4. Network Technologies and Systems in Railways

This chapter provides an in-depth exploration of the wired communications networks that form the backbone of modern railway systems. It begins with an overview of basic networking concepts, setting the stage for a detailed examination of optical fibers, the dominant type of wire in contemporary railway networks. The chapter then delves into specific network technologies, with a focus on Synchronous Digital Hierarchy (SDH) and Multiprotocol Label Switching (MPLS). SDH, a legacy technology, is discussed for its reliability and deterministic nature, while MPLS is highlighted for its flexibility, efficiency, and scalability. The transition from SDH to MPLS is explored, illustrating how railways are moving towards more adaptable and efficient network solutions. The chapter also addresses the critical topic of cybersecurity in railways, discussing the unique challenges and solutions specific to this industry. It provides a comprehensive overview of the cybersecurity landscape, including standards, tools, and best practices. The chapter concludes with a summary of key points, exercises for practical application, and recommendations for further reading, making it an essential resource for anyone seeking to understand the intricacies of wired communications in railway systems.