OSI layers and their protocols

As mentioned previously, the OSI reference model consists of seven layers in which certain network functions are performed by their respective protocols. In addition to describing the processes that happen within layers, the OSI reference model also describes the interaction of each layer with the neighboring layers above and below. To avoid confusion, you will often encounter situations in the literature where the layers of the OSI reference model are named with numbers instead of their respective names (for example, the physical layer as Layer 1).