Differences between Hub, Network Bridge, Switch and Router

Before we talk about the differences between these network devices, we had to understand the conflict domain and Brocast Domain first.

Take bus network topology-example, all PCs is connecting to the same bus line. If multiple PCs is sending the signal at the same time, it would create a conflict domain on the bus line. So some signals would be weaken or terminated due to the conflict. Just Like many cars is sharing the same lane. If they all would the same lane at the same time, for sure, they would run into congestion or even crash each Other.

As to Brocast domain, it is quite straight-forward. Let's say a PC would like to brocast a signal. The signal is brocast to all the PCs which is connecting to the same network channel.

Hub is a outdated network device which are used for amplify the transmission signal. It does not separate the conflict domain and Brocast domain.

Network Bridge could separate the conflict domain but usually it is only have both ports and not powerful enough. It is replaced by switch fastly after the switch had been lauched.

Switch could be considered as a Multiports network bridge. Typical Layer 2 switch could separate the conflict but not brocast domain. Switch could provide different communication channels for different ports so there won't have conflict domain created. Just like different cars is running on different lanes. They is fast and safe. However, if a PC would like to brocast the signal, whether the destination PCs would like to take it not, as long as they is within the same brocast domain, they'll all receive the signals. It's like someone was sending the leaflets on the street, and whether you like it or not, he forces your it. It wastes a lot resource.

Nowadays, we have a lot of so called Layer 3 switches which could provide routing services as well. In the other words, they is routers. and routers can not be separate the conflict domain but also the brocast domain. So if you would like to brocast a message to a group, you could does it with a purpose. Only the target receipients could receive your brocast memssages.