The need to introduce computer technology into the educational process is no longer in doubt. The obvious fact is that our schools have different equipment with computer technology. Differences appear in everything: in the number of computers, in their hardware configuration, in the composition of peripheral equipment (printers, scanners, etc.), in the presence of a local network and Internet connection.

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Local computer network as the basis of the school information center.

The need to introduce computer technology into the educational process is no longer in doubt. The main tasks that can be most effectively solved only through the real and high-quality use of computer technology and information resources in the educational process:

• OS management – ​​processing and analysis of information, working with databases.

• Profile, subject training, innovative activities using all available educational and methodological information.

• Work of the school media library
• Preparation of training courses
• Active work in one information space using the Internet and telecommunications

The obvious fact is that our schools have different equipment with computer equipment. Differences appear in everything: in the number of computers, in their hardware configuration, in the composition of peripheral equipment (printers, scanners, etc.), in the presence of a local network and Internet connection.

There are three main categories of schools according to the physical organization of the information environment:

• schools equipped with one or more computers not connected to each other by a local network;
• schools with computer classes based on peer-to-peer networks;
• schools in which the network of an educational institution operates - several computer classes and administration computers interconnected by a local network with a dedicated server.

Single computers	They represent a stand for solving both educational and administrative tasks by users of different levels of preparedness, and are repositories of various data. Direct data exchange between computers and group work are not possible
Computer class based on a peer-to-peer network	As a rule, a technique similar in hardware platform, connected by a peer-to-peer local network. The tasks that can be solved are also diverse; it is possible to distribute the load between computers, ensure direct data exchange, and organize group work
Information environment of an educational institution based on a network with a dedicated server	In general, various equipment is networked, not grouped in one room (classroom). It is possible to divide computers by types of tasks (for example, educational - separately, administrative - separately) or, if there are several computer classes, by types of educational tasks. Differentiation of user rights, hierarchy of access to information, organization of multi-level group work on the network

Traditionally, in informational resources schools include:

• school library,
• classrooms,
• educational television,
• archives.

New resources are currently being added:

• media library,
• School website,
• file archives..
• legal databases
• Internet resources

Media library usually consists of reference books, encyclopedias, dictionaries in book format, computer training programs on floppy disks, CDs, and educational videos. In our conditions, it is possible to merge the media library with the school library or create a common media library in the Information Center. (The basis may be: Federal set of electronic textbooks, etc.)

One of the indicators of the mastery of computer technology by school administration, subject teachers, and schoolchildren is the creation of a school educational Web site located in the school local version or on the Internet. The success of the school’s interaction with parents, students and the outside world in general depends on the content, organizational structure and functioning of the school’s educational website.

File archive - these are those materials that can be either organized in the form of databases, or simply as a digital archive of the school - a piggy bank of teaching experience (various notes of open lessons, extracurricular activities, photographic materials, etc.);

Legal databases- these are databases like Guarantor, Consultant+,

RELFW system and others, information from which will allow school administrations to make correct, verified decisions.

In education, it is necessary to proceed from the fact that ICT and VT tools should be implemented by participants in the educational process as follows:

• to the teacher when preparing classes, systematization and creation of educational

methodological materials as a working tool.

• the student to master new material, master new technologies, actively participate in the educational process.
• administration effectively manage the educational process and on time

make effective management decisions.

If previously the channels for delivering information at school were:

• telephone (external, internal),
• Speakerphone,
• stands,
• Bulletin board,
• meetings,
• mail,

then now they add:

• school computer local network based on Internet technologies (intranet),
• the Internet itself,
• Email,
• network discussions (chats),
• elements of (video)conferences

To ensure the effective use of ICT in the school education system, it is necessary:

• work of information
• educational center based
• educational institution (not just 1 computer class)
• conducting systematic work
• on attracting to education
• ICT specialists, retraining of personnel and increasing the efficiency of educational activities.

The question of the school’s ability to operate using modern telecommunications is especially acute now. After all, the most timely and complete information is available only if there are both the means and the ability to use communication technologies.

It is working in the Internet environment that provides virtually unlimited creative opportunities for both students and teachers.

There is a smart, knowledgeable assistant nearby - a teacher, plus the opportunity to use the accumulated world experience and knowledge from any field of science and social life.

This is such a powerful tool for influencing minds that it is simply shameful and insulting to underestimate the economic and political potential of modern telecommunications projects.

At the beginning of 2012 in Russia, the number of people using the Internet at least once every three months is estimated at 5.5 million people, of which 4 million 252 thousand people are residents of large and medium-sized cities (100 thousand inhabitants or more).

Internet density per 1000 people:

Tatarstan -20

Samara region – 7

Bashkortostan – 12

Mari El -13

St. Petersburg – 29

Moscow -93 users.

A little about the place of the Internet in education.

Today I see the use of Internet technologies in school as follows:

• Internet access is provided according to needs (reasonable, justified, but still according to needs);
• Any teacher (at first if desired), and even more so an administrator, has a real opportunity to use Internet resources to solve teaching, methodological, educational problems and for management purposes, to receive advice, including on-line, to communicate with colleagues ;
• School students receive a real and constant opportunity (under the guidance and with the direct participation of a teacher) to use Internet technologies to search for information, to participate in the implementation of Internet projects, to communicate with peers, especially with foreign ones. And mostly in school media centers;
• Creation of an intra-school local network and a unified regional educational network with the ability to access the Internet from each teacher’s workplace, providing the teacher with the opportunity to constantly work with a home computer with Internet access. And naturally, the connection between parent – ​​student – ​​teacher – administrator at a personalized level with their rights and capabilities, for example, like “ NET-school".

Information is almost the main value in our time. And its number is increasing every day. The achievements currently available in the field of informatization are primarily due to the highest level of hardware and software modern communication technologies. The digital future that was thought and dreamed about is becoming the familiar digital present. Nowadays you won’t surprise anyone with a personal computer, or the Internet, or a mobile phone, or any other digital device.

When implementing the educational process in computer science at the present stage, school management in the field of computer science and computer science teachers face a number of problems that require resolution. Among them, two main ones can be identified - the need for periodic software updates, which entails financial costs, and the creation of an information and educational environment, which, according to the law on education, includes electronic information resources, electronic educational resources, a set of information technologies, telecommunication technologies, relevant technological means and ensuring students’ mastery educational programs in full, regardless of their location.

One of the methods for solving these problems is cloud technologies. The concept of cloud technologies has gained popularity relatively recently, and the most interesting thing is that it has been used by us for quite a long time. Registering your first address Email We, without knowing it, became users of cloud services. The term “cloud services” (English: cloud computing) is applicable to any services that are provided via the Internet.

The essence of how these services work is that all information is processed and stored on remote computer the Internet, as is the case with your email inbox. All your emails are stored on the mail provider's server, and not on your computer. By deleting and moving letters, you only give the necessary commands to the mail server using your computer. The process of deleting and moving letters is carried out directly by the mail server.

As an example of use cloud technologies in education, we can call electronic diaries and magazines, personal accounts for students and teachers, interactive reception area and more. These are thematic forums where students can exchange information. This includes the search for information, where students can solve certain educational problems even in the absence of a teacher or under his guidance.

For this you can use:

Computer programs

Electronic textbooks

Diagnostic, test and training systems

Applied and instrumental software

Telecommunication systems (e-mail, teleconferencing

Electronic libraries and more.

Thanks to modern technologies and services provided via the Internet, you can create, edit, store and collaborate on various documents on the Google service. Children to use the cloud Google service Docs have created their accounts. After entering Google account was completed, they logged into Google Docs and the service desktop opened in front of them. Cloud technologies have one feature: “sharing” provides other users with the ability to view or edit a document. In “shared access,” students were able to do laboratory work that was kept by the teacher and back created “shared access” for the teacher to evaluate their activities.

The advantage of cloud technologies is obvious. Now you don’t need to buy a powerful and expensive computer, as well as a lot of programs and applications for it, you only need a simple computer with access to the Network, the “cloud” will take care of everything else (processing, storing and backing up information). You are not tied to your computer, because to obtain the necessary information, you only need to remember the data (login, password) to access the service and any computer with Internet access.

The only disadvantage is that your information is not stored directly with you, but on a remote computer. But this is also controversial, since all services take care of the preservation and non-distribution of their clients’ data, because the concept of business reputation has not yet been abolished.

Thus, the use of cloud technologies based on Internet services in the process of teaching computer science provides such opportunities as performing various educational tasks in real time using online editors, eliminating the cost of updating commercial software licenses, ensuring openness and accessibility of educational materials, performing online group projects. Most experts in the development of communication technologies say that over time, all users will prefer to switch to cloud technologies.

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Course work

Designing a LAN in a secondary school

Introduction 3

1. Creating a LAN at school 4
2. Design part 8

2.1 Selection and justification of LAN construction technology 8

2.2 Data transmission medium analysis 8

2.3 Network topology 8

2.4 Access method 9

1. Selection and justification of network hardware 10

3.1 Communication devices 10

3.2 Network equipment 13

3.3 Room layout 16

3.4 Calculation of cable quantity 19

1. Network installation instructions 22
2. Equipment cost calculation 30

Conclusion 31

References 33

Introduction

A local area network is a joint connection of several computers to a common data transmission channel, which ensures the sharing of resources such as databases, equipment, and programs. Using a local network, remote workstations are combined into a single system, which has the following advantages:

1. Resource sharing - allows you to share resources, for example, peripheral devices (printers, scanners), among all stations on the network.
2. Data sharing - allows you to share information located on hard drives workstations and servers.
3. Software sharing - ensures the sharing of programs installed on workstations and the server.
4. Processor resource sharing is the ability to use computing power to process data by other systems on the network.

The development of a local computer network will be carried out in the building of a secondary school.

The purpose of this work is to calculate technical characteristics the network being developed, determination of hardware and software, location of network nodes, communication channels, calculation of the cost of network implementation.

1. Creating a LAN at school

In recent years, there has been a radical change in the role and place of personal computers and information technologies in the life of society. The modern period of development of society is defined as the stage of informatization. Informatization of society involves the comprehensive and massive introduction of methods and means of collecting, analyzing, processing, transmitting, and archival storage of large volumes of information based on computer technology, as well as a variety of data transmission devices, including telecommunication networks.

The concept of modernization of education, the project “Informatization of the education system” and, finally, technological progress pose the task of forming an ICT - a competent person capable of applying knowledge and skills in practical life for successful socialization in the modern world.

The process of school informatization involves solving the following tasks:

• development of pedagogical technologies for the use of information and communication means at all levels of education;
• use of the Internet for educational purposes;
• creation and use of automation tools for psychological and pedagogical testing, diagnostic methods for monitoring and assessing the level of knowledge of students, their advancement in learning, establishing the level of intellectual potential of the student;
• automation of the school administrative apparatus;
• training in the field of communication and information technologies.

A local network unites computers installed in one room (for example, a school computer lab consisting of 8-12 computers) or in one building (for example, in a school building several dozen computers installed in different subject rooms can be combined into a local network).

Local Area Network (LAN) is a computer network covering a relatively small area.

In small local networks, all computers usually have equal rights, i.e., users independently decide which resources of their computer (disks, directories, files) to make publicly available over the network. Such networks are called peer-to-peer.

To increase the performance of the local network, as well as to ensure greater reliability when storing information on the network, some computers are specially allocated for storing files or application programs. Such computers are called servers, and a local area network is called a server-based network.

A typical school LAN looks like this. There is one Internet access point to which the corresponding router (ADSL or Ethernet) is connected. The router is connected to a switch (switch), to which user PCs are already connected. A DHCP server is almost always activated on the router, which means automatic distribution of IP addresses to all user PCs. Actually, this solution has both its pros and cons. On the one hand, the presence of a DHCP server simplifies the process of creating a network, since there is no need to manually make network settings on user computers. On the other hand, in the absence of a system administrator, it is quite typical that no one knows the router access password, and the standard password has been changed. It would seem, why do you need to “get into” the router if everything works anyway? That's how it is, but there are unpleasant exceptions. For example, the number of computers at the school increased (another computer science class was equipped) and problems began with IP address conflicts on the network. The fact is that it is not known what range of IP addresses is reserved on the router for distribution by the DHCP server, and it may well turn out that these same IP addresses are simply not enough. If such a problem occurs, then the only way to solve it without going into the settings of the router itself is to manually register all network settings (IP address, subnet mask and gateway IP address) on each PC. Moreover, in order to avoid IP address conflicts, this must be done on each PC. Otherwise, manually assigned IP addresses may fall out of the range reserved for distribution by the DHCP server, which will eventually lead to an IP address conflict.

Another problem is that all computers connected to the switch and, accordingly, having access to the Internet through the router form one peer-to-peer local network, or simply a workgroup. This working group includes not only the computers installed in the school computer lab, but also all other computers available at the school. This includes the director’s computer, the head teacher’s computer, secretaries’ computers, accounting computers (if there is one at the school), and all other computers with Internet access. Of course, it would be wise to divide all these computers into groups and assign appropriate rights to each user group. But, as we have already noted, no domain controller is provided, and therefore it will simply not be possible to implement this. Of course, this problem could be partially solved at the hardware level by organizing several virtual local networks (VLANs) and thereby physically separating student PCs from other computers. However, this requires a managed switch (or at least a Smart switch), the presence of which is very rare in schools. But even if there is such a switch, you still need to be able to configure virtual networks. You can even not use virtual networks, but install an additional router and switch and use different IP addressing (IP addresses from different subnets) for computers in the computer science class and all other computers. But again, this requires additional costs for purchasing the appropriate equipment and experience in setting up routers. Unfortunately, it is impossible to solve the problem of dividing school computers into groups isolated from each other without additional financial costs (the presence of a managed switch in a school is an exception to the rule). At the same time, such a division is not mandatory. If we consider the need for such separation from the point of view of network security, then the problem of protecting the computers of teachers and administration from attacks by students can be solved in another way.

1. Design part

2.1 Selection and justification of LAN construction technology.

The main purpose of the designed computer network is to ensure communication between network computers and provide the ability to transfer files at speeds of up to 100 Mbit/s. Thus, Fast Ethernet technology will be used to build a LAN for all departments of the building.

LAN construction technologies. In this work, Fast Ethernet technology will be used to build a network, providing a data transfer rate of 100 Mbit/s. A star topology will also be used using unshielded twisted pair CAT5 cable as communication lines.

2.2 Analysis of the data transmission medium.

For data transmission in Fast Ethernet the 100 Base-TX standard will be used. A 4-pair CAT5 cable is used. All pairs participate in data transmission. Options:

 data transfer rate: 100 Mbit/s;

 type of cable used: unshielded twisted pair CAT5;

 maximum segment length: 100 m.

2.3 Network topology.

The topology of a network is determined by the placement of nodes in the network and the connections between them. The term network topology refers to the path along which data travels on a network. For Fast Ethernet technology, a star topology will be used.

To build a network with a star architecture, it is necessary to place a hub (switch) in the center of the network. Its main function is to ensure communication between computers on the network. That is, all computers, including the file server, do not communicate directly with each other, but are connected to a hub. This structure is more reliable, since if one of the workstations fails, all the others remain operational. The star topology is the fastest of all computer network topologies because data transfer between workstations passes through a central node (if its performance is good) over separate lines used only by these workstations. The frequency of requests for information transfer from one station to another is low compared to that achieved in other topologies.

2.4 Access method.

Fast Ethernet networks use the CSMA/CD access method. The basic concept of this method is as follows:

All stations listen to transmissions on the channel, determining the state of the channel;

Carrier check;

The start of transmission is possible only after the free state of the channel is detected;

The station monitors its transmission, when a collision is detected, the transmission stops and the station generates a collision signal;

The transmission is resumed after a random period of time, the duration of which is determined by a special algorithm, if the channel is free at that moment;

Several unsuccessful transmission attempts are interpreted by the station as a network failure.

Even in the case of CSMA/CD, a collision situation may arise when two or more stations simultaneously determine free channel and begin attempting to transfer data.

1. Selection and justification of network hardware

3.1 Communication devices

Selecting a network adapter.

A network adapter is a computer peripheral device that
directly interacting with the data transmission medium, which
directly or through other communications equipment connects it with
other computers. This device solves the problem of reliable exchange
binary data, represented by corresponding electromagnetic signals, over external communication lines. The network adapter is connected via PCI buses to the motherboard.

A network adapter typically performs the following functions:

• registration of transmitted information in the form of a frame of a certain format.
• gaining access to the data transmission medium.
• encoding a sequence of frame bits by sequence electrical signals when transmitting data and decoding when receiving it.
• converting information from parallel to serial form and vice versa.
• synchronization of bits, bytes and frames.

TrendNet TE 100-PCIWN network cards are selected as network adapters.

Selecting a hub (switch).

A hub (repeater) is the central part of a computer network in the case of a star topology.

The main function of a hub is to repeat signals arriving at its port. The repeater improves the electrical characteristics of the signals and their synchronization, and due to this it becomes possible to increase the total cable length between the most remote nodes in the network.

A multiport repeater is often called a hub or hub, reflecting the fact that this device implements not only the signal repetition function, but also concentrates the functions of connecting computers into a network in one central device.

The lengths of cable connecting two computers or any two other network devices are called physical segments, so hubs and repeaters, which are used to add new physical segments, are a means of physically structuring the network.

A hub is a device in which the total throughput of input channels is higher than the throughput of the output channel. Since the input data streams in the concentrator are larger than the output stream, its main task is data concentration.

The hub is active equipment. The hub serves as the center (bus) of a star-shaped network configuration and provides connection to network devices. The hub must have a separate port for each node (PCs, printers, access servers, phones, etc.).

Switches.

Switches control network traffic and control its movement by analyzing the destination addresses of each packet. The switch knows which devices are connected to its ports and routes packets only to the required ports. This makes it possible to simultaneously work with several ports, thereby expanding the bandwidth.

Thus, switching reduces the amount of unnecessary traffic that occurs when the same information is transmitted to all ports,

Switches and hubs are often used on the same network; hubs expand the network by increasing the number of ports, and switches break the network into smaller, less congested segments. However, the use of a switch is justified only in large networks, since its cost is an order of magnitude higher than the cost of a hub.

The switch should be used in the case of building networks in which the number of workstations is more than 50, which includes our case, as a result of which we choose D-Link DES-1024D/E, 24-port Switch 10/100Mbps switches.

3.2 Network equipment

Selecting the cable type.

Today, the vast majority of computer networks use wires or cables as transmission media. There are different types of cables that suit the needs of all kinds of networks from large to small.

Most networks use only three main groups of cables:

• coaxial cable;
• twisted pair:

* unshielded (unshielded); o * shielded;

Fiber optic cable, single mode, multimode (fiber
optical).

Today, the most common type of cable and the most suitable in terms of its characteristics is twisted pair. Let's look at it in more detail.

Twisted pair is a cable in which an insulated pair of conductors is twisted with a small number of turns per unit length. Twisting the wires reduces electrical interference from outside as signals propagate along the cable, and shielded twisted pairs further increase the degree of signal immunity to noise.

Twisted pair cable is used in many network technologies, including Ethernet, ARCNet, and IBM Token Ring.

Twisted pair cables are divided into: unshielded (UTP -Unshielded Twisted Pair) and shielded copper cables. The latter are divided into two varieties: with shielding of each pair and a common screen (STP - Shielded Twisted Pair) and with only one common screen (FTP - Foiled Twisted Pair). The presence or absence of a shield on a cable does not at all mean the presence or absence of protection of the transmitted data, but only speaks of different approaches to suppressing interference. The absence of a shield makes unshielded cables more flexible and resistant to kinks. In addition, they do not require an expensive ground loop for normal operation, like shielded ones. Unshielded cables are ideal for laying indoors inside offices, while shielded cables are best used for installation in places with special operating conditions, for example, near very strong sources of electromagnetic radiation, which are usually not found in offices.

Due to the selected Fast Ethernet 100Base-T technology and star topology, it is suggested that you select Category 5 unshielded twisted pair (UTP) cable.

Selection of connectors.

To connect workstations and the switch, RJ-45 connectors, 8-pin sockets, the cable of which is crimped in a special way, are selected.

When a computer is used to exchange information over the telephone
network, you need a device that can receive a signal from a telephone
network and convert it into digital information. This device
called a modem (modulator-demodulator). The purpose of the modem is to replace the signal coming from the computer (a combination of zeros and ones) with an electrical signal with a frequency corresponding to the operating range of the telephone line.

Modems can be internal or external. Internal modems are made in the form of an expansion card, inserted into a special expansion slot on the computer motherboard. The external modem, unlike the internal one, is made as a separate device, i.e. in a separate case and with its own power supply, when the internal modem receives electricity from the computer's power supply.

Internal modem Advantages

1. All internal models, without exception (unlike external ones), have a built-in FIFO. (First Input First Output - first to come, first to be accepted). FIFO is a chip that provides data buffering. A regular modem, when a byte of data passes through a port, requests interruptions from the computer every time. The computer, using special IRQ lines, interrupts the operation of the modem for a while, and then resumes it again. This slows down the computer overall. FIFO allows you to use interrupts several times less often. This is of great importance when working in multitasking environments. Such as Windows95, OS/2, Windows NT, UNIX and others.
2. When using an internal modem, the number of wires stretched in the most unexpected places is reduced. Also, the internal modem does not take up space on the desktop.
3. Internal modems are a serial port on the computer and do not occupy existing computer ports.
4. Internal modem models are always cheaper than external ones.
   Flaws
5. They occupy an expansion slot on the computer motherboard. This is very inconvenient on multimedia machines that have a large number of additional cards installed, as well as on computers that work as servers in networks.
6. There are no indicator lights that, if you have a certain skill, allow you to monitor the processes occurring in the modem.
7. If the modem freezes, you can restore functionality only by pressing the “RESET” key to restart the computer.

External modems Advantages

1. They do not occupy an expansion slot, and if necessary, they can be easily disabled and transferred to another computer.
2. There are indicators on the front panel that help you understand what operation the modem is currently performing.
3. If the modem freezes, you do not need to restart the computer; just turn off and turn on the modem's power.

Flaws

1. A multicard with built-in FIFO is required. Without a FIFO, the modem will of course work, but the data transfer speed will drop.
2. The external modem takes up space on the desktop and requires additional wires to connect. This also creates some inconvenience.
3. It occupies the computer's serial port.
4. An external modem is always more expensive than a similar internal one, because includes a housing with indicator lights and a power supply.

For our network, we will choose the internal ZyXEL Omni 56K modem. V.90 (PCTel) int PCI.

3.3 Room layout

All diagrams contain symbols:

SV - server.

PC - workstation.

K - switch.

Rice. 1 Network diagram on the first floor

Rice. 2 Network diagram on the second floor

Rice. 3 Network diagram on the 3rd floor

3.4 Calculation of cable quantity

Calculation of the total cable length by floor, required to build a local network, is given in tables 1,2,3. The cable is laid along the walls in special boxes.

Table 1. Cable length on the 1st floor.

K1-K2 16 meters

K1-K3 14 meters

The total cable length on the ground floor is 96 meters.

Table 2. Cable length on 2nd floor

Work station	Length of cable From RS to K

Cable length between switches:

K4K5 17 meters

The length of the cable from the server to K 4 is 1 meter

The total cable length on the second floor is 156 meters.

Table 3. Cable length on 3rd floor

Work station	Cable length from RS to K

Cable length between switches:

K7K6 17 meters

K7K8 15 meters

The total cable length in segment C is 230 meters.

Cable length between floors is 2 meters

The total cable length of the entire local network, taking into account the safety factor, is (96+156+230+2+2)* 1.2=583.2 m.

1. Network installation instructions

At the beginning of the development of local networks, coaxial cable was the most common transmission medium. It was and is used primarily in Ethernet networks and partly ARCnet. There are “thick” and “thin” cables.

Thick Ethernet is typically used as follows. It is laid along the perimeter of a room or building, and 50-ohm terminators are installed at its ends. Due to its thickness and rigidity, the cable cannot connect directly to the network card. Therefore, “vampires” are installed on the cable in the right places - special devices that pierce the cable sheath and connect to its braid and central core. “Vampire” sits so firmly on the cable that once installed it cannot be removed without a special tool. A transceiver, in turn, is connected to the “vampire” - a device that matches the network card and cable. And finally, a flexible cable with 15-pin connectors on both ends is connected to the transceiver - the other end is connected to the AUI (attachment unit interface) connector on the network card.

All these difficulties were justified by only one thing - the permissible maximum length of a “thick” coaxial cable is 500 meters. Accordingly, one such cable can serve a much larger area than a “thin” cable, the maximum permissible length of which, as is known, is 185 meters. With some imagination, you can imagine that a “thick” coaxial cable is an Ethernet hub distributed in space, but completely passive and does not require power. It has no other advantages, but there are more than enough disadvantages - first of all, the high cost of the cable itself (about 2.5 dollars per meter), the need to use special devices for installation (25-30 dollars per piece), inconvenient installation, etc. . This gradually led to the fact that "thick Ethernet" slowly but surely disappeared from the scene, and is currently used in few places.

"Thin Ethernet" is much more widespread than its "thick" counterpart. Its principle of use is the same, but due to the flexibility of the cable it can be connected directly to the network card. To connect the cable, BNC (bayonet nut connector) connectors are used, installed on the cable itself, and T-connectors, which are used to route the signal from the cable to the network card. BNC type connectors can be crimped or dismountable (an example of a collapsible connector is the domestic connector SR-50-74F).

T-connector

To install the connector on the cable, you will need either a special crimping tool or a soldering iron and pliers.

The cable must be prepared as follows:

1. Carefully cut so that its end is even. Place the metal sleeve (a piece of tubing) that comes with the BNC connector onto the cable.
2. Remove the outer plastic sheath from the cable to a length of approximately 20 mm. Be careful not to damage any of the braided conductors if possible.
3. Carefully unravel the braid and spread it apart. Strip the insulation from the center conductor to a length of approximately 5 mm.
4. Install the center conductor into the pin that also comes with the BNC connector. Using a special tool, securely crimp the pin, fixing the conductor in it, or solder the conductor into the pin. When soldering, be especially careful and attentive - poor soldering will cause network failures after some time, and it will be quite difficult to localize this place.
5. Insert the center conductor with the pin installed on it into the connector body until it clicks. A click means that the pin has settled into place in the connector and is locked there.
6. Distribute the braided conductors evenly over the surface of the connector, if necessary, cut them to the required length. Slide the metal sleeve over the connector.
7. Using a special tool (or pliers), carefully crimp the coupling until the braid is in reliable contact with the connector. Do not crimp too hard - you may damage the connector or pinch the insulation of the center conductor. The latter can lead to unstable operation of the entire network. But you also can’t crimp it too loosely - poor contact of the cable braid with the connector will also lead to operational failures.

I note that the domestic CP-50 connector is mounted in approximately the same way, with the exception that the braiding in it is embedded in a special split sleeve and secured with a nut. In some cases this may be even more convenient.

Twisted pair cables

Twisted pair (UTP/STP, unshielded/shielded twisted pair) is currently the most common signal transmission medium in local networks. UTP/STP cables are used in Ethernet, Token Ring and ARCnet networks. They vary by category (based on bandwidth) and conductor type (flexible or solid). A Category 5 cable usually contains eight conductors twisted in pairs (that is, four pairs).

UTP cable

A structured cabling system built on Category 5 twisted pair cable is very flexible in use. Her idea is as follows.

For each workplace At least two (three recommended) four-pair RJ-45 sockets are installed. Each of them is connected with a separate category 5 cable to a cross-connect or patch panel installed in a special room - the server room. Cables from all workplaces are brought into this room, as well as city telephone inputs, dedicated lines for connecting to global networks, etc. Naturally, servers are installed in the premises, as well as office PBX, alarm systems and other communication equipment.

Due to the fact that the cables from all workstations are brought together on a common panel, any socket can be used to connect a workstation to a LAN, for telephony, or anything else at all. Let's say two sockets at the workplace were connected to a computer and a printer, and the third was connected to a telephone exchange. During the work process, it became necessary to remove the printer from the workplace and install a second phone in its place. There is nothing simpler - the patch cord of the corresponding outlet is disconnected from the hub and switched to the telephone cross-connect, which will take no more than a few minutes from the network administrator.

2-port socket

A patch panel, or connection panel, is a group of RJ-45 outlets mounted on a 19-inch wide plate. This is the standard size for universal communication cabinets - racks, in which equipment (hubs, servers, sources) is installed uninterruptible power supply and so on.). On the back side of the panel there are connectors into which the cables are mounted.

The cross, unlike the patch panel, does not have sockets. Instead, it carries special connecting modules. In this case, its advantage over the patch panel is that when used in telephony, the inputs can be connected to each other not with special patch cords, but with ordinary wires. In addition, the cross can be mounted directly on the wall - it does not require a communication cabinet. In fact, there is no point in purchasing an expensive communications cabinet if your entire network consists of one or two dozen computers and a server.

Cables with multicore flexible conductors are used as patch cords, that is, connecting cables between a socket and a network card, or between sockets on a connection panel or cross-connect. Cables with single-core conductors - for laying the cable system itself. The installation of connectors and sockets on these cables is completely identical, but usually cables with single-core conductors are mounted on sockets of user workstations, connection panels and cross-connects, and connectors are installed on flexible connecting cables.

Patch panel

Typically, the following types of connectors are used:

• S110 - the general name of connectors for connecting a cable to a universal cross-connect "110" or switching between inputs on a cross-connect;
• RJ-11 and RJ-12 are six-pin connectors. The former are usually used in general-purpose telephony - you can find such a connector on the cords of imported telephone sets. The second is usually used in telephone sets designed to work with office mini-PBXs, as well as for connecting cables to ARCnet network cards;
• RJ-45 is an eight-pin connector usually used to connect cables to Ethernet network cards or for switching on the connection panel.

RJ-45 connector

Depending on what needs to be connected with what, different patch cords are used: “45-45” (on each side an RJ-45 connector), “110-45” (on one side S110, on the other - RJ-45 ) or "110-110".

To install RJ-11, RJ-12 and RJ-45 connectors, special crimping devices are used, which differ in the number of knives (6 or 8) and the size of the socket for fixing the connector. As an example, consider installing a Category 5 cable to an RJ-45 connector.

1. Carefully trim the end of the cable. The end of the cable must be smooth.
2. Using a special tool, remove the outer insulation from the cable to a length of approximately 30 mm and cut the thread embedded in the cable (the thread is designed to make it easier to remove longer insulation from the cable). Any damage (cuts) to the conductor insulation is absolutely unacceptable - that is why it is advisable to use a special tool whose cutter blade protrudes exactly to the thickness of the outer insulation.
3. Carefully separate, unravel and align the conductors. Align them in one row, while observing the color coding. There are two most common color pairing standards: T568A (recommended by Siemon) and T568B (recommended by ATT and in fact the most commonly used).

On the RJ-45 connector, the colors of the conductors are arranged as follows:

The conductors must be located strictly in one row, without overlapping each other. Holding them with one hand, cut the conductors evenly with the other so that they protrude 8-10 mm above the outer winding.

1. Hold the connector with the latch facing down and insert the cable into it. Each conductor must fall into its place in the connector and rest against the limiter. Before crimping the connector, make sure that you have not made a mistake in wiring the conductors. If the wiring is incorrect, in addition to the lack of correspondence with the contact numbers at the ends of the cable, which is easily detected using a simple tester, a more unpleasant thing is possible - the appearance of “splitted pairs”.

To identify this defect, a conventional tester is not enough, since electrical contact between the corresponding contacts at the ends of the cable is ensured and everything seems to be normal. But such a cable will never be able to provide normal connection quality even in a 10-megabit network over a distance of more than 40-50 meters. Therefore, you need to be careful and take your time, especially if you do not have enough experience.

1. Insert the connector into the socket on the crimping device and crimp it to the stop stop on the device. As a result, the latch on the connector will snap into place, holding the cable stationary in the connector. The contact blades of the connector will each cut into its own conductor, ensuring reliable contact.

In the same way, you can install RJ-11 and RJ-12 connectors using the appropriate tool.

No special crimping tool is required to install the S110 connector. The connector itself is supplied unassembled. By the way, unlike “disposable” RJ-type connectors, the S110 connector allows for repeated disassembly and reassembly, which is very convenient. The installation sequence is as follows:

1. Remove the outer insulation of the cable to a length of approximately 40 mm, spread the pairs of conductors apart without unraveling them.
2. Secure the cable (in the half of the connector that does not have a contact group) with a plastic tie and cut off the resulting “tail”.
3. Carefully place each wire into the organizer on the connector. Do not unravel the pair longer than required - this will degrade the performance of the entire cable connection. The sequence of pairs is the usual - blue-orange-green-brown; in this case, the light wire of each pair is laid first.
4. Using a sharp tool (side cutters or a knife), trim each conductor along the edge of the connector.
5. Replace the second half of the connector and crimp it with your hands until all the latches click into place. In this case, the knives of the contact group will cut into the conductors, ensuring contact.

Fiber optic cable

Fiber optic cables are the most promising and fastest-performing signal propagation medium for local networks and telephony. In local networks, fiber optic cables are used to operate over the ATM and FDDI protocols.

Connector stripper and crimper

Optical fiber, as its name suggests, transmits signals using pulses of light. Semiconductor lasers and LEDs are used as light sources. Optical fiber is divided into single-mode and multimode.

Single-mode fiber is very thin, its diameter is about 10 microns. Thanks to this, the light pulse passing through the fiber is less often reflected from its inner surface, which ensures less attenuation. Accordingly, single-mode fiber provides longer range without the use of repeaters. The theoretical throughput of single-mode fiber is 10 Gbps. Its main disadvantages are high cost and high complexity of installation. Single-mode fiber is mainly used in telephony.

Multimode fiber has a larger diameter - 50 or 62.5 microns. This type of optical fiber is most often used in computer networks. The higher attenuation in multimode fiber is due to the higher dispersion of light in it, due to which its throughput is significantly lower - theoretically it is 2.5 Gbps.

Special connectors are used to connect the optical cable to active equipment. The most common connectors are SC and ST types.

Installing connectors on a fiber optic cable is a very responsible operation that requires experience and special training, so you should not do this at home without being a specialist.

1. Equipment cost calculation

The cost of components is shown in Table 4 (according to the M-video online store in Balakovo).

Table 4 equipment cost

The table shows that the costs of network design do not exceed reasonable limits.

1. Prospects for network development

The LAN presented in this work can develop and expand. At this stage, the following measures can be taken to improve the local network:

Connecting an additional network segment on the second and third floors;

Connecting additional workstations on any part of the network;

Installation of managed switches in the most loaded network segments (directly in computer classes);

Unloading the most loaded network segments by splitting it into branches;

Software updates to improve network quality.

Conclusion

During the work, a local area network was developed, consisting of 38 workstations and 1 server based on Fast Ethernet technology, the most common type of network at present, the advantages of which include ease of configuration and low cost of components. The star topology used in the project provides the possibility of centralized network management and makes it easy to find a failed node. The network is built taking into account future development. As operating system server selected Windows Server 2003 R2. Required quantity calculated network equipment, its price shows data and calculations of the equipment used, construction costs are 66,539 rubles. A detailed network plan has been drawn up, indicating all the characteristics of the components used. The design tasks were generally completed. The work has all the necessary data and calculations to build a network.

Bibliography

1. Aktersky, Yu.E. Computer networks and telecommunications: textbook Yu.E. Acting. - St. Petersburg: PVIRE KV, 2005. - 223 p.
2. Archibald, R.D. Management of high-tech programs and projects / - M.: DMK Press, 2010. - 464 p.
3. Balafanov, E.K. New information technologies. 30 computer science lessons / E.K. Balafanov, B.B. Buribaev, A.B. Dauletkulov. - Alma-Ata.: Patriot, 2004. - 220 p.
4. Brezgunova, I.V. Personal computer hardware and software. operating room Microsoft system Windows XP / - M: RIVSH, 2011. - 164 p.
5. Bryabrin V.M. Personal computer software. - M.: Nauka, 1990. 22 p.
6. Velikhov A.V., Strochnikov K.S., Leontyev B.K. Computer networks: A textbook on the administration of local and united networks / - M: Educational Book-Press, 2004 - 320 p.
7. Voroisky, F.S. Computer science. New systematized explanatory dictionary-reference book (Introduction to modern information and telecommunication technologies in terms and facts) / F.S. Voroisky - 3rd ed., revised. and additional -- M.: FIZMATLIT, 2003. -- 760 s
8. Gilyarevsky, R.S. Information management. Management of information, knowledge, technology - M.: Profession, 2009. - 304 p.
9. Granichin, O.N. Information technologies in management / - M.: Binom, 2011. - 336 p.
10. Guk M. Local network hardware. Encyclopedia - St. Petersburg: Peter, 2000. -576 p.
11. Dodd, A.Z. World of telecommunications. Review of technologies and industry / A.Z. Dodd. - M.: Olymp-Business, 2005. - 400 p.
12. Dan Holme, Nelson Rest, Daniel Rest. Setting up Active Directory. Windows Server 2008. Training course Microsoft / - M: Russian edition, 2011 - 960 p.
13. Zhurin A. Self-instruction manual for working on a computer. MS Windows XP. Office XP/ A. Zhurin. - M.: Korona - Print, 2009. - 370 p.
14. Zaika, A. Computer networks / A. Zaika, M.: Olma-Press, 2006. - 448 p.
15. Zacker Craig. Network infrastructure planning and support Microsoft Windows Server 2003 / - M: Russian edition, 2005 - 544 p.
16. Kangin, V.V. Hardware and software of control systems / - M.: Binom. Knowledge Laboratory, 2010. - 424 p.

Download: You do not have access to download files from our server.

The local network- a computer network covering a relatively small area. It is assumed that you have two or more computers in your classroom.

Computers can connect to each other in a network using various information transmission media: twisted pair, coaxial cable, fiber optic cable, radio channel (Wi-Fi, BlueTooth), infrared range.

We will create a regular wired network on twisted pair. It's not difficult or expensive. Twisted pair cable is widely used in networking technologies and communications; now Category 6 cable is replacing coaxial cable in many places.

twisted pair- type of communication cable, consists of one or more pairs of insulated conductors, twisted together and covered with a plastic sheath. Twisting of conductors is carried out in order to increase the connection of the conductors of one pair (electromagnetic interference equally affects both wires of the pair) and subsequently reduce electromagnetic interference from external sources, as well as mutual interference when transmitting differential signals.

Twisted pair cable comes in several categories:

Category 1 Telephone cable, only for transmitting an analog signal. Just one pair. Category 2 Capable of transmitting data at speeds up to 4 Mbit/s. Old type of cable, two pairs of conductors. Category 3 Capable of transmitting data at speeds up to 10 Mbit/s. Still found in telephone networks. Two pairs of conductors. Category 4 Capable of transmitting data at speeds up to 16 Mbit/s. The cable consists of 4 twisted pairs. Not currently used. Category 5 Capable of transmitting data at speeds up to 100 Mbit/s. A 4-pair cable is what is usually called a “twisted pair” cable. When laying new networks, they use a slightly improved CAT5e cable (125 MHz frequency band), which better transmits high-frequency signals. Limit on cable length between devices (computer-switch, switch-computer, switch-switch) 100 m. Hub-hub limitation 5 m. Category 6 Capable of transmitting data at speeds up to 1000 Mbit/s. Consists of 4 pairs of conductors. Used in Fast Ethernet and Gigabit Ethernet networks. Category 7 Capable of transmitting data at speeds up to 100 Gbit/s. Specification for this type cable has not yet been approved.

Before you go and buy twisted pair, you need to decide how much you need, where and how it will be laid. It is necessary to measure, at least approximately, the distance between the computers of the future network, and it is necessary to take into account all the bends of the classroom, corridors, etc.

If you are making a network of more than two computers, then you need to decide where and how the switch will be located; it must be positioned in such a way that it is at the minimum possible distance from the largest number of machines.

The cable is connected to network devices using connector 8P8C(often erroneously called RJ45 or RJ-45), slightly larger than an RJ11 telephone connector. RJ45 simply took root to designate all 8P8C cables and connectors, but has nothing to do with them.

You can attach the special ferrule using a special crimping tool (some schools have one), but you can use a regular screwdriver to crimp just a few cables.

Network cables can either be purchased at a store or made yourself (especially if a certain length of cable is required).

There are two cable crimping schemes: straight cable and crossover cable. The first circuit is used to connect a computer to a switch or hub, the second is used to connect 2 computers directly.

A network hub or Hub is a network device for combining several Ethernet devices into a common segment. Devices are connected using twisted pair, coaxial cable or optical fiber. Currently, they are almost never produced - they have been replaced by network switches (switches), separating each connected device into a separate segment. Network switches are mistakenly called “smart hubs.” A network switch or switch (jarg from the English switch) is a device designed to connect several nodes of a computer network within one segment. Unlike a hub, which distributes traffic from one connected device to all others, a switch transmits data only directly to the recipient. This improves network performance and security by freeing other network segments from having to (and being able to) process data that was not intended for them.

Each computer connected to the local network must have a special card (network adapter). Modern network adapters support transfer rates of 10 and 100 Mbps and can be integrated on the motherboard or produced as a separate card.

Consider making your own cable

When using a four-pair Category 5 cable, only two pairs are used: one for transmitting and the other for receiving the signal. All wires are color coded.

In order to put the tip on the cable, you need to carefully remove the braid from the cable 2-3 cm long. After this, arrange the wires in the prescribed order.

Take the tip and carefully insert the cable into it until it stops, so that each wire fits into its own groove. After this, insert the tip into the crimping tool and crimp. If crimping is done using a screwdriver, you must first press in all the contacts, positioning the plane of the screwdriver perpendicular to the contacts of the connector, and then press in each contact individually.

The cable obtained in this way is used to connect the network card to a hub or switch. These cables are called straight– in the sense that the same cable layout is used on both sides.

We have already indicated that, in addition to straight cables used to connect the network adapter to a hub (switch), sometimes it becomes necessary to crossover cable. This cable is used to connect two network cards directly to each other.

During production crossover cable At one end of the cable, exactly the same cable layout is observed as for a straight cable, and at the other end, the transmitting pair is replaced with the receiving pair. To do this, you need to swap the first and second wires with the third and sixth ones, respectively. Those. arrange the wires like this:

This cable can be used to create a network of two computers.

Create the required number of cables and connect the computers to the network. We'll talk about it in the next article.

Ministry of Education and Science of the Russian Federation

FSBEI HPE "Nizhny Novgorod State Pedagogical University named after K. Minin"

Faculty of Mathematics, Computer Science and Physics

Department of Informatics and Information Technologies

Final qualifying work

"School local network: setup and support"

Work completed

full-time student

Kochanov I.A.

Scientific director

Isaenkova N.V.

Nizhny Novgorod 2012

Introduction

Chapter 1. Local networks. Structure, characteristics, functions

1.1 History of the development of computer networks

1.2 What is a local area network

1.3 General structure of local area networks organization

1.4 Classification of local area networks

1.5 Addressing in local area networks

1.5 Local network topology

1.7 Access methods and data transfer protocols in local networks

1.8 Methods of accessing communication channels

1.9 Methods of data exchange in local networks

1.10 Technology comparison and configuration determination

1.11 Protocols, interfaces, protocol stacks

1.12 Network communications equipment

1.13 Access to network resources of the local computer network

1.14 Basic technologies of local networks

Chapter 2. Organization of local computing

networks at school

2.1 Goals and objectives of school informatization

2.2 Selecting an operating system

2.3 Choosing the school local network structure

2.4 Server setup

Filtration system control

2.5 Creating group users and setting access rights

Conclusion

Bibliography

Introduction

A computer network is a collection of nodes (computers, terminals, peripheral devices), having the ability to communicate with each other using special communication equipment and software.

The sizes of networks vary widely - from a couple of interconnected computers standing on neighboring tables, to millions of computers scattered around the world (some of them may be located in space objects).

Based on the breadth of coverage, it is customary to divide networks into several categories: local area networks - LAN or LAN (Local-Area Network), allow you to connect computers located in a limited space.

For local networks, as a rule, a specialized cable system is laid, and the position of possible connection points for subscribers is limited by this cable system. Sometimes in local networks they use wireless communication(Wireless), but the ability to move subscribers is very limited.

Local networks can be combined into large-scale formations: (Campus-Area Network) - a campus network that unites local networks of nearby buildings; MAN (Metropolitan-Area Network) - a city-scale network;

WAN (Wide-Area Network) - wide-area network; (Global-Area Network) - global network

The network of networks in our time is called the global network - the Internet.

For larger networks, special wired and wireless ones are installed.

In modern organizations, such as educational institutions, business offices, shops or administrative buildings, it is customary to use local area networks (LANs) to ensure faster, more convenient collaboration. All of the above determines relevance of the topic diploma work "School local network: setup and support."

An object: Local network design.

Item: Design and organization of a school network.

Purpose thesis: study and systematize the theoretical material necessary for building a LAN; organize and configure the work of the LAN at school No. 15 in Zavolzhye.

To achieve this goal, it is necessary to solve the following tasks:

Study the theoretical foundations of LAN.

2. Study the software and hardware.

Study the mechanisms of construction and operation of a LAN.

Explore LAN administration.

Consider the mechanisms for maintaining a LAN at school.

The thesis consists of two chapters: theoretical and practical. The first chapter discusses the basic theory of local networks, namely:

Protocols, methods of transmitting information over a network, hardware for data transmission. The second chapter covers the following aspects:

General goals of informatization of the school, terms of reference of the school director, choice of operating system, choice of local network type, server setup, remote access to students’ computers, as well as restricting access rights to certain operating system resources.

school local area network

Chapter 1. Local networks. Structure, characteristics, functions

1.1 History of the development of computer networks

It should be noted that nowadays, in addition to computer networks, terminal networks are also used. A distinction should be made between computer networks and terminal networks. Terminal networks are built on principles other than computer networks and on a different computer technology. Terminal networks, for example, include: ATM networks, pre-sale ticket offices for various types of transport, etc.

The first powerful computers of the 50s, the so-called mainframes, were very expensive and were intended only for batch data processing. Batch data processing is the most efficient mode of using the processor of an expensive computer.

With the advent of cheaper processors, interactive terminal time-sharing systems based on mainframes began to develop. Terminal networks connected mainframes to terminals. A terminal is a device for interacting with computer, which consists of an input means (for example, a keyboard) and an output means (for example, a display).

The terminals themselves did virtually no data processing, but used the capabilities of a powerful and expensive central computer. This organization of work was called “time-sharing mode,” since the central computer solved the problems of many users sequentially over time. At the same time, expensive computing resources were shared.

Remote terminals were connected to computers through telephone networks using modems. Such networks allowed numerous users to gain remote access to the shared resources of powerful computers. Then powerful computers were united with each other, and thus global computer networks appeared. Thus, networks were first used to transmit digital data between a terminal and a large computer. The first LANs appeared in the early 70s, when minicomputers were released. Mini-computers were much cheaper than mainframes, which made it possible to use them in the structural divisions of enterprises. Then the need arose to exchange data between machines of different departments. To achieve this, many enterprises began to connect their mini-computers and develop the software necessary for their interaction. As a result, the first LANs appeared. The advent of personal computers served as an incentive for the further development of LANs. They were quite cheap and were ideal elements for building networks. The development of LAN was facilitated by the emergence of standard technologies for connecting computers in a network: Ethernet, Arcnet, Token Ring. The emergence of high-quality communication lines provided a fairly high data transfer rate - 10 Mbit/s, while global networks, which used only telephone communication channels poorly suited for data transmission, had a low transmission speed - 1200 bit/s. Due to this difference in speeds, many technologies used in LANs were not available for use in global ones. Currently, network technologies are rapidly developing, and the gap between local and global networks is narrowing, largely due to the emergence of high-speed territorial communication channels that are not inferior in quality to LAN cable systems. New technologies have made it possible to transmit information media such as voice, video images and drawings that were previously uncharacteristic of computer networks. The difficulty of transmitting multimedia information over a network is associated with its sensitivity to delays in the transmission of data packets (delays usually lead to distortion of such information at the end communication nodes). But this problem is being solved and the convergence of telecommunication networks (radio, telephone, television and computer networks) opens up new opportunities for transmitting data, voice and images over global Internet networks.

1.2 What is a local area network

Local area network (LAN, local network, slang local area network; English Local Area Network, LAN) is a computer network that usually covers a relatively small area or a small group of buildings (house, office, company, institute). There are also local networks, the nodes of which are geographically separated over distances of more than 12,500 km (space stations and orbital centers). Despite such distances, such networks are still classified as local.

There are many ways to classify networks. The main classification criterion is considered to be the method of administration. That is, depending on how the network is organized and how it is managed, it can be classified as a local, distributed, urban or global network. The network administrator manages the network or its segment<#"657138.files/image001.gif">

Advantages of bus topology networks:

the failure of one of the nodes does not affect the operation of the network as a whole;

the network is easy to set up and configure;

The network is resistant to failures of individual nodes.

Disadvantages of bus topology networks:

a cable break can affect the operation of the entire network;

limited cable length and number of workstations;

difficult to identify connection defects

Star topology

In a network built using a star topology, each workstation is connected by a cable (twisted pair) to a hub or hub ( hub). The hub provides a parallel connection between PCs and thus all computers connected to the network can communicate with each other.

Data from the network transmitting station is transmitted through the hub along all communication lines to all PCs. Information arrives at all workstations, but is received only by those stations for which it is intended. Since signal transmission in the physical star topology is broadcast, i.e. Since signals from the PC propagate simultaneously in all directions, the logical topology of this local network is a logical bus.

This topology is used in local networks with 10Base-T Ethernet architecture.

Advantages of star topology networks:

easy to connect a new PC;

there is the possibility of centralized management;

The network is resistant to failures of individual PCs and to interruptions in the connection of individual PCs.

Disadvantages of star topology networks:

hub failure affects the operation of the entire network;

high cable consumption;

Ring topology

In a network with a ring topology, all nodes are connected by communication channels into a continuous ring (not necessarily a circle) through which data is transmitted. The output of one PC is connected to the input of another PC. Having started the movement from one point, the data ultimately ends up at its beginning. Data in a ring always moves in the same direction.

The receiving workstation recognizes and receives only the message addressed to it. A network with a physical ring topology uses token access, which grants a station the right to use the ring in a specific order. The logical topology of this network is a logical ring.

This network is very easy to create and configure. The main disadvantage of ring topology networks is that damage to the communication line in one place or PC failure leads to the inoperability of the entire network.

As a rule, the “ring” topology is not used in its pure form due to its unreliability, therefore, in practice, various modifications of the ring topology are used.

Token Ring Topology

This topology is based on the star physical ring topology. In this topology, all workstations are connected to a central hub (Token Ring) like a physical star topology. A central hub is an intelligent device that, using jumpers, provides a serial connection between the output of one station and the input of another station.

In other words, with the help of a hub, each station is connected to only two other stations (previous and subsequent stations). Thus, workstations are connected by a cable loop through which data packets are transmitted from one station to another and each station relays these sent packets. Each workstation has a transceiver device for this purpose, which allows you to control the passage of data in the network. Physically, such a network is built according to the “star” type of topology.

The hub creates a primary (main) and backup ring. If a break occurs in the main ring, it can be bypassed by using the backup ring, since a four-core cable is used. A failure of a station or a break in the communication line of a workstation will not result in a network failure as in a ring topology, because the hub will disconnect the faulty station and close the data transmission ring.

In a Token Ring architecture, a token is passed from node to node along a logical ring created by a central hub. Such token transmission is carried out in a fixed direction (the direction of movement of the token and data packets is represented in the figure by blue arrows). A station holding a token can send data to another station.

To transmit data, workstations must first wait for a free token to arrive. The token contains the address of the station that sent the token, as well as the address of the station to which it is intended. After this, the sender passes the token to the next station in the network so that it can send its data.

One of the network nodes (usually a file server is used for this) creates a token that is sent to the network ring. This node acts as an active monitor that ensures that the marker is not lost or destroyed.

Advantages of Token Ring topology networks:

the topology provides equal access to all workstations;

high reliability, since the network is resistant to failures of individual stations and to interruptions in the connection of individual stations.

Disadvantages of Token Ring topology networks: high cable consumption and, accordingly, expensive wiring of communication lines.

1.7 Access methods and data transfer protocols in local networks

Different networks use different network protocols (data transfer protocols) to exchange data between workstations.

In 1980, Committee 802 was organized at the International Institute of Electrical and Electronics Engineers (IEEE) to standardize local area networks. The 802 Committee developed the IEEE802 family of standards. x, which contain recommendations for designing lower levels of local networks. Standards of the IEEE802 family. x cover only the two lower levels of the seven-layer OSI model - physical and data link, since these are the levels that best reflect the specifics of local networks. The senior levels, starting with the network level, largely have common features for both local and global networks.

The most common access methods include: Ethernet, ArcNet and Token Ring, which are implemented respectively in the IEEE802.3, IEEE802.4 and IEEE802.5 standards. In addition, for local networks operating on optical fiber, the American standardization institute ASNI has developed a standard FDDI, providing a data transfer rate of 100 Mbps.

In these standards, the data link layer is divided into two sublayers, which are called layers:

Logical Link Control (LCC - Logical Link Control)

media access control (MAC - Media Access Control)

The Media Access Control (MAC) layer emerged because LANs use shared media. In modern local networks, several MAC level protocols have become widespread, implementing different algorithms for accessing the shared medium. These protocols completely define the specifics of such local network technologies as Ethernet, Fast Ethernet, Gigabit Ethernet, Token Ring, FDDI.

After access to the medium is obtained, it can be used by a higher channel layer - the LCC layer, which organizes the transfer of logical data units, information frames, with different levels of quality of transport services.

1.8 Methods of accessing communication channels

In local networks that use a shared data transmission medium (for example, local networks with a bus and physical star topology), it is important for workstations to access this medium, since if two PCs begin to simultaneously transmit data, then a collision occurs on the network.

In order to avoid these collisions, a special mechanism is needed that can solve this problem. Bus arbitration is a mechanism designed to solve the problem of collisions. It sets the rules by which workstations determine when the environment is clear and data can be transferred. There are two methods of bus arbitration in local networks:

collision detection

token passing

Collision detection.

When the collision detection method works in local networks, the computer first listens and then transmits. If the computer hears that someone else is transmitting, it must wait for the data transfer to finish and then try again.

In this situation (two computers transmitting at the same time), the collision detection system requires the transmitting computer to continue listening to the channel and, upon detecting someone else's data on it, stop transmitting, trying to resume it after a short (random) period of time. Listening to a channel before transmission is called carrier sense, and listening during transmission is called collision detection. A computer doing this uses a technique called carrier sniffing collision detection, or CSCD.

Passing a token on local networks

Token passing systems work differently. In order to transmit data, the computer must first obtain permission. This means that it must “catch” a special type of data packet circulating in the network, called a token. The marker moves in a closed circle, passing each network computer in turn.

Every time the computer needs to send a message, it catches and holds the token. Once the transmission has finished, it sends a new token to travel further along the network. This approach guarantees that any computer will sooner or later have the right to catch and hold the token until its own transmission ends.

1.9 Methods of data exchange in local networks

To control the exchange (network access control, network arbitration), various methods are used, the features of which largely depend on the network topology.

There are several groups of access methods based on time division of the channel:

centralized and decentralized

deterministic and random

Centralized access is controlled from a network control center, such as a server. The decentralized access method operates on the basis of protocols without control actions from the center.

Deterministic access provides each workstation with a guaranteed access time (for example, scheduled access time) to the data transmission medium. Random access is based on the equality of all stations in the network and their ability to access the medium at any time to transmit data.

Centralized access to mono channel

In networks with centralized access, two access methods are used: the polling method and the delegation method. These methods are used in networks with an explicit control center.

Survey method.

Data exchange on a LAN with a star topology with an active center (central server). With a given topology, all stations can decide to transmit information to the server at the same time. The central server can communicate with only one workstation. Therefore, at any time it is necessary to select only one station broadcasting.

The central server sends requests to all stations in turn. Each workstation that wants to transmit data (the first one polled) sends a response or immediately begins transmission. After the end of the transmission session, the central server continues polling in a circle. Stations, in this case, have the following priorities: the maximum priority is for the one that is closest to the last station that completed the exchange.

Data exchange in a network with a bus topology. In this topology, perhaps the same centralized control as in the "star". One of the nodes (the central one) sends requests to all the others, finding out who wants to transmit, and then allows the transmission to whichever one of them, after the end of the transmission, reports it .

Transfer of authority method (passing token)

A token is a service package of a certain format into which clients can place their information packages. The sequence of transmitting a token over the network from one workstation to another is set by the server. The workstation receives permission to access the data transmission medium when it receives a special token packet. This access method for networks with bus and star topologies is provided by the ArcNet protocol.

Let's consider decentralized deterministic and random methods of access to the data transmission medium. The decentralized deterministic method includes the token passing method. The token passing method uses a packet called a token. A token is a packet that does not have an address and circulates freely over the network; it can be free or busy.

Data exchange in a network with a ring topology ( decentralized deterministic method access)

1. This network uses the “token passing” access method. The transmission algorithm is as follows:

a) a node wishing to transmit waits for a free token, upon receiving which it marks it as busy (changes the corresponding bits), adds its own packet to it and sends the result further into the ring;

b) each node that receives such a token accepts it and checks whether the packet is addressed to it;

c) if the packet is addressed to this node, then the node sets a specially allocated acknowledgment bit in the token and sends the modified token with the packet further;

d) the transmitting node receives back its message, which has passed through the entire ring, releases the token (marks it as free) and again sends the token to the network. In this case, the sending node knows whether its package was received or not.

For the normal functioning of this network, it is necessary that one of the computers or special device made sure that the token was not lost, and if the token was lost, this computer must create it and launch it on the network.

Data exchange in a network with bus topology(decentralized random method access)

In this case, all nodes have equal access to the network and the decision when to transmit is made by each node locally, based on an analysis of the network state. Competition arises between nodes for network capture, and, therefore, conflicts between them are possible, as well as distortion of transmitted data due to packet overlap.

Let's look at the most commonly used carrier sense multiple access with collision detection (CSMA/CD). The essence of the algorithm is as follows:

) a node that wants to transmit information monitors the state of the network, and as soon as it is free, it begins transmission;

) the node transmits data and simultaneously monitors the state of the network (carrier sensing and collision detection). If no collisions are detected, the transfer is completed;

) If a collision is detected, the node amplifies it (transmits for some more time) to ensure detection by all transmitting nodes, and then stops transmitting. Other transmitting nodes do the same;

) after the unsuccessful attempt is terminated, the node waits for a randomly selected period of time tback, and then repeats its attempt to transmit, while controlling for collisions.

In case of a second collision, trear increases. Eventually, one of the nodes gets ahead of the other nodes and successfully transmits the data. The CSMA/CD method is often called the race method. This method for networks with a bus topology is implemented by the Ethernet protocol.

.10 Technology comparison and configuration determination

Characteristics
Transmission speed		10 (100) Mbit/s
Topology			ring/star	tire, star
Transmission medium	fiber optic, twisted pair		twisted pair, fiber optic	coaxial cable, twisted pair, fiber optic
Access Method
Maximum network length
Maximum number of nodes
Maximum distance between nodes

This page presents comparative characteristics of the most common LAN technologies.

Determining Network Configuration

Before designing a LAN, it is necessary to determine the goals of creating the network, the features of its organizational and technical use:

What problems are supposed to be solved when using a LAN? 2. What tasks are planned to be solved in the future?

Who will perform technical support and LAN maintenance?

Do you need access from a LAN to a global network?

What are the requirements for confidentiality and security of information? It is necessary to take into account other problems that affect the goals of creating networks and the characteristics of its organizational and technical use.

When building a network, the network configuration is determined by the requirements for it, as well as the financial capabilities of the company, and is based on existing technologies and internationally accepted LAN construction standards.

Based on the requirements, in each individual case the network topology, cable structure, protocols and methods of data transmission, methods of organizing the interaction of devices, and a network operating system are selected.

The efficiency of the LAN is determined by the parameters selected when configuring the network:

type (peer-to-peer or dedicated server);

topology;

type of access to the data transmission medium;

maximum network throughput;

type of computers on the network (homogeneous or heterogeneous networks);

maximum permissible network length;

the maximum permissible distance of workstations from each other;

quality and capabilities of the network operating system;

volume and technology of use of information support (databases);

means and methods of protecting information on the network;

means and methods of ensuring LAN fault tolerance;

And other parameters that affect the efficiency of the LAN.

Multilayer network model

The entire network hardware and software complex can be described by a multilayer model consisting of layers:

computers or computer platforms;

communications equipment;

OS;

network applications.

Computers

At the heart of any network is a hardware layer of standardized computer platforms. Currently, computer platforms of various classes are widely used - from personal computers to mainframes and supercomputers. Computers connect to the network using a network card.

Communication equipment

The second layer includes communications equipment, which plays no less important role than computers. Network communications equipment can be divided into three groups:

) network adapters (cards);

) network cables;

) intermediate communications equipment (transceivers, repeaters, hubs, switches, bridges, routers and gateways).

OS

The third layer that forms the network software platform is operating systems. Depending on which concepts for managing local and distributed resources form the basis of the network OS, the efficiency of the entire network depends.

Network Applications

The fourth layer is network applications. Network applications include applications such as network databases, email applications, collaboration automation systems, etc.

Technical support for computing systems Let's take a closer look at network hardware - computers. Computer architecture includes both a structure that reflects the hardware of the PC and software and mathematical support. All network computers can be divided into two classes: servers and workstations.

Server - This is a multi-user computer dedicated to processing requests from all workstations. This powerful computer or mainframe, which provides workstations with access to system resources and distributes those resources. The server has a network operating system under control, which allows the entire network to work together.

The main requirements for servers are high performance and reliability of their operation. Servers in large networks have become specialized and, as a rule, are used to manage network databases, organize e-mail, manage multi-user terminals (printers, scanners, plotters), etc.

There are several types of servers:

File servers. Control user access to files and programs.

Print servers. Control the operation of system printers.

Application servers. Application servers are powerful computers running on a network that have an application program that clients can work with. Applications based on user requests are executed directly on the server, and only the query results are transferred to the workstation.

Mail servers. This server used to organize electronic correspondence with electronic mailboxes.

Proxy server. This is an effective means of connecting local networks to the Internet. A proxy server is a computer that is constantly connected to the Internet, through which local network users communicate with the Internet.

1.11 Protocols, interfaces, protocol stacks

Computer networks, as a rule, consist of various equipment from different manufacturers, and without the adoption by all manufacturers of generally accepted rules for constructing PCs and network equipment, it would be impossible to ensure the normal functioning of networks. That is, to ensure normal interaction of this equipment in networks, a single unified standard is needed that would define the algorithm for transmitting information in networks. In modern computer networks, the role of such a standard is performed by network protocols.

Due to the fact that it is not possible to describe the interaction between devices on the network with a single protocol, it is necessary to divide the process of network interaction into a number of conceptual levels (modules) and determine the functions for each module and the order of their interaction using the decomposition method.

A multi-level approach of the decomposition method is used, according to which a set of modules that solve particular problems are ordered by levels forming a hierarchy; the process of network interaction can be represented as a hierarchically organized set of modules.

1.12 Network communications equipment

Network adapters are communication equipment A network adapter (network card) is a device for bidirectional data exchange between a PC and the data transmission medium of a computer network. In addition to organizing data exchange between the PC and the computer network, the network adapter performs buffering (temporary data storage) and the function of pairing the computer with a network cable. Network adapters implement the functions of the physical layer, and the functions of the data link layer of the seven-layer ISO model are implemented by network adapters and their drivers.

Adapters are equipped with their own processor and memory. Cards are classified by the type of port through which they connect to the computer: ISA, PCI, USB. The most common of these are PCI network cards. The card is usually installed in a PCI expansion slot located on the PC motherboard and connected to network cable connectors type: RJ-45 or BNC.

Network cards can be divided into two types:

adapters for client computers;

adapters for servers.

Depending on the Ethernet, Fast Ethernet or Gigabit Ethernet technology used, network cards provide data transfer rates of 10, 100 or 1000 Mbit/s.

Computer network cables

The following cables are used to connect individual PCs and communication equipment in computer networks: twisted pair, coaxial cable, optical cable, the properties of which are described in the section "Communication lines and data channels"<#"657138.files/image005.gif">

Figure 1. Creating network parameters.

After creation, the opportunity was given to edit the text of the ban page. The administrator's email has been removed to prevent dissatisfied users from attempting to use the address inappropriately. The page text turned out to be as follows:

Oh, the site is NOT related to the learning process!

Access to the resource is blocked!

Send a request to open a site to the administrator

%user_query_form%

The resulting page contained the entry shown in Figure 2:

Figure 2. User networks.

Filtering parameters are configured on the page Control Panel > Filter. From the proposed work options, I chose Custom Filter(Figure 3). Selecting a category prevents users from viewing resources in that category.

At this stage, the basic filtering settings can be considered complete. All user requests regarding incorrect categorization of resources will be sent to the E-mail specified when registering for the service.

Integration of service and server

The apparent difficulty of filtering lies in the use of a dynamic external IP address of a local network, which does not apply to the owners of a permanent external IP address. We have considered the task of specifying an IP address to the system Rejector.ru for a specific user. For this purpose, the following script was created:

# User parameters for the Rejector.ru service

username=your_login # E-mail=your_password # Password

ipname=your_network_address # network IP address

log_dir= $HOME # Directory for output of execution results

log_file=rejectorupd. log #Output file

date >> $log_dir/rejectorupd. log

/usr/bin/curl - i - m 60 - k - u $username: $passwd "#"657138.files/image008.gif"><#"657138.files/image009.gif"> <#"657138.files/image010.gif"> <#"657138.files/image011.gif">

Please note that sudo is a purely console utility, so you cannot use it in the application launch dialog, although you can launch graphical applications from the terminal through it. Agksudo, on the contrary, is a graphical utility, so it should not be used in the terminal, although this is not prohibited.

As a result, an editor will open with the ability to save changes:

Conclusion

Local computer networks are currently widespread in various fields of science, technology and production.

Computer-aided design systems can be created on the basis of a LAN. This makes it possible to implement new technologies for designing mechanical engineering products, radio electronics and computer technology.

In the conditions of development of a market economy, it becomes possible to create competitive products, quickly modernize them, ensuring the implementation of the economic strategy of the enterprise.

LANs also make it possible to implement new information technologies in organizational and economic management systems. The use of network technologies greatly facilitates and speeds up the work of personnel, allows the use of unified databases, as well as regularly and promptly replenishing and processing them.

The choice of the type of network and the method of connecting computers into a network depend both on the technical and, not least important, on the financial capabilities of those who create it.

So, in the thesis the tasks were solved, namely:

· Studied theoretical material on local networks

· Built a local network at school

· Configured remote access to access student computers

· Configured a file and Internet server with content-filter ohm

This thesis will help a computer science teacher organize a local network at school, because all the necessary information is presented in this thesis.

Bibliography

1. Bashly P.N. Modern network technologies: textbook, - M., 2006

Boguslavsky L.B. Control of data flows in computer networks, M. - 1984

Melnikov D.A. Information processes in computer networks. Protocols, standards, interfaces, models... - M: KUDITS-OBRAZ, 1999.

Morozov V.K. Fundamentals of the theory of information networks. - M., 1987

Honnikant D. Internet Research. Kyiv-M. - St. Petersburg, 1998

Evolution of computing systems [electronic resource]: http://sesia5.ru/lokseti/s_11. htm

7. Communication lines [electronic resource]: http://sesia5.ru/lokseti/s211. htm

Olifer V.G., Olifer N.A. Computer networks. Principles, technologies, protocols: Textbook for universities. 2nd ed. - St. Petersburg: "Peter", 2005. - 864 p.

Computer networks. Training course/Trans. from English - M.: Publishing department "Russian Edition" of LLP "Channel Trading Ltd.". - 2nd edition, 1998. - 696 p.

Educational works. Corporate standard FS RK 10352-1910-U-e-001-2002. General requirements to construction, presentation, design and content. - Almaty, AIES, 2002. - 31 p.

Fundamentals of modern computer technologies: Textbook / Ed. Prof. HELL. Khomonenko. - St. Petersburg: CORONA print, 2005. - 672 p.

Solovyova L.F. Network technologies. Practical textbook. - St. Petersburg: BHV-Petersburg, 2004. - 416 p.

Novikov Yu.V., Kondratenko S.V. Local networks: architecture, algorithms, design. - M.: EKOM, 2001 - 312 p.

Guk M. Local network hardware. Encyclopedia. - St. Petersburg: Publishing house "Peter", 2000. - 576 p.

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INTRODUCTION

1.4 Local network topologies

1.5 Network technologies

2.1 Characteristics of the object

2.4 Network administration

2.5 Protecting information on the network

3.2 Payroll

3.3 Calculation of the total cost of installation work

3.4 Calculation of total cost

3.5 Determination of selling price

4. OCCUPATIONAL SAFETY

4.1 Ensuring safety and labor protection of the computer operator

4.2 Safety precautions when servicing electrical equipment

CONCLUSION

BIBLIOGRAPHY

INTRODUCTION

In modern organizations, such as educational institutions, business offices, shops or administrative buildings, it is customary to use local area networks (LANs) to ensure faster, more convenient collaboration. All of the above determines the relevance of the topic of the thesis "Deployment of a local computer network."

Object: Design and deployment of a local computer network.

Subject: Design and deployment of a school network.

The purpose of the thesis: to study and systematize the theoretical material necessary for constructing a LAN; organize and configure the work of the LAN at school No. 15 in Krasnoturinsk.

To achieve this goal, it is necessary to solve the following tasks:

- Study the theoretical foundations of LAN.

- Study hardware and software.

- Study the mechanisms of construction and operation of a LAN.

- Explore LAN administration.

1. THEORETICAL BASIS FOR BUILDING LOCAL NETWORKS

1.1 Equipment necessary for building various computer networks

Network adapter.

In order for a user to connect his computer to a local network, a special device must be installed in his computer - a network controller.

The network adapter performs many tasks, the most important of which are encoding/decoding information and gaining access to the information environment using a unique identifier (MAC address).

Network cards come in the form of expansion cards that are inserted into the appropriate slot.

Also, network cards can be built into motherboards, which is common today.

The main indicators of a network card can be considered the supported standard and type of connection to the computer.

Supported standard. There are networks with different network standards. This means that the network card must have a certain type of connector (or connectors) and be able to operate at a certain speed of information exchange. The most important thing in this case is the type of connector.

The type of network card connector depends on the choice of network topology and the cable through which data is transferred. There are several types of connectors: RJ-45 (for twisted pair), BNC (for coaxial cable) and for fiber optics.

Figure 1 - Network adapter

Figure 2 - RJ-45 (twisted pair)

Figure 3 - BNC (coaxial cable)

Figure 4 - Fiber optic cable

They differ significantly in design, so it is impossible to use the connector for other purposes. Although there are combined network adapters that contain, for example, RJ-45 and BNC connectors. But since a network on a coaxial cable is becoming less and less common, the same thing happens with adapters of the same name.

Type of connection to the computer. In personal computers, the network card is usually installed in a PCI slot or USB port. Moreover, almost any modern motherboard already has an integrated network controller.

Network adapters for wireless network By appearance practically do not differ from wired options, with the exception of the presence of a socket for an antenna - internal or external. Network cards that connect via a USB port are quite common, especially for wireless options.

Figure 5 - Network adapter for WIFI

Hub.

When a network contains more than two computers, special devices must be used to connect them, one of which is a hub. The hub is usually used in networks based on twisted pair cables.

A hub (also called a hub, repeater, repeater) is a network device that has two or more connectors (ports), which, in addition to switching computers connected to it, also performs other useful functions, such as signal amplification.

The hub serves to expand the network, and its main purpose is to transmit information received at the input to all network devices connected to it.

All devices connected to the hub receive exactly the same information, which is also its disadvantage - the presence of several hubs in the network clogs the airwaves with unnecessary messages, since the hub does not see the real address to which it needs to send information, and is forced to send it to everyone. In any case, the hub fulfills its task - it connects computers that are in the same workgroup. In addition, it analyzes errors, in particular collisions that occur. If one of your network cards is causing frequent problems, the port on the hub it is connected to may be temporarily disabled.

The hub implements the physical layer of the ISO/OSI model, on which standard protocols operate, so it can be used in a network of any standard.

There are two main types of hubs:

- Hubs with a fixed number of ports are the simplest. Such a hub looks like a separate case, equipped with a certain number of ports and operating at a selected speed. Typically, one of the ports serves as a link between another hub or switch.

- Modular hubs consist of blocks that are installed in a special chassis and connected by a cable. It is also possible to install hubs that are not interconnected by a common bus, for example, when there are different local networks, the connection between which is not fundamental.

Figure 6 - Hub

Bridge.

A bridge (also called a switch, switch) is a fairly simple device, the main purpose of which is to separate two network segments in order to increase its total length (respectively, the number of connected repeaters) and thereby overcome the limitations of the network topology.

Typically, a bridge has two or more ports to which network segments are connected. By analyzing the packet's destination address, it can filter messages destined for another segment. The device simply ignores packets intended for the “native” segment, which also reduces traffic

Three types of bridges are used to build a network:

- local - works only with segments of the same type, that is, having the same data transfer rate;

- transformative - designed for the same thing as a local bridge, in addition, it works with heterogeneous segments, for example Token Ring and 100Base;

- remote - connects segments located at a considerable distance, and any means of connection, for example a modem, can be used.

Figure 7 - Network bridge

Switch.

The switch combines the capabilities of a hub and a bridge, and also performs some other useful functions.

The hub, having received a data packet from any network card, without knowing who it is addressed to, sends it to all network devices connected to it. It is easy to imagine what kind of traffic is generated if there is not one, but several hubs on the network.

A switch is a more intelligent device that not only filters incoming packets, but, having a table of addresses of all network devices, determines exactly which of them the packet is destined for. This allows it to transmit information to several devices at once at maximum speed. Switches operate at the data link level, which allows them to be used not only in different types networks, but also to combine different networks into one.

Therefore, switches are more preferable for organizing a large network. In addition, recently the cost of switches has dropped significantly, so the use of hubs is clearly not justified.

Figure 8 - Switch

Router.

The main task of a router (also called a router) is to divide a large network into subnets; it has a large number useful functions and, accordingly, has great capabilities and “intelligence”. It combines a hub, bridge and switch. In addition, the ability to route packets is added. In this regard, the router operates at a higher level - the network level.

The table of possible packet routes is automatically and constantly updated, which gives the router the opportunity to choose the shortest and most reliable path for message delivery.

One of the important tasks of a router is connecting heterogeneous network segments of a local network. Using a router, you can also organize virtual networks, each of which will have access to certain resources, in particular Internet resources.

The organization of filtering broadcast messages in a router is performed at a higher level than in a switch. All protocols using the network are seamlessly “accepted” and processed by the router’s processor. Even if an unfamiliar protocol is encountered, the router will quickly learn to work with it.

The router can be used in both wired and wireless networks. Very often, routing functions fall on wireless access points.

Figure 9 - Router

Modem.

A modem is also a networking device and is still often used to connect to the Internet.

Modems come in two types: external and internal. An external modem can be connected to a computer using an LPT, COM or USB port.

The internal modem is an expansion card that is usually inserted into a PCI slot. Modems can operate over a telephone line, leased line, and radio waves.

Depending on the type of device and data transmission medium, the data transfer speed differs. The speed of a conventional digital-analog modem operating with an analog telephone line is 33.6-56 Kbps. Recently, digital modems that take advantage of DSL technology and can operate at speeds exceeding 100 Mbit/s have become increasingly common. Another undeniable advantage of such modems is that the telephone line is always free.

To communicate with another modem, its own protocols and algorithms are used. Much attention is paid to the quality of information exchange, since the quality of the lines is quite low. The modem can be used in both wired and wireless networks.

Figure 10 - Modem

Access point.

An access point is a device used to operate a wireless network in infrastructure mode. It acts as a hub and allows computers to exchange the necessary information using routing tables, security features, built-in hardware DNS and DHCP servers, and much more.

Not only the quality and stability of the connection, but also the standard of the wireless network depends on the access point. There are a large number of different models of access points with different properties and hardware technologies. However, today the most optimal devices can be considered to be those that work with the IEEE 802.11g standard, since it is compatible with the IEEE 802.11a and IEEE 802.11b standards and allows operation at speeds of up to 108 Mbit/s. More promising and faster is IEEE standard 802.11n, devices supporting which are starting to appear on the market.

Figure 11 - Access point

1.2 Principles of building local networks

Server or client are functions that a computer performs. Any computer on the network can perform the functions of a server or a client, or it can perform both of these functions simultaneously. It all depends on the software.

Server functions (serve - serve) - perform operations based on client requests. This could be: storing and transferring files, running applications with results, servicing printers, etc. If a computer performs only server functions, it is usually called a dedicated server. Often such a computer has a monitor or keyboard that is turned off or does not have a monitor at all, and all control is done from other computers via the network.

If a computer does not perform any server functions on the network, then such a computer is called a workstation; users work at it.

If computers on the network simultaneously perform both server and client functions, then such a network is called peer-to-peer.

Different Operating Systems (OS) are designed differently for server and client functions. There are a number of operating systems specifically designed to perform server tasks.

Many organizations use several servers at once, between which the load is distributed: each server performs a specific task. For example, one may accept all print requests, while the other provides access to files. Each such server can be configured to provide a specific type of service as efficiently as possible.

Computers that act as servers fall into two main categories:

- general purpose, capable of providing many different services;

- specialized, designed for a specific type of service.

1.3 Methods of organizing a computer network

Depending on the task and purpose, the methods of creating a local enterprise network (corporate network) may be different. Most often, it is a combination of various technological solutions that allows us to achieve the optimal solution. Each of the methods used has its own advantages and disadvantages. For example, combining local networks into a single corporate network of an organization can be carried out:

- Using wired data networks.

- Using wireless data networks.

Since there are a lot of laptops in the school, a mixed-type peer-to-peer network was chosen (some clients are connected via cable, and the rest are connected to the network via Wifi).

Figure 12 - Example of a mixed network

1.4 Local network topologies

The topology of a computer network refers to the way in which its individual components (computers, servers, printers, etc.) are connected. There are three main topologies:

- star topology (Fig. 4);

- ring type topology (Fig. 5);

- common bus type topology (Fig. 6);

Figure 13 - Star topology

Figure 14 - Ring topology

Figure 15 - Common bus topology

When using a star topology, information between network clients is transmitted through a single central node. A server or a special device - a hub (Hub) can act as a central node.

The advantages of this topology are as follows:

- High network performance, since the overall network performance depends only on the performance of the central node.

- No collision of transmitted data, since data between the workstation and the server is transmitted via separate channel without affecting other computers.

- However, in addition to the advantages, this topology also has disadvantages:

- Low reliability, since the reliability of the entire network is determined by the reliability of the central node. If the central computer fails, the entire network will stop working.

- High costs for connecting computers, since a separate line must be installed for each new subscriber.

Active star - at the center of the network there is a computer that acts as a server.

Passive star - in the center of a network with this topology there is not a computer, but a hub, or switch, which performs the same function as a repeater. It renews the signals that are received and forwards them to other communication lines. All users on the network have equal rights.

In a ring topology, all computers are connected to a line closed in a ring. Signals are transmitted along the ring in one direction and pass through each computer (Fig. 16).

Figure 16 - Transfer algorithm in ring topology

The transmission of information in such a network occurs as follows. A token (special signal) is transmitted sequentially, from one computer to another, until it is received by the one that needs to transfer the data. Once the computer receives the token, it creates what is called a "packet" in which it places the recipient's address and data, and then sends the packet around the ring. The data passes through each computer until it reaches the one whose address matches the recipient's address.

After this, the receiving computer sends confirmation to the information source that the data has been received. Having received confirmation, the sending computer creates a new token and returns it to the network.

The advantages of the ring topology are as follows:

- Message forwarding is very efficient because... You can send several messages one after another in a ring. Those. a computer, having sent the first message, can send the next message after it, without waiting for the first one to reach the recipient.

- The length of the network can be significant. Those. computers can connect to each other over considerable distances, without the use of special signal amplifiers.

The disadvantages of this topology include:

- Low network reliability, since the failure of any computer entails the failure of the entire system.

- To connect a new client, you must disable the network.

- With a large number of clients, the speed of the network slows down, since all information passes through each computer, and their capabilities are limited.

- Overall network performance is determined by the performance of the slowest computer.

In a common bus topology, all clients are connected to a common data transmission channel. At the same time, they can directly come into contact with any computer on the network.

The transmission of information in this network occurs as follows. Data in the form of electrical signals is transmitted to all computers on the network. However, the information is received only by the computer whose address matches the recipient's address. Moreover, at any given time, only one computer can transmit data.

Advantages of the common bus topology:

- All information is online and accessible to every computer.

- Workstations can be connected independently of each other. Those. When a new subscriber connects, there is no need to stop the transmission of information on the network.

- Building networks based on a common bus topology is cheaper, since there are no costs for laying additional lines when connecting a new client.

- The network is highly reliable, because The performance of the network does not depend on the performance of individual computers.

The disadvantages of a common bus topology include:

- Low data transfer speed, because all information circulates through one channel (bus).

- Network performance depends on the number of connected computers. The more computers are connected to the network, the slower the transfer of information from one computer to another.

- Networks built on the basis of this topology are characterized by low security, since information on each computer can be accessed from any other computer.

The most common type of network with a common bus topology is an Ethernet standard network with an information transfer rate of 10 - 100 Mbit/s.

In practice, when creating a LAN, an organization can simultaneously use a combination of several topologies. For example, computers in one department can be connected according to a star scheme, and in another department using a common bus scheme, and a communication line is laid between these departments.

1.5 Network technologies

Network technology is an agreed upon set of standard protocols and software and hardware that implement them (for example, network adapters, drivers, cables and connectors), sufficient to build a computer network. The epithet “sufficient” emphasizes the fact that this set represents the minimum set of tools with which you can build a working network. Perhaps this network can be improved, for example, by allocating subnets in it, which will immediately require, in addition to standard Ethernet protocols, the use of the IP protocol, as well as special communication devices - routers. The improved network will most likely be more reliable and faster, but at the expense of add-ons to the Ethernet technology that formed the basis of the network.

The term “network technology” is most often used in the narrow sense described above, but sometimes its expanded interpretation is also used as any set of tools and rules for building a network, for example, “end-to-end routing technology”, “technology for creating a secure channel”, “IP technology -networks."

The protocols on which a network of a certain technology is built (in the narrow sense) were specifically developed for joint work, so the network developer does not require additional efforts to organize their interaction. Sometimes network technologies are called basic technologies, meaning that the basis of any network is built on their basis. Examples of basic network technologies include, in addition to Ethernet, such well-known local network technologies as Token Ring and FDDI, or X.25 and frame relay technologies for territorial networks. To obtain a working network in this case, it is enough to purchase software and hardware related to the same basic technology - network adapters with drivers, hubs, switches, cable system etc. - and connect them in accordance with the requirements of the standard for this technology.

1.6 Cables used in local networks

During the development of local networks, quite a lot of types of cables have appeared, and all of them are the result of increasingly complex standards requirements. Some of them are already a thing of the past, and some are just beginning to be used, and thanks to them, it has become possible to achieve the high data transfer speed that we need so much.

Coaxial cable.

Coaxial cable is one of the first conductors used to create networks. Coaxial cable consists of a central conductor encased in thick insulation, a copper or aluminum braid, and an outer insulating sheath of coaxial cable.

Figure 17 - Coaxial cable

To work with coaxial cable, several connectors of different types are used:

- BNC connector. Installed at the ends of the cable and used to connect to the T-connector and barrel connector.

Figure 18 - BNC connector

- BNC T-connector. It is a kind of tee that is used to connect a computer to the main line. Its design contains three connectors at once, one of which is connected to the connector on network card, and the other two are used to connect the two ends of the highway.

Figure 19 - BNC T-connector

- BNC barrel connector. With its help, you can connect the broken ends of the trunk or sharpen part of the cable to increase the radius of the network and connect additional computers and other network devices.

Figure 20 - BNC barrel connector

- BNC terminator. It is a kind of stub that blocks further propagation of the signal. Without it, the functioning of a network based on coaxial cable is impossible. A total of two terminators are required, one of which must be grounded.

Figure 21 - BNC terminator

Coaxial cable is quite susceptible to electromagnetic interference. Its use in local computer networks has long been abandoned.

Coaxial cable began to be mainly used to transmit signals from satellite dishes and other antennas. Coaxial cable received a second life as a backbone conductor of high-speed networks that combine the transmission of digital and analog signals, for example, cable television networks.

Twisted pair.

Twisted pair is currently the most common cable for building local networks. The cable consists of pairs of intertwined copper insulated conductors. A typical cable has 8 conductors (4 pairs), although cables with 4 conductors (2 pairs) are also available. The colors of the internal insulation of conductors are strictly standard. The distance between devices connected by twisted pair cable should not exceed 100 meters.

Depending on the presence of protection - an electrically grounded copper braid or aluminum foil around the twisted pairs, there are types of twisted pair:

- Unshielded twisted pair (UTP, unprotected twisted pair). Apart from conductors with their own plastic protection, no additional braiding or grounding wires are used

Figure 22 - Unshielded twisted pair

- Foiled twisted pair (F/UTP, foil twisted pair). All pairs of conductors of this cable have a common foil shield

Figure 23 - Foiled twisted pair

- Shielded twisted pair (STP, protected twisted pair). In a cable of this type, each pair has its own braided shielding, and there is also a common mesh screen for all

Figure 24 - Shielded twisted pair

- Screened Foiled twisted pair (S/FTP, foil shielded twisted pair). Each pair of this cable is in its own foil braid, and all pairs are enclosed in a copper shield

Figure 25 - Screened Foiled twisted pair

- Screened Foiled Unshielded twisted pair (SF/UTP, unprotected shielded twisted pair). Features a double shield of copper braid and foil braid

Figure 26 - Screened Foiled Unshielded twisted pair

There are several categories of twisted pair cables, which are labeled CAT1 to CAT7. The higher the category, the higher quality the cable and the better performance it has. Local computer networks of the Ethernet standard use twisted pair cable of the fifth category (CAT5) with a frequency band of 100 MHz. When laying new networks, it is advisable to use an improved CAT5e cable with a frequency band of 125 MHz, which better transmits high-frequency signals.

To work with a twisted pair cable, an 8P8C (8 Position 8 Contact) connector is used, called RJ-45 - RG-45 connector

Fiber optic cable.

Fiber optic cable is the most modern data transmission medium. It contains several flexible glass light guides protected by heavy plastic insulation. The data transfer speed over optical fiber is extremely high, and the cable is absolutely free from interference. The distance between systems connected by optical fiber can reach 100 kilometers.

Figure 27 - Fiber optic cable

There are two main types of fiber optic cable - single-mode and multi-mode. The main differences between these types are associated with different modes of passage of light rays in the cable. For crimping a fiber optic cable, many connectors and connectors of different designs and reliability are used, among which the most popular are SC, ST, FC, LC, MU, F-3000, E-2000, FJ and other connectors for fiber optics. The use of optical fiber in local networks is limited by two factors. Although the optical cable itself is relatively inexpensive, prices for adapters and other equipment for fiber optic networks are quite high. Installation and repair of fiber optic networks requires high qualifications, and cable termination requires expensive equipment. Therefore, fiber optic cable is used mainly for connecting segments of large networks, high-speed Internet access (for providers and large companies) and data transmission over long distances.

In a wired network, cable is used to create the appropriate physical medium for data transmission. At the same time, it often happens that the next network standard implies the use of its own cable.

Thus, there are several types of cables, the main ones being twisted pair cable, coaxial cable and fiber optic cable.

Again, the network standard requires certain characteristics from the cable, which directly affect the speed and security of the network.

In connection with all of the above, the main distinguishing parameters of the cable are the following:

- frequency bandwidth;

- diameter of conductors;

- diameter of the conductor with insulation;

- number of conductors (pairs);

- presence of a screen around the conductor(s);

- cable diameter;

- temperature range at which quality indicators are normal;

- the minimum bending radius that is allowed when laying the cable;

- maximum permissible interference in the cable;

- characteristic impedance of the cable;

- maximum signal attenuation in the cable.

All these parameters are included in the concept of cable category. For example, twisted pair cable comes in five different categories. In this case, the higher the category, the better the cable performance, the greater its throughput.

1.7 Network interconnection and routing

Routing is the process of determining the route that packets will take. Routes can be set directly by the administrator (static routes), or calculated using routing algorithms based on information about the topology and network state obtained using routing protocols (dynamic routes).

The routing process in computer networks is carried out by special software and hardware - routers. In addition to routing, routers also perform channel/message/packet/cell switching, and a computer network switch also performs routing (determining which port to send a packet to based on a table MAC addresses), and is named after its main function - switching. The word routing means the transfer of information from a source to a destination through an internetwork. In this case, at least once it is necessary to overcome the branching of the network.

Routing has two main components. Determining the optimal route between the source and receiver of information, and transmitting information over the network. The last function is called commutation.

Route determination is based on various metrics calculated from a single variable, such as route length or combinations of variables. Routing algorithms calculate route metrics to determine the optimal path to a destination.

To facilitate the route determination process, routing algorithms initialize and maintain routing tables that contain routing information. Routing information changes depending on the routing algorithm used.

Routing algorithms populate routing tables with the necessary information. The combinations tell the router that the destination can be reached by the shortest path when sending a packet to a specific router on the way to the final destination. When a router receives an incoming packet, it checks the destination address and tries to associate that address with the next forwarding.

Figure 28 - Routing algorithm

2. ORGANIZATION OF A LOCAL NETWORK OF MOU SOSH

2.1 Characteristics of the object

School No. 15 is located on Chernyshevsky Street 19. The school has 30 classrooms, including equipped classrooms for physics, chemistry, biology, history, life safety, foreign language, technology (with full kitchen equipment), a computer science and ICT classroom, a library ( with a fund of more than 36 thousand books), a sports hall and stadium, an assembly hall, medical and treatment rooms, a canteen for 150 seats (student meals are provided on a contract basis with the school catering plant).

The acquisition of new computer and multimedia equipment, increasing the efficiency of its use play a big role in the development of the information and learning environment of an educational institution - the creation of teacher workplaces equipped with modern computer and multimedia tools (offices of computer science, physics, biology, history, life safety, 2 foreign languages, 4 classrooms for primary classes, mathematics, 3 classrooms for the Russian language, a multimedia classroom, 2 demonstration classrooms equipped with computer equipment for conducting lessons by subject teachers).

2.2 Functional diagram of a local area network

Figure 29 - Principle of network operation

Equipment used and their quantity:

- Personal computers (35);

- Laptops (14);

- Linksys router model - WRT54GL (1);

- D-Link router model - DIR300 (2);

- TP-Link router model - TL-WR841N (10);

- D-Link switch model - DES-1008d (4);

- Coil UTP cable 4 pairs 300 meters (2);

- Connectors RJ - 45.

More detailed description The operation of each network element is found in paragraph 2.4.

2.3 Network structure planning

When choosing the type of network, many factors had to be taken into account, namely the main and decisive ones were:

* Finance allocated for network installation and network equipment;

* estimated network load;

* the need for a common data storage;

* number of computers working in the network;

* compact arrangement of users;

* global expansion of the network will not be required in the future;

* the issue of data protection is not critical.

Based on the above factors, it was decided to build a peer-to-peer network using wireless modules.

This network excludes the presence of a server. Because each computer is both a client and a server, there is no need for a powerful central server or other components required for more complex networks, meaning there is no need to plug it into the network and waste money and time.

To connect computers into a peer-to-peer network, it was enough just to create a network structure (run cables or buy wireless access points, install switches and other equipment). We connect the computer to the network and configure it to use the resources of other systems. In turn, the administrator of each computer determines which local system resources are provided for general use and with what rights.

When installing a peer-to-peer network, no additional software was required.

The convenience of a peer-to-peer network is characterized by a number of standard solutions:

- computers are located on user desktops;

- users themselves act as administrators and ensure information security.

2.4 Network administration

Network administrator - a specialist responsible for the normal functioning and use of resources automated system and (or) computer network.

Administration information systems includes the following goals:

- Installation and configuration of the network;

- Support for its further performance;

- Installation of basic software;

- Network monitoring;

In this regard, the network administrator must perform the following tasks:

- System planning;

- Installation and configuration of hardware devices;

- Software installation;

- Network installation;

- Installation and control of protection;

Installation and configuration must begin from the very beginning of the network, in this case from setting up the main router, also known as the DHCP server. The Linksys router model WRT54GL was chosen for this role.

Figure 30 - Linksys WRT54GL

DHCP (Dynamic Host Configuration Protocol) is a network protocol that allows computers to automatically obtain an IP address and other parameters needed to operate on a network. Its use avoids manual settings computers on the network and reduces the number of errors. Typically, the DHCP server provides clients with at least the basic information:

- IP address

- Subnet mask

- Main gate

However, additional information is also provided, such as DNS and WINS server addresses. The system administrator configures the parameters on the DHCP server that are sent to the client.

To configure, you need to connect the Internet cable to the “INTERNET” port (also known as WAN port), and the cable going to the computer to the “LAN” port. After this, you need to go to any Internet browser on a computer connected to the router and write “192.168.0.1” or “192.168.1.1” in the address bar, after which an authorization request will appear, the login and password can be viewed on the router (usually on the bottom sticker), or in the router documentation included (mostly on all routers, the login is “admin”, the password is “admin”). Next, depending on your provider, the WAN connection type is set.

Basic WAN connection types:

- Dynamic IP;

- Static IP;

- PPPOE;

- PPTP/Russia PPTP;

- L2TP.

In our case, the provider is “Information Technology Center”, in which a static connection is made, which means it is necessary to fill in the appropriate fields. After the IP addresses, mask, gateway and DNS servers, you need to configure DHCP. To do this, in the section of the same name, enable the DHCP function and specify the range of IP addresses that will be distributed to clients involved in the network. For example: 192.168.1.50 - 192.168.1.150

After these settings, our main router (DHCP server) is ready for use.

Figure 31 - Result of setting up the Linksys router

After setting up the main router, for convenience, you need to configure the remaining routers (they will work as access points, namely, they will transmit information from the main router to computers via wifi networks or via cable), they will be immediately connected to switches and computers after all the necessary settings.

First of all, we set up D-Link routers model DIR-300. In order to enter the settings menu of these routers, you need to carry out the same actions that were necessary to enter the settings menu of the main router, namely, you need to go to any Internet browser on the computer connected to the router and write “192.168.0.1” in the address bar. or “192.168.1.1”, after which an authorization request will appear, the login and password can be found on the router (usually on the bottom sticker), or in the router documentation included in the kit (mostly on all routers, the login is “admin”, the password is “admin” "). After this, the type of Internet connection is configured. Since we already have Internet access configured on the main router, we select the connection type - static IP. This means that the router will accept all addresses and forward those received from the main router.

Figure 32 - Setting up an Internet connection on the D-Link DIR300

The DHCP function must be disabled, since our main router acts as a DHCP server. In the “IP router” item, for the convenience of further management, we set the IP address according to the number of the office in which the router itself will be located. The number of D-Link DIR300 routers is 2, they will be located in rooms 4 and 13, which means their IP addresses will look like this - “192.168.1.4” and “192.168.1.13”. If in the future we need to reconfigure them, we can go to the settings menu from any computer by entering their IP address in the address bar of the browser and then go through the appropriate authorization.

Figure 33 - Example of setting up an IP address on the router, which will be located in office number 4

Because this network mixed type (wired and wireless), then wifi must be configured on the routers, namely, password protection is set and the network name is changed to the number of the office in which the router itself is located.

In the “Setting up a wireless network” section, enter the name of the wifi network with the same name as the account number, then select the security mode “wpa/wpa2psk” and enter the password for the wifi network itself.

Figure 34 - Example wifi settings on the router located in office number 4

After all these settings, the router is ready to work on our network.

The next step is to configure the remaining TP-LINK TL-WR841N routers. Logging into the router settings is the same as for the routers described earlier, namely, in any browser, enter “192.168.0.1” or “192.168.1.1” in the address bar, and then go through authorization. The setup follows the same plan as the D-Link DIR300 described above.

We disable the DHCP function, since we have a DHCP server.

Figure 35 - Configuring DHCP on the TP-LINK TL-WR841N router

Set the WAN connection type to Dynamic IP.

Figure 36 - Setting up the WAN type on the TP-LINK TL-WR841N router

In the LAN settings, set the IP address to the same number as the office in which the router will be located.

Figure 37 - Configuring the IP address of the TP-LINK TL-WR841N router

In the wireless network settings, enter the name of the wifi network itself, which is the same as the number of the office in which the router is located. Then select the type of wireless network security, namely WPA-PSK/WPA2-PSK and enter the security password.

Figure 38 -Name of the wireless network on the TP-LINK TL-WR841N router

Figure 39 - Creation WIFI password on the TP-LINK TL-WR841N router

After all the settings have been made on TP-LINK routers TL-WR841N, they are ready to work on our network. computer network local cable

When all elements of our network are configured, we can begin connecting the network. It is advisable to start connecting devices from the very first element of the network due to convenience. The first device is the main router, as described earlier, the Internet cable is connected to the INTERNET port or WAN port, and the cable that goes further (In our case to the hub) is connected to the LAN port.

Figure 40 - Main router connected to the network

The next element of our network is the hub. Connecting the cable coming from the main router and connecting the cables going to the next elements of our network (hubs distributed on the floors) does not matter which port they are connected to. This is due to the fact that the hub is not programmable. Same with the following hubs.

Figure 41 - Network-connected hub

Since the routers are configured as access points, namely, as described earlier, DHCP is disabled, and the connection type is dynamic IP, the cable coming from the hubs and the main router is connected in the same way as the cable going to the following network elements (either the next router or a computer) to the LAN port.

After all the steps, our network is ready for work, all that remains is to connect computers (via cable from access points) and laptops (via wireless network).

Figure 42 - School computer working group

2.5 Protecting information on the network

School management, according to laws 139-FZ and 436-FZ “On the protection of children from information harmful to their health and development,” is obliged to protect students from dangerous Internet resources (pornography, drugs, extremism). This is necessary both for the children themselves, whose psyche is just developing, and for the school administration - failure to comply with the law may result in sanctions from the prosecutor's office. Therefore, it is necessary to organize protection at school from sites that are harmful and prohibited for children to visit. The choice was content filtering from SkyDNS.

The SkyDNS content filtering system is used not only in schools. Using high technologies, expert opinions and user notifications, a database of several million sites was collected, divided into 50 categories, allowing you to individually configure filtering parameters.

For especially critical cases (small children, prosecutor's inspection) it is provided special mode filter operation, which blocks access to any resources except trusted sites from the white list.

In addition, it supports special search system poisk.skydns.ru, which additionally filters everything search queries, increasing the safety of children. Ministry of Justice lists are regularly monitored to keep blacklists up to date.

Figure 43 - SKYDNS Safe Search

SkyDNS is a true "cloud" solution that works as a web service, blocking access to dangerous sites even before their resources are actually accessed.

In most cases, there is no need to install any software on students' computers. All that is required is to configure the Internet gateway network parameters and specify the categories to block on the site.

In addition, SkyDNS has a low cost. The cost of an annual subscription to filtering services is only 300 rubles per computer.

In order to start using the SkyDNS DNS filtering service you need to:

- determine what filtering settings are required - the same or different for each computer (group of computers). In our case, the filtering settings are the same;

- find out what external IP address the provider provided - static or dynamic. As stated earlier, the school's ISP provides a static IP address;

- determine how computers receive network settings (via DHCP or manually registered). A DHCP server is included in the network, which means you do not have to manually register addresses (see paragraph 2.4).

- bind an external static IP address to a profile in your SkyDNS account;

- use the DNS server SkyDNS 193.58.251.251 to resolve external DNS names.

Offered special solution, a school SkyDNS filter that received the highest Gold Parental Control award from the AntiMalware.ru laboratory. The Internet filter demonstrated results comparable to those of the leader - the developments of Kaspersky Lab.

Figure 44 - An example of blocking a malicious site with a filter.

3. ECONOMIC CALCULATION OF THE COST OF THE DESIGN OBJECT

3.1 Calculation of the cost of basic and Supplies

To determine the cost of installing a local network, it is necessary to calculate the labor intensity.

Labor intensity is the cost of working time to produce a unit of product in physical terms and at all stages of the work performed.

The complexity for each operational transition is presented in Table 1

Table 1 - Labor intensity on operational transitions

Based on Table 1, it can be seen that the total labor intensity for all operational transitions is 990 minutes.

In this thesis project, the composition of material costs can be determined taking into account some features relating to the laying of a local network. The staff of employees is united under a single name of costs.

As background information To determine the amount of all expenses of the Sbcom, rubles, you must use the formula:

,

where M is the cost of materials;

WFP - basic salary for specialists participating in the development of the program;

DZP - additional salary for specialists participating in the development of the program;

UST - unified social tax;

CO - costs associated with the operation of equipment (depreciation);

OCR - general economic costs;

KZ - non-production (commercial) expenses.

All equipment used during installation work is presented in Table 2.

Table 2 - List of costs for basic and consumable materials, components and low-value tools.

Name Materials	Unit		Quantity, pcs.	Amount, rub.
UTP 5E cable
Roulette Stayer
RG-45 connector
Crimping Tools
Cable stripping tool HT-322
Phillips screwdriver ORK-2/08 GOST 5264-10006
Name Materials	Unit	Price per unit of measurement, rub.	Quantity, pcs.	Amount, rub.
Marker GOST 9198-93
Drill 60x120 victorious
Linksys WRT54GL Router
Router
Router TP-Link TL-WR841N
Switch D-link DES-1008D

The volume of material costs for product M, rub., is calculated using the formula:

,

where pi is the type of material i according to the quantity;

qi is the cost of specific unit i of material.

The volume of material costs according to formula (3.2) is obtained:

3.2 Payroll

The calculation of the basic salary is carried out on the basis of the developed technological process of the work performed, which should include information:

? about the sequence and content of all types of work performed;

? on the qualifications of workers involved in performing certain types of work at all production stages (transitions, operations);

? about the labor intensity of performing all types of work;

? on the technical equipment of workplaces when performing work at all stages.

An employee's salary per hour of work is calculated using the formula:

,

where is the worker’s salary per month;

TR - working time per month, taken equal to 176 hours.

The tariff rate for a fifth-grade employee is 5150 (rub/month)

The employee’s tariff rate per hour of work using formula (2.3) is obtained:

(rub.)

The basic salary, wage, rub., is determined by the formula:

,

Where Zprobsch is direct wages.

KOZP is an increasing reference coefficient; its value is determined on the basis of increasing interest rates relative to the direct costs of paying employee wages. It is recommended to choose increasing interest rates in the range from 20% to 40%; in this work, an interest rate of 30% is chosen, or KZP = 0.3.

To determine direct wages for transitions, the total amount of direct wages is determined using the formula:

, (3.5)

where Zpr.i is the direct wage at the i-th transition.

ZPR is calculated using formula (3.6):

where Om is the employee’s salary per hour;

T - operation time;

D-working time fund per month, 176 hours

t- working hours per day

Zpr is calculated using formula (3.6).

For preparatory:

(rub.)

For the blank:

(rub.)

For the editing room:

(rub.)

For installation:

(rub.)

For styling:

(rub.)

For the test:

(rub.)

For setup:

(rub.)

Wages for transitions are calculated using formula (3.5):

(rub.)

The basic salary according to formula (3.4) is obtained:

(rub.)

The general calculation of the basic salary, based on the qualifications and salary of the employee, is presented in Table 3.

Table 3- Calculation of basic salary

the name of the operation	Operating time, min.	Employee qualification	Employee salary, rub./hour.	Actual costs of operations, rub.
Preparatory
Procurement
Assembly
Installation
Laying
Control
Tuning
Correction factor =0.30
Total: OZP taking into account the correction factor

Additional wages are actual allowances to encourage the employee to complete his work on time, exceed the plan, and work with high quality. This should include bonuses, etc. Additional salary, additional salary, rub., is calculated using the formula:

...

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