OSI LAYERS

The Open Systems Interconnection (OSI) model is a reference tool for understanding data communications

between any two networked systems. It divides the communications processes into seven layers. Each layer

both performs specific functions to support the layers above it and offers services to the layers below it. The

three lowest layers focus on passing traffic through the network to an end system. The top four layers come

into play in the end system to complete the process.

This white paper will provide you with an understanding of each of the seven layers, including their functions

and their relationships to each other. This will provide you with an overview of the network process, which

can then act as a framework for understanding the details of computer networking.

Since the discussion of networking often includes talk of “extra layers”, this paper will address these unofficial

layers as well.

Finally, this paper will draw comparisons between the theoretical OSI model and the functional TCP/IP model.

Although TCP/IP has been used for network communications before the adoption of the OSI model, it supports

the same functions and features in a differently layered arrangement.