Balancing traffic load for devolved controllers in data center networks

Using a centralized controller for resource management and coordination is a common practice in cloud services. For scalability concern, in recent literature a novel approach, namely devolved controllers, was proposed. Such approach splits the network into regions, while each controller only monitors a portion of the traffic. This technique alleviates scalability issue, but brings other critical problems, such as unbalanced work load among controllers and reconfiguration complexities. In this paper, we investigate the usage of devolved controllers for large-scale data centers, and design a new scheme to overcome shortcomings, and to improve system performance. We first define Load Balancing problem for Devolved Controllers (LBDC), and prove its NP-completeness. For LBDC, we design an f-approximation, where f is the largest number of potential controllers for a switch in the network. We also propose both centralized and distributed approaches to solve LBDC time effectively. The numerical results validate our designs, which become a solution to manage and coordinate large-scale data centers.