Describe briefly the types of models used for communication model and different communication task. (20) (a) Describe the OSI seven-layer model. Name each of the layers in the model and draw a diagram that shows the ordering of these layers. Write a paragraph describing the areas of function that each layer is responsible for. (b) Contrast the OSI model you have just described with the TCP/IP reference model. Using a diagram show the correspondence between relevant protocol layers in the two models. (c) Discuss the relative merits of each of these models in the context of modern computer networking.