Simulating Spanning Tree Protocols in a Cable-based Tsunameter System with an Arbitrary Number of Ocean Bottom Units

As a country with the fourth largest population in the world prone to tsunami disasters, Indonesia needs a reliable, timely early warning system to mitigate the impact of disasters. Indonesia cable-based tsunameter (INA-CBT) is an undersea tsunami detection system comprising undersea pressure sensors and a shore station connected by underwater fiber optics designed to provide early warning to the threatened area. Since this system performs a critical role in disaster mitigation, the system must be resilient to link failure and deliver timely warning information. This system is still in its early implementation and still on a small scale. Network-wise, it uses a proprietary Layer 2 (L2) communication protocol. Extending such a network to a larger scale and assessing the system's performance may introduce challenges due to high costs and offer less flexibility. This paper aims to address those challenges and presents a scalable simulation framework of the INA-CBT system by using L2 open protocols such as spanning tree protocol (STP) and rapid spanning tree protocol (RSTP). The framework is conducted in OMNET++ simulator. The experiment shows that the downtime duration using STP and RSTP is still below the allowed value. RSTP shows a faster failover time than STP, but RSTP downtime duration fluctuates compared to a steady one of STP. The experiments also demonstrated that the variation of downtime is affected by two aspects: the number of ocean bottom units (OBUs) in the network and the position of their blocked port.