Network hub. Principle of operation

A network hub, otherwise known as a hub, is a controller that combines several Ethernet devices into one network segment. Devices are connected to the hub using a fiber optic or coaxial cable. Used for this and Twisted pair. The principle of the concentrator is simple: it multiplies all the incoming data packets and sends them to all the ports connected to it.

The network concentrator, like the other types of concentrators, has its own qualitative characteristics. First, the performance and price of the hub depends on the number of ports. The more Ethernet devices connected to it, the higher the performance and cost of the hub. Typically, the hub is equipped with an even number of connectors, the number of which varies from four to 24, but some types have five outputs. The number of ports can be increased by cascading several hubs. For this connection, a special connector is provided in each hub.

It has a network hub and one more important characteristic - the speed of copying and transmission of data packets. Some hubs are capable of Change its speed in the range of ten to one hundred megabits per second. In such devices, it is changed in two ways: either automatically, or manually, using a switch. In this case, the installed speed applies to all active ports. Distinguish between hubs and the type of network media. As a rule, this role goes to either a fiber-optic cable or a twisted pair, but there are concentrators that support other types of media. Also there are hubs for mixed types, for example, supporting a "hybrid" of twisted pair with a coaxial cable.

The principle of hubs is very imperfect. A data packet that comes from one channel, the network hub copies to all other connected channels, which greatly reduces the speed of the Internet, because all web devices connect to the network through a common channel. If two packets are copied simultaneously, a collision may occur, i.e., a collision of the same signals, in which some data is lost. Some types of hubs are protected from too many collisions. As a rule, they are based on a twisted pair. In the event of a failure, this makes it possible to isolate a single Device, whereas a network hub connected via a coaxial cable disconnects the entire segment at once.

The hub's working principle also affects data security. If the computer enters the local network, the data packets of one system reach all other nodes. Because of this, all personal settings of social networks, passwords for blogs, forums and other private data can become known to all members of this network. For these reasons, the network USB hub is increasingly replaced with a network switch or switch. This device, which received an erroneous title of "smart hub", distinguishes MAC addresses of computers entering the network and sends data only to the user's chosen port. Packages in this case pass through the buffer, which eliminates collisions, line overload and data leakage. Due to reliability and low price, switches are increasingly used in home systems, while hubs are almost not sold.