Aigazieva Saltanat, Afanasyeva Svetlana, Kutepova Natalya

Group Research Topic

Computer networks

Problematic question (research question)

What types of networks are there?

Research hypothesis

Computer networks are: Local, Global, Regional

Objectives of the study

Study the structure of a computer network; Learn basic networking tools.

Progress of the study

What is a computer network? Network - a group of computers and/or other devices connected in some way to exchange information and share programs, data files and peripheral devices.

Server is a computer with a server operating system installed on it, providing its software and hardware resources to network users.

Peer is an equal participant in the network, providing services to other participants in the peer-to-peer network and using their services.

Trunk - a transmission channel between two points - nodes or switches.

The Internet is a collection of networks connected to each other by telecommunications infrastructure.

A domain is a group of computers that are under unified control and have a common segment in the Internet address. IP address is a 32-bit Internet protocol address assigned to a node. An IP address contains two components: a host number and a network number. Modem is a device that converts digital signals to analog for transmission over a telephone line, as well as performing reverse conversion of incoming analog signals into digital ones for computer processing. Router (router) is a network equipment that operates at the network level and establishes connections between different networks. Network switch, switch, switch (jarg from the English switch - switch) - a device designed to connect several nodes of a computer network within one or more network segments. A network hub or hub (jarg from the English hub - activity center) is a network device designed to combine several Ethernet devices into a common network segment. A protocol is a standard that describes the rules for interaction of functional blocks when transmitting data. A packet is a formatted block of data transmitted over a network. What types of networks are there? Classification of computer networks By territorial distribution: PAN (Personal Area Network) - a personal network designed for the interaction of devices belonging to the same owner. LAN (Local Area Network) - local networks that have a closed infrastructure before reaching service providers. Access to local networks is permitted only to a limited number of users. CAN (Campus Area Network) is a campus network that unites local networks of nearby buildings. MAN (Metropolitan Area Network) - urban networks between institutions within one or several cities. WAN (Wide Area Network) - a global network covering large geographic regions, including both local networks and other telecommunication networks and devices. By type of functional interaction. Client-server is a computing or network architecture in which tasks or network load are distributed between service providers, called servers, and service customers, called clients. A mixed network is a network architecture in which there are a number of servers that form a peer-to-peer network among themselves. End users each connect to their own server using a client-server scheme. A peer-to-peer network is an overlay computer network based on the equality of participants. In such a network there are no dedicated servers, and each node (peer) is both a client and a server. A multi-rank network is a network in which there is a leader, or “master” controller that coordinates the work of “slave” controllers that actually control one or more access points. By type of network topology: Basic: A bus is a common cable (called a bus or backbone) to which all workstations are connected. There are terminators at the ends of the cable to prevent signal reflection. A ring 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. There is only one transmitter and one receiver on each communication line. A star is a computer network topology in which all computers on the network are connected to a central node (usually a switch), forming a physical segment of the network. Derivatives: A double ring is a topology built on two rings. The first ring is the main path for data transfer. The second is a backup path that duplicates the main one. Mesh - the basic fully connected topology of a computer network, in which each work station network connects to several other workstations on the same network. A lattice is a topology in which the nodes form a regular multidimensional lattice. In this case, each edge of the lattice is parallel to its axis and connects two adjacent nodes along this axis. The tree is a more developed “bus” type configuration. The connection of several simple buses to a common backbone bus occurs through active repeaters or passive multipliers. Fat Tree is a computer network topology for supercomputers. In a thicker tree, the connections between nodes become more bandwidth efficient with each level as they approach the root of the tree. By type of transmission medium: Wired (telephone wire, coaxial cable, twisted pair, fiber optic cable. Wireless (transmission of information via radio waves in a certain frequency range). By functional purpose: Storage area networks - architectural solution for connection external devices storing data in such a way that the operating system recognizes the connected resources as local. A server farm is an association of servers connected by a data network and operating as a single unit. Process control networks are computerized systems capable of converting information, performing calculations, logical operations, using various types computer networks and modern information technologies. SOHO networks & Home network - a type of local computer network, laid within one building or combining several nearby buildings. By transmission speed: low-speed (up to 10 Mbit/s) medium-speed (up to 100 Mbit/s) high-speed (over 100 Mbit/s) By network OS: Based on Windows On UNIX based Based on NetWare As required for maintenance permanent connection: Packet network, such as Fidonet and UUCP Online network, such as Internet and GSM How do computers on a network find each other? Every computer in local network has its own unique address, just like a person has his own postal address. It is at these addresses that computers find each other on the network. There should not be two identical addresses on the same network. The address format is standard and defined by the IP protocol. The computer's IP address is written in 32 bits (4 octets). Each octet contains decimal number from 0 to 255 (in binary, the entry represents a sequence of 0s and 1s). An IP address is four numbers separated by a dot. For example, a computer with an IP address of 192.168.3.24. The total number of IP addresses is 4.2 billion, all addresses are unique. An IP address can be assigned not only to a computer, but also to other network devices, for example, a print server or router. Therefore, all devices on the network are usually called nodes or hosts. The same physical device (computer or other) can have several IP addresses. For example, if several network adapters are installed on your computer, then each adapter must have its own unique IP address. Such computers are used to connect several local networks and are called routers. A large IP network is divided into several subnets, each with its own address. Subnets are separate, independently functioning parts of the network that have their own identifier. For the subnet address, the IP address is allocated space from the host address. A subnet mask is used to determine the network address and subnet. The format of the subnet mask entry is the same as the format of the IP address, it is four fields separated by a dot. Thus, a subnet mask must be indicated in conjunction with the IP address of the computers.

conclusions

A computer network is an association of several computers for the joint solution of information, computing, educational and other problems.

All computer networks Without exception, they have one purpose - to provide shared access to shared resources. There are three types of resources: hardware, software, information. Based on the method of organization, networks are divided into real and artificial. Based on the speed of information transfer, computer networks are divided into low-, medium- and high-speed. According to the territorial distribution, networks can be local, global, regional and urban.

A local computer network is a collection of computers connected by communication lines, providing network users with the potential opportunity to share the resources of all computers. A local network is created for the rational use of computer equipment and the efficient work of employees.

A global network (WAN or WAN - World Area NetWork) is a network that connects computers that are geographically distant from each other. It differs from a local network in more extensive communications (satellite, cable, etc.). The global network connects local networks.

Internet is a global computer network covering the whole world. The Internet is a constantly developing network, which still has everything ahead, let’s hope that our country will not lag behind the progress.

Perhaps every schoolchild knows that the entire modern world is a giant virtual web. The times when the exchange of information was carried out on the principle of “hand to hand”, and the main data carrier was a stamped paper folder, are in the distant past, but now countless virtual highways connect all points of the planet into a single information system– computer data transmission network.

What is a computer network?

In a general sense, a computer data network is a communication system of various computer technology(including PCs and user office equipment), necessary for automatic data exchange between end users, and remote control functional units and software this network.

There are a great many ways to classify computer networks (by architecture, type of transmission medium, network operating systems etc.), however, delve into the jungle of theory network technologies we will not: particularly inquisitive users can always find this information in educational literature. Here we will limit ourselves to the simplest classification of networks depending on their length.

So, computer networks are divided on a territorial basis into local and global:

A global computer network is a data transmission network that covers the entire world (or individual large regions) and unites an unlimited number of unconnected subscribers.

A local computer network is a collection of PCs and network equipment connected by communication channels, designed to transmit data to a finite number of users. By the way, the term “local network” was assigned to the system at a time when the capabilities of the equipment did not allow organizing such communication for subscribers remote over long distances, but now local computer networks are used both for organizing local communications(within one building or organization) and cover entire cities, regions and even countries.

Types of computer networks

According to the method of organizing communication between subscribers, the topology of computer networks distinguishes the following local network schemes:

Where the network nodes are computers, office equipment and various network equipment.

More complex topologies (such as tree network, mesh network, etc.) are built by various connections of the three elementary types of local network.

Local network functions

We will not talk about the purpose of global networks and how the Internet benefits the world: the main functions of the World Wide Web are already well known to every user, and detailed description More than one book could be devoted to all the possibilities of the network.

At the same time, home networks are unfairly deprived of informational attention, and many users do not understand why they need a local network at all.

So, the main functions of a local network:

• - Optimization of the workflow. Thus, a home local network, organized, for example, in an office, provides all its employees with the opportunity to remotely exchange data, as well as share the use of all types of office equipment;
• - Communication. Of course, local networks will not be able to completely replace “Internet connection”, but in cases where you need to organize your own, closed from external users, communication channel (for example, a forum for corporate employees), local networks are simply irreplaceable;

• - Opportunity remote administration. Thus, a corporate local network allows one specialist to provide technical support several dozen various devices;
• - Saving. Agree, it is more logical to pay for an Internet connection once and provide all employees of the organization (user devices) with the opportunity to free access, than to pay for access to world wide web each employee (gadget) individually;
• - Games, security of data exchange, user comfort and much more.

Thus, the local network is very, very useful tool in any field of activity. In fact, it was local networks that replaced the well-known “ pigeon mail“both at any enterprise and between friends (after all, this is a much more functional alternative to tapping on the battery and “cactus” signals on the windowsill). And our lessons will help you not only create a local network from scratch with your own hands, but also solve much more complex issues of administering corporate networks and setting up different types of network equipment.

Articles on computer networks and modern telecommunication technologies present wireless computer networks, Internet communications, Web communications and IoT/WoT telecommunication technologies. Internet communications include: messaging systems; on-line video; VoIP. Messaging systems include services that operate off-line: E-mail, SMS sending and instant messaging services: IRC, chats, IM, PTT and so on in on-line mode.

Most promising directions Internet communications are Web-based communications in real time. Web communications include: p2p video chats on WebRTC base; SIP softphones in web interface based on WebRTC, SIPML5, webrtc2sip; file sharing platform based on the WebRTC Data Channel API; video conferencing based on HTML5 and WebRTC API, etc. One of the modern solutions in the field of web communications are WebRTC technologies, HTML5 with JavaScript and CSS3, the Node.JS platform, as well as the WebSocket protocol.

Browsers supporting WebRTC, WebSocket and SIPML5 is a single tool (interface) for all user devices (PCs, smartphones, iPads, IP phones, mobile phones etc.) that provide real-time Web communications.

Computer network is a collection of computers and various devices that provide information exchange between computers on a network without the use of any intermediate storage media.

The creation of computer networks is caused by the practical needs of users remote friend from each other's computers in the same information.

Networks provide users with the opportunity not only to quickly exchange information, but also to collaborate on printers and other peripheral devices, and even to process documents simultaneously.

The entire variety of computer networks can be classified according to a group of characteristics:

• Territorial distribution;
• Departmental affiliation;
• Information transfer speed;
• Type of transmission medium.

According to the territorial distribution, networks can be local, global, and regional.

By affiliation, departmental and state networks are distinguished.

Departmental ones belong to one organization and are located on its territory.

Based on the speed of information transfer, computer networks are divided into low-, medium- and high-speed.

Based on the type of transmission medium, they are divided into coaxial networks, twisted pair networks, fiber optic networks, with information transmission via radio channels, and in the infrared range.

Local computer networks

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

In small local networks, all computers usually have equal rights, that is, 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.

If more than ten computers are connected to the local network, then the peer-to-peer network may not be efficient enough.

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

Each computer connected to the local network must have a special card (network adapter). Computers between each other ( network adapters) are connected using cables.

Network topology

The general scheme for connecting computers into local networks is called network topology. Network topologies can be different.

Ethernet networks can have a bus or star topology. In the first case, all computers are connected to one common cable (bus), in the second, there is a special central device (hub), from which “rays” go to each computer, that is, each computer is connected to its own cable.

The bus type structure is simpler and more economical, since it does not require an additional device and consumes less cable. But it is very sensitive to cable system faults. If the cable is damaged in even one place, then problems arise for the entire network. The location of the fault is difficult to locate.

Bus topology

Star topology

In this sense, the “star” is more stable. A damaged cable is a problem for one specific computer, this does not affect the operation of the network as a whole. No effort is required to isolate the fault.

Ring topology

In a network with a “ring” type structure, it is transmitted between stations along the ring with reception in each network controller. Reception is carried out through buffer drives made on the basis of random access memory devices, so if one network controller fails, the operation of the entire ring may be disrupted. The advantage of the ring structure is the ease of implementation of devices, and the disadvantage is low reliability.

Regional computer networks

Local networks do not allow shared access to information among users located, for example, in different parts of the city. Regional networks come to the rescue, connecting computers within one region (city, country, continent).

Corporate computer networks

Many organizations interested in protecting information from unauthorized access (for example, military, banking, etc.) create their own, so-called corporate networks.

A corporate network can unite thousands and tens of thousands of computers located in different countries and cities (an example is the Microsoft Corporation network, MSN).

Global computer network Internet

Currently, tens of millions of computers connected to the Internet store a huge amount of information (hundreds of millions of files, documents, etc.) and hundreds of millions of people use information services global network.

The Internet is a global computer network that unites many local, regional and corporate networks and includes tens of millions of computers.

In each local or corporate network there is usually at least one computer that has permanent connection to the Internet using a high-speed connection throughput(server).

The reliability of the global network is ensured by the redundancy of communication lines: as a rule, servers have more than two communication lines connecting them to the Internet.

The basis, the “framework” of the Internet consists of more than one hundred million servers constantly connected to the network. Internet servers can be connected using local networks or dial-up telephone lines hundreds of millions of network users.

Here is an example of one from the global center

Large Google center for storing Internet data

BASIC CONCEPTS FOR INTERNET USERS ON MODERN UNITED COMPUTER NETWORKS

Shcherbakova Svetlana Mikhailovna 1, Krupina Tatyana Aleksandrovna 1
1 Moscow Pedagogical State University, Master's student of the Department of Applied Mathematics and IT

BASIC CONCEPTS FOR INTERNET USERS ON CONTEMPORARY UNITED COMPUTER NETWORKS

Shcherbakova Svetlana Mikhailovna 1 , Krupina Tatiana Aleksandrovna 1
1 Moscow State Pedagogical University, Graduate of the Department of Applied Mathematics and IT

Bibliographic link to the article:
Shcherbakova S.M., Krupina T.A. Basic concepts for Internet users on modern unified computer networks // Modern technology and technology. 2016. No. 10 [Electronic resource]..02.2019).

Due to the annual increase in services provided to the population through computers and the global computer network Internet (for work, education, leisure), there is increasingly a need for network specialists to communicate with ordinary users, using some network terms. Therefore, the time has come for a certain educational program on computer networks for ordinary, more or less active Internet users.

A computer network is an interconnected group of computers in the same room or on different continents that exchange information via special wired or wireless communication channels. By scale, computer networks can be classified as follows: personal, local, corporate, city and global.

Network administrators, unlike the user, have access to configure the network and troubleshoot problems associated with achieving the desired level of operability and performance.

According to the method of connecting computers and other network devices computer networks can be classified according to the hardware technology implemented during the network creation, which is used to connect individual network devices, for example, fiber optic, twisted pair (Ethernet), wireless (Wireless LAN), telephone line based. In addition to computers, the network contains such network devices as: hubs, switches, bridges, routers and gateways. Wireless technology Wireless LAN uses radio frequencies to connect devices on the network.

Based on the functional connection between computers, networks can be classified as client-server (where there is a dedicated main computer and subordinates) and peer-to-peer (all computers are of the same rank). Based on topology, computer networks can be classified according to the logical connection of all network devices, for example, bus, star, ring, tree, hierarchical topologies, etc. Network topology refers to the way in which smart devices on a network see logical connections with each other. That is, the network topology does not depend on the “physical” location of the network. Even network computers physically in a linear arrangement, if they are connected through a hub, the network has a star topology rather than a bus topology. Because of this, the logical network topology does not necessarily match the physical layout.

The rules for transferring information between computers on a network are called a protocol. Commonly used protocols are TCP and IP.

Let's look at the main types of networks. A personal area network (PAN) is a computer network between computers and devices owned by one person. Some examples of devices that can be used in a personal area network are: printers, fax machines, telephones, PDAs, or scanners. PAN is usually located at home within approximately 5-12 meters.

A local area network (LAN) covers a small area; it can be a separate room, home, office or business center. Modern local networks are based on Ethernet technologies. The defining characteristics of local networks, as opposed to global networks, are that they are more high speeds data transfer, smaller size, and no need to rent communication lines. Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbps. This is the data transfer rate. However, IEEE also has standards up to 100 Gbit/s.

A wide area network (WAN) is a data network that covers a relatively wide geographic area (ie, entire cities and countries), and often uses telephone company lines to carry data. WAN technologies typically operate at the bottom three layers reference model OSI: physical layer, link layer and network layer.

Global Area Network (GAN). Specifications wide area networks (GANs) are under development by several groups and there is no single definition. Overall, GAN is a model to support mobile communications over an arbitrary number of wireless local networks, satellite coverage areas, etc. The main task in the field of mobile communications is to “switch” user messages from one local area to another.

Two or more networks or network segments connected by devices that operate at Layer 3 (the 'network' layer) of the OSI Basic Reference Model, such as a router. Any interconnection between public, private, commercial, industrial or government networks can be referred to as an internetwork.

In the modern practice of interconnected networks, there are at least three variations of networks, depending on who manages and who participates in them. These are: 1. Intranet 2. Extranet 3. Internet. Intranets and extranets may or may not have Internet connections. When connected to the Internet, an intranet or extranet is generally protected from unauthorized access from the Internet without specific permission. The Internet is not considered part of an intranet or extranet, although it can serve as a portal to access parts of the extranet.

An intranet is a collection of interconnected networks that use the Internet Protocol and use tools such as Web browsers and FTP tools that are under the control of the administrator. The administrator closes and opens the intranet from the rest of the world, and gives access only to certain users. Most often, an intranet is the internal network of a company or other enterprise. A large intranet usually has its own web server to provide more information to users.

An extranet is a network that is limited within a single organization or entity, but also has limited connections to the networks of one or more trusted organizations or legal entities(for example, a company's clients may be given access to some part of its intranet network, thus creating an extranet, but at the same time clients cannot be considered "inside people" from a security point of view). From a technical point of view, an extranet can also be classified as a corporate type of network, although, by definition, an extranet cannot consist of a single local network; it must have at least one connection to an external network.

The Internet consists of a worldwide interconnection of government, scientific, public and private networks. Internet participants, or their service providers, use IP addresses obtained from address registrars.

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