SEVEN LAYERS OF NETWORKING: The OSI model

Network architecture needn't be complicated. Darien Graham-Smith walks through the seven-step model that explains it all

- Darien Graham-Smith

Networking is one of those magical areas of technology where complex processes are made beautifully simple for the end user. Operations such as downloading a web page or backing up a file to a NAS appliance take just a few clicks or taps. Behind the scenes, though, there's a lot of highly advanced engineering going on.

Do you need to know about the under-the-bonnet technical details? Perhaps not. But if you have an understanding of what's going on, physically and digitally, then that can help you troubleshoot networking problems when they arise, and write your own programs that make efficient use of networked resources. It's also just pretty darn interesting and the OSI model makes it highly accessible, providing an easy way to visualise the various processes that make a network tick.

What is OSI?

The OSI model is a structured description of the operation of a computer network. Its name identifies the body that created it, the Open Systems Interconnection group. That group is part of the International Standards Organisation, so if you're palindromically inclined you could call it the ISO OSI.

The OSI model was originally developed in the 1970s and 1980s, to provide a standard way of talking about networks that could aid in designing, building and managing every level of a functional network, from the physical wires right up to how individual programs and services communicate with one another. The OSI model is intentionally couched in general terms, focusing on functions rather than specific technologies - so despite its age, it's still applicable to modern networking systems.