A congestion control mechanism for SDN-based fat-tree networks

Nowadays, data centers are experiencing increasing applications' need that is mandating a software-oriented network architecture. A Software-Defined Network (SDN) is the new technology to overcome the traditional network's limitations. QoS is one current limitation that needs to be well-structured for successful software-oriented network architecture. Considerable key factors affect QoS, comprising traffic shaping and congestion control. This paper proposes a congestion control mechanism in SDN-based networks to enhance the overall QoS. The proposed mechanism monitors and detects congested parts and reacts automatically to reduce traffic load. The traffic load is redistributed to ensure better performance by re-routing subset flows. The re-routing decision is based on a passively measured QoS metric, port utilization. Experiments are conducted to prove the effectiveness of the proposed mechanism in an SDN-based fat-tree network. Results showed that the TCP recorded a noticeable improvement, namely, 22.4% in the average delay, 21.3% in throughput, 18.6% in max delay, and 15.3% for jitter. Moreover, the maximum monitored port utilization in the aggregation and core switches was also reduced by 22% on average.