Queueing Analysis of Auxiliary-Connection-Enabled Switches for Software-Defined Networks

Software-Defined Networking (SDN) is a powerful technology to enable future network innovations, especially for data center networks. However, the limited capacity of the switch-to-controller link is a scalability issue for data center deployments. Auxiliary connections are introduced in the OpenFlow 1.3 Specification to help alleviate switch-to-controller link overflow and improve the scalability of SDN. In this paper, an analytical model is proposed to study the performance of auxiliary connections with OpenFlow switches. This model characterizes different interactions between the controller and the auxiliary-connection-enabled switches with limited buffer space. The model produces evaluation results in seconds for switches with realistic data center traffic loads, which would require days of compute time with network simulation. The analytical model is validated for lower traffic loads using ns3 and an example in-depth analysis of switch performance is carried out with typical data center traffic loads to illustrate the utility of the approach. To the best of our knowledge, this is the first paper to study auxiliary connections for SDN analytically.