network has opened a new dimension in wireless networks. It allows wireless nodes to communicate with each other in the absence of centralized support. It does not follow any fixed infrastructure because of the mobility of nodes and multi-path propagations. Link instability and node mobility make routing a core issue in MANETs. A suitable and effective routing mechanism helps to extend the successful deployment of MANETs. In this paper, we have studied details of TORA, OLSR and GRP routing protocols we have found that among the three protocols, no single protocol can successfully provide optimum efficiency in different MANET scenarios. Figure: 1.1 working of MANET network 2 Routing Protocols in MANET: A routing protocol uses software and routing algorithms to determine optimal network data transfer and communication paths between network nodes. On the basis of topology routing protocols categorization is as follow: 2.1 Temporally ordered routing algorithm (TORA): TORA is proposed for highly dynamic mobile, multi-hop wireless networks. TORA is a source-initiated on-demand routing protocol. It is a highly efficient, scalable, and adaptive distributed routing algorithm based on the concept of link reversal. It finds multiple routes from a source node to a destination node. 2.2Optimized link state routing (OLSR): OLSR, proactive routing protocol exchanges routing information with other nodes in the network. The key concept used in OLSR is of MPRs (Multi Point Relays). It is optimized to reduce the number of control packets required for data transmission using MPRs 2.3 Geographic Routing Protocol (GRP) GRP offers an efficient framework that can simultaneously draw on the strengths of PRP (Proactive routing protocol) and RRP (reactive routing protocol). The goal of this