SpaceFibre is the forthcoming technology for very high-speed reliable data links in on-board satellite networks. Thanks to the evolution of detectors, each payload may generate data at very high rates, beyond 1 Gbps, for which there are no standardised network technologies available. SpaceFibre satisfies this need, making possible to reach data-rates higher than 2.5 Gbps per lane. Moreover, it also integrates a link-level Fault Detection Isolation and Recovery system and a Quality of Service mechanism using several Virtual Channels. While these features greatly simplify the upper layer applications, they also make undoubtedly complex for the system engineers to correctly configure the whole SpaceFibre network in order to achieve the desired end-to-end Quality of Service. In this paper, a Simulator for HIgh-speed Networks (SHINe) is presented. It has been developed to help the design of SpaceFibre and SpaceWire network architectures and to support the development and test of new upper layer protocols.