Latency-aware Topology Discovery in SDN-based Time-Sensitive Networks

Time-Sensitive Networking (TSN) is a set of standards currently being defined by the IEEE 802.1 Time-Sensitive Networking Task Group [1] for Real-Time behavior in the network. Software-Defined Networking (SDN) provides a good solution for implementing TSN networks due to its characteristics such as run-time flexibility, benefits in management, cost efficiency, and performance. For achieving Real-Time behavior in TSN networks, the high-priority traffic should be scheduled precisely to fulfill its timing requirements. For this purpose, in SDN-based implementation, the control plane must have a good knowledge of the network topology and the delay in the network to be able to schedule the traffic. In this paper, we propose a topology discovery mechanism for the Central Network Controller (CNC) in TSNs based on the Link Layer Discovery Protocol (LLDP) able to discover accurate link latency characteristics as required for time-aware scheduling without relying on external time synchronization protocols such as PTP. We evaluate its feasibility and assess its performance in terms of required bandwidth and achieved accuracy.