Hubs, switches, and routers are devices allowing connectivity between our systems. Each of these has two connectors, named ports, which are used to physically connect cables for a successful connectivity.
A hub is the most simple and less expensive device. There is basically no configuration, in most cases. Its role is to replicate information that comes to one port to all others. Thus, if a message is sent to computer A, the hub will replicate it to all its ports, reaching computers that have probably not requested the information to be sent to them. All hub connected computers can then see the message, and it is going to be up to them to determine whether they need to reply to it or not.
A switch has the same role as the hub, but it does it more efficiently. At the beginning, it behaves like a hub. But, it has the ability to learn information about the network, such as identity of devices connected to its ports. Later, when the information needs to be sent through it, it knows which ports it will use to send the data, without replicating it to all the ports. If the destination address is unknown, it will broadcast the information, however it will eventually memorize the connected systems, as they reply to it. This greatly improves network performance and reduces the need to transmit information if not required.
Most of today’s network use switches to connect computers, servers, and printers, being more efficient and more secure.
Routeurs are most intelligent devices. They have the role to define a transmission route on a network, and to route the information through it, to the destination network. A router is a like a dispatch system – it chooses the most optimal route, so the information can get to its destination quickly. Routers are devices that have installed a complex software, specific for the need of routing purposes. In an internal network, the router acts as a gateway, providing Internet connectivity to the network to which it is connected.
Related training: Network+