The primary purpose of all models, and especially use OSI model, is to allow different vendors to interoperate.
The top three layers define how the applications within the end stations will communicate with each other and with users. The bottom four layers define how da
The application layer of the OSI model is where users communicate to the computer. The application lyaer is responsible for identifying and establishing the availability of the intended communication partner and determining if sufficient resources for the intended communcation exist.