Software-defined Networking (SDN) can facilitate the deployment of
deterministic algorithms with stringent Quality of Service (QoS)
requirements that pave the way for commodity Real-time (RT) networks.
However, current QoS approaches are conservative and under-provision the
network, that becomes a bottleneck when scaling or upgrading
infrastructure. In this paper, we argue that the use of fixed priorities
for flows – a common practice in RT networks, is the root-cause of this
issue. We develop algorithms that use the global view provided by SDN to
develop on-demand, variable priority schemes. Evaluation shows that this
“correct by construction” approach increases network utilization while
still meeting the necessary QoS requirements, thereby improving network
robustness under high utilization.