Robert Rogers
In a network with a star topology, the hub acts as the centerpiece, which receives the signals transmitted by the stations and retransmits them to all the others. There are two types of hubs, passive hubs and active hubs.
Passive hubs are limited to functioning as a mirror, reflecting received signals to all stations connected to them. As it only distributes the signal, without making any amplification, the total length of the two sections of cable between one PC and another, passing through the hub, cannot exceed the 100 meters allowed by the twisted pair cables.
An active Hub, in turn, in addition to distributing the signal, serves as a repeater, reconstituting the weakened signal and retransmitting it. While using a passive Hub, the signal can travel only 100 meters added. The two stretches of cables between the stations, using an active hub, the signal can travel for 100 meters to the hub, and after being retransmitted by it, it travels a total of 100 meters. Although more expensive, this type of hub allows you to extend the network over greater distances.
Smart Hubs
In addition to common hubs, which only distribute network signals to other computers connected to them, there is a particular category of hubs, smart hubs, or smart hubs. This type of hub incorporates a processor and diagnostic software, being able to detect and, if necessary, disconnect stations with problems from the network, preventing a talking station from damaging traffic or even bringing down the entire network; detect points of congestion in the network, making it possible to normalize traffic; detect and prevent unauthorized network access or intrusion attempts and other potential problems among other functions, which vary depending on the sophistication of the hub.
Switches
A Hub relays all incoming data to all stations connected to it, like a mirror. This means that the available data bus is shared between all stations and that only one can transmit at a time.
A switch such as Cisco SG350X can also link multiple hubs or even link stations directly, replacing the hub. But the switch is smarter, as instead of simply forwarding packets to all stations, it only forwards to the correct recipient. This brings a considerable advantage in terms of performance for congested networks, in addition to allowing that, in cases of networks where 10/10 and 10/100 cards are mixed, communications can be made at the speed of the cards involved. When two 10/100 cards exchange data, communication will be done at 100 megabits. When one of the 10-megabit cards is involved, it will be made at 10 megabits. The cheapest switches,
In general, the switch function is very similar to that of a bridge, except that a switch has more ports and better performance. Using bridges or switches, all interconnected segments remain part of the same network. The only advantages are improved performance and the possibility of adding more nodes than possible by joining the hubs directly together. Routers, in turn, are even more advanced, as they allow the interconnection of several different networks, creating communication but keeping them as distinct networks.
