The mobile ad-hoc network is the self configuring type of network in which mobile nodes can change its location any time. Due to its decentralized nature, much type of active and passive attacks is possible in the network. Jamming is the active type of attack which degrades network performance in terms of throughput, Packetloss, Retransmission attempts, Delay and PDR. In this work, novel technique is been proposed which will detect and isolate malicious nodes from the network. The proposed technique will be based on monitor mode and threshold. The simulation is been performed in NS2 and it is been analyzed that proposed technique performs better in terms of throughput, Packetloss, Retransmission attempts, Delay and PDR.