Impact of Malicious Nodes under Different Route Refresh Intervals in Ad Hoc Network

Abstract

Problem statement: Ad hoc networks are formed dynamically by group of mobile devices co operating with each other. Intermediate nodes between source and destination act as routers so that source node can communicate with the destination node even if it is out radio range and thus eliminating the necessity of infrastructure. Co operation of nodes is a very important feature for the successful deployment of Ad hoc networks. The intermediate nodes should not only be involved in the route discovery process but also should be involved in the re transmission of packets as an intermediate between source and destination. Approach: Since nodes have to be co operative for successful deployment of Ad hoc networks, the security mechanisms cannot afforded to be stringent which enables malicious nodes to successfully attack the network. The capability of optimized link state routing protocol has been studied extensively for different types of ad hoc networks and has been proved to behave somewhere in between pro active and reactive routing protocols. Results: In this study we investigate the impact of malicious nodes on the Optimized Link State Routing (OLSR) protocol under different hello intervals which affects the route discovery process and subsequently investigate the degradation of Quality Of Service (QOS). Conclusion: It is observed that the throughput deteriorates when the network is attacked by malicious nodes which selectively retransmit data to some of the destinations. The performance degradation increases as the hello interval time is set beyond 4 sec. Higher hello interval decreases the control packet overheads. It is observed that even with higher hello intervals the network performance is much better than an attack by small group of malicious nodes.