1. Introduction

Protocols are a set of rules governing how something is done. There are many protocols in use across networks. Sometimes it can be hard to understand how they all relate to one another.

Various "models" have been developed to help people think about how protocols are organised. These models split the protocols into different groups, called 'layers', according to their role in network communications.

One of the more common models is known as the 'four layer model'. The other is the OSI model.

It is important to understand the different models because they allow you to come up with solutions to things such as network security, network communication and anything else related to computer networking.

You are more likely to be asked about the four layer model in your exams, however, we have also taken a brief look at the OSI model, just so that you are familiar with it.