R2T-DSDN: reliable real-time distributed controller-based SDN

Software-defined network (SDN) is an emerging network architecture in which the network control task is separated from packet forwarding. This architecture can be considered as a suitable infrastructure for fifth-generation mobile network (5G) and Internet of things due to its flexibility and dynamism. In real-time networks, time-sensitive packets that miss their deadlines are considered useless or less worthy. As with traditional networks, SDN is expected to support real-time communications and handle a variety of failures (including local controller, switch, and link failures) simultaneously. This study focuses on real-time communication of time-sensitive applications that operate on distributed SDN. We propose an efficient and customized scheduling algorithm to send packets, taking into account some types of fault occurrence, as a part of our proposed solution called R2T-DSDN. Two types of statistical and probabilistic performance models are developed for the determination of the critical and non-critical states of the network. R2T-DSDN allocates priority and adaptive budget to each scheduling scheme in both modes and delivers packets according to their relative deadlines. In the proposed architecture, a leader controller distributes network traffic dynamically across local controllers. The architecture is finally evaluated by the Mininet tool in terms of real-time characteristics and other quality criteria to test how robust it is in case of failures. The emulation results show that for different types of failures, the average deadline hit ratio is 97.9%, which is quite acceptable for multimedia and firm or soft real-time applications in the network.