Abstract: A generic definition of security is “freedom from risk, danger or safety”. Mobile Ad-Hoc Networks (MANETs) are a kind of wireless network that usually has a routable network environment above the link layer. It is a peer-peer self forming and self healing network. The nodes which are present in this network can move from one place to another in the network or may leave or join the network at any time. Due to this the topology of the network changes rapidly. Due to the absence of central administrator the MANETs are vulnerable to attacks. In this paper, performance comparison of MANET in the presence and absence of two types of wormhole attack such as replay and tunnelling has been carried out. The performance of the network is measured using metrics like Link Breakage and Delay in the network by varying the number of nodes and number of attackers. The study results prove that the network performance is severely affected in the presence of wormhole attack.

Keywords: Link Breakage, AODV, Mobile Ad-hoc Networks, Wormhole, Tunnelling, Replay.