Ring topology is a topology in which each computer is connected by communication lines to only two others: from one it only receives information, and to the other it only transmits. On each communication line, as in the case of a star, there is only one transmitter and one receiver. This allows you to avoid using external terminators.
Each computer relays (renews) the signal, that is, acts as a repeater, therefore the attenuation of the signal throughout the ring does not matter, only the attenuation between neighboring computers of the ring is important. In this case, there is no clearly defined center; all computers can be the same. However, quite often a special subscriber is allocated in the ring who manages the exchange or controls the exchange. It is clear that the presence of such a control subscriber reduces the reliability of the network, because its failure will immediately paralyze the entire exchange.
Connecting new subscribers to the “ring” is usually completely painless, although it requires a mandatory shutdown of the entire network for the duration of the connection. As in the case of a bus topology, the maximum number of subscribers in a ring can be quite large (1000 or more). Twisted pair or optical fiber is used as media in the network. Messages circulate in circles.
A workstation can transmit information to another workstation, only after receiving the right to transmit (token), so collisions are excluded. Information is transmitted along the ring from one workstation to another, so if one computer fails, unless special measures are taken, the entire network will fail.
The ring topology is usually the most resistant to overloads; it ensures reliable operation with the largest flows of information transmitted over the network, because, as a rule, there are no conflicts (unlike a bus), and there is no central subscriber (unlike a star) .

1. A computer network is:

1) a group of computers located in one room;

2) combining several computers to jointly solve problems;

3) a set of terminals connected by communication channels to a large computer;

4) multimedia computer with printer, modem and fax.

2. Network technologies- This:

1) the main characteristics of computer networks;

2) forms of information storage;

3) technologies for processing information in computer networks;

4) a method of connecting computers on a network.

3. Information systems are:

1) computer networks;

2) information storage;

3) systems that control the operation of the computer;

4) systems for storing, processing and transmitting information in a specially organized form.

4. Local network is:

1) a group of computers in one building;

2) a complex of connected computers for joint problem solving;

3) low-current communications;

4) ln1erpe1 system:.

5. What is not typical for a local network:

1) high speed of information transfer;

2) the ability to exchange information over long distances;

3) the presence of a connection for all subscribers of a high-speed channel for transmitting information in digital form;

4) the presence of a channel for transmitting information to graphical form?

6. What communication lines are used to build local networks:

1) twisted pair only;

2) fiber optic only;

3) only thick and thin coaxial cable;

4) twisted pair, coaxial cable, optical fiber and wireless communication lines?

7. The network adapter performs the following functions:

1) implements one or another access strategy from one computer to another;

2) encodes information;

3) distributes information;

4) converts information from numerical form to text form, and vice versa.

8. Types network adapters:

1) Arspe!, 1n1erne1; 2) 8oin(1B1a81er, Token Shn§; 3) E1berne1, hard drive; 4) Agspe!, Token Shp§, EShegpe!.

9. Server is:

1) one or more powerful computers for network maintenance;

2) high-performance computer;

3) program keeper bootstrap;

4) multimedia computer with modem.

10. Main function of the server:

1) performs specific actions based on client requests;

2) encodes information provided by the client;

3) stores information;

4) sends information from client to client.

11. Basic schemes are used to transmit data on the network:

1) competitive and logical;

2) competitive and with lexical access;

3) competitive with token access;

4) with marker access and with lexical access?

12. What scheme does the Emerne* network use to transmit data over the network: 1) with token access; 2) competitive scheme;

3) logical circuit; 4) with lexical access.

13. The Token Ripd network uses the following scheme: 1) logical; 2) competitive;

3) with token access; 4) with lexical access?

14. What scheme is used to transfer data in the Arspe! network: 1) logical; 2) with lexical access;

3) with token access; 4) competitive?

15. What are the configurations (topologies) of LAN:

1) tree-like, simply connected, fully connected, parallel;

2) bus, simply connected, star-shaped, fully connected;

3) ring, bus, star, fully connected and tree;

4) tree-like, multi-connected, few-ringed, sequential?

16. What methods of access from computer to computer are used in the LAN:

1) marker method, direct access;

2) time reservation method, coding method;

3) direct access, coding method;

4) marker method, time reservation method?

17. Components involved in data transmission over the network:

1) source computer, transmitter, cable network, receiver;

2) source computer, cable network, receiver and destination computer;

3) file server, puncture unit, cable network, destination computer;

4) source computer, protocol unit, transmitter, cable network, receiver and destination computer.

18. The protocol is:

1) data package;

2) rules for organizing data transmission in the network;

3) rules for storing data on the network;

4) structuring of data on the network. 19. Specific functions of drugs for educational purposes:

1) support file system, data protection and access control;

2) system of control and lesson management;

3) definition working system, data decoding, control system;

4) data delimitation, data protection, access system, definition of a working system, access delimitation, control and lesson management system.

>> Informatics: Practical work No. 7. Sharing resources in local areas.

Practical work on the subject Computer Science 9th grade.

Review of topics: Practical work No. 7. Shared resource utilization of local measures.

Network Test

1. What is not typical for a local network:

1) high speed of information transfer;
2) the ability to exchange information over long distances;
3) the presence of a connection for all subscribers of a high-speed channel for transmitting information in digital form;
4) availability of a channel for transmission in graphical form?

The correct answer is 2.

2. Protocol is...

1) data package;
2) rules for organizing data transmission in the network;
3) rules for storing data on the network;
4) structuring data on the network?

The correct answer is 2.

3. Local network is...

1) a group of computers in one building;
2) a complex of connected computers for joint problem solving;
3) low-current communications;
4) Internet system?

The correct answer is 2.

4. Main function of the server:

1) performs specific actions based on client requests;
2) encodes information provided by the client;
3) stores information;
4) sends information from client to client?

The correct answer is 1.

5. Specific functions of drugs for educational purposes:

1) file system support, data protection and access control;
2) system of control and lesson management;
3) definition of the working system, data decoding, control system;
4) data delimitation, data protection, access system, definition of a working system, access delimitation, control and lesson management system?

The correct answer is 4.

6. Of-line is...

1) information packet exchange mode;
2) team;
3) telecommunications network;
4) operating system?

The correct answer is 1.

7. BBS is intended:

1) to determine the route of information;
2) for exchanging files between users;
3) to view addresses;
4) for information management?

The correct answer is 2.

8. A modem is...

1) conversion device digital signals to analog and vice versa;
2) transport basis of the network;
3) information storage;
4) a device that controls the process of information transfer?

The correct answer is 1.

9. To connect computers via modems, the following are used:

1) only telephone lines;
2) only satellite channels;
3) radio waves only;
4) telephone lines, fiber optics, satellite channels and radio waves?

The correct answer is 4.

10. Modem functions:

1) connects to the nearest node;
2) serves network card for connecting computers into a local network;
3) carries out logging of transmitting information;
4) protects information?

The correct answer is 1.

11. The transport basis of global networks is...

1) twisted pair;
2) coaxial cable;
3) telephone lines and satellite channels;
4) telegraph?

The correct answer is 3.

12. FTP archive is...

1) Archie server;
2) file storage;
3) database;
4) WEB site?

The correct answer is 2.

13. Typical email structure:

1) title, subject of the message, full name of the addressee;
2) title, subject of the message, type of letter, sender's address;
3) date of departure, address, return address, message subject and text;
4) message subject, address book, text and title?

The correct answer is 3.

14. A domain is...
1) the name of the file in the mailbox;
2) Mailbox hub station;
3) country code;
4) short name of the recipient?
The correct answer is 2.

15. What is more important for networking:

1) the presence of a large number of computers;
2) protocol system;
3) several network operating systems;
4) high-speed modems?

The correct answer is 2.

16. Technical structure of E-mail is...

1) a set of node stations communicating with each other for exchange;
2) a set of computers on the local network;
3) computers that store and encode information;
4) computers sending information upon requests?

The correct answer is 1.

17. To support E-mail on the Internet, a protocol has been developed:

1) STTP; 2)SMTP; 3) SCTP; 4) SSTP?

The correct answer is 2.

18. What is the protocol basis of the Internet:

1) IP address system;
2) network computer testing protocols;
3) sequence of addresses;
4) address book?

The correct answer is 1.

19. WWW is...

1) distributed Information system hypertext-based multimedia;
2) e-book;
3) protocol for posting information on the Internet;
4) file sharing information environment?

The correct answer is 1.

20. Client-server interaction when working on the WWW occurs according to the following protocol:

1) HTTP; 2) URL; 3) Location; 4) Uniform?

The correct answer is 1.

21. Which programs are not WWW browsers:

1) Mosaic;
2) Microsoft Internet Explorer;
3) Microsoft Outlook Express;
4) Netscape Navigator?

The correct answer is 3.

22. In HTML you can use:

1) text in ASSCII format;
2) highlighting a paragraph, point;
3) any multimedia files;
4) any data types?

The correct answer is 1.

23. What characters in HTML separate the main text from the accompanying text:

1) ;
2)

;
3) ;
4) ?

The correct answer is 3.

1) < A HREF=’’ имя файла’’>;
2) indicating their URL;
3) < A name=” имя файла ”>;
4) ?

The correct answer is 1.

25. HTML is...

1) program viewing WWW documents;
2) application program;
3) hypertext markup language;
4) client-server interaction protocol?

An important part modern world are computers. To make our lives easier and easier, and to speed up our work, computer networks were created. This is what they call the connection between computers and computing equipment into a single network. Such equipment are routers, Wi-Fi routers, servers and other similar equipment.

To transfer data via computer network physical phenomena apply: electromagnetic radiation, electricity, optical channels.

Classification

Types of networks by:

• Switching.
• Transmission technologies.
• Length.
• Speed ​​of work.
• Functional purpose.

Based on the type of switching, computer networks are divided into two types:

1. Channel switching.
2. Packet switching.

In the first form Before the transfer of information begins, a connection between the recipient and the sender is required. After such switching, the information arrives via established network. Such computer networks are used in conditions telephone communication.

Second type of network – used for networks consisting of computers. In this case, the information is divided into several parts, which are called packets. This type of network gets its name from them. Packets are transmitted independently, separately. Each packet has the ability to travel its own path through the network.

The advantage of this network is its high reliability. If one of the network nodes malfunctions, you can find a workaround through other nodes. In other words, the routing issue is resolved for each packet separately, at each intermediate node. This takes some time and loads the intermediate computer.

In networks with a connection of channels, if one of the nodes fails, the switching is interrupted. As a result, the transfer of information stops. For such networks, switching occurs once, and there are no costs for solving the routing issue.

Based on transmission technology, computer networks are divided into:

• Broadcast network (transmitted information is available to all computer nodes).
• Point to point(information is transferred between two separate computers, or through several intermediate machines).

Separation of networks by length:

• The shortest in this classification are personal networks. Their length is about one meter, located on the table in close proximity to the computer user. An example of a personal network is wireless network"bluetooth".
• The next type are local networks, which are usually located in one or more buildings nearby. Their length can range from several meters to 1 km.
• Municipal network organized, as a rule, on the scale of a locality. Today, municipal networks have become the most popular, making it possible to guarantee access to landline telephone, television and Internet resources with one connection. Their length can be several kilometers, depending on the size of the settlement.
• Global computer networks are created on the scale of a country or part of the world. In our country, they are created by well-known telephone companies; various information is transmitted through them and access to the Internet is provided. Their length is unlimited, sometimes reaching several thousand kilometers.
• Network interconnection- World Wide Web of the Internet.

Based on transmission speed, networks are classified into:

• Low speed connections. These include data paths that operate at speeds less than 10 megabits per second.
• Medium speed. These include those connections that operate with packets of information at speeds from 10 to 100 megabits per second.
• High speed. These include those that are capable of transmitting data at speeds of more than 100 megabits per second.

By functional purpose:

• Data storage.
• Server station.
• Work management.
• House connections.

Features of local networks

Everyone knows about the purpose and features of the global network, as well as its benefits for the whole world. To describe in detail all the capabilities of the Internet will require a lot of time and money.

At the same time, local networks are not sufficiently covered in the literature and are deprived of attention. Therefore, many computer users do not understand or know what purposes they serve.

Main functions

• Optimization of enterprise operation. The local network created in the office guarantees for all employees the possibility of remote data exchange and the use of various office equipment.
• Possibility of communication. Local networks are not capable of replacing access to the World Wide Web, but when it is necessary to create your own private channel for outside users, then you can’t do without such networks. For example, you can organize a forum for company employees.
• Remote administration. The network allows one administrator to provide technical assistance to several users at once.
• Saving. It’s better to pay once for connection to the World Wide Web, and do it for all employees general access than to separately connect each employee to Internet access and pay for it.
• Security of information exchange, comfort of use, games.

Local computer networks bring benefits in various areas of life. They served as a replacement for “pigeon mail” in production and in everyday life.

Communication standards

It is natural for us that we have the opportunity to connect to the Internet in any way and from any device - smartphone, computer, laptop and even TV or modern refrigerator. It doesn’t matter what brand these devices are or what system is installed on them.

When computer networks were just beginning, equipment from one company could only interact on the network with devices manufactured by that particular company, and no one else. There were many reasons for this - incompatibility of equipment, software and network protocols.

To avoid this problem, it is necessary to have and implement standards for equipment, network protocols and software.

There are two types of standards:

• Legal(formal). These are standards adopted by organizations entitled to do so.
• Actual(de facto). These are standards that are not accepted by anyone, but are self-imposed. For example, developed new technology, which spread widely and gained great popularity. This is what happened with the protocol, which is the basic one on the World Wide Web.

Computer networks have many communication standards, but the most important of them are four types:

• The international organization ISO develops standards for reference model work open systems, describing an approach to building networks of computers.
• The IEEE Institute of Engineers adopts standards for communications technologies.
• The Internet Architecture Council develops communication standards for Internet protocols.
• The W3C consortium develops standards for the Web (creation and design of websites).

Standards play a big role in the functioning of computer connections. We all work with the Internet, access it from any device running on any operating platform, and from any manufacturer. Open standards are used for this.

Transmission channels

To ensure the possibility of high-quality connection of computers, there must be a special transmission system - a channel.

The main types of transmission channels through which computer networks operate:

• Analog.
• Digital.
• Broadband and narrowband.
• Radio and satellite.
• Fiber optic cable.

Analog channels They were the first to be used for sending data over computer connections and made it possible to introduce public telephone communications.

Data transfer via them is carried out in two ways:

• Wires connect two objects that are connected to each other by direct switching; this is a dedicated line.
• The connection is made by dialing a telephone number using switched networks.

Through dedicated lines, the efficiency of information transmission is greater, and their operation is more reliable. A single channel requires an individual device, although multi-channel devices are available. With a dial-up line, you can communicate with other nodes through a single switching device.

Along with analog channels, the digital form of communication also developed. Together with discrete packages, voice communications and fax data, modified into digital form, are transmitted over a digital line.

High speeds over short distances are achieved through the use of special conductors called. It allows you to avoid the influence of neighboring wiring on the quality of work.

Cable lines, called pairs, consist of two coaxial conductors separated by a dielectric. One type of cable is used for narrowband information packets, the other for broadband data. These types of cable make it possible to work at high speed.

At short distances cable channels gradually replaced by twisted pair, and at a considerable distance - by cable. It uses a phenomenon in which light rays are reflected inside the cable. This makes it possible to transmit light rays over long distances without any loss. The sources of luminous flux in fiber optic structures are , or , and work instead of receivers.

Fiber optic channels have a high cost, unlike other types, but are increasingly being used not only for small networks, but also in areas with very long cable lines.

The use of radio waves of different frequencies in computer connections has become economically beneficial to ensure high-quality communication with other computer equipment located at long distances using satellites. Radio waves are also widely used to communicate with non-permanently used devices or mobile equipment.

Data transmission over radio channels is most often carried out digitally and analoguely. The first method is developing more intensively today, as it makes it possible to combine satellite channels and computer networks located on the surface of the Earth into unified system. A powerful impetus in the development of radio channels was the emergence cellular communications, which makes it possible to transmit audio signals, transmit information via radiotelephone and other devices.

Local computer network(LAN) is a complex of equipment and software that provides transmission, storage and processing of information.

Purpose of local networks

The purpose of a local network is to provide shared access to data, programs and equipment. A team of people working on one project has the opportunity to work with the same data and programs not in turn, but simultaneously. A local network provides the opportunity to share equipment. The best option- creation of a local network with one printer for each department or several departments. A network file server allows for shared access to programs and data.

The local network also has an administrative function. Monitoring the progress of projects online is easier than dealing with multiple offline computers.

The local network (LAN) includes the following equipment:

• Active equipment – ​​switches, routers, media convectors
• Passive equipment - cables, mounting cabinets, cable ducts, patch panels, information sockets
• Computer and peripheral equipment – ​​servers, workstations, printers, scanners.

Depending on the requirements for the designed network, the equipment used during installation may vary.

Basic characteristics of a local network

Currently, various countries around the world have created and operated Various types LAN with different sizes, topology, operating algorithms, architectural and structural organization. Regardless of the type of network, they are subject to general requirements:

• Speed ​​- most important characteristic local network
• Adaptability - the ability of a local network to expand and install workstations where required
• Reliability is the property of a local network to maintain full or partial functionality, regardless of the failure of some nodes or end equipment.

Local network topology

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

The topology determines the requirements for equipment, the type of cable used, the permissible and most convenient methods of managing the exchange, reliability of operation, and possibilities for network expansion. And although a network user rarely has to choose a topology, it is necessary to know about the features of the main topologies, their advantages and disadvantages.

There are three basic topologies networks:

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

Star (star) - comes in two main types:

• Active star (true star) - one central computer is connected to other peripheral computers, each of them using separate line communications. Information from a peripheral computer is transmitted only to the central computer, from the central one - to one or more peripheral
• A passive star that only looks like a star (Fig. 2). Currently, it is much more widespread than an active star. Suffice it to say that it is used in the most popular Ethernet network today

In the center of a network with this topology, there is not a computer, but a special device - a switch or, as it is also called, a switch (What is a Switch?), which restores incoming signals and sends them directly to the recipient.

Ring - computers are sequentially combined into a ring.

The transmission of information in the ring is always carried out in only one direction. Each computer transmits information only to one computer next in the chain behind it, and receives information only from the previous computer in the chain.

In practice, other local network topologies are often used, but most networks are focused on three basic topologies.