Adaptive Slave Controller Assignment for Fault-tolerant Control Plane in Software-Defined Networking

Multi-controller is a promising control plane solution for the large-scale Software-Defined Networks (SDNs). Some existing works (e.g., OpenFlow 1.2) have proposed to use backup controllers named slave controllers to achieve fault-tolerance in the control plane. In this paper, we identify that the unreasonable slave controller assignment could cause the controller chain failure and eventually crash the entire network. We consider some important factors for designing the fault-tolerant control plane and formulating the Slave Controller Assignment (SCA) problem. SCA is an NP-complete problem, and we solve it with the Adaptive Slave Controller Assignment (ASCA) scheme, which adaptively assigns slave controllers according to load variance difference. The numerical results validate the efficiency of ASCA.