2.2.1 and 2.2.2: The OSI model is often described in terms of the upper and lower layers. The upper layers include Layers 5, 6, and 7, and the lower layers include Layers 1, 2, 3, and 4. The upper layers deal with the data’s format, organization, and communication. The lower layers primarily implement protocols to transport and route data across a network. Table 30-5 outlines the function of each layer and associated network devices.