Networking Basics

All new computers contain an Ethernet port so that an Ethernet network can simply be "plugged in" to the computer.

Networks can be considered as three "layers":

- the actual network cabling infrastructure;

- the electronic components (hubs) that join the wires together;

- the network operating system (NOS) which is running "over" the cabling.

This page discusses the cabling infrastructure details. Basics 5 discusses the electronic components (active equipment)

 

There is now only one basic type of topology infrastructure which is acceptable in schools - a "star" topology (see picture below).

The name of this infrastructure refers to the connection of all components directly to one central point.

Previously, an infrastructure known as "bus" topology was very common (see picture below), where components were connected in a daisy-chain arrangement. With this daisy-chaining, if one component failed, the whole network failed, much like the old Christmas tree lights.

A star arrangement ensures that one faulty network connection on one computer will not bring the whole network down (unless that connector is at the centre!)

Wireless networks are also becoming an option. Wireless networks are an extension of the "star" arrangement, but do not require electrical cable to join the various components to each other.

In most cases, wireless networks are still more expensive than equivalent wired networks, though this will change as the various components become cheaper and more widely available. Wireless networking is also slower than the faster wired networks.

Wireless networking may currently be an option where difficult terrain, or heritage buildings are a factor.

Bus networking

A "bus" network involves connecting computers together in a daisy-chain fashion:

This type of networking is how old administrative networks were originally installed in schools, using black co-axial cable with silver "T" connectors at each computer workstation. It often suffered the same fate as christmas-tree lights - when one connection went down, so did the whole network!

Bus networking is no longer considered suitable for new installations in a school environment.

Star Networking

This is the preferred model for school use. A star network connects each individual computer to a central server, and to each other, via a "hub":

In the example above, each workstation has its own direct link to the central "hub" (a distribution device) which is also connected to a server. This can be taken one step further, where the "central server" is more remote from the workstations. The server (or servers) can be connected to more than one hub, and thus serve more than one "sub-network":

The limitations of the above network revolve around the number of machines which each hub can support, the speed of the hubs (particularly the central hub), and the distances the cables have to run. The cable which is generally used for these networks is limited to runs of 90 metres or less, and always internally.

Longer cable runs, and any external connections, are made using fibre-optic cable.

It is now common practice to install a switching hub (known as a switch) at the Campus Distributor and Building Distributors, with at least 1000 Mb throughput between distributors.