Wednesday, 14 September 2016

Hub, What is Hub, Three Types of Hub

 What is a Hub?

A hub is often made of plastic, it is usually a small rectangular box, which receives its power from an ordinary wall outlet. It joins multiple computers (or other network devices) together to form a single network segment. On this network segment, all computers can communicate directly with each other. Ethernet hubs are by far the most common type, but hubs for other types of networks such as USB also exist. A hub includes a series of ports that each accepts a network cable Small hubs can network four computers together. They contain four or sometimes five ports. Many times the fifth port is reserved for "uplink" which is the connecting of one hub to another hub or similar device (joining two segments together). Larger hubs contain eight, 12, 16, and even 24 ports.
Hubs classify as Layer 1 devices in the OSI model.

OSI stands for (The Open Systems Interconnection) Basic Reference Model. At the physical layer, hubs can support little in the way of sophisticated networking. Hubs do not read any of the data passing through them and are not aware of their source or destination. Essentially, a hub simply receives incoming packets, possibly amplifies the electrical signal, and broadcasts these packets out to all devices on the network - including the one that originally sent the packet! a packet is a formatted block of data carried by a computer network.

Technically speaking, three different types of hubs exist

                               Passive    -:-    Active    -:-    Intelligent

Passive hubs

Passive hubs do not amplify the electrical signal of incoming packets before broadcasting them out to the network. It is known as central connecting device in a network that joins wires from several stations in a star configuration. It does not provide any processing or regeneration of signals. Contrast with active hub and intelligent hub.

Active hubs
Active Hubs amplify the electrical signal of incoming packets back to their original level before broadcasting them back out on the network. A central connecting device in a network that regenerates signals on the output side to keep the signal strong. Also called a "multiport repeater." Contrast with passive hub and intelligent hub.

Intelligent hubs
Add extra features to an active hub that are of particular importance to businesses. An intelligent hub is typically stackable (built in such a way that multiple units can be placed one on top of the other to conserve space).

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