Topology Discovery is a crucial task for a controller in Software Defined Networks (SDN). In this paper, we present an attack model to disturb topology discovery service of controller, by injecting fake links in the network. Our attack model assumes, some switches present in the network are compromised by attacker. Fake links injected through compromised switches, causes a huge packet loss in the network. We have performed a comparative analysis of packet loss for our proposed attack model and packet loss for previously proposed model. We also provide an efficient countermeasure for proposed attack model based on detection of fake link at controller. Both attack model and countermeasure are tested for a real time network.