Open System Interconnection Model
Analyzing the seven layers of the OSI model, a conclusion to be made is that the layer three, also known as the network layer is the one that WAN protocols operate on. The network layer performs routing functions and identifies end-to-end addressing and routing datagrams. There is a unit called brouter that some layers contain which functions as a router and a bridge. Routers and switches operate on layers 2-4 (data link layer, network layer and transport layer). As stated before, on layer two of the OSI model, network layer, is where the addressing and routing is performed. On the transport layer of the OSI model is where the flow control and error handling performs. Finally, on layer four the synchronizations and assemblies are done.
Being composed of different components each layer has a different function within the network. Moreover, each layer contains things to the data that is transferred from one point to another. The protocols that operate on this layer are HDLC, PPP and the frame relay protocol. HDLC protocol stands for High-Level Data Link Control protocol. Another protocol that operates on layers of the OSI model is the Point-to-Point protocol (PPP) which is similar to HDLS protocol. The frame relay protocol operates at the data links layer of the OSI model.
