A QoS and Cost Aware Fault Tolerant Scheme Insult-Controller SDNs

Software Defined Networking (SDN) is envisioned as a novel technology to enable reliable and scalable network management by decoupling the control plane and data plane. As the network scale increases, multiple controllers have been proposed to solve the problems of scalability and reliability caused by single controller. Although some controller placement schemes based on controller replication have been proposed to recover the controller failure in SDNs, few of them can solve the failure with the existing controllers. In this paper, we propose a QoS and cost aware fault tolerant scheme in multi-controller SDNs by exploring a fine-grained trade-off between controller cost and recovery time. With considering the controlle cost, load and communication delay in the failure recovery, we propose a heuristic algorithm to select backup controllers aiming to minimize the average recovery time, meanwhile avoiding the load oscillation in switch migration. Extensive simulations highlight that our scheme can improve the recovery efficiency compared with some other existing approaches.