On a LAN, every workstation is connected to the network by means of some sort of transmission medium. Usually, each file server has only one NIC. Therefore, it would
be impossible to connect every workstation directly to the file servers. To solve this problems, LANs may use hubs, which are common networking devices.
The term hub is used instead of repeater when referring to
the device that serves as the center of a network.The following are the most important properties of hubs:
- They amplify signals.
- They propagate signals through the network.
- They do not require filtering.
- They do not require path determination or switching.
- They are used as network concentration points.
Hubs can also be understood to be hardware devices that contain multiple independent but connected modules of network equipment.In a LAN, where hubs act as multiport repeaters, they sometimes referred to as a concentrators. In such cases, hubs are used to split the networking media or provide for multiple connections.
The disadvantage of using a hub is that it cannot filter network traffic. Filtering generally refers to a process or device that screens network traffic for certain characteristics, such as source address, destination address, or protocol, and determines whether to forward or discard that traffic based on the established criteria. On a hub, data arriving at one port is sent out on all other ports. Consequently, a hub passes data to all other sections or segments of a network, regardless of whether the data needs to go there or not.
How it's work?
When data enters the hub through any of its ports, the hub
amplifies the signal and transmits it out through all of the other ports. This
enables a star network to have a shared medium, even though each computer has
its own separate cable The hub relays every packet transmitted by any computer
on the network to all of the other computers, and amplifies the signals. The
maximum segment length for a UTP cable on an Ethernet network is 100 meters. A
segment is defined as the distance between two communicating computers.
However, because the hub also functions as a repeater, each of the cables connecting
a computer to a hub port can be up to 100 meters long, allowing a segment
length of up to 200 meters when one hub is inserted in the network.
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