Networking Devices Hub Switch Router Modem Bridges Brouters Gateways

1. HUB :Networks using a Star topology require a central point for the devices to connect. Originally this device was called a concentrator since it consolidated the cable runs from all network devices. The 

basic form of concentrator is the hub.

 

As shown in Figure; the hub is a hardware device that containsmultiple, 

independent ports that match the cable type of the network. Most common hubs interconnect Category 3 or 5 twisted-pair cable with RJ-45 ends, although Coax BNC and Fiber Optic BNC hubs also exist. The hub is considered the least common denominator in device concentrators. Hubs offer an inexpensive option for transporting data between devices, but hubs don't offer any form of intelligence. Hubs can be active or passive.

An active hub strengthens and regenerates the incoming signals before sending the data on to its destination.