What is sks and lvs. Local area network (LAN). Technologies for building local networks. \\

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What is the difference between SCS and Local Area Networks (LAN)?

A LAN is a computer network built on the basis of the requirements of one technology that will be used in this network, most often Ethernet and it covers only computers. The main difference between SCS and LAN is its independence from the applications that will be used later, which allows it to support a wide range of applications.

SCS is a broader concept than a LAN, since it covers the transmission of information of a wide range of tasks, such as the transmission of voice, data and video images, thereby allowing integration into a single information structure computer and telephone network, fire and burglar alarms, video surveillance, television, radio, etc. A properly constructed SCS is a reliable and flexible structure with advanced tools for its management, monitoring and expansion.

SCS allows you to quickly and easily change the configuration of the cable system without changing its capital base.

Advantages of structured cabling systems over conventional ones:

• a single cable system (transmission medium) is used for data, voice and video transmission;
• long term exploitation that justifies the investment;
• modularity and the ability to change the configuration and expand without replacing the entire existing network;
• allow the simultaneous use of several different network protocols;
• do not depend on changes in technology and equipment supplier;
• use standard components and materials (copper unshielded and shielded twisted cable, fiber optic cable);
• allow management and administration of a minimum number of service personnel;
• allow combining fiber-optic and copper cables in one network.
• reduction of the cost and time of installation of systems, since the laying of the entire cable infrastructure can be carried out by one, not several companies.

Design and installation of SCS are carried out in accordance with the international standard ISO / IEC 11801. The department implements a quality management system for certification for compliance state standard DSTU ISO 9001-2001.

The works are carried out using high quality AMP, R&M components. We carry out 100% testing and certification of the objects being handed over with the provision of a component or system guarantee from manufacturers of passive equipment (15-25 years).

Usually covering a relatively small area or a small group of buildings (home, office, firm, institute). There are also local networks, the nodes of which are geographically dispersed over distances of more than 12,500 km (space stations and orbital centers). Despite such distances, such networks are still classified as local.

Here it is necessary to mention such important concepts as subscriber, server, client.

Subscriber (node, host, station) is a device connected to a network and actively participating in information exchange. Most often, the subscriber (node) of the network is a computer, but the subscriber can also be, for example, a network printer or other peripheral devicethat has the ability to directly connect to the network. Further in the course instead of the term "subscriber" for simplicity, the term "computer" will be used.

Server a subscriber (node) of the network is called, which provides its resources to other subscribers, but does not itself use their resources. Thus, it serves the network. There can be several servers in the network, and it is not at all necessary that the server is the most powerful computer. Dedicated a server is a server that only deals with network tasks. Non-dedicated server can perform other tasks in addition to maintaining the network. A specific type of server is a network printer.

Client is a network subscriber who only uses network resources, but does not give his resources to the network himself, that is, the network serves him, and he only uses it. A client computer is also often referred to as a workstation. In principle, each computer can be both a client and a server at the same time. The server and the client are often understood as not the computers themselves, but those working on them. software applications... In this case, the application that only gives the resource to the network is the server, and the application that only uses the network resources is the client.

Tasks of drugs

Local area networks allow individual users to communicate with each other easily and quickly. Here are just a few of the tasks that drugs can perform:

• joint work with documents;
• simplification of document flow: you get the opportunity to view, correct and comment on documents without leaving your workplace, without organizing meetings and meetings that take a lot of time;
• saving and archiving your work on the server, so as not to use valuable space on your PC's hard drive;
• easy access to applications on the server;
• facilitating the sharing of expensive resources in organizations such as printers, CD-ROM drives, hard drives and applications (eg word processors or database software);

LAN components

Basic components and technologies related to architecture local area networksmay include:

Hardware:

• Cables;
• Servers;
• Network interface cards (NIC, Network Interface Card);
• Concentrators;
• Remote access servers;

Software:

• Network control software

A little history of computer communications

Communication over short distances in computer technology existed long before the appearance of the first personal computers.

Large computers (mainframes) were attached to numerous terminals (or "smart displays"). True, there was very little intelligence in these terminals, they practically did not do any information processing, and the main purpose of organizing communication was to share the intelligence ("machine time") of a large powerful and expensive computer between users working at these terminals. This was called time-sharing because big computer consistently in time solved the problems of many users. In this case, it was achieved sharing the most expensive resources at that time were computing resources (Fig. 1.1).

Figure: 1.1. Connecting terminals to a central computer

Then microprocessors and the first microcomputers were created. Now it is possible to place a computer on the desk of each user, since computing and intellectual resources have become cheaper. But all the other resources were still quite expensive. And what does naked intelligence mean without the means of storing information and documenting it? Every time you turn on the power, you will not retype the program being executed or store it in a small permanent memory. Means of communication came to the rescue again. By combining several microcomputers, it was possible to organize their joint use of computer peripherals (magnetic disks, magnetic tape, printers). At the same time, all information processing was carried out on site, but its results were transferred to centralized resources. Here, again, the most expensive thing in the system was shared, but in a completely new way. This mode is called the inverse time-sharing mode (Fig. 1.2). As in the first case, communications reduced the cost computer system generally.

Figure: 1.2. Networking of the first microcomputers

Then came personal computers, which differed from the first microcomputers in that they had full set sufficiently developed for fully autonomous work peripherals: magnetic disks, printers, not to mention more advanced user interface (monitors, keyboards, mice, etc.). Peripherals fell in price and became quite comparable with a computer at a price. It would seem, why now connect personal computers (Fig. 1.3)? What should they share, when everything is already divided and is on the table of each user? There is enough intelligence on the spot, as well as the periphery. What can the network give in this case?

Figure: 1.3. Networking of personal computers

The most important thing is, again, the sharing of the resource. The same reverse division of time, but on a fundamentally different level. Here it is already used not to reduce the cost of the system, but to more efficiently use the resources available to computers. For example, a network allows you to combine the volume of disks of all computers, providing each of them with access to the disks of all the others as their own.

But the advantages of the network are most evident when all users are actively working with a single database, requesting information from it and entering a new one into it (for example, in a bank, in a store, in a warehouse). You can't do with any floppy disks here: you would have to transfer data from each computer to all the others for days on end, maintain a whole staff of couriers. And with the network everything is very simple: any data changes made from any computer immediately become visible and accessible to everyone. In this case, special processing on site is usually not required, and in principle it would be possible to get by with cheaper terminals (return to the first considered situation), but personal computers have an incomparably more convenient user interface, which makes the work of staff easier. In addition, the ability to process complex information on site can often significantly reduce the amount of data transferred.

Figure: 1.4. Using a local network for an organization working together computers

It is also impossible to do without a network in the case when it is necessary to ensure the coordinated operation of several computers. This situation most often occurs when these computers are used not for computing and working with databases, but in control, measurement, control tasks, where the computer is interfaced with one or another external devices (fig. 1.4). Examples are various production technological systems, as well as control systems for scientific installations and complexes. Here, the network allows synchronizing the actions of computers, parallelizing and accordingly speeding up the process of data processing, that is, adding up not only peripheral resources, but also intellectual power.

It is the indicated advantages of local networks that ensure their popularity and wider application, despite all the inconveniences associated with their installation and operation.

Local area network topology

Under topology (layout, configuration, structure) computer network usually refers to the physical location of computers on a network relative to each other and the way they are connected by communication lines. It is important to note that the concept of topology refers primarily to local area networks, in which the structure of connections can be easily traced. AT global networks the structure of connections is usually hidden from users and is not too important, since each communication session can be made along its own path.

The topology determines the requirements for the equipment, the type of cable used, the acceptable and most convenient methods of exchange control, reliability of operation, and the possibility of expanding the network. And although a network user does not often have to choose a topology, it is necessary to know about the features of the main topologies, their advantages and disadvantages.

Factorsthat affect the physical performance of the network and are directly related to the concept of topology.

1)Serviceability of computers (subscribers)connected to the network. In some cases, a subscriber breakdown can block the operation of the entire network. Sometimes a subscriber malfunction does not affect the operation of the network as a whole, does not interfere with other subscribers to exchange information.

2)Serviceability of network equipment, that is, technical means directly connected to the network (adapters, transceivers, connectors, etc.). Failure of the network equipment of one of the subscribers can affect the entire network, but can disrupt the exchange with only one subscriber.

3)Network cable integrity... If the mains cable breaks (for example, due to mechanical stress) exchange of information in the entire network or in one of its parts may be disrupted. Equally critical for electrical cables short circuit in the cable.

4)Cable length limitationassociated with attenuation of the signal propagating along it. As you know, in any medium, during propagation, a signal is attenuated (attenuated). And the greater the distance the signal travels, the more it is attenuated (Fig. 1.8). It is necessary to ensure that the length of the network cable does not exceed the maximum length Lpr, when exceeding which the attenuation becomes unacceptable (the receiving subscriber does not recognize the weakened signal).

Figure: 1.8. Signal attenuation during propagation over the network

There are three basic network topologies:

Bus (bus) - all computers are connected in parallel to one communication line. Information from each computer is simultaneously transmitted to all other computers (Fig. 1.5).

Figure: 1.5. Bus network topology

Bus topology (or, as it is also called, a common bus) by its very structure assumes the identity of the network equipment of computers, as well as the equality of all subscribers to access the network. Computers on the bus can transmit information only one by one, since there is only one communication line in this case. If several computers transmit information at the same time, it will be distorted as a result of overlap (conflict, collision). The bus always implements the so-called half duplex exchange mode (in both directions, but in turn, and not simultaneously).

In the bus topology there is no clearly expressed central subscriber through which all information is transmitted, this increases its reliability (after all, if the center fails, the entire system controlled by it ceases to function). Adding new subscribers to the bus is quite simple and usually possible even while the network is running. In most cases, using the bus requires a minimum amount of interconnect cable compared to other topologies.

Since there is no central subscriber, the resolution of possible conflicts in this case falls on the network equipment of each individual subscriber. As a result, the network hardware in the bus topology is more complex than in other topologies. Nevertheless, due to the widespread use of networks with a bus topology (primarily the most popular network Ethernet), the cost of network equipment is not too high.

Figure: 1.9. Broken cable in a bus topology network

An important advantage of the bus is that if any of the computers on the network fails, serviceable machines can continue to exchange normally.

It would seem that when the cable breaks, two completely workable buses are obtained (Fig. 1.9). However, it should be borne in mind that due to the peculiarities of the propagation of electrical signals along long communication lines, it is necessary to provide for the inclusion of special matching devices, terminators shown in Fig. 1.5 and 1.9 as rectangles. Without termination on, the signal is reflected off the end of the line and distorted so that communication over the network becomes impossible. In the event of a break or damage to the cable, the coordination of the communication line is disrupted, and the exchange stops even between those computers that remained connected to each other. A short circuit at any point in the bus cable will destroy the entire network.

Failure of any subscriber's network equipment on the bus can disable the entire network. In addition, such a failure is rather difficult to localize, since all subscribers are connected in parallel, and it is impossible to understand which one is out of order.

When passing through the communication line of a network with a bus topology, information signals are weakened and not restored in any way, which imposes severe restrictions on the total length of communication lines. Moreover, each subscriber can receive signals of different levels from the network, depending on the distance to the transmitting subscriber. This places additional requirements on the receiving nodes of network equipment.

If we assume that the signal in the network cable is attenuated to an extremely acceptable level on the length Lpr, then the total length of the bus cannot exceed the value of Lpr. In this sense, the bus provides the shortest length compared to other basic topologies.

To increase the length of a network with a bus topology, several segments (parts of the network, each of which is a bus) are often used, interconnected using special amplifiers and signal restorers - repeaters or repeaters (Figure 1.10 shows the connection of two segments, the maximum network length in this case, it increases to 2 Lpr, since each of the segments can be of length Lpr). However, this increase in the length of the network cannot continue indefinitely. Length constraints are related to the finite speed of propagation of signals along the communication lines.

Figure: 1.10. Connecting bus network segments using a repeater

Star - other peripheral computers are connected to one central computer, each of them using a separate communication line (Fig. 1.6). Information from the peripheral computer is transmitted only to the central computer, from the central one - to one or several peripheral ones.

Figure: 1.6. Star network topology

Star is the only network topology with an explicitly dedicated center to which all other subscribers are connected. The exchange of information goes exclusively through a central computer, which bears a heavy load, therefore, as a rule, it cannot be engaged in anything other than the network. It is clear that the network equipment of the central subscriber must be significantly more complex than the equipment of the peripheral subscribers. In this case, there is no need to talk about the equality of all subscribers (as in the bus). Usually, the central computer is the most powerful, it is on it that all the functions of managing the exchange are assigned. In principle, no conflicts in a network with a star topology are possible, since the management is completely centralized.

If we talk about the stability of the star to computer failures, then the failure of a peripheral computer or its network equipment does not in any way affect the functioning of the rest of the network, but any failure central computer makes the network completely inoperable. In this regard, special measures should be taken to improve the reliability of the central computer and its network equipment.

A broken cable or a short circuit in it with a star topology disrupts communication with only one computer, and all other computers can continue to work normally.

In contrast to the bus, in a star on each communication line there are only two subscribers: the central one and one of the peripheral ones. Most often, two communication lines are used to connect them, each of which transmits information in one direction, that is, there is only one receiver and one transmitter on each communication line. This is the so-called point-to-point transmission. All this greatly simplifies the network equipment in comparison with the bus and eliminates the need for additional, external terminators.

The problem of signal attenuation in the communication line is also solved in a star more easily than in the case of a bus, because each receiver always receives a signal of the same level. The maximum length of a network with a star topology can be twice that in the bus (that is, 2 Lpr), since each of the cables connecting the center with a peripheral subscriber can have a length of Lpr.

A serious disadvantage of star topology is the severe limitation of the number of subscribers. Typically, a central subscriber can serve no more than 8-16 peripheral subscribers. Within these limits, the connection of new subscribers is quite simple, but beyond them it is simply impossible. In a star, it is permissible to connect another central subscriber instead of a peripheral one (as a result, a topology of several interconnected stars is obtained).

The star shown in Fig. 1.6 is called an active or true star. There is also a topology called a passive star, which only looks like a star (Figure 1.11). It is now much more widespread than the active star. Suffice it to say that it is used in today's most popular Ethernet network.

In the center of the network with this topology, not a computer is placed, but a special device - a hub or, as it is also called, a hub, which performs the same function as a repeater, that is, it restores incoming signals and sends them to all other communication lines ...

Figure: 1.11. Passive star topology and its equivalent circuit

It turns out that although the cabling scheme is similar to a true or active star, in fact we are talking about a bus topology, since information from each computer is simultaneously transmitted to all other computers, and there is no central subscriber. Of course, a passive star is more expensive than a conventional bus, since in this case a hub is also required. However, it provides a range of additional opportunitiesassociated with the benefits of the star, in particular, simplifies the maintenance and repair of the network. That is why, in recent years, a passive star is increasingly displacing a true star, which is considered an unpromising topology.

An intermediate type of topology between active and passive stars can also be distinguished. In this case, the concentrator not only retransmits the incoming signals, but also controls the exchange, but does not participate in the exchange itself (this is done in the 100VG-AnyLAN network).

The great advantage of a star (both active and passive) is that all connection points are collected in one place. This allows you to easily monitor the network, localize faults by simply disconnecting certain subscribers from the center (which is impossible, for example, in the case of a bus topology), as well as restrict access outsiders to vital network connection points. In the case of a star, a peripheral subscriber can be approached by either one cable (through which there is transmission in both directions), or two (each cable transmits in one of two opposite directions), and the latter is much more common.

A common disadvantage for all star topologies (both active and passive) is that the cable consumption is significantly higher than with other topologies. For example, if computers are located in one line (as in Fig. 1.5), then when choosing a star topology, you will need several times more cable than with a bus topology. This significantly affects the cost of the network as a whole and significantly complicates the cabling.

Ring - computers are sequentially combined into a ring. The transfer of information in a ring is always done in only one direction. Each of the computers transmits information to only one computer, the next in the chain after him, and receives information only from the previous computer in the chain (Fig. 1.7).

Figure: 1.7. Network topology ring

Ring - This is a topology in which each computer is connected by communication lines with two others: from one it receives information, and transmits to the other. On each communication line, as in the case of a star, only one transmitter and one receiver (point-to-point communication) operates. This eliminates the need for external terminators.

An important feature of the ring is that each computer retransmits (restores, amplifies) the signal coming to it, that is, it acts as a repeater. The signal attenuation in the entire ring is irrelevant, only attenuation between adjacent computers in the ring is important. If the maximum cable length, limited by attenuation, is Lpr, then the total ring length can reach NLpr, where N is the number of computers in the ring. The total size of the network in the limit will be NLpr / 2, since the ring will have to be folded in half. In practice, the dimensions of the ring networks reach tens of kilometers (for example, in fDDI networks). The ring is significantly superior in this respect to any other topology.

There is no clearly defined center in a ring topology, all computers can be the same and equal. However, quite often a special subscriber is allocated in the ring, which manages the exchange or controls it. It is clear that the presence of such a single control subscriber reduces the reliability of the network, since its failure immediately paralyzes the entire exchange.

Strictly speaking, computers in a ring are not completely equal in rights (unlike, for example, a bus topology). After all, one of them necessarily receives information from the computer transmitting at the moment, earlier, and the others - later. It is on this feature of the topology that the methods of controlling the exchange over the network, specially designed for the ring, are built. In such methods, the right to the next transfer (or, as they say, to capture the network) is sequentially transferred to the next computer in the circle. Connecting new subscribers to the ring is quite simple, although it requires a mandatory shutdown of the entire network during the connection. As in the case of the bus, the maximum number of subscribers in a ring can be quite large (up to a thousand or more). The ring topology is usually highly resistant to overloads, ensures reliable operation with large flows of information transmitted over the network, since, as a rule, there are no conflicts in it (unlike the bus), and there is also no central subscriber (unlike a star), which can be overloaded with large streams of information.

Figure: 1.12. Two-ring network

The signal in the ring passes sequentially through all the computers on the network, so failure of at least one of them (or its network equipment) disrupts the operation of the network as a whole. This is a significant disadvantage of the ring.

Likewise, an open or short circuit in any of the cables in the ring makes the entire network impossible. Of the three topologies considered, the ring is the most vulnerable to cable damage, therefore, in the case of a ring topology, it is usually envisaged to lay two (or more) parallel communication lines, one of which is in reserve.

Sometimes a network with a ring topology is based on two parallel circular communication lines that transmit information in opposite directions (Figure 1.12). The purpose of such a solution is to increase (ideally, twice) the speed of information transfer over the network. In addition, if one of the cables is damaged, the network can work with another cable (however, the maximum speed will decrease).

In the case of a star-ring topology, not the computers themselves are combined into a ring, but special hubs (shown in Figure 1.16 in the form of rectangles), to which computers are connected using star-shaped double communication lines. In reality, all computers on the network are included in a closed loop, since communication lines form a closed loop inside the hubs (as shown in Figure 1.16). This topology provides the ability to combine the benefits of a star and ring topology. For example, hubs allow you to collect all the cable connection points on your network in one place. If we talk about the distribution of information, this topology is equivalent to a classical ring.

In conclusion, it should also be said about the grid topology (mesh), in which computers are connected to each other not by one, but by many communication lines that form a mesh (Fig. 1.17).

Figure: 1.17. Mesh topology: full (a) and partial (b)

In a full grid topology, each computer is directly connected to all other computers. In this case, with an increase in the number of computers, the number of communication lines increases sharply. In addition, any change in network configuration requires changes to the network hardware of all computers, so full mesh topology has not been widely adopted.

Partial grid topology assumes direct connections only for the most active computers transmitting the maximum amount of information. The rest of the computers are connected through intermediate nodes. The grid topology allows you to choose a route for the delivery of information from subscriber to subscriber, bypassing faulty sections. On the one hand, this increases the reliability of the network, on the other hand, it requires a significant complication of the network equipment, which must choose a route.

In the modern world, local networks have become more than just necessary - they are actually necessary to achieve a good level of labor productivity. However, before you start using such a network, you must create and configure it. Both of these processes are quite difficult and require maximum concentration, especially the first one. An improperly designed and configured LAN will not work at all or will function completely differently than necessary, so the creation of a local network should become the focus of the person doing this.

What is a local network

As a rule, the creation of such communication systems is caused by the need for the collective use of data by users who work on remote computers. LAN not only allows for almost instant exchange of information and simultaneous work with files, but also allows you to use network printers and other devices remotely.

A local area network is a full range of software and hardware resources aimed at creating a single information space. In fact, this is a number of computers located at a distance from each other and connected by a communication line - a cable. The main difference between a LAN and other types of networks is short distancewhere the workstations are located.

Pre-project preparation and design

Before creating a local network, you must first design it, that is, plan the process of its creation. This stage is one of the most significant, since the LAN includes a huge number of components and nodes.

Initially, a technical assignment is drawn up on the basis of primary data, defining several points:

• Functions and tasks of the LAN.
• Selected topology.
• List of available equipment.

Only after deciding on these points, you can start designing. The project itself should contain LAN diagrams, points of arrangement of network equipment, a list of required software and hardware.

A local network is a complex mechanism, but if it is designed correctly and the equipment is selected in accordance with the requirements, in this case, the likelihood of problems in the operation of the communication mechanism becomes minimal.

Required hardware

There is a list of equipment without which no LAN can function. It includes:

• Data transmission lines. The most commonly used coaxial cable and fiber optic. In this case, the length of the coaxial cannot exceed several hundred meters, however, if it is necessary to extend the network over long distances, special repeaters are used - signal repeaters that prevent it from fading.
• Communication equipment: network cards (devices that perform duplex exchange of information between a computer and a data transmission medium), hubs (divide the network into separate segments, structuring the network physically), routers (take on the choice of the packet transmission route), switches (logically divide the LAN into segments, combining several physical circuits), repeaters (provide signal recovery, allowing to increase the length of the transmission medium), transceivers (amplify the signal and convert it into other types, allowing you to use different data transmission media).

List of software tools

No LAN is complete without software... Must-have programs for a local area network include:

• Operating systems of worker nodes. The most frequently used operating system remains Windows 7, although Windows XP is not losing ground either.
• Network operating systems installed on servers are the basis of a LAN, since it is impossible to configure a local network without them. Exactly these software take control of all data flows between the main nodes and the secondary nodes, providing the ability to share network resources. Typically, Microsoft Corporation OS is used: Windows Server 2003 or 2008.

• Network services and applications that enable users to access deleted files, printouts of documents on network printer, viewing work nodes on the network, and sending electronic messages... These services are implemented using software.

Creation and installation of a LAN

Installation and commissioning work takes the most time, since a local network will have to be created in several stages:

• Before starting the installation of communication lines and switching devices, you must first prepare the room.
• Next, you can lay the cable, as well as install the necessary equipment.
• TO cable line communication should connect the server devices and workstations.
• After that, the software is installed and configured.

The installation of cable and equipment has a number of features, therefore, if there are difficulties with how to connect a local network, it is better to entrust the solution of this issue to specialists.

Connecting two computers on a LAN

In some cases, it may be necessary to combine two computers into one network, for example, to create a common information space. This is not very difficult to do if you follow a certain algorithm of actions:

• If necessary, install network adapters in both computers, not forgetting about the drivers.

• Purchase a crimped network cable for connection. If you have the necessary knowledge and skills, crimping can be done on your own - the local network of two computers will not become the worst quality from this.
• Connect both workstations with a communication line.
• Configure the LAN in a specific order.

Algorithm for setting up a local network between two computers for Windows 7

• Select the "Start" menu, then by clicking right click mouse on the "Computer" icon, enter the "Properties" submenu.
• You need to find in the list "Computer and domain name", and then select the item with changing the settings.
• The working name of the computer must be changed by clicking on the corresponding icons.
• The group name should remain unchanged - "Workgroup", but the computer names are changed to "pc1" and "pc2" for the first and second subscribers, respectively.
• Now you can click OK and restart your computer.

In most cases, you may need to assign each host an individual IP address:

• From the start menu select "Settings" and then "Network Connections".
• Right-click the mouse to bring up the "Properties" submenu next to the "Local Area Connection" icon.
• In the "General" tab, select "Properties" of the item "Internet Protocol".
• Make active the line "Use the following IP address" and enter the value 192.168.0.100. Then save the changes made.

Local network and Internet

Work nodes connected to a LAN can be connected to the Internet. A local network, the Internet to which can be connected in two ways, will work at halved speed.

The first connection method is to use a router, which is assigned an identification IP address. And in the second case, you can use a wireless connection.

In this case, a local network is the interaction of two computers, a master and a slave, so the IP address is registered in the gateway of the main one, which is previously connected to the world wide network.

If the LAN is based on the use of a server, each workstation must have an individual IP address, and the proxy server through which the Internet is accessed is indicated in the browser settings.

Wireless LAN

A wireless local area network (WLAN) is a subset of LANs that uses high-frequency radio waves to transmit information. WLAN is an excellent alternative to conventional wired communication, offering several advantages:

• Improving labor productivity. WLAN makes it possible to use the Internet and at the same time not be tied to one room. You can freely change your location without losing your internet connection.
• Easy installation and setup, financial savings and reliability - all these factors are due to the absence of a cable communication line.
• Flexibility. Wireless network installation is real where there is no way to stretch the cable.
• Expandability. Network scalability is greatly simplified with wireless network adaptersthat can be installed on any work node.

WLANs have a certain range, which depends on the characteristics of the network devices and the noise immunity of the building. Typically, the range of radio waves reaches 160 m.

Equipment Needed to Create a Wireless LAN

An access point is used to connect other workstations to the network. This device is equipped with a special antenna that controls the duplex transmission of data (send and receive) using radio signals. Such a point can transmit a signal at a distance of up to 100 m indoors and up to 50 km in an open area.

Access points significantly expand computing power the entire communication system, allowing users to move freely between each of them without losing their connection to the LAN or the Internet. In fact, these radio points act as hubs, providing a connection to the network.

Using access points allows you to scale up your entire WLAN by simply adding new devices. The number of subscribers that one radio point can withstand generally depends on the network congestion, since the traffic is divided equally between each of the users.

Wireless LAN: Windows 7. Configuration Algorithm

First, you should prepare an ADSL modem with WiFi technology, as well as the client points connected to them wireless adapters... After that, you can start building a wireless LAN:

• Connect the modem to the electrical network.
• Launch the WLAN setup wizard on the client device.
• Select the SSID from the list of found wireless networks.

Access point setting:

• The first step is to configure the TCP / IP properties by specifying the IP address and subnet mask.
• After that, specify the value dNS server, since it is not possible to fully configure the local network without this parameter. In most cases, it is enough to make active the item on the automatic assignment of the DNS address.
• It is also mandatory to configure the parameters of the wireless network itself, in which security is important.
• At this stage, you need to configure an Internet connection and filtering for the Windows 7 firewall.
• And the last thing is to connect the wires and check the functionality of the WLAN network.

To create an optimal information space, you can combine the types of networks - cable and wireless, allowing you to take advantage of each of them for the benefit of the enterprise. However, it is important to remember that in our time, it is more and more used wireless networks WLAN with all the benefits cable networks and devoid of their shortcomings.

After completing the creation and configuration of a local network, it is important to provide for its administration and the possibility of maintenance. Even if the LAN installation is perfect, during its operation, various hardware or software malfunctions almost inevitably occur, which is why maintenance should be regular.

A local computer network is also called a local computer network, as it serves to combine network devices into a small group. The interconnection of network devices can be carried out not only using cables, but also using wireless technologies.

Purpose of LAN

Consolidation of network devices is its main purpose. Using a LAN, users can exchange data, connect to shared printers and print documents, store data on a shared server or on their own computer, with the ability to access them by other LAN users.

LAN capacity

Typically, a local area network extends to an office, home, premises or building. A LAN can even connect several buildings, however, if you use twisted pair cable to connect buildings, the distance (cable length) should not exceed 100 meters. Otherwise, data transmission delays may occur. Twisted pair cables are rarely used to connect two or more buildings into one LAN. Most often, an optical cable and associated equipment are used to accomplish this task.

LAN types

Peer-to-peer LAN

A peer-to-peer local area network is used to connect a small number of computers (up to 10 pieces). In a peer-to-peer local area network, each user of his computer makes a decision about access to data for other network users. This LAN is also called peer-to-peer.

Server-based local area network

It is a more widespread type of LAN, more efficient and reliable. The server can serve as regular computer, as well as special, the features and software of which are designed specifically for these purposes. The server can perform a lot of functions: store the data of LAN users, assign rights and restrict access to users, determine optimal routes when sending messages, and much more.

LAN topology / structure

The topology of a local area network determines the structure of how computers will connect to each other.

1. Bus is a serial connection of computers to a network using a common cable.

2. Star is a parallel connection of computers. Each computer is connected with a cable to one device - a hub or hub.

3. Ring - computers are connected by a cable in an inseparable ring. Failure of any computer or cable break - will lead to inoperability of the LAN.