Resource-saving Replication for Controllers in Multi-controller SDN against Network Failures

Software-defined networking (SDN) develops a logically centralized control plane from the data plane, which makes the network management more intelligent. As the network becomes larger, the control plane with one controller can no longer manage the network efficiently. Therefore, multiple controllers are needed to manage the network. However, the survivability has been a key challenge in multi-controller SDN, which is sensitive to the controller failures. Once the controller breaks down, the switches will lose connections to the controller. This leads to severe consequences. In this regard, we propose an approach to improve fault tolerance of network in face of controller failures. In our work, we also attach great importance to the survivability of connections between controller and switch under random-link failures. Propagation delay is considered in our approach. Simulation results show that our approach guarantees that the controller failures can be effectively recovered. Moreover, after the controller failure is recovered, the survivability of multi-controller SDN in face of random-link failures can be improved.