Designs, develops, manages and supports more than just your IT

By Alan M Johnson

So what is a network?

A network supports the interconnection of many devices and a protocol for ensuring they can communicate with one another in the most effective way. The best way to understand how networks work is to visualise each element of the network as a layer, one on top of another. The conceptual model that describes this layered model is known as the OSI Reference Model, which has seven layers. All Network professionals use this in their day to day design and engineering work.

For our purposes we can simplify it into three layers, going from the bottom up there is:

1.  The Physical layer - the cable between machines (typically called 100BaseT, uses four pairs), the card in the back of your machine (802.3 Ethernet NIC) or Wireless Networking adapter (802.11n etc) etc.

2.  Data Link, Network and Transport Layers - Responsible for managing the addressing, routing