Topologies

A network topology is the physical layout of a network: the pattern its devices are connected in. It tells you which device is joined to which, whether each connection is a cable or a wireless signal, and whether one device sits at the centre joining all the others. A network can be fully wired, fully wireless, or a mixture of both.

Topology is only the layout. Two networks with the same pattern of connections have the same topology, even if the devices on them do completely different jobs.

An example layout

Picture a small climbing centre with a till computer, a booking tablet and an office laptop. In one arrangement every cable runs back to a single cupboard behind the till. In another, the three devices are joined directly to each other. The devices do the same jobs in both cases — only the pattern of the connections has changed, so only the topology is different.

Star and mesh

• Star — each device has its own separate connection to a central switch, and wireless devices join through a wireless access point.
• Mesh — devices connect directly to one another rather than through one central switch, so there is more than one route between two devices. A mesh does not have to join every device directly to every other one.

Both layouts can be wired, wireless or a mix. Neither is automatically faster than the other, because speed depends on the connections and what they are made of.