The structure and basic concepts of a local network. Main functions and advantages of LAN Types of local networks

Local network, device and basic concepts of local network

The article is devoted to the basics of a local network, the following topics will be discussed here:

1. Local network - concept;

4. Local network topology;

5. Protocols used in the local network TCP/IP;

6.IP addresses.

Local network - concept

Net - a group of computers connected to each other using equipment, cables, wi fi or otherwise providing packet information exchange between them. All information on the network is transmitted in packets using the IP and TCP protocols. Today, exchange between computers is carried out in this way, and we will not consider other methods in detail due to their rare use. The connection between two computers can be direct or using a local network controlled by a router.

There are many types of networks, and local area network (LAN) Local Area Network) one of types of connection. If you translate it literally, you get a local territorial network. A local area network is essentially a network used in one building or separate room to ensure the interaction of the computers used in them. Local networks located in different buildings or cities can be connected to each other using satellite communication channels or fiber optic cable, which allows you to create a local network under the control of one company, i.e. A network that includes several local networks is called a corporate network.

The Internet is a global network that connects hundreds of thousands of different networks and hundreds of millions of computers. Regardless of how you access the Internet, every Internet user is, in fact, a network user. Internet users use a wide variety of programs, protocols, ports such as Internet browsers, FTP clients, email programs, instant messengers, WebRTC protocol, https.

A computer that is connected to a network is called a workstation ( Workstation), a person works with this computer. Computers on which no one works, but where information is stored, are called servers. They are used as control centers in the network and as information storage devices. Servers are divided into workgroup server, domain controller server, proxy server, email server, web server, terminal server, database server, file server, application servers, firewalls, DHCP servers, FTP servers, print servers, home server.

How does a local network work?

There are two types of network architecture: peer-to-peer ( Peer-to-peer) and client/server ( Client/Server), At the moment, the client/server architecture has practically replaced the peer-to-peer architecture.

In networks with decentralized control, there is no single center for managing the interaction of workstations and a single computer for storing data. A peer-to-peer local network is a LAN of peer computers, each of which has a unique name and, as a rule, a password to enter it at the time the OS boots.

PC equality means that the administrator of each computer on the local network can convert its local resource into a shared resource and set access rights and passwords. He is also responsible for the safety or performance of this resource. A local resource is a resource that is accessible only from the PC on which it is located. A PC resource that is available to other computers is called shared or shared.

Thus, a peer-to-peer LAN is a LAN in which each workstation can share all or some of its resources with other workstations on the network.

But the absence of a dedicated server does not allow the administrator to centrally manage all resources of a peer-to-peer local network.

Each workstation can perform the functions of both a client and a server, i.e. provide resources to other workstations and use resources from other workstations.

Peer-to-peer local networks can be organized on the basis of all operating systems - starting with Windows 95

Advantages of a peer-to-peer local network:

a) low cost;

b)high reliability.

Flaws:

b) poor information security;

c) the difficulty of updating and changing workstation software.

In local networks with centralized management, the server ensures interactions between workstations, performs the functions of storing public data, organizes access to this data and transmits the data to the client. The client processes the received data and provides the processing results to the user. It should be noted that data processing can also be carried out on the server.

Local networks with centralized control, in which the server is intended only to store and provide information to clients upon requests, are called networks with a dedicated file server. Systems in which the server, in addition to storing information, also processes information are called “client-server” systems.

It should be noted that in server local networks, only server resources are directly available to the client. But workstations that are part of a centrally managed LAN can simultaneously organize a peer-to-peer local network with all its capabilities among themselves.

The software that controls the operation of a centrally managed LAN consists of two parts:

a) the network operating system installed on the server;

b) workstation software, which is a set of programs running under the operating system that is installed on the workstation. At the same time, different operating systems can be installed on different workstations on the same network.

In large hierarchical local networks, UNIX and LINUX are used as network operating systems, which are more reliable. For medium-sized local networks, the most popular network OS is Windows Server.

From all that has been said, we can conclude that the only advantage of the peer-to-peer architecture is its simplicity and low cost.

Client/server networks provide higher levels of performance and security.
Quite often, the same server can perform the functions of several servers, for example, a file server and a web server.

Naturally, the total number of functions that the server will perform depends on the load and its capabilities. The higher the server power, the more clients it can serve and the more services it can provide. Therefore, a powerful computer is almost always assigned as a server.

Local network equipment

To operate a network, network cards and a cable are sufficient; if you need to create a fairly complex network, you will need special network equipment.

Cable

Computers within a local network are connected using cables that transmit signals. A cable connecting two network components ( for example, two computers), is called a segment. Cables are classified depending on the possible values ​​of information transfer speed and the frequency of failures and errors. The most commonly used cables are of two main categories:

Twisted pair;

Fiber optic cable,

Nowadays it is most widely used for building local networks. twisted pair. Inside, such a cable consists of four pairs of copper wire twisted together. Twisted pair also has its own varieties: UTP ( Unshielded Twisted Pair ) and STP ( Shielded Twisted Pair). These types of cable are capable of transmitting signals at a speed of 100 Mb/s over a distance of about 100 m. As a rule, UTP is used in local networks.

In the STP cable, each pair of wires was additionally shielded ( it is wrapped in a layer of foil ), which protects the data being transmitted from external interference. This solution allows you to avoid interference during signal transmission and maintain high transmission speeds over longer distances than when using UTP cable. The twisted pair cable is connected to the computer using an RJ-45 connector. Twisted pair cable is capable of providing network operation at speeds of 10,100 and 1000 Mbit/s.

At the core fiber optic cable There are optical fibers capable of transmitting light, data is transmitted in the form of light pulses. Electrical signals are not transmitted via fiber optic cable, so the signal is transmitted without interference, interference and at a very high speed; data transmission cannot be intercepted, which virtually eliminates unauthorized access. Fiber optic cable is used to transport large amounts of information at the speed of light.

The main disadvantage of such a cable is the complexity of installation.

Network cards

Network cards are designed to connect a computer and a network cable. The network card converts transmitted information from packets using the TCP\IP network protocols. The packet consists of a header with address information and information itself. The header contains address fields, which contain information about the origin and destination of the data. Special software - the router allows you to process all packets that pass within the network.
Any network card has an individual address built into its chips. This address is called the physical or MAC address

This article is dedicated to local network basics, the following topics will be covered here:

• The concept of local network;
• Local network device;
• Equipment for local network;
• Network topology;
• TCP/IP protocols;
• IP addressing.

The concept of a local network

Net - a group of computers connected to each other using special equipment that allows the exchange of information between them. The connection between two computers can be direct ( point-to-point connection) or using additional communication nodes.

There are several types of networks, and a local area network is just one of them. A local area network is essentially a network used within a single building or individual space, such as an apartment, to allow the computers and programs used within them to communicate. Local networks located in different buildings can be connected to each other using satellite communication channels or fiber-optic networks, which makes it possible to create a global network, i.e. a network that includes several local networks.

The Internet is another example of a network that has long since become worldwide and pervasive, containing hundreds of thousands of different networks and hundreds of millions of computers. Regardless of how you access the Internet, through a modem, local or global connection, every Internet user is effectively a network user. A wide variety of programs are used to surf the Internet, such as Internet browsers, FTP clients, email programs, and many others.

A computer that is connected to a network is called a workstation ( Workstation). As a rule, a person works with this computer. There are also computers on the network that no one works on. They are used as control centers in the network and as information storage devices. Such computers are called servers,
If computers are located relatively close to each other and connected using high-speed network adapters, then such networks are called local networks. When using a local network, computers are usually located within the same room, building, or in several nearby houses.
To connect computers or entire local networks that are located at a considerable distance from each other, modems are used, as well as dedicated or satellite communication channels. Such networks are called global. Typically, the data transfer speed in such networks is much lower than in local ones.

LAN device

There are two types of network architecture: peer-to-peer ( Peer-to-peer) and client/server ( Client/Server), At the moment, the client/server architecture has practically replaced the peer-to-peer architecture.

If a peer-to-peer network is used, then all computers included in it have the same rights. Accordingly, any computer can act as a server that provides access to its resources, or a client that uses the resources of other servers.

In a network built on a client/server architecture, there are several main computers - servers. The remaining computers that are part of the network are called clients, or workstations.

Server - it is a computer that serves other computers on the network. There are various types of servers, differing from each other in the services they provide; database servers, file servers, print servers, mail servers, web servers, etc.

Peer-to-peer architecture has become widespread in small offices or home local networks. In most cases, to create such a network, you will need a couple of computers that are equipped with network cards and a cable. The cable used is twisted pair cable of the fourth or fifth category. Twisted pair gets its name because the pairs of wires inside the cable are twisted ( this avoids interference and external influences). You can still find fairly old networks that use coaxial cable. Such networks are obsolete, and the information transmission speed in them does not exceed 10 Mbit/s.

After the network has been created and the computers are connected, you need to configure all the necessary parameters programmatically. First of all, make sure that the computers you are connecting to have operating systems that support networking ( Linux, FreeBSD, Windows)

All computers in a peer-to-peer network are united into workgroups that have their own names ( identifiers).
In the case of a client/server network architecture, access control is carried out at the user level. The administrator has the opportunity to allow access to the resource only to certain users. Let's assume that you make your printer available to network users. If you do not want anyone to print on your printer, then you should set a password for working with this resource. With a peer-to-peer network, anyone who knows your password can gain access to your printer. In a client/server network, you can restrict certain users from using the printer, whether they know the password or not.

To gain access to a resource on a local network built on a client/server architecture, the user must enter a username (Login) and password (Password). It should be noted that the username is public information, and the password is confidential.

The process of verifying a username is called authentication. The process of checking whether the entered password matches the username is authentication. Together, identification and authentication constitute the authorization process. Often the term " authentication" - used in a broad sense: to indicate authentication.

From all that has been said, we can conclude that the only advantage of the peer-to-peer architecture is its simplicity and low cost. Client/server networks provide higher levels of performance and security.
Quite often, the same server can perform the functions of several servers, for example, a file server and a web server. Naturally, the total number of functions that the server will perform depends on the load and its capabilities. The higher the server power, the more clients it can serve and the more services it can provide. Therefore, a powerful computer with a large amount of memory and a fast processor is almost always assigned as a server ( As a rule, multiprocessor systems are used to solve serious problems)

Equipment for local network

In the simplest case, network cards and a cable are enough to operate the network. If you need to create a fairly complex network, you will need special network equipment.

Cable

Computers within a local network are connected using cables that transmit signals. A cable connecting two network components ( for example, two computers), is called a segment. Cables are classified depending on the possible values ​​of information transfer speed and the frequency of failures and errors. There are three main categories of cables most commonly used:

• Twisted pair;
• Coaxial cable;
• Fiber optic cable,

Nowadays it is most widely used for building local networks. twisted pair. Inside, such a cable consists of two or four pairs of copper wire twisted together. Twisted pair also has its own varieties: UTP ( Unshielded Twisted Pair - unshielded twisted pair) and STP ( Shielded Twisted Pair - shielded twisted pair). These types of cable are capable of transmitting signals over a distance of about 100 m. As a rule, UTP is used in local networks. STP has a braided copper strand jacket that has a higher level of protection and quality than UTP cable jacket.

In the STP cable, each pair of wires was additionally shielded ( it is wrapped in a layer of foil), which protects the data being transmitted from external interference. This solution allows you to maintain high transmission speeds over longer distances than if you use a UTP cable. The twisted pair cable is connected to the computer using an RJ-45 connector ( Registered Jack 45), which closely resembles an RJ-11 telephone jack ( Regi-steredjack). Twisted pair cable is capable of providing network operation at speeds of 10,100 and 1000 Mbit/s.

Coaxial cable consists of a copper wire covered with insulation, shielding metal braiding and an outer sheath. The central wire of the cable transmits signals into which the data has previously been converted. Such a wire can be either solid or multi-core. To organize a local network, two types of coaxial cable are used: ThinNet ( thin, 10Base2) and ThickNet ( thick, 10Base5). At the moment, local networks based on coaxial cable are practically not found.

At the core fiber optic cable There are optical fibers (light guides), through which data is transmitted in the form of light pulses. No electrical signals are transmitted through a fiber optic cable, so the signal cannot be intercepted, which virtually eliminates unauthorized access to data. Fiber optic cable is used to transport large amounts of information at the highest available speeds.

The main disadvantage of such a cable is its fragility: it is easy to damage, and can only be mounted and connected using special equipment.

Network cards

Network cards make it possible to connect a computer and a network cable. The network card converts the information that is intended to be sent into special packets. A packet is a logical collection of data that includes a header with address information and information itself. The header contains address fields that contain information about the origin and destination of the data. The network card analyzes the destination address of the received packet and determines whether the packet was actually sent to a given computer. If the output is positive, the board will transmit the packet to the operating system. Otherwise, the package will not be processed. Special software allows you to process all packets that pass within the network. This opportunity is used by system administrators when analyzing the operation of the network, and by attackers to steal data passing through it.

Any network card has an individual address built into its chips. This address is called the physical or MAC address ( Media Access Control - access control to the transmission medium).

The order of actions performed by the network card is as follows.

1. Receiving information from the operating system and converting it into electrical signals for further sending via cable;
2. Receiving electrical signals over a cable and converting them back into data that the operating system can work with;
3. Determining whether the received data packet is intended specifically for this computer;
4. Controlling the flow of information that passes between a computer and a network.

Hubs

Hub (hub) is a device capable of combining computers into a physical star topology. The hub has several ports that allow you to connect network components. A hub with only two ports is called a bridge. A bridge is required to connect two network elements.

The network together with the hub is " common bus" Data packets when transmitted through the hub will be delivered to all computers connected to the local network.

There are two types of concentrators.

Passive hubs. Such devices send the received signal without preprocessing it.
Active hubs ( multi-post repeaters). They receive incoming signals, process them and transmit them to connected computers.

Switches

Switches are needed to organize a closer network connection between the sending computer and the destination computer. During data transfer through the switch, information about the MAC addresses of computers is recorded in its memory. Using this information, the switch compiles a routing table, in which for each computer it is indicated that it belongs to a specific network segment.

When the switch receives data packets, it creates a special internal connection ( segment) between two of its Ports using a routing table. It then sends a data packet to the appropriate port on the destination computer, based on the information described in the packet header.

Thus, this connection is isolated from other ports, which allows computers to exchange information at the maximum speed that is available for this network. If a switch has only two ports, it is called a bridge.

The switch provides the following features:

• Send a packet with data from one computer to the destination computer;
• Increase data transfer speed.

Routers

A router is similar in principle to a switch, but has a greater range of functionality. It studies not only the MAC, but also the IP addresses of both computers involved in data transfer. When transporting information between different network segments, routers analyze the packet header and try to calculate the optimal path for the packet to travel. The router is able to determine the path to an arbitrary network segment using information from the route table, which allows you to create a shared connection to the Internet or WAN.
Routers allow packets to be delivered in the fastest way, which increases the throughput of large networks. If some network segment is overloaded, the data flow will take a different path,

Network topology

The order in which computers and other elements are located and connected on a network is called network topology. A topology can be compared to a network map, which shows workstations, servers and other network equipment. The selected topology affects the overall network capabilities, the protocols and network equipment that will be used, and the ability to further expand the network.

Physical topology - it is a description of how the physical elements of the network will be connected. Logical topology defines the routes for data packets to take within a network.

There are five types of network topologies:

• Common bus;
• Star;
• Ring;

Common bus

In this case, all computers are connected to one cable, which is called a data bus. In this case, the packet will be received by all computers connected to this network segment.

Network performance is largely determined by the number of computers connected to the common bus. The more such computers there are, the slower the network works. In addition, such a topology can cause various collisions that occur when several computers simultaneously try to transmit information to the network. The likelihood of a collision increases with the number of computers connected to the bus.

Advantages of using networks with a topology " common bus» the following:

• Significant cable savings;
• Easy to create and manage.

Main disadvantages:

• the likelihood of collisions occurring as the number of computers on the network increases;
• a cable break will shut down many computers;
• low level of protection of transmitted information. Any computer can receive data that is transmitted over the network.

Star

When using a star topology, each cable segment coming from any computer on the network will be connected to a central switch or hub. All packets will be transported from one computer to another through this device. Both active and passive hubs can be used. If the connection between the computer and the hub is lost, the rest of the network continues to work. If the hub fails, the network will stop working. With the help of a star structure, even local networks can be connected to each other.

Using this topology is convenient when searching for damaged elements: cables, network adapters or connectors, " Star" more comfortable " common bus"and in case of adding new devices. It should also be taken into account that networks with transmission speeds of 100 and 1000 Mbit/s are built according to the topology “ star».

If in the very center " stars» position the hub, the logical topology will change to a “common bus”.
Advantages " stars»:

• ease of creation and management;
• high level of network reliability;
• high security of information transmitted within the network ( if there is a commutator in the center of the star).

The main disadvantage is that a failure of the hub leads to the cessation of operation of the entire network.

Ring topology

When using a ring topology, all computers on the network are connected to a single ring cable. Packets pass along the ring in one direction through all the network cards of computers connected to the network. Each computer will amplify the signal and send it further along the ring.

In the presented topology, packet transmission along the ring is organized using the token method. A marker is a specific sequence of binary bits containing control data. If a network device has a token, then it has the right to send information to the network. Only one token can be transmitted within the ring.

The computer that is about to transport the data takes the token from the network and sends the requested information around the ring. Each subsequent computer will transmit data further until this packet reaches the recipient. Once received, the recipient will return an acknowledgment of receipt to the sending computer, and the latter will create a new token and return it to the network.

The advantages of this topology are as follows:

• Large volumes of data are serviced more efficiently than in the case of a shared bus;
• each computer is a repeater: it amplifies the signal before sending it to the next machine, which allows you to significantly increase the size of the network;
• the ability to set different network access priorities; in this case, a computer with a higher priority will be able to hold the token longer and transmit more information.

Flaws:

• a broken network cable leads to the inoperability of the entire network;
• any computer can receive data that is transmitted over the network.

TCP/IP protocols

TCP/IP protocols ( Transmission Control Protocol/Internet Protocol) are the main internetworking protocols and manage data transfer between networks of different configurations and technologies. It is this family of protocols that is used to transmit information on the Internet, as well as in some local networks. The TPC/IP protocol family includes all intermediate protocols between the application layer and the physical layer. Their total number is several dozen.

The main ones are:

• Transport protocols: TCP - Transmission Control Protocol ( transmission control protocol) and others - manage data transfer between computers;
• Routing protocols: IP - Internet Protocol ( internet protocol) and others - ensure the actual transfer of data, process data addressing, determine the best path to the recipient;
• Network address support protocols: DNS - Domain Name System ( domain name system) and others - provides determination of a unique computer address;
• Application service protocols: FTP - File Transfer Protocol ( file transfer protocol), HTTP - HyperText Transfer Protocol, TELNET and others - are used to gain access to various services: file transfer between computers, access to the WWW, remote terminal access to the system, etc.;
• Gateway protocols: EGP - Exterior Gateway Protocol ( external gateway protocol) and others - help transmit routing messages and network status information over the network, as well as process data for local networks;
• Mail protocols: POP - Post Office Protocol ( mail reception protocol) - used to receive email messages, SMPT Simple Mail Transfer Protocol ( mail transfer protocol) - used to transmit mail messages.

All major network protocols ( NetBEUI, IPX/SPX and TCIP) are routed protocols. But you only have to manually configure TCPIP routing. Other protocols are routed automatically by the operating system.

IP addressing

When building a local network based on the TCP/IP protocol, each computer receives a unique IP address, which can be assigned either by a DHCP server - a special program installed on one of the network computers, or using Windows tools, or manually.

The DHCP server allows you to flexibly distribute IP addresses to computers and assign permanent, static IP addresses to some computers. The built-in Windows tool does not have such capabilities. Therefore, if there is a DHCP server on the network, then it is better not to use Windows tools, setting automatic ( dynamic) assigning an IP address. Installing and configuring a DHCP server is beyond the scope of this book.

It should be noted, however, that when using a DHCP server or Windows tools to assign an IP address, loading computers on the network and assigning IP addresses takes a long time, the longer the larger the network. In addition, the computer with the DHCP server must be turned on first.
If you manually assign static networks to computers ( constant, unchanging) IP addresses, then computers will boot faster and immediately appear in the network environment. For small networks, this option is the most preferable, and it is what we will consider in this chapter.

For the TCP/IP protocol bundle, the IP protocol is the basic one, since it is the one that deals with the movement of data packets between computers through networks that use various network technologies. It is thanks to the universal characteristics of the IP protocol that the very existence of the Internet, consisting of a huge number of heterogeneous networks, became possible.

IP protocol data packets

The IP protocol is the delivery service for the entire TCP-iP family of protocols. Information coming from other protocols is packaged into IP protocol data packets, an appropriate header is added to them, and the packets begin their journey through the network

IP addressing system

Some of the most important fields in the IP data packet header are the packet's source and destination addresses. Each IP address must be unique on the internetwork where it is used in order for the packet to reach its intended destination. Even on the entire global Internet, it is impossible to find two identical addresses.

An IP address, unlike a regular postal address, consists solely of numbers. It occupies four standard computer memory cells - 4 bytes. Since one byte (Byte) is equal to 8 bits (Bit), the length of the IP address is 4 x 8 = 32 bits.

A bit represents the smallest possible unit of information storage. It can only contain 0 ( bit cleared) or 1 ( bit set).

Although an IP address is always the same length, it can be written in different ways. The format for recording an IP address depends on the number system used. At the same time, the same address can look completely different:

The binary number 10000110 is converted to decimal as follows: 128 + 0 + 0 + 0 + 0 + 4 + 2 + 0 =134.
The most preferable option, from the point of view of human readability, is the format of writing the IP address in dotted decimal notation. This format consists of four decimal numbers separated by periods. Each number, called an Octet, represents the decimal value of the corresponding byte in the IP address. An octet is so called because one byte in binary consists of eight bits.

When using dotted decimal notation to write octets in an IP address, keep the following rules in mind:

• Only integers are valid;
• Numbers must be in the range from 0 to 255.

The most significant bits in the IP address, located on the left, determine the class and number of the network. Their collection is called a subnet identifier or network prefix. When assigning addresses within the same network, the prefix always remains unchanged. It identifies the ownership of an IP address on a given network.

For example, if the IP addresses of computers on the subnet 192.168.0.1 are 192.168.0.30, then the first two octets define the subnet ID - 192.168.0.0, and the next two - host IDs.

Exactly how many bits are used for certain purposes depends on the class of the network. If the host number is zero, then the address does not point to any one specific computer, but to the entire network as a whole.

Network classification

There are three main classes of networks: A, B, C. They differ from each other by the maximum possible number of hosts that can be connected to a network of a given class.

The generally accepted classification of networks is shown in the following table, which indicates the largest number of network interfaces available for connection, which octets of the IP address are used for network interfaces (*), and which remain unchanged (N).

For example, in the most common class C networks there cannot be more than 254 computers, so only one, the lowest byte of the IP address, is used to number network interfaces. This byte corresponds to the rightmost octet in dotted decimal notation.

A legitimate question arises: why can only 254 computers be connected to a class C network, and not 256? The fact is that some intranet IP addresses are intended for special use, namely:

O - identifies the network itself;
255 - broadcast.

Network segmentation

The address space within each network can be divided into smaller subnets based on the number of hosts ( Subnets). The process of subnetting is also called segmentation.

For example, if the class C network 192.168.1.0 is divided into four subnets, then their address ranges will be as follows:

• 192.168.1.0-192.168.1.63;
• 192.168.1.64-192.168.1.127;
• 192.168.1.128-192.168.1.191;
• 192.168.1.192-192.168.1.255.

In this case, for host numbering, not the entire right octet of eight bits is used, but only the 6 least significant ones. And the remaining two most significant bits determine the subnet number, which can take values ​​from zero to three.

Both regular and extended network prefixes can be identified using a subnet mask ( Subnet Mask), which also allows you to separate the subnet identifier from the host identifier in the IP address, masking with a number the part of the IP address that identifies the subnet.

The mask is a combination of numbers that resembles an IP address in appearance. The binary representation of the subnet mask contains zeros in the bits that are interpreted as the host number. The remaining bits set to one indicate that this part of the address is a prefix. The subnet mask is always used in conjunction with the IP address.

In the absence of additional subnetting, standard network class masks have the following meanings:

When the subnetting mechanism is used, the mask is modified accordingly. Let us explain this using the already mentioned example of dividing a class C network into four subnets.

In this case, the two most significant bits in the fourth octet of the IP address are used to number subnets. Then the mask in binary form will look like this: 11111111.11111111.11111111.11000000, and in dotted decimal form -255.255.255.192.

Private network address ranges

Each computer connected to the network has its own unique IP address. For some machines, such as servers, this address does not change. This permanent address is called static. For others, such as clients, the IP address can be permanent (static) or assigned dynamically each time they connect to the network.

To get a unique static, that is, permanent IP address on the Internet, you need to contact a special organization InterNIC - Internet Network Information Center ( Internet Network Information Center). InterNIC assigns only a network number, and the network administrator must handle further work on creating subnets and numbering hosts independently.

But formal registration with InterNIC to obtain a static IP address is usually required for networks that have a permanent connection to the Internet. For private networks that are not part of the Internet, several blocks of address space are specially reserved, which can be freely used to assign IP addresses without registering with InterNIC:

However, these addresses are used only for internal addressing of networks and are not intended for hosts that directly connect to the Internet.

The LINKLOCAL address range is not a network class in the usual sense. It is used by Windows to automatically assign personal IP addresses to computers on the local network.

I hope you now have an idea about the local network!

Networks? Why is it necessary? What functions does a local network server perform in practice? How to set it up - here is a list of questions that will be discussed in the article.

What is a local server?

A local server is a device that provides its services to users of the Intranet (not to be confused with the Internet). This is the name given to several interconnected computers. Usually there is no Internet access in this case.

Now imagine an office server - this is a device that performs a certain range of functions, relieving the workers’ computers of them. The main device in this case is a hub or switch. Nothing else is needed except But if there are many computers and they are at a great distance, then repeaters can also be used. We will consider further what functions the local network server performs.

Functional

Speaking about what functions a local network server performs, you need to know what tasks are assigned to it. Basically, auxiliary capabilities are transferred to them. So, a local network server can look like:

• file device;
• print server;
• database storage;
• main operating point in the terminal network, etc.

Speaking about the first three cases, it is meant that the server is used as a large device on which there is certain data. So, it can be a storage for files of an automated enterprise management system, simply save the work of personnel and be used in a similar way.

A terminal network is usually used to reduce the cost of existing equipment. Thus, for work in such cases, employees are offered computers with a minimum configuration, the task of which is simply to connect to local servers. All necessary actions, calculations, processing, etc. take place on them, and the data is only transferred to the user’s computer, where it is displayed on the monitor and from where instructions to change them come.

There is also a certain range of other functions. But they are so specialized that it is very inconvenient to talk about each of them - it will take a lot of time and will only be interesting to certain people. Therefore, we will omit information about them.

Thus, the question of what functions the local network server performs can be considered clarified. Now let's talk about how to prepare it for work.

Setting up a local network server

There are many software products available to achieve this task. Therefore, to make the information more specific, let’s consider an example of work in Denver. Its basic package contains all the necessary tools, which means that setting up a local network server will be simple.

To do this, you need to download the software (you can use the official website, since it’s all free). During installation, specify the directory where the files are located. We create it on a computer that will always work when the computer is turned on. Next, you need to configure it to work on a specific port (choose above 1024), and indicate to other computers where to connect.

Now let's talk about how to make it a local network proxy server. To do this, you must have a static IP address for constant stable operation. Then you should disable it (but you must understand that this will reduce the level of security, which will need to be compensated using specialized software). Then we create the following directive: /home/"Your ip"/www. There you need to place a file that will be sent to the address that the user enters. That's it, the proxy server is ready!

Conclusion

As you can see, working with a local server is not a difficult task. Creating various websites on it will not be difficult for almost anyone. Which means it’s worth a try!

This article will discuss what functions a local network server performs. This is a hardware and software complex, with its help the operation of all user computers is regulated. It is based on a very powerful computer with high performance, good optimization, and multitasking. This is what makes it possible to quickly process commands from clients’ personal devices.

Features of server equipment

The server must be multi-core, with a high degree of fault tolerance. It should also have a hot-swappable hardware feature. In other words, any part can be replaced without disconnecting the server from clients and the power grid. As for client computers, they much more often require repairs due to the failure of some parts.

An operating system is used, a kind of layer necessary for communication between executable programs and hardware.

File server

It is worth noting that this is one of the most important functions of any server equipment. Local networks provide all users with access to stored files on a central PC. In addition, they can manage all directories. For example, any user on the network can access the storage for the necessary documents, reports, projects, tables, even multimedia.

Planned work on a file server can never do without publishing some documents. This will significantly reduce time and speed up task completion. Any participant can view changes, track the status of document corrections or any reports.

The main feature of such a server is that you can control access to files. Assign public or personal access. This means that all users of client personal computers will be able to read and change any file. If only personal access is open, then only a few people can view and change documents.

Terminal server

This is a server that provides computing resources to all its users. As a rule, when using it, it is allowed to run only the licensed software necessary for operation. All users have a client called the “desktop protocol” installed on their computers. If the connection with the server is correct, then the user will definitely see all the content on the desktop. Now you know what functions the local network server performs when organizing access to files.

He will also be able to work with all programs remotely; for this, only his resources are used, there is no load on the client computer. It is worth noting about the features of working with a client. And it lies in the fact that information coming from the client to the server is intercepted through the clipboard.

Print server

The functions of this type of server include organizing access to printing devices. Sometimes it is called a print server, it is necessary so that several workers can use one fax or printer at once. This method implies that remote printing will be performed on the device. Moreover, this printer does not connect directly to one specific work computer. These are the functions that a local network server performs in the case of shared access to printers and faxes.

The print server allows you to process several flows of operations at once, and ensures printing documents from several personal computers without significant downtime. It is also worth noting that installing all printers in one room will greatly simplify office work. If you know the address, then you just need to select the one you need from the list of public devices.

Database server

It is necessary in order to work with SQL queries that come from a personal computer user to a specific database. With the help of such a server, the safety and integrity of all data is ensured. This tool allows you to work with sections, tables, formulas, and reports.

Now you know about databases and what a local network is. The functions of the computer network in this case are to provide access to specific documents to PC users.

When a user connects to a database, he uses only the computing power of the server hardware. An example is computers with the most common versions of software, for example “1C:Enterprise”, “Parus-Accounting”, etc. On such platforms you can implement a server that uses a database management system:

1. Oracle Database Server.
2. Microsoft SQL Server.
3. My-SQL.
4. Informix.
5. Firebird.

There are other similar DBMSs. But what functions does a local network server perform besides these? He can play the role of a “postman” who delivers letters from the boss to the workers and back.

Mail server

It is necessary in order to store letters, as well as exchange information between all users of the local network. Moreover, the functions of such a server include storing all user addresses that are available on the network.

In addition, correspondence is exchanged between all participants, you can send reports, participate in the mailing list, and also create calendar projects for any meetings and events. In this case, the server and local stations must be on the same network.

Flaws

Now we need to consider what disadvantages server-based local networks may have:

1. In the event of a server emergency, there is a very high probability of downtime of the entire network. This usually happens when the integrity of network equipment is compromised.
2. High costs, from a financial point of view, for the purchase of licensed software and equipment.
3. Setting up all equipment is quite complex, so qualified technical personnel are required.

Now you know what functions the local network server performs. We briefly listed all his responsibilities in the article.

Do you want to optimize your company's work as much as possible? You just need to install a local area network. This will allow employees to use the computer equipment, databases and programs needed in their work. Regardless of the location of the workplace, team members will be able to transfer information, send email, etc.

Main functions and advantages of LAN

The main functions of a LAN are identified. This:

• prompt sending of documentation (electronically) to all branches of the organization;
• constant communication between the team. The LAN will ensure communication between employees located in
• head office and branches;
• the ability to access office equipment (printers, faxes, modems) from different points in the office;
• automation of the use of all databases (archives, storage);
• providing public access to the Internet;
• remote communication (teleconferences). This is important for meetings and conferences;
• possibility of remote network administration.

Current LAN installation price available on the website of the company providing such a service. Please read the price list carefully before submitting your application.

After installing the LAN, you get the opportunity to quickly receive and send any information. Plus, by connecting all computers to a single communication network, the overall speed of work increases significantly.

What does LAN installation involve? The work consists of several stages:

• visit of a specialist to the site;
• system design;
• selection of necessary equipment;
• direct installation work;
• adjustment and configuration of equipment;
• testing and delivery.

LAN installation should only be carried out by professionals. This process requires strict adherence to technology. The slightest mistake will lead to the fact that the office equipment simply will not function. This is unacceptable downtime in the company's work and losses.

Firms offering LAN installation must have a license to engage in such activities. An important factor is the minimum time frame within which the work will be completed. After the installation is completed, it is wiser to conclude a contract for system maintenance.

After connecting your computers to a single network, you will immediately feel the difference. The work will be done much faster. LAN capabilities allow you to connect devices to it in different offices, cities and even countries.