## 2 Related Works
This highlights the challenges faced in large-scale OT systems, where communication reliability and scalability are crucial for maintaining system performance and security. This scalability issue is further addressed in [20], where the authors design and configure a hardware-in-the-loop testbed based on the 2000-bus Texas synthetic grid. This testbed is monitored by DNP3 using real-world equipment, providing valuable insights into the challenges of scaling OT communication protocols while ensuring both operational efficiency and security. Similarly, [PERSON] and [PERSON] [21] explore how the larger packet frame of DNP3 can reduce computational and transmission times, particularly in large-scale Distributed Energy Resource (DER) networks. Through network emulation with an OPAL-RT simulator, the study demonstrates that DNP3's design is well-suited to support high-volume data exchanges in large-scale OT systems, providing both operational efficiency and improved performance in communication-heavy environments. Recent studies have highlighted vulnerabilities in encrypted communications. One such study, published in [22], demonstrates that even when Modbus traffic is encrypted using unpadded cipher modes like AES-GCM or RC4, side-channel attacks still manage to exploit variations in packet sizes to infer specific Modbus function codes. This is due to the limited set of Modbus commands and their distinct payload sizes, which can be distinguished through differential packet size analysis. In [23], the authors demonstrated how the manipulation of Linux's IP identification assignment can create a side channel for off-path attackers to infer TCP sequence numbers, enabling session hijacking without direct access to packet contents. Similarly, traffic-based and energy-based side-channel attacks in wireless networks have shown that encrypted communications and even device energy patterns can be exploited to leak sensitive information. In addition to traffic-based side-channel attacks that incorporate packet sizes or timing; recent work by [PERSON] et al. [24] presents a principled method for discovering TCP side-channel vulnerabilities using a model-checking tool called SCENT. Their work highlights violations of the non-interference property between TCP connections and discovers 12 previously unknown side-channel vulnerabilities in Linux and FreeBSD. These vulnerabilities could, in theory, enable attackers to infer the state of TCP connections even without being on the path of the connection. While research efforts have been published that provide an overview of attacks on SCADA systems and provide datasets for different attack vectors they investigated, there is no review of mitigation strategies and their outcomes against these attacks with specific OT security mechanisms. For example, in [25], the authors create a dataset from a testbed utilizing virtual OT equipment such as PLCs and water tank sensors protected by a _rbfense_ firewall and a Suricata IDS. In [26], the authors present a dataset from industrial control systems controlling gas pipeline and water storage traffic over Modbus. However, our work utilizes hardware designed for OT applications with OT-specific security features. The primary contribution of our work presented in this paper is the exploration of underlying assumptions when delivering application data over IT protocols, that is, the timely and reliable delivery of data. We show that the resilience of communication utilizing these protocols may be different based on the outlined behavior of each device within the protocol. Specifically, we focus on the impacts of the single-ended method of communication outlined in Modbus and how that affects reliability. We collect extensive results on a multi-tiered testbed to show the implications of communication issues within safety-critical applications.