Understanding the functions of each of the OSI Reference Model layers is very important when it comes to troubleshooting connections between network components. Once you understand these functions and the troubleshooting tools available to you at various layers of the model, troubleshooting problems will be much easier. The Open Systems Interconnection (OSI) model is a reference tool for understanding data communications between any two networked systems. It divides the communications processes into seven layers. Each layer both performs specific functions to support the layers above it and offers services to the layers below it. The three lowest layers focus on passing traffic through the network to an end system. The top four layers come into play in the end system to complete the process. In other words, Layers 1-4 are concerned with the flow of data from end to end through the network and Layers 5-7 are concerned with services to the applications. This project indicates the OSI model in more details, also containing the practical project that implements the idea of it that is called: Simulation the Data flows in a Network Using the OSI Model