Network switch

A switch in a local area network is a device which connects all the different devices together, and allows them to communicate with each other.

How it works

• A device sends a frame (basically a packet) over the wire to the switch (e.g. via ethernet).
• The switch then looks at the frame, and sees which device it’s meant to be sent to. It does that by looking at the MAC address of the frame, which is a unique identifier (basically name) for each device.
• The switch then sends the frame to the correct device, so that it can be received and read / processed by that device.

‘Dumb’ switches, or hubs

Generally, switches are ‘smart’ and they can look at the frames and send them to the correct device only.

But we also have ‘dumb’ switches, which are called hubs. A hub just sends the frame to every device on the network, and then the device that it’s meant for can read it and process it, while the other devices just ignore it.

This makes hubs act functionally like a bus topology - because the data is sent to every device on the network, and the devices have to ignore the data if it’s not meant for them, just like in a bus network.