The OSI model
No network book is complete without first going over the OSI model. The model is a conceptional model that componentizes the telecommunication functions into different layers. The model defines seven layers, and each layer sits independently on top of another one with defined structures and characteristics.
For example, in the network layer, IP is located on top of the different types of data link layers, such as Ethernet or frame relay. The OSI reference model is a good way to normalize different and diverse technologies into a set of common languages that people can agree on. This greatly reduces the scope for parties working on individual layers and allows them to look at specific tasks in depth without worrying too much about compatibility:
Figure 4: OSI model
The OSI model was initially worked on in the late 1970s and was later published jointly by the International Organization for Standardization (ISO), what is now known as the Telecommunication...
