Hubs: what are they and how do they work?

A hub receives data and then sends it in full to all connected devices (hosts). All ports of the hub operate at the same speed and are located in a collision domain (which includes all connected network devices). Unlike other network devices, a hub does not offer the option to control or exclude only individual receivers. This means that all data packets are always forwarded to all computers during a transfer. This means that even those devices the data wasn’t intended for also receive the data. Since all hosts are occupied in this way, the other devices cannot send any data themselves in the meantime. Instead, simultaneous requests are processed one after the other.

If you need more hosts, you can connect one hub to another hub. This connection is created with a simple crossover cable over one of the ports. However, the number of hosts is automatically limited by the 5-4-3 rule, or repeater rule. This states that a maximum of five segments with four repeaters can be used between two end devices. In addition, the connected hosts share the entire bandwidth when a hub is used. This inevitably leads to speed losses, especially when transferring large data packets.