This work has been carried out at the University of Padua within the research program “Methods and instrumentation for performance measurement in real-time networks”, supported by the Italian Ministry for University and Research (MiUR). The X-Simulator is able to reproduce typical sources of uncertainty that may affect the performance of synchronization protocols in a network. In particular, it focuses on the Precision Time Protocol (PTP) IEEE 1588. See the project website for further info.