HUBS A hub centralizes the control of the network, as there is normally one main hub and many other hubs connected to this. A hub repeats the signal and passes it on to the other nodes connected to it, they are mainly used to link together and increase the network. For Internet users not connected to a local area network, this is the general topology used by your access provider. Other common network topologies are the bus network and the ring network. In telecommunication networks, a repeater is a device that receives a signal on an electromagnetic or optical transmission medium, amplifies the signal, and then transmits it along the next leg of the medium.
Repeaters overcome the attenuation caused by electromagnetic fields or cable loss.
A series of repeaters make possible the extension of a signal over a distance. They're also used to amplify and extend wide area network transmission on wire and wireless media. On the Internet, a router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two networks and decides which way to send each information packet based on its current its current understanding of the state of the networks it is connected to. A router is often included as part of a network switch.