Hub
As you learned earlier, in a star topology Ethernet network, a hub is the device that connects all the segments of the network together. Every device in the network connects directly to the hub
through a single cable. Any transmission received on one port will be sent out all the other ports in the hub, including the receiving pair for the transmitting device, so that CSMA/CD on the transmitter can monitor for collisions. So, if one station sends it, all the others receive it; but based on addressing in the frame, only the intended recipient listens to it. This is to simulate the physical bus
that the CSMA/CD standard was based on. It’s why we call the use of a hub in an Ethernet environment a physical star/logical bus topology. It is important to note that hubs are nothing more
than glorified repeaters, which are incapable of recognizing frame boundaries and data structures; that’s why they act with such a lack of intelligence. A broadcast sent out by any device on the hub
will be propagated to all devices connected to the hub. Any two or more devices connected to the hub have the capablity of causing a collision with each other, just as in the case of a physical bus.
Example:
Hub
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