Boosting The Benefits Of Hybrid SDN
Wen Wang, Wenbo He and Jinshu Su
McGill University, McMaster University, National University of Defense Technology

The upgrade of a legacy network to a full software-defined networking (SDN) deployment is usually an incremental process, during which SDN switches and legacy switches coexist in the hybrid network. However, with inappropriate deployment of SDN switches and design of hybrid control, the advantages of SDN control could not exert, and it even results in performance degradation or inconsistency (e.g., loops, black-holes). Therefore, the hybrid SDN requires considerable coordination of the centralized control and distributed routing. In this paper, we propose a full-fledged solution to handle the heterogeneity caused by distinct forwarding characteristics of SDN and legacy switches, therefore boosting the benefits of hybrid SDN. Our solution spans three aspects: 1) planning SDN placement to enhance the SDN controllability over the hybrid network, 2) traffic engineering considering both the forwarding characteristics of SDN and legacy switches, 3) reconstructing and applying optimal forwarding paths to overcome the limitation of distributed routing. The experiments with various topologies show that the SDN placement planning and hybrid forwarding yield better network performance especially in the early 60% SDN deployment, while path reconstruction achieves much higher throughput with more flexibility.