Network topologies

Topology is the arrangement of computers and other devices in a network: how they are connected. Picture the cables:

• Mesh: every device is connected to every other. With n devices, that needs n(n−1)/2 cables: 5 devices need 10. It is reliable and secure (data can take many routes), but costly.
• Ring: each node is connected to its two neighbours, forming a ring; data travel in one direction, from node to node.
• Bus: all nodes share one main cable, the backbone. It is cheap, but less secure and less reliable: if the backbone fails, the whole network fails.
• Star: each node connects to a central hub or switch. Easy to manage, but if the centre fails, the whole network stops.
• Tree (hybrid): a hierarchy of branches, combining star, ring and bus topologies.