# Architectural Design for Digital Twin Networks  
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reliability. This complexity has driven the evolution of software-managed networking solutions that integrate advanced techniques such as Artificial Intelligence (AI) [4; 5; 6; 7] or the Digital Twin Network (DTN) [8; 9; 10]. These innovations are essential for navigating the complexities of modern networks and ensuring their scalability and resilience in the face of rapid technological advancements. A digital twin is a virtual representation of a physical asset, process, or system that exists in the digital world. This concept, originating in academia and prominently adopted in Industry 4.0, involves creating a digital counterpart that mirrors the real-world entity in detail. Digital twins are used extensively to simulate and test processes and services before actual implementation, allowing for predictive analysis, optimization, and troubleshooting in a controlled virtual environment. By mimicking the behavior and performance of their physical counterparts, digital twins enable organizations to enhance efficiency, reduce costs, and accelerate innovation across various sectors, from manufacturing and logistics to healthcare and beyond [11; 12]. In recent years, researchers have increasingly looked into the application of digital twin concepts to networks. Thus, the term Network Digital Twin or Digital Twin Network has emerged to describe these virtual replicas that attempt to simulate entire network infrastructures and continuously update themselves with real-time data. This approach allows these digital replicas to accurately mirror the current state and behavior of physical networks. Controlled digital environments provide invaluable insights into network performance, enable the prediction of potential issues, and support thorough testing of various scenarios. This innovative use of digital twins is poised to revolutionize network management practices, offering opportunities to optimize operations, enhance reliability, and drive advancements in communication infrastructure development. The term Network Digital Twin is occasionally used in the literature [13; 14] to denote a network comprised of multiple digital twins, though this usage is becoming less common. Instead, the term is increasingly applied to refer to a digital twin specifically developed for modeling and simulating networks, which is the focus of this work. The definition of Digital Twin Networks remains fluid, reflecting the rapid evolution of this technology. Efforts have been made to establish a standardized concept, currently a work in progress by the Internet Research Task Force (IRTF) [15]. While this ongoing effort provides a foundational framework aligning conceptually with digital twins but tailored specifically for networks, it primarily offers concepts and a reference architecture. Therefore, the focus of this study is to bridge the gap between practical implementation and standardization of DTNs. Building on our expertise in developing and deploying a fully operational DTN for managing a Bluetooth Mesh network [16], the aims of this work are as follows:  
* Provide insights into the concepts and reference architecture of DTNs, offering practical guidance for their realization;
* Evaluate existing frameworks against our design, sharing best practices and lessons learned to help readers develop their own DTN implementations;
* Map state-of-the-art ideas to a standardized approach for DTNs;
* Offer a focused discussion on tools and technologies used in research and literature;
* Conceptualize unified security in the DTN by building upon already established, robust security principles. The paper is structured as follows: Section 2 presents an overview of the existing literature on related work. In Section 3, we look into the DTN architecture as defined by the current standard, providing a foundational understanding. Section 4 outlines our functional implementation of the Digital Twin Network, demonstrating its mapping with the IRTF definition.