Optimal load balancing method for symmetrically routed hybrid SDN networks

Software Defined Networking (SDN) makes load balancing efficient and intelligent. However, fully deploying an SDN presents economical, organizational and technical challenges. Therefore, load balancing in hybrid SDN networks where the routing protocol parameters are designed through an SDN channel is one of the hottest topics in the field. In addition, symmetrically routing is a practical requirement for network operators since asymmetrically routed flows make the network too complex to manage. In this paper, we propose a load balancing method for symmetrically routed hybrid SDN networks that can handle existing distributed routing parameters, link cost and path selection. The proposed method optimizes link cost and path selection simultaneously under a symmetrically routed condition, while traditional methods optimize them individually. In a numerical simulation, the load balancing performance of the proposed method is better and more stable than any of the traditional methods. Furthermore, the proposed method has high versatility, and provides the best performance even in networks without distributed routing protocols.