The difference between a hub and a switch. The difference between a hub and a switch. What is a switch

A network concentrator or hub is a network device necessary to combine local network nodes into a single network segment. The nodes are connected using twisted pair, coaxial cable or optical fiber. The term hub is also applicable to other data transfer technologies: USB, FireWire, etc.

Currently, hubs are almost never produced - they have been replaced by (switches) that highlight each connected device in
separate segment. Network switches are sometimes called "smart hubs".

How the hub works

The hub works on a simple principle - it redirects received packets to all other ports. Collisions may occur during the process - when packets arrive on two or more ports at the same time. Another problem is security - all packets reach all computers on the network and, if desired, an attacker can collect private information, passwords from social networks. Another disadvantage of hubs is that copying packets increases the load on the network, and quite significantly - in fact, all the traffic of a network segment goes to each of the computers and loads every millimeter of wire.

Typical hub

Unlike a hub, a smarter switch remembers the MAC addresses of computers in a special table and forwards packets only to the port that matches the recipient address. In addition, packets are buffered, which eliminates collisions. Due to this, data is sent only to the required ports - there are no security problems or excessive load on wires and computers that do not need the appropriate packages.

Today, hubs are practically not available for sale, and cheap switches, also known as switches for home use, are quite inexpensive.

Many people are interested in the question of what hubs are and what they are used with. Now let's look at this issue. In general, a hub is a node in a network. This term has different meanings in different industries.

Using the hub in various industries

For example, in transport, hubs are transfer or transshipment nodes, hub airports. In the energy industry, this is a kind of special center in which one route is divided into several. On SUVs, this word refers to the freewheel installed on the front axle. Various Internet networks also use hubs. What is this on the Fidonet network? Here, a hub is a node that serves to transmit mail. In the Direct Connect file sharing network, this is the name of the network server.

But the concept is most widely used in computer technology and the Internet. A specific set of network equipment is based on the tasks assigned to the designed network and the costs of implementing a specific solution. An important element of such tasks is the choice of devices, among which routers, switches and hubs play the main role. What is this, we will try to figure it out.

Hubs in computer networks

Construction technologies are constantly evolving. The devices that underlie them and are used to organize communication between computers are called differently: hub, switch and router. We will look at what this is in more detail.

Each of the listed devices plays its role in organizing communication between network computers. Externally, they may look the same: small metal boxes with a number of ports or connectors where an Ethernet cable is connected. As for such concepts as switch, hub, hub, router, they are often used as synonyms, but this is a mistake. These are all different devices.

Hub

One of the first network devices are hubs. What kind of devices are these? The term is of English origin. The word hub means center of activity. Hub, or designed to connect computers into a simple peer-to-peer network. The device has a number of ports to which you can connect all personal computers on the network. Most often, twisted pair cables, which are crimped in a special way, are used for this purpose.

How the hub works

Let's consider the principle of operation of a network hub. When any computer on a network equipped with a hub attempts to access 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 figure it out using an example of a circuit with three computers. Let's say computers PC1, PC2 and PC3 are connected to the device. The role of the hub is to replicate the data packet from PC1 by transmitting it to other devices connected to the local network, that is, PC2 and PC3. At the moment the signal arrives at PC3, for which it was intended, the latter sends a response packet to the hub. The network hub again sends this packet to all network computers until the response from PC3 returns to the sending computer PC1.

This is an approximate diagram of the interface of computers connected to a local network with a hub. The main disadvantage of such networks is that too much information is sent. A network hub continuously sends data packets to all devices on a computer network, even if the destination is one specific PC. At the same time, computers receive blocks of information that they often do not need at all. The technology turns out to be very expensive. This is why network hubs are now almost obsolete. Instead, more intelligent devices were developed - network switches, which are commonly called switches.

Switch

The term is of English origin and means a switch, or network switch. Like a hub, a switch is required to connect computers on the same local network. The circuit for connecting it to computers is no different from the circuit with a network hub. Instead of a hub, PCs are simply connected to a switch.

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

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

The switch has the ability to remember the addresses of all computers that are connected to its ports, and thanks to this it can work as a regulator, transmitting information only to the recipient’s PC and ignoring others.

The operation of the network switch is based on a table of special MAC addresses of users’ network equipment in the external and internal networks. As a result, the information packet arriving at each of the ports is compared with the routing table and sent to the port address where the corresponding equipment is located.

Router

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

How the router works

Just like a network switch stores a table of registered MAC addresses, a router stores a table of IP addresses as its routing table. The router's main job is to store this data and ensure that other routers know about changes in the network configuration. It is solved by using it to coordinate with other routers. When packets arrive at a router, the router uses different protocols and criteria to determine the best path to forward the packet of information to the destination.

The router can be programmed to enable multi-level rules that are determined by the content of the information packets that arrive at it. The router is programmed to enable network equipment security, translate network NAT addresses, and provide DHCP network services.

Packed with intelligence, routers are among the most sophisticated network devices. In addition to the ability to redirect information packet traffic, routers can be used to control 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, calculating packets for blocking or passing.

USB hub

In addition to Ethernet network hubs, the term "hub" is used to refer to USB technologies. The development of new equipment places increased demands on the level of development of user interfaces of computer equipment. The wide variety of computer peripherals that connect via USB require a special device that allows you to connect multiple devices simultaneously via USB. It's called a USB hub. What is the principle of its operation?

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

USB hub device

The design and arrangement of the hubs are not very complicated. They are designed to switch signals and provide supply voltage. In addition, they monitor the status of peripherals connected to them, making the host aware of changes.

The hub includes two modules - a controller and a repeater. A repeater is a managed switch that connects the input and output ports. It has the ability to reset and pause signal transmission. The controller includes registers that allow you to interact with the host. Registers are controlled using special commands that allow you to configure the hub, monitor the status and change the parameters of downstream ports. It is possible to use a contract hub when the devices are connected sequentially.

Types of USB hubs

One such type is an internal card on the system bus. It is used to connect USB devices to the motherboard. This is done using a USB PCI card installed in the free space of the PCI bus located directly on the motherboard. This type of USB hub is best used by those who are familiar with the structure of a computer. For those who do not have experience, it is better to choose another type.

Another type is an external USB hub without power. Such a device is simple and relatively inexpensive. This type of USB hub connects to the USB port of your computer. This device is great for laptop owners. For home computer users, it is also possible to use such a USB hub, but it must be taken into account that a number of devices connected to the computer require power supplied through the USB port. This type of hubs is not capable of powering several similar devices at once. In this situation, it is best to use powered hubs. What are these devices and how do they differ from devices without power?

A powered USB hub operates in exactly the same way as an unpowered hub. The difference is that it can be plugged into an outlet. This allows you to provide adequate power to all devices that are connected via USB. The largest USB hubs are seven-port.

Another type of such device is a USB computer board. This device is suitable for laptop users. It connects to a special USB port located on the laptop body and makes it possible to use two ports instead of one.

HUB. A HUB, or hub (repeater) is a signal amplifier-splitter that relays any packet received from one port to all other ports. Devices can be designed for speeds of 10 Mbit or 100 Mbit, as well as universal - 10/100. The delay introduced by the hub into signal propagation is very small - less than 3 microseconds. Despite the star-shaped physical topology of a twisted-pair network built using a hub, it is logically no different from a network based on coaxial cable - the same common bus with random access and collision detection (attempts to simultaneously transmit data by different devices). Accordingly, as the number of active nodes in a segment increases, the number of collisions increases, as a result of which the actual network throughput decreases. Another disadvantage of hubs is that generic 10/100 Mbps hubs only operate at 100 Mbps if there are no 10 Mbps devices connected to it. If such a device is found, all hub ports will be switched to 10 Mbit. Devices called Switch Hub (not to be confused with Switching Hub, or simply Switch - we will talk about them later) do not have this last drawback. The Switch Hub is equipped with a buffer that allows you to work with ports of different speeds.
Switching Hub, or just Switch (switch) is a more intelligent device compared to a hub. Switches are capable of dividing networks into segments and forwarding packets between ports based on the destination address included in each packet. This is achieved by creating an internal table that links ports with the addresses of devices connected to them. The network administrator can create this table himself or set it to be created automatically using the switch. Using the address table and the destination address contained in the packet, the switch creates a virtual connection from the source port to the destination port and transmits the packet through this connection, while the delay in signaling is minimal. The virtual connection between the switch ports is maintained during the transmission of one packet, i.e. it is created anew for each package. Because the packet is sent only to the port to which the destination is connected, other users will not receive the packet, so switches reduce network collisions and provide security features that hubs cannot. As noted earlier, data is transmitted directly from port to port, however, when transmitting packets between ports operating at different speeds, on-the-fly switching cannot be used, therefore, when organizing a virtual connection between ports with different speeds, packets are buffered, which leads to an increase in packet transmission delays up to 30-40 microseconds. Unfortunately, typical switches operate on an "address aging" algorithm. This means that if after a certain period of time there have been no calls to any address, this address is removed from the address table. When a new packet arrives at this address, it will be impossible to establish a direct connection, which will cause the same delay in data transmission as when connecting ports of different speeds - 30-40 microseconds. This problem has been solved in a series of switches that support SNS technology, which was previously called SFS. One of its features is that the switches that make up the network store the address table “eternally” and exchange these tables with each other, and can also upload them to a special server. This allows not only to reduce the time it takes for a packet to travel through the network, but also to solve a number of specific problems, especially those related to security. Many switches have the ability to organize simultaneous connections between any pairs of device ports - this significantly expands the total network throughput.

Issues of building local networks seem very complex to non-specialist users due to the extensive terminological dictionary. Hubs and switches are imagined as complex equipment reminiscent of telephone exchanges, and the creation of a local home network becomes a reason to turn to specialists. In fact, the switch is not as scary as its name: both devices are elementary network nodes that have minimal functionality, do not require knowledge of installation and operation, and are quite accessible to everyone.

Definition

Hub— a network hub designed to connect computers into a single local network by connecting Ethernet cables.

Switch(switch) is a network switch designed to connect several computers into a local network via an Ethernet interface.

Comparison

As we can see from the definition, the difference between a hub and a switch is related to the type of device: hub and switch. Despite one task - organizing a local network via Ethernet - devices approach its solution in different ways. A hub is a simple splitter that provides a direct connection between network clients. A switch is a more “smart” device that distributes data packets between clients in accordance with the request.

The hub, receiving a signal from one node, transmits it to all connected devices, and reception depends entirely on the recipient: the computer itself must recognize whether the packet is intended for it. Naturally, the answer assumes the same pattern. The signal pokes into all segments of the network until it finds one that will receive it. This circumstance reduces network throughput (and data exchange speed, respectively). The switch, receiving a data packet from the computer, sends it exactly to the address that was specified by the sender, relieving the network of load. A network organized through a switch is considered more secure: traffic exchange occurs directly between two clients, and others cannot process a signal that is not intended for them. Unlike a hub, a switch provides high throughput of the created network.

Logitec LAN-SW/PS Hub

The switch requires correct configuration of the network card of the client computer: the IP address and subnet mask must match each other (the subnet mask indicates part of the IP address as the network address, and the other part as the client address). The hub does not require any settings, because it works at the physical level of the OSI network model, broadcasting a signal. The switch operates at the channel level, exchanging data packets. Another feature of the hub is the equalization of nodes in terms of data transfer speed, focusing on the lowest rates.

Switch COMPEX PS2208B

Conclusions website

1. Hub is a hub, switch is a switch.
2. The hub device is the simplest, the switch is more “intelligent”.
3. The hub transmits the signal to all network clients, the switch only to the recipient.
4. The performance of a network organized through a switch is higher.
5. The switch provides a higher level of data transmission security.
6. The hub operates at the physical layer of the OSI network model, the switch at the channel layer.
7. The switch requires proper configuration of network cards of network clients.

Now, in a time of all kinds of gadgets and electronic devices that overwhelm the living environment of an ordinary person, the urgent problem is how to link all these smart devices with each other. Almost every apartment has a TV, a computer/laptop, a printer, a scanner, a sound system, and you want to somehow coordinate them, and not transfer an endless amount of information via flash drives, and at the same time not get confused in endless kilometers of wires. The same situation applies to offices - with a considerable number of computers and MFPs, or other systems where it is necessary to link different representatives of the electronic community into one system. This is where the idea of ​​building a local network arises. And the basis of a well-organized and structured local network is a network switch.



DEFINITION

Switch, or switch- a device that connects several smart devices into a local network for data exchange. When information is received on one of the ports, it transmits it further to another port, based on the switching table or MAC address tables. In this case, the process of filling the table is not carried out by the user, but by the switch itself, during operation - during the first data transfer session, the table is empty, and initially the switch relays the incoming information to all its ports. But in the process of operation, it remembers the paths of information, records them in its table, and in subsequent sessions sends the information to a specific address. The table size can include from 1000 to 16384 addresses.

Other devices are also used to build local networks - concentrators (hubs) and routers (routers). Right away, in order to avoid confusion, it is worth pointing out the differences between them and the switch.

Concentrator (aka hub)– is the progenitor of the switch. The time of using hubs is actually a thing of the past, due to the following inconvenience: if information came to one of the hub ports, it immediately relayed it to others, “clogging” the network with excess traffic. But occasionally they are still found, however, among modern network equipment they look like self-propelled carriages of the early 20th century among modern electric cars.

Routers- devices with which switches are often confused because of their similar appearance, but they have a wider range of operating capabilities, and therefore a higher cost. These are a kind of network microcomputers with which you can fully configure the network by registering all device addresses in it and applying logical operating algorithms - for example, network protection.

Switches and hubs are most often used to organize local networks, routers are used to organize a network connected to the Internet. However, it should be noted that now the boundaries between switches and routers are gradually blurring - switches are being produced that require configuration and work with registered addresses of local network devices. They can function as routers, but they are usually expensive devices not for home use.
The simplest and cheapest configuration option for a medium-sized home local network (with more than 5 objects), with an Internet connection, will contain both a switch and a router:

FEATURES OF THE WORK

When purchasing a switch, you need to clearly understand why you need it, how you will use it, and how you will maintain it. To choose a device that best suits your goals and not overpay, let’s consider the main parameters of switches:

• Switch type – managed, unmanaged and customizable.

1. Unmanaged switches – do not support network management protocols. They are the simplest, do not require special settings, and are inexpensive: from 440 to 2990 rubles. The optimal solution for a small local network. Even a person who is far from these matters can handle assembling a local network based on them - you just need to buy the switch itself, cables of the required length to connect the equipment (preferably in the form of an patch cord, i.e. “with plugs” assembled - don’t forget Before purchasing, inspect the equipment to which the cable will be connected, and clarify what type of connector you will need), and assemble the network itself. The simplest setup is described in the documentation for the device.
2. Managed switches - support network management protocols, have a more complex design, offer wider functionality - using a WEB interface or specialized programs, they can be managed by specifying the parameters of the network connected to them, the priorities of individual devices, etc. It is this type of switches that can replace routers . The price for such devices ranges from 2,499 to 14,490 rubles. This type of switches is of interest for specialized local networks - video surveillance, industrial network, office network.
3. Configurable switches are devices that support some settings (for example, configuring VLANs (creating subgroups)), but are still in many ways inferior to managed switches. Configurable switches can be either managed or unmanaged.

• Switch placement – can be of three types:

1. Desktop - a compact device that can simply be placed on a table;
2. Wall-mounted - a small device that, as a rule, can be placed both on a table and on a wall - special grooves/mounts are provided for the latter;
3. Rack-mountable – A device with slots provided for rack-mounting network equipment, but which typically can also be placed on a desk.

• Basic data rate – the speed at which each of the device ports operates. As a rule, several numbers are indicated in the switch parameters, for example: 10/100 Mbit/s - this means that the port can operate at speeds of 10 Mbit/s and 100 Mbit/s, automatically adjusting to the speed of the data source. Models with basic speed are presented:

• Total number of switch ports – one of the main parameters; in principle, it is the one that most influences the configuration of the local network, because it determines how much equipment you can connect. The range is from 5 to 48 ports. Switches with a number of ports of 5-15 are most interesting for building a small home network; devices with a number of ports from 15 to 48 are aimed at more serious configurations.

• – ports supporting speeds of 100 Mbit/s, sometimes up to 48;
• Number of ports with a speed of 1 Gbit/s – ports supporting speeds of 1 Gbit/s – which is especially important for high-speed data transfer, up to 48;
• PoE support – if such a parameter exists , it means that a device connected to a port with this option can be powered via a network cable (twisted pair), without any influence on the transmitted information signal. The function is especially attractive for connecting devices to which it is undesirable or impossible to connect an additional power cable - for example, for WEB cameras.
• SFP ports  – switch ports for communication with higher-level devices, or with other switches. Compared to conventional ports, they can support data transmission over longer distances (a standard port with an RJ-45 connector and a connected twisted pair cable supports transmission within 100m). This port is not equipped with a transceiver, it is only a slot to which you can connect an SFP module, which is an external transceiver for connecting the required cable - optical, twisted pair.

• Packet service speed – a characteristic indicating equipment performance, measured in millions of packets per second – MPps. As a rule, packets of 64 bytes are meant (to be specified by the manufacturer). The value of this characteristic of various devices ranges from 1.4 to 71.4 Mpps.

AREA OF APPLICATION

The scope of application of switches is wide, the most common areas of application are:

• small home local network, including, for example, several computers, a printer, a TV and a stereo system (provided that all equipment supports a network connection);