Effect of varying node mobility in the analysis of black hole attack on MANET reactive routing protocols

Mobile Ad-hoc Networks (MANETs) features such as open medium, dynamic topology, lack of centralised management and lack of infrastructure expose them to a number of security attacks. Black hole attack is one type of attack that is more common in MANET reactive routing protocols such as Ad-hoc On-demand Distance Vector (AODV) and Dynamic Source Routing (DSR). Black hole attack takes advantage of route discovery process in reactive routing protocols. In this type of attack, a malicious node misleads other nodes in the network by pretending to have the shortest and updated route to a target node whose packets it wants to interrupt. It then redirects all packets destined to a target node to itself and discards them instead of forwarding. This paper analyses the performance of AODV and DSR when attacked by black hole, by varying the mobility of the nodes in the network. The analysis is carried out by simulating scenarios of AODV based MANET and DSR based MANET using Network Simulator 2 (NS-2) and introducing the black hole attack in each of the scenarios. The different scenarios are generated by changing the mobility of the nodes. The performance metrics that are used to do the analysis are throughput, packet delivery ratio and end-to-end delay. The simulation results show that the performance of both AODV and DSR degrades in the presence of black hole attack. Throughput and packet delivery ratio decrease when the network is attacked by black hole because the malicious node absorbs or discards some of the packets. End-to-end delay is also reduced in the presence of a black hole attack because a malicious node pretends to have a valid route to destination without checking the routing table, and therefore shortens the route discovery process. The results also show that throughput decreases slightly when mobility of the nodes is increased in the network. The increase in the speed of the nodes decreases both end-to-end delay and packet delivery ratio.