The IEEE Audio Video Bridging (AVB) Task Group (TG) was created to provide Ethernet with soft real-time guarantees. Later on, the TG was renamed to Time-Sensitive Networking (TSN) and its scope broadened to support hard real-time and critical applications. The Stream Reservation Protocol (SRP) is a key work of the TGs as it allows reserving resources in the network, guaranteeing the required quality of service (QoS). AVB’s SRP is based on a distributed architecture, while TSN’s is based on centralised ones. The distributed version of SRP is supported and used in TSN. Nevertheless, it was not designed to provide properties that are important for critical applications. In this work we model SRP using UPPAAL and we study the termination and consistency. We verify that SRP does not provide such properties. Furthermore, we propose an improved protocol called Consistent Stream Reservation Protocol (CSRP) and we formally verify its correctness using UPPAAL.
First published in Early Access: 12 August 2020