Avoidance of Co-operative black hole attack in AODV in MANET

Adhoc wireless networks are defined as the category of wireless networks that utilize multihop radio relaying and are capable of operating without the support of any fixed infrastructure and hence they are also called infrastructureless networks. This type of network allows for spontaneous communication without previous planning between mobile devices. A variety of routing protocols for adhoc wireless networks has been proposed in recent past but Adhoc On demand Distance Vector (AODV) protocol is popular due to its dynamic nature that is routing information is exchanged and path finding process is initiated only when path is required by a node to communicate witha destination node. Attack is launched on this protocol if an intermediate node maliciously behaves during the path finding process and drop packets which goes through it. This attack becomes more severe if group of nodes co-ordinately work to launch this attack. In this paper mechanism is proposed to avoid such an coordinated attack called cooperative black hole attack by calculating trust value at each node using only control packets which helps in reducing routing overhead.