Enhancing the effectiveness of traffic engineering in hybrid SDN

A lot of researches exploit the flexibility of Software-Defined Networking (SDN) to conduct traffic engineering in order to improve network performance and enhance robustness to failures. As the upgrade of a traditional network to a full SDN deployment is an incremental process, the coexistence of SDN switches and legacy switches forms a hybrid SDN. Due to the different forwarding characteristics of these switches, it is essential to coordinate the forwarding of SDN control and distributed routing to avoid inconsistency and achieve high network utilization. In this paper, we note that the effectiveness of traffic engineering in hybrid SDN strongly depends on both the structures of forwarding graphs and traffic distribution, while existing approaches mainly focus on the latter. We first define the consistent forwarding graph, and then construct forwarding graphs with potential high throughput for effective traffic engineering, while maintaining forwarding consistency. The evaluation results show that the proposed forwarding graph construction approach improves network throughput and achieves better load balancing compared with existing simple forwarding path constructing approaches, especially with more fraction of SDN deployment.