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Definition: Network Hub
A hub is a common point of connection for devices in a network, mostly used to connect the segments of a Local Area Network (LAN). Multiple ports are present in a hub and when data or information reaches at one port, copies of it is created in the other ports, thereby enabling all the segments of the local network to view all the packets. It looks like a small rectangular box that receives power from a simple wall outlet. Ethernet hubs are the most common type of used hubs, however hubs for other networks like Universal Serial Bus (USB) is also prevalent.
Hubs serve as a central connection for all the equipments of the network. The data type handled by hubs are called frames which carries the data. A frame is broadcasted along to every other port along its journey. When it is received, it is amplified and transmitted to the port of the destination computer. The hub cannot distinguish which port the frame belongs to and it doesn’t matter also. It is ensured that the frame passing along every port will reach its desired destination. This results in the increase in traffic on the network leading to poor response time.
Fig: A network hub
Source : thebryantadvantage
Hubs can be of different types depending of the functionality. A passive hub simple serves as a channel of transmitting data, enabling it to go from one device to another. There are intelligent hubs (also called manageable hubs) which have features that allow an administrator to monitor the transfer of data through the hub and configure each port in that hub. A third kind of hub is the switching hub which actually reads the destination address of the frames and then transfers the packet to the right port. As a network device a hub may also comprise a group of modem cards for telephone users, a gateway card for connections to a LAN or a simple connection to a line. Hubs are quite popular devices used for smaller networks because of their low cost.