On Reliability-optimized Controller Placement for Software-Defined Networks

• Published in: China communications 2014-02, Vol.11 (2), p.38-54
• Main Authors: Hu, Yannan, Wang, Wendong, Gong, Xiangyang, Que, Xirong, Cheng, Shiduan
• Format: Article
• Language: English
• Subjects: controller placement; network optimization; Optimization; Reliability; SDN; Software-Defined Networking; Topology; 可靠性优化; 控制器; 控制网络; 放置; 数据平面; 网络管理; 软件定义
• ISSN: 1673-5447
• DOI: 10.1109/cc.2014.6821736

By decoupling control plane and data plane, Software-Defined Networking （SDN） approach simplifies network management and speeds up network innovations. These benefits have led not only to prototypes, but also real SDN deployments. For wide-area SDN deployments, multiple controllers are often required, and the placement of these controllers becomes a particularly important task in the SDN context. This paper studies the problem of placing controllers in SDNs, so as to maximize the reliability of SDN control networks. We present a novel metric, called expected percentage of control path loss, to characterize the reliability of SDN control networks. We formulate the reliability-aware control placement problem, prove its NP-hardness, and examine several placement algorithms that can solve this problem. Through extensive simulations using real topologies, we show how the number of controllers and their placement influence the reliability of SDN control networks. Besides, we also found that, through strategic controller placement, the reliability of SDN control networks can be significantly improved without introducing unacceptable switch-to-controller latencies.