## 1 Introduction  
Science and earth observation missions are experiencing a constant technology evolution, with their payload instruments needing higher and higher data-rates in order to stream the generated data. Typical examples are high-resolution optical payloads, as demonstrated in missions like MTG [1], Juice [2] and Plato [3]. In addition to the increased demand of data-rate, there is also a need to reduce satellite complexity by reducing the number of different on-board network technologies, and hopefully using one single network for all kinds of traffic in the future. This would bring a great harness reduction, together with a noticeable simplification of the overall system management. SpaceFibre [4] is the solution, supported by the European Space Agency (ESA) [5], aiming at solving all these problems. It supports a link speed up to 6.25 Gbps per lane, with the possibility to run up to 16 lanes in parallel, on both copper and optical fibre. Moreover, SpaceFibre provides up to 32 Virtual Channels (VCs) per link, each one independently configurable with different Quality of Service parameters (priority level, reserved bandwidth, and assigned time-slots). The use of Virtual Channels allows carrying different traffic classes using the same network technology. Hence, the network infrastructure can be effectively shared among different applications, even when the requirements are completely different. In particular, it would be possible to use a SpaceFibre network both for payload applications (usually requiring high data-rates but with little time requirements) and for platform applications (usually requiring low data-rates but with stringent time and reliability requirements). These features represent a big step forward in comparison with older technologies such as SpaceWire [6; 7] and make the configuration of a SpaceFibre network undoubtedly complex. Moreover, The core layers of the SpaceFibre standard have already underwent public review and are expected to be released as a standard in 2019, while the SpaceFibre network layer is still under standardization process and some features have yet to be defined. In order to help to finalize the standard and to simplify the development of new SpaceFibre networks, the Simulator for HIgh-speed Networks (SHINe) has been developed [8]. SHINe is a discrete event simulator supporting both SpaceFibre and SpaceWire protocols and it is entirely based on the open-source framework OMNeT++ [9]. With SHINe, it is possible to easily deploy a network via drag&drop from a palette and simulate it, collecting and analysing the results. Being based on OMNeT++, SHINe is completely written in C++ and it is easily extensible, allowing the user to develop custom nodes to use together with the existing ones. SHINe implements not only the basic SpaceFibre and SpaceWire protocols, but it also offers a Routing Switch node, both Remote Memory Access Protocol (RMAP) Target and RMAP Initiator nodes, and an advanced Hardware-in-the-Loop mechanism to connect physical devices to the simulator.  
After this introduction, Section 2 presents an overview of the already existing network simulators in this field. Section 3 provides internal details of the SHINe software architecture. Section 4 shows an example of a simple network setup, briefly going through all the steps needed to define and simulate a network. Finally, the conclusions are drawn in Section 5.