Hubs - what is it? Device hubs

Many people are interested in the question of what hubs are and what they use. Now we shall understand this question. A hub is generally understood as a node of a network. This term has different meanings in different branches.

Using a hub in different industries

For example, in transport, hubs are transshipment or transshipment nodes, hub airports. In the energy sector, this is a kind of special center, in which one route is divided into several. On off-road vehicles this word refers to a freewheel clutch mounted on the front axle. In various Internet networks, hubs are also used. What is it in the network "Fidonet"? Here the hub is a node that serves for mail transfer. In a file exchange network, Direct Connect is a network server.

But the most widely used concept is used in computer technology and the Internet. A specific set of network equipment is based on the tasks that are put before the projected network and the costs of implementing a specific solution. An important element of such tasks is the choice of devices, among which the main role is played by routers, switches and hubs. We will try to understand what this is.

Hubs in computer networks

Technologies for building computer networks are constantly evolving. Devices that are based on them and are used to organize communication between computers are called differently: a hub, a switch and a router. What this is, we will consider in more detail.

Each of these devices performs its role in the organization of communication between network computers. Externally, they can look the same: small metal boxes, having a number of ports or connectors, where an Ethernet cable is connected. As for such concepts as a switch, hub, hub, router, they are often used as synonyms, but this is a mistake. All these are different devices.

Hub

One of the first network devices are hubs. What are these devices? The term is of English origin. The word hub means the center of activity. A hub, or network hub, is designed to combine computers into a simple peer-to-peer network. The device provides a certain number of ports to which all personal computers of the network can be connected. Most often, a twisted pair is used for this purpose, which is compressed in a special way.

Principle of operation of the hub

Consider the principle of the network hub. At the moment of attempting to access any of the computers of the network equipped with the hub to another PC, the first device sends a special block of information called a packet to the address of the network hub.

Let's try to understand the example scheme with three computers. Suppose that PC1, PC2 and PC3 are connected to the device. The role of the hub is to multiply the data packet from PC1 by transferring it to other devices connected to the local network, that is, PC2 and PC3. At the time of receipt of the signal to the PC3 computer, for which it was intended, the latter sends the reply packet to the hub. The network hub again sends this packet to all network computers until the response from PC3 returns to the PC1 sender.

This is an approximate scheme of the interface of computers connected to a local network, with a hub. The main drawback of such networks is that too much information is being sent. The network hub continuously sends data packets to all devices on the computer network, even if the destination is one particular PC. At the same time, computers receive blocks of information, which are often completely unnecessary to them. The technology turns out to be very expensive. That's why now the network concentrators are almost out of use. In return, more intelligent devices were developed - network switches, which in everyday life are called switches.

Switch

The term "switch" is of English nature and means a switch, or a network switch. Like a hub, a switch is required to connect computers to the same local network. The scheme for connecting it to computers does not differ from the scheme with a network hub. Just instead of the hub, the PCs are connected to the switch.

Being outwardly very similar to a network hub, the switch has principal differences from it, consisting in the method by which information is transferred between the computers of the local network.

After receiving the information packet from the computer, the network switch, unlike the hub, does not forward it to all PCs participating in the network, but organizes the direction of the packet to the address of the computer for which the premise is intended. For example, when PK1 sends a packet of information to the PK3 computer, the switch arranges the transfer to him, bypassing PK2. The return packet from the PK3 network switch also returns only to the sender of the information packet - PK1.

Switch has the ability to memorize the addresses of all computers that are connected to its ports, and therefore can work as a regulator, transmitting information only to the destination's PC and ignoring the others.

The table of special MAC-addresses of the network equipment of users in the external and internal network was based on the work of the network switch. As a result, the packet of information that falls on each of the ports goes through a comparison with the routing table and is sent to the port address where the corresponding equipment is located.

Router

The name "router" spawned an English router. This is a router that can organize the transfer of information between two or more different local networks. In addition, the router provides the ports that are required to connect some other devices to it using a cable.

How does the router work?

Like a network switch that stores a table of registered MAC addresses, the router stores the IP address table as the routing table. The main task of the router is to store this data and to ensure that other routers know about the changes in the network configuration. It is solved by applying routing protocols to coordinate with other routers. When packets arrive at the router, the latter uses different protocols and criteria to determine the best way to forward the information packet to the destination.

The router can be programmed to include multi-level rules, which are determined by the content of the information packets that arrive at it. The router is programmed to activate the network equipment protection system, broadcast NAT network addresses and represent DHCP network services.

With intelligent stuffing, routers are among the most complex network devices. In addition to the ability to redirect traffic to an information packet, routers can be used to monitor traffic on the network. In addition, they have the ability to respond to changes in the network, dynamically detecting them, protecting it with packet filtering, computing packets for blocking or skipping.

USB hub

In addition to the network hubs of the Ethernet network, the term "hub" is used with respect to USB technologies. The development of new equipment places high demands on the level of development of user interfaces of computer equipment. A lot of various computer peripherals connected through a USB connection, needs a special device that allows you to connect several devices simultaneously via USB. It is called a USB hub. What is the principle of its operation?

USB hub (USB hub) is a small device with several ports. Connect it through the computer socket. It allows you to connect several USB devices to one USB port on the PC.

USB Hub Device

The design and construction of hubs are not very complex. They are designed to switch signals and provide power supply voltage. In addition, they monitor the status of the periphery connected to them, setting the host aware of the changes.

The hub consists of two modules - a controller and a repeater. A repeater is a managed key that connects the input and output ports. It has the ability to reset and suspend signal transmission. Registers are included in the controller, allowing to interact with the host. Registers are managed through special commands that allow you to configure the hub, monitor the status and change the parameters of the downstream ports. It is possible to use the hub of the contract, when the devices are switched in series.

Types of USB Hubs

One such type is the internal card on the system bus. It serves to connect USB devices to the motherboard. This is done using a USB PCI card, installed on the free space of the PCI bus, located directly on the motherboard. This kind of USB hub is best used by those who are familiar with the computer device. Those who do not have experience, it is better to dwell on a different form.

Another kind is an external USB hub without power. Such a device is simple and relatively inexpensive. This kind of USB hub connects to the USB port of your computer. This device is great for laptop owners. It is also possible for users of home computers to use such a USB hub, however, one should take into account that a number of devices connected to the computer require power supplied via the USB port. This type of hub is not able to power several such devices at once. In this situation, it is best to use the powered hubs. What are these devices and how do they differ from devices without power?

The powered USB hub operates exactly the same as the hub without power. The difference is that it can be plugged into the outlet. This allows you to provide full power to all devices that connect through the USB. The biggest USB hubs are seven-port.

Another kind of such device is a computer USB board. This device is suitable for laptop users. It connects to a special USB port located on the laptop and allows you to use two ports instead of one.