Due to the necessity of developing analysis tools inthe integrated ICT and power system domain, this paperdescribes and compares the architecture and configuration oftwo different co-simulation approaches called SITL and HLACo-simulation platforms. We provide several details on theirimplementation and present their features by means of theresults obtained for two test cases. The paper aims at clarifyingthe type of analysis that can be effectively carried out by usingthe two different platforms. Both platforms make use of thecommunication network simulator OPNET (Optimum NetworkPerformance). One of the two platforms operates in real time, inorder to perform system-in-the-loop (SITL) simulations. Theother platform is based on the interface between OPNET and thepower network simulation environment EMTP (ElectromagneticTransient Program). The interface is based on the application ofthe High-Level Architecture (HLA) standard.