Intended for routing, switching, transmission and / or reception of signs, signals, written text, images and sounds or messages of any kind by radio, wire, optical or other electromagnetic systems between terminal equipment
Departmental communication network- a communication network operated by a legal or natural person to meet their own needs.
Examples of telecommunications networks:
1. Components
All telecommunications networks are made up of five main components that are present in every network environment, regardless of type or use. These main components include terminals, telecommunications processors, communication channels, computers, telecommunications and software management.
- Terminals are starting and stopping points in any conditions of the telecommunications network. Any input or output of the device,
used to transmit or receive data can be classified as a terminal component.
- Telecommunications processors support data transmission and reception between terminals and computers, providing various control and
helper functions. (i.e. converting data from digital to analog and vice versa).
- Telecommunications channels are the path by which data is transmitted and received. Telecommunication channels are created using various
media, of which the most popular include copper wire and coaxial cable (SCC). Fiber optic cables are more commonly used to bring faster and reliable connection for business and home.
- In a telecommunications environment, computers are connected through media to perform their communication tasks.
- The Telecom control software is present on all computers on the network and is responsible for monitoring network activity and functionality.
Early networks were built without computers, but at the end of the 20th century their switching centers were computerized or the networks were replaced by computer networks.
1.1. Network structure
In general, every telecommunications network is conceptually composed of three parts, or planes (so-called because they can be seen as being, and often, separately superimposed networks):
- The control plane implements information management (also known as signaling).
- Data plane or user plane or bearer aircraft carries network user traffic.
- Traffic control is defined in the operations plane.
1.2. Example: TCP / IP data network
The data network is widely used throughout the world to connect individuals and organizations. Network data can be connected to allow users seamless access to resources hosted outside of the specific provider they are connected to. Internet is best example Moreover, many data networks from different organizations all operate within the same address space. Terminals attached to TCP protocol/IP networks are resolved using the IP address. Exist Various types IP addresses, but the most common is IP version 4. Each unique address consists of 4 integers from 0 to 255, usually separated by dots when written, for example, 82.131.34.56. TCP/IP are the main protocols that provide control and routing of messages over data networks. There are many different TCP/IP structures you can use to route messages efficiently, for example:
- wide area networks (WANs)
- city networks (MAN)
- local area networks (LAN)
- campus networks (CAN)
- virtual private networks (VPNs)
There are three features that distinguish MANs from LANs or WANs:
1. Area network size is between LAN and WAN. MAN will be a physical space between 5 and 50 km in diameter. 2. MAN, as a rule, do not belong to the same organization. The equipment that connects the network, the connection, and the individual himself is often owned by an association or network provider that provides or leases service to others. 3. MAN is a means for sharing resources at high speed within a network. It often provides connectivity to WANs, networks for accessing resources outside the scope of the MAN
An information and telecommunications network is a set of methods and technologies used to obtain necessary information, which is able to ensure the activities of the company, as well as satisfy the personal needs of users. It is important to understand that quality characteristics of the received information, that is, its reliability, volume, relevance and other characteristics, often depend on the owner of the information product, and not on the computer network.
Information and users
An information and telecommunication network is a set of resources that face one important problem - information content. The development of the world's infrastructure makes it more and more relevant, because many subnets and data sets make the process of servicing each user very complicated. The use of information and telecommunication networks requires High Quality information that is supplied in them, as well as high-quality comprehensive user service, high-quality equipment. Important point concerns and search engines, which often do not correspond to the capabilities stated in the advertisement.
Practice shows that even trained users are not able to fully evaluate the parameters of the presented systems. Quite often, those systems that have become known thanks to advertising actually turn out to be not so effective, since in these cases the main part of the efforts of manufacturers is aimed specifically at advertising promotion, and the quality problems of the supplied software go by the wayside.
Types of information and telecommunication networks
There are two separate classes of telecommunications networks: universal and specialized. Characteristics universal systems is an high price with a wide coverage. In specialized systems, all possible information is missing, and therefore their cost is lower. It is important to understand that the number of documents included in the brochures does not always serve as a sign of completeness and the advantage of the system being purchased. Quite often, the full texts of documents are replaced by short library cards. If an information and telecommunications network is created, this makes it necessary to attract certain funds. At the same time, a supplier of products is selected that offers: the most convenient conditions for payments, low cost, technology for updating, a warranty service system, documents that indicate the possibility of selling.
Foreign telecommunications networks
The use of information and telecommunication networks implies the existence of several different types who became the progenitors of one single. That is, it implies a certain evolutionary process, the result of which was the emergence of the world-famous Internet.
ARPANET - was for 15 years the most developed global network linking computers. On the this moment it is one of the largest subnets of the Internet. The main reference point of this complex is taken on tasks related to research activities.
INTERNET
INTERNET is the largest information and telecommunication network. Its definition as global is due to the fact that it covers every corner of the globe. There are more than 30 million people here as users, and this figure is increasing every year. Here, at the moment, all services that are typical for public information and telecommunication networks are presented. The US National Science Foundation maintains and finances most of the Internet, which is focused on solving educational and research problems. For these purposes, there are several specialized subnets:
NSFnet is characterized by a hierarchical structure and concentration around large university centers in the United States of America;
Milnet is a network owned by the US Department of Defense;
NASA Science Internet (NSI) - this information and telecommunications network is a collection of several computer networks engaged in space research, space physics, as well as other areas of a scientific nature, which are combined into a common global internet.
BITNET
BITNET, like the Internet, is one of the oldest global networks. It provides network access to a research nature. Bitnet has several regional parts:
Central and Western Europe - EARN; here computers of the research centers of England, France, Germany, Italy and other states are included;
Canada - NetNorth.
EVnet is the largest in Europe, which was launched in 1982. This information and telecommunications network is an extensive structure that has regional offices in all European countries, as well as in the Baltic States and Russia.
Fidonet is a youth network for informal communication.
Russian telecommunications networks
The use of information and telecommunication networks occurs everywhere, and in Russia they were formed on the basis of industry networks. Not so long ago, their task was the formation of databases and electronic communications to provide access to them. Therefore, these two areas information activities on the Russian territory and are now virtually unrestricted. At the moment, there are three closed systems that have become the main ones: the network of the Presidential Administration, which has become an association of subjects of the Russian Federation, all bodies and ministries of legislative and executive power; network "Atlas" - a combination of the banking network and public authorities; network PIENet SIC "Kontur" FAPSI. All these networks are designed for special needs and are not available to ordinary users.
Industry networks
When the old system of economic management collapsed in the 1990s on the territory of the former USSR, many enterprises were faced with the fact that they lacked business information. It was at this time that the business in the field of information and intermediary services flourished. The collapse of the usual system gave impetus to attract financial resources and the formation of a commercial information infrastructure. It was then that many industry networks served as the basis for the formation of commercial organizations providing telecommunications services.
Basis for business development
At that moment, many firms from abroad joined in Russian market in order to form such a development tool as an information and telecommunications network. Foreign representatives had a concept of how it should work, because many networks and subnets have been operating there quite successfully for many years. It was then that specialized systems were formed, designed to provide access to the international level: Sprint, BizLink, Infonet, PIENet, GTS interlinc, Infotel. They were created by forces on the basis of foreign equipment and technologies. Now they have become part of the Internet information and telecommunications network.
Development of telecommunications and networks
At the moment, the development of the industry around the world is carried out at a rapid pace. If we talk about compliance with the law, then the information and telecommunication network is a technological system designed to broadcast information over communication lines. Access to information can be carried out exclusively with the use of computer technology. Data transmission via the Internet information and telecommunications network is carried out without restrictions, provided that the requirements of federal laws for the dissemination of information and the protection of intellectual property are strictly observed. At the moment, many companies, both in Russia and around the world, are engaged in the development of networks for global, federal, regional, corporate purposes, and also supply enterprises participating in networks with high-quality technological equipment manufactured in full compliance with television and communication standards.
Computer network (CS) - a set of computers and terminals connected via communication channels in single system, which satisfies the requirements of distributed data processing .
In general, under telecommunications network (TS) understand a system consisting of objects that perform the functions of generating, transforming, storing and consuming a product, called points (nodes) of the network, and transmission lines (communications, communications, connections) that transfer the product between points.
Depending on the type of product - information, energy, mass - information, energy and material networks are distinguished, respectively.
Information network (IS) - a communication network in which the product of generating, processing, storing and using information is information. Traditionally for transmission sound information are used telephone networks, images - television, text - telegraph (teletype). Nowadays information is becoming more and more widespread. integrated service networks, allowing to transmit sound, image and data in a single communication channel.
Computing network (CN)- information network, which includes computing equipment. The components of a computer network can be computers and peripherals, which are sources and receivers of data transmitted over the network.
Aircraft are classified according to a number of criteria.
- 1. Depending on the distance between network nodes, aircraft can be divided into three classes:
- · local(LAN, LAN - Local Area Network) - covering a limited area (usually within the remoteness of stations no more than a few tens or hundreds of meters from each other, less often 1 ... 2 km);
- · corporate (enterprise scale)- a set of interconnected LANs covering the territory where one enterprise or institution is located in one or more closely spaced buildings;
- · territorial- covering a significant geographical area; Among territorial networks, one can single out regional networks (MAN - Metropolitan Area Network) and global networks (WAN - Wide Area Network), having, respectively, regional or global scales.
Particularly distinguish the global network of the Internet.
2. An important feature of the classification of computer networks is their topology, which determines the geometric arrangement of the main resources of the computer network and the connections between them.
Depending on the topology of node connections, there are bus (backbone), ring, star, hierarchical, and arbitrary networks.
Among the LANs, the most common are:
- · bus - the local network, in which communication between any two stations is established through one common path and the data transmitted by any station is simultaneously available to all other stations connected to the same data transmission medium;
- · ring- the nodes are connected by a ring data transmission line (only two lines go to each node). Data, passing through the ring, alternately becomes available to all network nodes;
- · stellar (star)- there is a central node from which data transmission lines diverge to each of the other nodes.
The topological structure of the network has a significant impact on its throughput, the network's resilience to failures of its equipment, the logical capabilities and cost of the network.
The Internet is the largest computer telecommunications system in the world, serving as a means of delivering information. She embodied the most important technological and in the field of electronics and telecommunications. Its emergence and development took place in the second half of the 20th century, when the necessary technical prerequisites for creating the system were in place:
- organized the mass production of personal computers and the saturation of them not only in the spheres of business life, but also in the life of many tens of millions of people;
- high-capacity lines were created and laid, connecting most countries and regions of the world;
- implemented unified with computers digital methods transmission of information through telecommunication systems;
- A wide telephonization of the leading industrial and industrial enterprises was achieved, which made it possible to connect national computer information networks to the Internet.
In the information space covering the whole world, sources of information and its consumers are often separated from each other by huge distances, different language barriers. A feature of an intangible information product (goods) is the ability to meet immediate demand for it with the help of modern technology and technologies of telecommunication systems. This product may be transferred by different systems telecommunications in the form necessary for the consumer - text, speech, music, graphics, still or moving video clips in color or black and white.
The value of modern telecommunications is determined by:
- the globalization of communications, i.e. coverage by all types of telecommunications of all territories and water areas of the planet and the entire near-Earth space;
- internationalization of communications, i.e. standardization of its technical, technological, organizational parameters in each of more than 200;
- integration of all types of telecommunications into a single powerful world system telecommunications;
- the growing provision of information consumers with various types of telecommunications in the most remote areas of the world.
The total number of technical means for receiving mass audio and video information (radios, televisions) and for active individual communication (all types of fixed and mobile phones) has already exceeded 4 billion units in the world and is increasing by hundreds of millions every year. Their density is quite high: on average, there are at least two types of this equipment per family on the planet. For a number of regions (, Western,) these figures are much higher, and in some states they are exceptionally large (in total, one family has an average of 15-17 units of radios, televisions, telephones connected to computer communication systems). This allows you to receive a wide variety of information from around the world.
The use of modern means of communication for the sustainable exchange of information flows was first widely used on the Internet. The beginning of the creation of the worldwide computer network Internet dates back to 1969, when in the USA the ARPA agency, fulfilling the order of the Pentagon, connected four powerful computers, organizing an experimental interregional network, called "Arpanet". It was intended exclusively for military purposes and had to function reliably in the event of a nuclear war: if some of the nodes (computers) or channels failed, the rest would continue to work, providing all communication conditions. The network guaranteed the receipt of the necessary information from the data banks that survived after the nuclear strikes for decision-making in critical situations.
The operation of extremely expensive computers and the networks connecting them, which remained lightly loaded outside of critical situations, was very costly for the US military. It was decided to connect to the Arpanet on a commercial basis local specialized computer networks of many universities, research centers and laboratories in different US states. This task was made easier by the fact that most of them performed research work on orders from the Pentagon. Thus, the main organizational and structural technological principles of the functioning of the Arpanet were preserved.
Until the beginning of the 80s. The Arpanet remained predominantly a dedicated US research and teaching computer network. The exchange of various information between scientific and educational centers grew very rapidly and reached impressive volumes. Therefore, a radical modernization of the communication lines connecting the computers of 1,500 such centers of the country was required. After its completion, the speed of information transfer through them increased 30 times and amounted to 45 million bits (1400 typewritten pages) per second. The problem arose of separating a scientific computer network into an independent highly specialized one and withdrawing it from the Arpanet. Such a network - CSNET - was created for computer scientists.
In 1983 Arpanet, fully converted and turned into a commercial network, was called the Internet. Its rapid development was facilitated by:
- the creation of personal computers in the same years, followed by their mass production, the ability to connect a computer to a telephone line in order to receive local, regional, national and international information and exchange it;
- showing interest in the services of many companies, firms and especially individuals;
- the accumulated experience of the population in the use of national information networks (a classic example is Information system"Minitel" in).
The Internet began to perform broad international functions after the World Wide Web system, or WWW - "World Wide Web" was developed at the European Center for Nuclear Research in Geneva. The new transmission protocol (WWW technology) united information nodes (servers) and communication channels, made it possible to coordinate the world scheme of addresses and codes for information providers and users of network services. Thanks to the WWW, the Internet has been connected to a variety of national specialized and universal networks. The number of Internet users began to grow rapidly, not only in the United States, but throughout the world.
The Internet has no organizational structure. Users of its services connect to various national or international, commercial or government companies in telecommunication systems. A complex multi-stage scheme has been formed for users to access the Internet through numerous intermediaries (“providers”). There are many thousands of companies and intermediaries providing access to the Internet. They own communication lines, but more often they rent them, determining different tariffs for services. Therefore, there is a fierce competition between them for profits. They often attract network users by providing certain benefits. Often, individual telecommunication channels experience severe congestion during business hours and cannot cope with excessively concentrated information flows over the Internet networks.
Internet services are provided by information embedded in the so-called main computers, the number of which, according to various estimates, ranges from 5 to 9.5 million. They are located in various countries and regions of the world, and their number is growing rapidly as commercial organizations increasingly strive to place their paid or free information on the Internet. By early 1996, approximately 170,000 commercial companies had posted their information online. The source of the most diverse information can be tens of millions of owners of personal computers through which any message can be transmitted on the Internet (such as Email and etc.).
The volume of work performed by the Internet is still purely estimated and is determined by a number of indirect indicators: the number of computers connected to its network, the number of its users, the volume or turnover of commercial companies participating in its activities. It is as easy to become an Internet subscriber as to refuse its services. Therefore, the number of Internet users in 1998, according to various estimates, ranged from 230 to 250 million. there could have been more users of Internet services. Commercial turnover on the Internet is estimated to be between $350 million and $1.2 billion.
The structure of Internet information flowing through networks is extremely complex and includes almost all areas of interest. modern society: from the most diverse reference material, educational courses to obtaining various commercial, technical, scientific and increasingly current newspaper, entertainment information. Through this worldwide computer system you can conduct much cheaper telephone conversations, e-mail messages pass through it. It allows you to organize video conferences with a large number participants. However, different types of information (often huge volumes) impose their far from the same requirements on the throughput of backbone, and especially local and individual (for example, telephone) telecommunication lines.
There are a number of unresolved problems in the functioning of such a complex system as the Internet. One of them is technical, which determines the future development of the Internet. With a large daily or seasonal overload, the quality of information from the consumer decreases. This is manifested in a strong drop in the speed of information transfer on communication lines. As a result, a number of types of information (graphics, videos) cannot pass through the channels at all. The transfer of large arrays of textual information is stretched for a long time. This causes a correspondingly higher consumer charge for Internet services.
Problems of poor-quality reception and transmission of information create trunk lines, local communications, which have different . Local telephone lines to which are connected Personal Computer, pass up to 33 Kbps. The most common speeds on the Internet are 64-128 Kbps. The poor technical condition of local lines and switches further reduces their capacity. Even the use of powerful modems does not always compensate for the shortcomings of the lines. Modern electronic technologies make it possible to pass information through modems and computers at a speed of tens of Mbps. Only such speeds can provide the highest quality reception of information of any kind. Lines can be cable television, new, cheaper types of fiber optic cable.
The main telecommunications networks include:
4. Computer networks(data transfer)
As for computer networks, they are designed for:
- data transmission;
- distributed data processing;
- sharing of resources;
- implementation of interactive communication;
Computer (computer) networks on one side of the network are a special case distributed computing systems, in which a group of computers performs a set of interrelated tasks in a coordinated manner, exchanging data automatically. On the other hand, computer networks can be considered as a means of communication or transmitting information at a distance, for which they use the methods of encoding and multiplexing data that have been developed in various telecommunication systems.
Computer networks also called data networks, are logical outcome evolution of the two most important scientific and technical branches of modern civilization - computer and telecommunication technologies.
Computer (information and computing) network- a set of computers and communication equipment that provides information exchange of computers in the network.
Information network- a communication network in which the product of generation, processing, storage and use is information.
Computing network- an information network, which includes computing equipment.
Fig 1. General scheme transmission of information
Under information network we will understand a set of geographically dispersed end systems and a telecommunications network that unites them, providing access for application processes of any of these systems to all network resources and their sharing.
All(computing) Computer networks can be classified according to a number of criteria. Depending on distances between PCs distinguish the following computer networks:
local computer networks - LAN(LAN - Local Area Networks) - computer networks located within a small limited area (building or in neighboring buildings) no more than 10 - 15 km;
· Territorial computer networks that cover a significant geographic area. Territorial networks include city (MAN - Metropolitan Area Network), regional (Regional computer network), national (National computer network), global (WAN - Wide Area Network) and corporate networks. City and regional networks connect subscribers of a district, city or region. global networks unite subscribers who are separated by a considerable distance, located in different countries or continents; Corporate networks enterprises - can combine computers of different branches of the enterprise located in different places.