Predictive Switch-Controller Association and Control Devolution for SDN Systems

In software-defined networking (SDN) systems, the scalability and reliability of the control plane still remain as major concerns. Existing solutions adopt either multi-controller designs or control devolution back to the data plane. The former requires a flexible yet efficient switch-controller association mechanism to adapt to workload changes and potential failures, while the latter demands timely decision making with low overheads. The integrate design for both is even more challenging. Meanwhile, the dramatic advancement in machine learning techniques has boosted the practice of predictive scheduling to improve the responsiveness in various systems. Nonetheless, so far little work has been conducted for SDN systems. In this paper, we study the joint problem of dynamic switch-controller association and control devolution, while investigating the benefits of predictive scheduling in SDN systems. We propose POSCAD, an efficient, online, and distributed scheme that exploits predictive future information to minimize the total system cost and the average request response time with queuing stability guarantee. Theoretical analysis and trace-driven simulation results show that POSCAD requires only mild-value of future information to achieve a near-optimal system cost and near-zero average request response time. Further, POSCAD is robust against mis-prediction to reduce the average request response time.