A hub is a center of activities. In network terminology, it is a device where all connecting mediums come together. It is a medium used to collect signals from the input line(s) and redistribute them in various available wirings around a topology (topologies such as: Arcnet, 10base-T, 10base-F etc). It basically acts as signal splitter, it accepts signal through its input port and passes it to the output ports. Some hubs help in regenerating the weak signals prior to sending them to the intended output lines, whereas some help in synchronizing the data communication (in simple words, the hub not only provides the means of interface within the network, it also provides some additional and useful features). Sometimes, multiple hubs are interconnected in the network. Generally they are used more commonly where star topology is used.
The Need of a Hub
Generally when we build a network using two or more computers, we need a hub. However, it is possible to connect two computers to each other directly without the need of a hub but when we add a third computer in the network, we need a hub to allow proper data communication within the network.
Types of Hubs
There are many types of hubs with various features/specifications, which provide the type of functionality you need in building a network. There are three main types of hubs: Passive, Active, and Intelligent hub.
As the name suggests, passive hubs are the ones which do not provide any additional feature except for working just as an interface between the topology. These types do not help in rectifying/enhancing the signals they pass on in the network, in other terms, they do not help in enhancing the performance of the network/LAN. It is very hard to get any help from the passive hubs while troubleshooting in case there is any fault in the hardware or the network. It simply receives signal(s) on input port(s) and broadcasts it (them) on the output port(s) without even rectifying it (them).
As you must have guessed from the name, active hub takes active participation in data communication within the network/LAN. They come with various features, such as receiving the signal (data) from the input port and storing it for sometime before forwarding it, this feature allows the hub to monitor the data it is forwarding, some hubs come with a feature that helps in transmitting data that has high priority before the data that has lower priority (this feature is very important for some applications and some types of network), some hubs help in synchronizing data communication (by retransmitting the packets, which are not properly received at the receiving computer or by adjusting re-transmission of the data packets to compensate timing), and some active hubs come with a feature that rectifies the data/signal before forwarding it in the network/LAN.
Active hubs also help in troubleshooting at a certain level. If there is a bottleneck within the network/LAN, they can be used to find out the problem to a certain extent. They have some benefits over the use of passive hubs; however, they are more expensive than passive hubs as they provide additional features.
They add some more features to that provided by the active hubs. It provides all the features of a passive and an active hub; it also provides some features, which help in managing the network resources effectively and efficiently. They help in improving the performance of the network/LAN that you are using. As an active hub helps in finding out where the problem persists, an intelligent hub itself finds out the problem in the network, diagnoses it and tries to rectify it without letting the problem hamper the performance of the network. They provide a feature that helps in determining the exact cause and exact place of the fault, this saves a lot of time and energy which otherwise would have been required for finding out the exact place of fault and identifying the solution for it. Another feature of the intelligent hub is that they can decide which packet goes in which output line, this helps in controlling and minimizing data traffic in the network, which results in improved performance of the network/LAN.
They also help in managing the data communication within the network, it recognizes the slower devices automatically and helps them to transmit the data with their own speed, and during this time, the hub manages the traffic within the network effectively. This feature also improves the performance of the network. It also adopts the changes in the network very easily and it also supports different technologies without the need of changing anything in configuration.
Nowadays, as the technology is progressing exponentially at every second, bigger and complex networks are built and need for hubs with additional features is increasing. The hubs are also being developed to incorporate the new features and help in building high performance, flexible and more manageable networks.