PRIS: Online Routing and Scheduling Making CQF Flexible in Dynamic Time-Sensitive Networks

The growing number of IoT devices has brought about a large number of time-sensitive applications, and time-sensitive networks (TSN) are widely regarded as promoting paradigm for enabling the deterministic transmission. However, most of the existing research is based on the static network where the flow information is known a priori, and the transmission scheduling scheme is synthesized offline. This makes their design mechanism unsuitable for industrial automation scenarios with equipment changes and flow changes. Meanwhile, joint routing and scheduling faces the problem of large search space and high algorithm complexity, which poses a challenge to how to solve the problem within the acceptable time range of dynamic scenarios.We present PRIS, an algorithm that combines pre-routing and online incremental scheduling. Considering the periodicity of time-sensitive flow, the pre-routing algorithm uses weight factors including scheduling compatibility and load balancing as routing indicators. The online incremental scheduling based on Cyclic-Queuing and Forwarding(CQF), which was proposed by IEEE 802.1 to achieve bounded delay transmission. Based on CQF, our PRIS is designed to be flexible and with high schedulability, low execution time. Simulation results show PRIS has a high scheduling success rate of 92.7% at 150 new flows in feasible sub-second execution time.