Any telecommunication network can be considered as an infocommunication network (Fig. 9.2), which is part of the above-mentioned global information infrastructure.
Rice. 9.2. The structure of the infocommunication network
The main task of transport networks is to transfer information flows between different objects (network nodes). Access networks provide individual delivery of information streams to the terminal equipment of specific users, i.e. transfer of information between the interface of the node providing the service and the network interface of each user. The concept of access and access networks is very ambiguous and can determine both the characteristics of networks or equipment, and the places of connection of communication facilities, as well as recalling data from the memory of computers, etc. The totality of transport networks and access networks form national, regional or local infocommunication networks.
An infocommunication network can be viewed as an information system designed for storing, transmitting or processing data, superimposed on a telecommunication network (which, in fact, carries out data transmission). The definition of the information system given by the ISO is given in table. 9.1. In general, a modern telecommunication network (telecommunication network) is the core of any information network that provides transmission and some types of data processing. Quite often, on the basis of one telecommunication network, a whole set of information (superimposed) networks for various purposes is created, providing various services. For example, the Internet exists on top of both telephone and data networks. The main difference between superimposed networks and networks built on the basis of dedicated communication channels is that the user gets at his disposal a certain network resource with certain characteristics (for example, a guaranteed data transfer rate).
Terminal equipment is a key element of infocommunication networks (as well as telecommunication networks). The list of types of terminals used is quite long. The simplest of these is the telephone, and the most common is the computer.

Table 9.1. Concepts and definitions

Term	Definition
Information system	A set of objects consisting of one or more computers, programming tools, physical processes, telecommunications and other objects that form an autonomous whole capable of processing or transmitting data. The information system contains subsystems of hardware, software, information, organizational and legal support
Terminal	A device for input / output of data and commands into an infocommunication network that interacts directly with the user and converts data into a form suitable for transmission over telecommunication networks
Interface	Standards-defined boundary between interacting objects or the means of this interaction
Information communication network architecture	The set of physical, logical and structural elements of the network, the connections between them and the rules of interaction
Physical topology	Placing network points and lines connecting them in space
Logical topology	Ways by which the interaction between sources and consumers of information can be organized in the network
Endpoint (endpoint)	The place where terminal equipment, operating systems and information resources are located. It can be used to interface various network segments, as well as provide access to the network or to any services / services of the network (respectively, an access node and / or service node). The service node implements the User-Network Interface (UNI) to provide user access and the Service Node Interface (SNI) to interact with the network
Transmission circuit	A set of technical means and distribution media for signal transmission in a telecommunication network between network stations, network nodes or between a network station and a network node, as well as between a network station or a network node and a terminal device of the primary network
Typical transmission channel	Channel, the parameters of which comply with the standards of the ESE RF. A basic digital channel is usually referred to as a typical 64 kbps digital channel. Voice frequency (TFC) transmission channel - a typical analog transmission channel with a frequency range from 300 to 3400 Hz
Transmission line	A set of linear paths of transmission systems and (or) typical physical circuits that have common linear structures, service devices and the same propagation medium within the range of these devices
Subscriber line	Primary network transmission line connecting a network station or network node and a terminal device of the primary network
Connecting line (SL)	A transmission line connecting a network node and a network station. Trunk lines are named depending on the primary network to which it belongs: backbone, intrazonal, local
Node point, or just a node (node) of the network	A network point at which two or more trunk lines converge and which is intermediate on the path of data streams. A node can simultaneously or separately perform functions such as switching, routing, multiplexing or concentration

Table 9.1 (continued)

Term	Definition
Local Area Network (LAN)	A network in which the bulk of the load generated by users is locked inside a relatively small area (enterprise, office, building, complex of buildings, etc.)
T territorial network (Metropolitan Area Network, MAN)	Megalopolis network designed to serve the territory of a large settlement or a small region
Wide Area Network (WAN)	A network designed to combine LAN and MAN networks located on the territory of a large region, state, continent and even different continents
End point	A junction point for various segments of the same network and infocommunication networks, where equipment is installed that performs the functions of input-output and transformation of relevant information (information flows). This can be an edge switch, multiplexer or a so-called gateway used to interconnect networks based on different telecommunication technologies.
Transit	Connection of transmission channels or paths of the same name, ensuring the passage of telecommunication signals without changing the frequency band or transmission rate
The logical structure of the infocommunication network	Composition of network services and connections between them. Within its framework, all tasks of servicing network users are solved from ensuring the interaction of terminals and organizing the transfer of information to converting the formats and codes in which it is presented.
Group link (GT)	A set of technical means of a transmission system, intended for the transmission of telecommunication signals or main digital channels, and which, depending on the normalized number of channels, is called the primary, secondary, tertiary, quaternary or N-th group path. Typical group tract - a group tract, the structure and parameters of which comply with the standards of the ESE RF
Asynchronous, or start-stop method of data transfer	Information is transmitted and received at irregular intervals with messages sent to the receiver to determine when the data bits begin and end. Used for relatively low-speed transmission channels and stand-alone equipment
Synchronous (or isochronous) transmission method	It is used in high-speed channels and is based on sending a synchronizing clock signal over a separate channel or by combining it with the transmitted data
Data transfer protocol	Determines the sequence of sync pulses, the size of data blocks, service characters, etc. and stipulates the rules for error-free data transmission
Fast Packet Switching (FPS)	Digital technology using a single fixed-length packet format for different types of information (data, voice and video). All switching and routing functions are performed only in hardware. At the same time, it is possible to preserve the efficiency and reliability of packet switching and high throughput of channel switching in distributed networks.

The terminal provides a user interface with an infocommunication network or with an information system that is used for transmission.

An information system that is created in one device or a group of devices installed in one place is called single-point. A multipoint system is formed on many interconnected devices installed geographically in different places. Any multipoint system (which cannot be created without an appropriate communication network) forms an infocommunication network. An organization engaged in the synthesis of information systems is called an integrator.
Let's consider various architectural aspects of building an infocommunication network. The architecture is displayed in the form of models, which are sometimes described using the expression topological structure, or topology. Distinguish between physical and logical network topology. The choice of the network topology is the first task solved by its developers, taking into account the requirements for the efficiency and reliability of communication. The topology of any real network consists of a set of basic topologies, which are discussed below.
Point-to-point is the simplest topology (Fig. 9.3, a), directly connecting (physically and logically) two points. The low reliability of such a network (for example, in the event of a cable break) can be increased by a redundant link called "1 + 1 protection" (shown by the dotted line) and providing 100% redundancy. If the main communication line fails, the network automatically switches to the backup one. The same type of redundancy is used when transmitting large amounts of information over high-speed trunk channels and in networks of other topologies.

Rice. 9.3. Examples of topologies: a - point-to-point; b - tree-like; c - radial-nodal; g - annular; d - double ring; e - fully connected topology; g - cellular

The tree topology (Figure 9.3, b) is the most economical because it has the smallest number of connecting lines (CJI) connecting all points, while the number of CJIs at the physical layer is 1 less than the number of points. At the logical level, there is always a single way of transferring information between each pair of points. A type of tree is the radial-node topology (Fig. 9.3, c).
In a network built on the basis of a ring topology, only two lines are connected to each point (Figure 9.3, d). The ring topology is widely used in various networks, since the number of CJIs at the physical layer is equal to the number of points connected by them, which gives a relatively low cost of the network. At the logical level, two independent paths in different directions (direct and alternative) can be organized between each pair of points, which increases the reliability of communication, especially when organizing redundancy according to the "1 + 1" ("double ring") scheme, as shown in Fig. 9.3, d.
Fully connected topology (Fig. 9.3, f) provides physical and logical connection of points on the principle "each with each". With the number of sites N, the number of CJIs is N (N - 1) / 2, which indicates a very high cost of the network. On the other hand, the number of independent paths between each pair of points, equal to N - 1, makes it possible to organize a large number of detour paths at the logical level and, accordingly, ensure maximum communication reliability without additional redundancy. In practice, networks based on such a topology are used to connect the most important points with a relatively small number of them.
The mesh topology (Figure 9.3, g) resembles network cells or a set of ring topologies. In it, each point has a direct connection with a small number of neighboring points. With a large number of sites N, the number of trunk lines is approximately equal to RN / 2, where R is the average number of CJIs suitable for each site. Such networks are highly reliable with fewer CJIs compared to a fully connected topology. Typically, this topology is used where a significant load must be passed through the network.
Structural network components (segments) of any topology are usually classified according to their scale, functions and telecommunication technology used. The classification of networks according to the scale principle is given in Fig. 9.4, and the corresponding definitions are in table. 9.1. Typically, a network can be broken up into an order of smaller scale segments. The connectivity of segments at any level is carried out by means of highways (trunk channels). The interconnection of endpoints within a segment and the implementation of backbone segments are carried out by using a common communication medium or by creating network nodes.

Level
backbone networks
Urban network level
Level
local area networks

A network (network segment) built as a connecting backbone, regardless of the topology used in it, is called a back-bone network. The set of backbone networks of different levels provides hierarchical connectivity of the distributed network. The backbone network of the upper level is usually called a transport network. An access network is a segment or a set of segments that form paths along which territories
Realistically dispersed points of the infocommunication network interact with the access node to the transport network. The network segment through which user terminals interact with the service node is called a subscriber access network. Access of individual terminals (groups of terminals) of users to any information systems or resources through a set of network segments is called remote access.
From the point of view of functioning, transport networks and access networks can be considered as independent structural components (see Fig. 9.2). The functional model describes the network at a logical level and displays the interconnection of network functions. Functions imply a particular task solved by some element of the network, and when physically implemented, they can be grouped into separate subsystems - logical modules. The main types of network functions are presented in table. 9.2.
Table 9.2. Network functions
Logical interfaces define the order in which communication network functions interact. The logical interface between functions of the same type is called a protocol.
Any infocommunication network has a technical control system, which in general has four hierarchical levels of control, the competencies of which are shown in Table. 9.3.
Table 9.3. Layers of the communication network management system

Level	Competencies
Administrative, or the level of management of the commercial sphere of the functioning of the network	The highest in the hierarchy, performs organizational and financial management functions, including the management of costs, revenues and other financial issues
Service management	Provides the removal and addition of new services, their redistribution among users, etc. In interaction with the level of network management, it is possible to monitor the quality of service provision, change quality indicators and quickly respond to their degradation
Network management	Allows you to perform operations on the entire network / networks as a whole, analyzes their state and collects and processes statistical performance indicators, including accounting for equipment and communications, their condition, technical parameters, etc.
Element controls	It affects only specific elements of the network and provides the possibility of reconfiguration, namely: turning the element into operation, monitoring it, determining a different route, setting new system parameters, communication addresses, etc. At the same time, failures are eliminated, operating parameters are displayed, security management (administrative passwords, etc.), maintenance and testing are performed

Thus, the device of the network as a whole constitutes its structure, which is understood as individual elements, their functions and principles of integration into separate structural components - subnets, which form segments of the infocommunication network in accordance with their purpose. In the general case, the elements of any network are points and communication lines connecting them. Points are subdivided into terminal and nodal. Communication lines provide the transmission of information flows in the form of signals and, in the general case, are structures, a signal propagation medium (cables, wires, etc.) and a complex of equipment that allows the use of lines in the mode of splitting into transmission channels. Depending on the type of medium, communication lines are usually divided into wired (cable) and wireless (radio lines).
In general, a telecommunication channel is a signal path formed by serially connected channels and lines of a secondary network using stations and nodes of a secondary network and providing, when connected to subscriber terminal devices (terminals), the transmission of a message from a source to a recipient (recipients). The telecommunication channel is named depending on the type of communication network, for example, telephone, telegraph or data transmission channel. On a territorial basis, telecommunication channels are divided into intercity, zonal and local.
The transmission channel is called analog or digital, depending on the methods of signal transmission. A transmission channel in which analog or digital methods of signal transmission are used in different parts of it is called mixed. In the presence of transits, the channel is called composite, in the absence of transits - simple. If there are sections in the composite channel, organized both in cable transmission systems and in radio relay systems, the channel is called combined. The digital channel, depending on the signal transmission rate, is called the main, primary, secondary, tertiary, quaternary.
Transmission lines are named depending on the type of primary network to which it belongs (backbone, intra-zone, local), as well as the distribution medium (for example, cable, radio relay, satellite). A transmission line, which is a serial connection of transmission lines of different distribution media, is called combined.
Linear paths are formed on the basis of group paths. Network path - several series-connected typical group paths with the equipment for the formation of the path included at the input and output. If there are transits of the same order as this network path, it is called composite, in the absence of such transits - simple. If there are sections in a composite network path, organized both in cable and radio relay transmission systems, the path is called combined. The path is named analog or digital, depending on the method of signal transmission.
The most important part of the primary network (transport networks) are transmission systems, which use two main methods (technologies) of transmission of telecommunication signals: synchronous and asynchronous (Table 9.4).
As a first approximation, the process of transmitting information over infocommunication networks is relatively simple and logical: first, you need to determine where the recipient of information is, then organize a communication channel to it, through which the information flow is directed in the most economical way. This procedure is helped to carry out the channels and other elements of the infocommunication network, which perform the ones given in table. 9.4 functions (see section 9.4).
In the general case, the data transfer protocol defines, in addition to synchronization, the elements presented in Table. 9.5.

Table 9.4. Functions of elements of the infocommunication system

Function	Explained
Routing (routing)	The procedure for finding a path between two points in a network based on address information, including databases of addresses / numbers, tables of route routes and algorithms for finding addresses / numbers
Commutation (switching)	The process of establishing a connection between lines converging at a node when distributing information flows in the network in accordance with the routing scheme. This process consists in establishing a connection, maintaining it during the transfer of information and then disconnecting. Networks are often referred to by the type of switching (packet or channel)
Concentration (consentration)	Combining several information streams in order to obtain a more powerful information stream for more efficient use of the communication line / channel
Multiplexer education (multiplexing)	Transmission of several information streams along one line by assigning to each of them a fixed part of the bandwidth resource of this line
Channel switching	The process of searching and connecting electrical circuits, in which an end-to-end connection is created between the input and output of the communication system, and then information exchange is carried out through it in real time, and calls received when all connection paths are busy are usually lost
Synchronization	A mechanism for recognizing the beginning of a data block and its end, as well as a sequence of acknowledgment signals for communication established between computers or other devices. In general, it is a procedure for establishing and maintaining certain temporal relationships between two or more processes. Distinguish between element-wise, group and frame synchronization

Table 9.5. Content of the data transfer protocol

Element	Functions
Data flow control	A mechanism for distributing and synchronizing information flows, which is a means of matching the rate of data transmission with the capabilities of the receiver. Although the bit rates of the receivers and the transmitters must always match, there may be situations where the transmitter is transmitting information at a rate that is not acceptable to the receiver. In this case, the input buffer of the receiver (where the incoming information flow is accumulated) overflows, and part of the transmitted information is lost. Flow controls allow the receiver to signal the transmitter to suspend or resume transmission. These means require a reverse transmission channel (from receiver to transmitter)
Methods recovery	Position return mechanism for retransmission of information
Permission access	Control and management of data access restrictions
Mode transmission	Determines the way of communication between two nodes. Simplex mode allows data to be transmitted in only one direction, the transmitting node completely occupies the channel. In telecommunications, this mode is practically not used - it does not allow the sender of information to receive confirmation of its receipt, which is necessary to ensure normal communication. Half-duplex mode allows two-way transmission, but only in one direction at a time. To change direction, a special signal and confirmation is required. Full duplex mode allows simultaneous transmission in two directions at once. In this case, the transmission in one direction occupies only part of the channel. Duplex mode can be symmetric (the channel bandwidth is the same in both directions) and unbalanced (the bandwidth in one direction is much more than in the opposite direction)

Infocommunication systems and networks are a new branch of the economy, the development of which determines the comfort of people's lives. They are necessary to transmit certain information of a different nature over specific distances.

Historical reference

Infocommunication systems and networks were initially developed separately. were associated with telecom operators building their business on the implementation of voice traffic. Information technologies followed their own path of development, they were associated with the creation of software.

The emergence of the Internet

The gradual development of digital technologies contributed to the fact that computers began to be combined into local networks for the rapid exchange of information. They began to allocate powerful specialized machines - servers, the main resources of which were available to other network users. This situation has led to development as the need for high-quality high-speed information transmission systems has grown.

There was a need to connect disparate networks that were at a significant distance from each other. This is how the Internet was born, which is an intermediary between networks. It unites separate local networks into one global system.

Modern tendencies

Currently, infocommunication systems and networks are an indispensable element of the domestic economy. The integration of information technology and telecommunications into one industry of infocommunications is a worldwide trend. In the near future, the term "infocommunication systems and networks" will become more commonly used, as the number of companies and organizations in which such technologies will form the basis of work will grow.

Useful information

Infocommunication networks and communication systems are a complex set of different technical means that ensure the transmission of different messages over the desired distances with specific quality characteristics.

They are based on multichannel transmission systems over electric cables and radio lines, which are designed to form standard paths and channels.

Features of training

How can you get the specialty "infocommunication networks and communication systems"? The profession associated with digital devices is currently especially in demand and relevant. We need specialists who are proficient in information technology.

In the system of secondary vocational education for graduates, the Federal State Educational Standard has been created. "Infocommunication systems and networks" - direction, graduates of which can get a job on the vacancy "technician".

Obligations of the employee

What are the requirements for specialists in the field of ICT FSES? "Infocommunication networks and communication systems" is a specialty, the owners of which must provide a certain territory with high-quality communications, radio broadcasting, television. The technician works with a variety of communication channels, which is necessary for the life of transmission systems.

Modern technologies for supporting infocommunication systems and networks allow technicians to provide high-quality information transfer over the required distances.

The main place in the technical support is given to optical technology, thanks to which the speed of information transmission is increased, and the quality of communication is improved.

Important aspects

Teaching the profession "multichannel telecommunication systems" involves the use of applied academic disciplines. In lectures, students learn software data encryption technologies to protect important information. In addition, future specialists in this field should have an idea of ​​the installation and operation of digital and cable information transmission systems, know the basics of building infocommunication systems and networks. Students of higher educational institutions master the curriculum of management of the organization of managerial work.

What graduates can do

Specialists must operate telecommunication multichannel systems. Work on information security of networks is mandatory. Young specialists carry out the convergence of services and technologies of telecommunication systems. Techniques are in demand in commercial and government enterprises. They carry out maintenance and installation of communication cables, carry out system diagnostics.

Employees are engaged in elimination of the consequences of equipment defects and failures, determine options for restoring their functioning. At enterprises, such specialists are engaged in measuring equipment performance, installing and professional servicing unified computer systems. The duties of the employee include installation, configuration, maintenance of network equipment.

The technician monitors the performance of network equipment, interacts with network protocols. They use reliable information security tools in their professional activities.

Among other duties of this specialist, it can be noted:

• analysis of the health of systems capable of detecting various problems;
• providing secure maintenance of computer systems;
• monitoring of innovation systems;
• work planning;
• marketing research

Professionals create and operate systems for transmitting important information, work at automatic stations. Graduates in the direction of "multichannel telecommunication systems" work in line equipment shops, communication centers, radio relay shops.

Telecommunications is everything that surrounds a modern person and is used by him on a daily basis. It is information technology that is the main engine of progress. This industry is one of the most developing industries. Thanks to telecommunications, the quality of life of a modern person is significantly improved.

The term "telecommunication" includes two words: "tele" (translated from Greek as "far"), "communication" (from Latin - "communication"). Thus, this is a method of transmitting information over significant distances using electromagnetic, electronic, information, computer, network technologies. Telecommunications include radio communications, the Internet, mobile and satellite communications, ATMs, online stores, and social networks. Telecommunication technologies are understood as the principles of organizing innovative digital and analog systems and communication networks, including the World Wide Web. The means of telecommunications are considered the sum of technical algorithms, devices, software that allow receiving and transmitting information by means of electrical and electromagnetic oscillations through radio engineering, cable channels in different wavelengths.

Telecommunication networks and systems are spatially distributed mass-use systems that allow transmitting, concentrating, distributing information, images, texts, transmitting multimedia and audio information, transmitting stereophonic programs, controlling the delivery of electronic messages, and providing services to the World Wide Web.

They can be local, capable of covering a very small area. There are also such territorial systems that cover a significant geographic area.

Global networks cover a significant world space.

To control the quality of training of specialists who are engaged in the maintenance and adjustment of computer systems, educational standards of a new generation have been developed.

Conclusion

Graduates of secondary vocational and higher educational institutions studying in the specialty "telecommunication systems and networks" must be fluent in network cards, modems, network cables, intermediate equipment. The specialty "telecommunications" guarantees the student high-quality training in the field of electronic technology, devices for transmitting important information, computer methods of design and analysis, programming, network design for the transmission of significant information ceilings at a significant speed, control of individual network elements, and the use of digital computer technologies.

Currently, the development trends of both information processing and distribution tools and information systems in general are characterized by the fact that, on the one hand, the development of telecommunication networks requires the use of digital channels and data transmission systems, computer technology for processing information in the process of its transmission, on the other hand, the development of information processing and computer technology requires more and more use of communication means for organizing the exchange of information in the interests of solving applied problems. And as a result, the processes of integration and convergence of telecommunication networks and informatization means contributed to the transformation of telecommunication networks into infocommunication networks(earlier the terms “information network”, “telecommunication computer network”, etc. were also used).

According to existing ideas, infocommunication system Is a set that includes the essence of information and telecommunication systems. An information system includes information and a user. The telecommunication system ensures the transfer of information from the source to the consumer. Thus, an infocommunication system is formed by a combination of a telecommunications network (telecommunications subsystem), an applied subsystem (means of storing and processing information, applied processes), as well as a subsystem of information sources and consumers (user subsystems).

Along with the terms “ infocommunication system» and« infocommunication network»The terms are used:

Information and telecommunication systems- a class of systems that implements many technological processes for collecting, processing, storing, searching for information and accessing it, transferring (transporting) all types of messages by combining them into single transport streams.

Information and telecommunication network- a technological system containing communication lines, nodes and user equipment that provides the ability to provide services for the delivery of information to users and, in part, for its storage and processing during transmission and delivery.

The Federal Law of the Russian Federation "On Information, Information Technologies and Information Protection", defines information and telecommunication network, "As a technological system designed to transmit information over communication lines, access to which is carried out using computer technology."

In order to ensure the correctness of the use of such terms as "infocommunications", "infocommunication network", "infocommunication technologies", etc., we will consider their definitions and interrelation.

The article P.P. Vorobienko, L.A. Nikityuk(Odessa National Academy of Telecommunications named after A.S. Popov) definitions are given to the basic concepts that characterize the subject of work of specialists in the infocommunication industry, namely: "infocommunications" as a field of activity, "infocommunication network" as a physical object, "infocommunication technologies" as a set of methods and ways to ensure the functioning of such an object and "infocommunication service" as the end result.

Infocommunications is a set of tools for processing, accumulating, storing information and transferring it in space, implemented (executed) into a single network structure, through which the availability of information resources and information exchange is ensured.

An Infocommunication Network is a set of geographically dispersed information, computing resources, control software systems located in the end systems of the network and terminal systems of users, interaction between which is provided through telecommunications, and which together form a single multiservice platform.

Infocommunication Technologies is a set of methods and techniques for processing, accumulating, storing, displaying and ensuring the integrity of information, as well as ways to implement modes of its transfer in space, providing a certain guaranteed level of quality of service.

Infocommunication Service is a multi-service that ensures the satisfaction of telecommunication or information, or both at the same time, the needs of the consumer, giving him the opportunity to participate in managing the process of implementing the service.

V RD 115.005-2002 infocommunication technologies are defined as "a set of methods and means for the implementation of information and telecommunication processes." This concept combines two components: information Technology and telecommunication technology.

Information processes- collection, processing, accumulation, storage, search and dissemination of information.

Telecommunication processes- transmission and communication of information (RD 115.005-2002).

Under information technology (Information Technology) means the processes, methods of searching, collecting, storing, processing, providing, disseminating information and ways of implementing these processes and methods (GOST R 52653-2006).

The term “ information and communication technology »(Information and Communication Technology), reflecting a set of information processes and methods of working with information, carried out using computer technology and telecommunications (GOST R 52653-2006).

Information and communication technologies (ICT)- technologies designed for the joint implementation of information and communication processes.

Thus, infocommunication networks are designed to provide users with services related to the exchange of information, its consumption, as well as processing, storage and accumulation.

Both individuals and legal entities (firms, organizations, enterprises) can act as users.

The user, organizing a request for the provision of a particular service, activates a certain application process in his end system that performs information processing for a specific communication service or application.

The terminal systems of the infocommunication network can be:

· Terminal systems providing access to the network and its resources;

· Working systems that provide network services (control of access to files, programs, network devices, call handling, etc.);

· Administrative systems that implement the management of the network and its individual parts.

The basic component, the core of the infocommunication network, is the telecommunications network.

The purpose of studying the discipline is to form knowledge about the principles of building ICS, modern technologies for their implementation and about the tasks solved with the help of such systems and networks, as well as the formation of skills to analyze and synthesize such systems. Information and communication technologies (ICT) - implies the integration of classical technologies based on IP with existing telecommunication networks and systems.

The concept of infocommunication technology is often used as a synonym for information technology with an emphasis on a communication tool. This concept includes:

IS hardware and software;

Telecommunication equipment;

Telecommunication services;

Infocommunication technologies are implemented using infocommunication networks. According to the law on information, an infocommunication network is a technological system designed to transmit information through communication lines, and access to this information is carried out using computer technology.

Infocommunication systems are intended for data transmission and storage, the main emphasis is placed on data transmission.

Classification of infocommunication systems (based on the classification of computer networks):

According to the coverage of this network of territory:

LAN (Local Area Network)

MAN-scale networks (Metropoliten Area Network)

WAN (World Area Network)

By topology (location description)

Basic concepts:

Host Is a device that is always connected to the network.

Gateway - a computer or network device that converts protocols when transferring information between different types of networks. As a rule, gateways are used to organize access to WAN resources from local networks.

Osi model

The interaction of computers in the network is described by the concepts formed in the reference model for the interaction of open systems (Open System Interconnection), which was developed by the International Organization for Standardization. In our country, the OSI model is described in the GOST RISO / IEC 7498-1-99 standard. The OSI model describes the procedures for the exchange of data between computers at different levels and the exchange of data between levels on the same computer.

	Level name	Description of functions
	Physical (Physical layer)	The physical environment in which the data link exists
	Channel (Data link layer)	Receiving and transmitting data packets, as well as determining the hardware addresses of hosts or network nodes.
	Network layer	Routing and accounting for data transmission.
	Transport layer	Ensuring correct data transfer.
	Session layer	Authentication and Authorization Check.
	Presentation layer	Data interpretation and compression.
	Application layer	Presentation of services at the end-use level and at the end-application level.

Physical layer

Receives data packets from the upper data link layer and converts them into electronic signals corresponding to 0 and 1 of the binary stream. These signals are sent through the transmission medium to the receiving node. The mechanical and electromagnetic properties of the transmission medium are determined at the physical level and include:

types of cables and connectors

pin assignment in connectors

signal coding scheme for values ​​0 and 1

Link layer

Provides creation, transmission and reception of data frames. This layer serves the requests of the higher network layer and uses the physical layer service to receive and transmit these data frames. the link layer is divided into 2 sublevels:

Logical Layer Control (LLC)

Media Access Control (MAC) sublayer

LLC provides services to the network layer, that is, it forms data coming from the network layer into data frames.

And MAC - regulates access to the physical data transmission medium

Network layer

Responsible for dividing hosts into groups. At this level, data packets are routed based on the translation of MAC addresses into network addresses. Also, at the network level, there is a transparent transfer of data packets to the higher level.

Transport layer

Divides the information streams of the higher layers into small enough fragments (packets) for their transmission to the network layer

Session level

Responsible for organizing data exchange sessions between hosts

Presentation layer

Responsible for the possibility of dialogue between applications on different computers. This layer transforms application layer data into a transport layer information stream.

Application level

Responsible for application access to the network (file transfer, data exchange, network resource management).

MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION Belgorod State Technological University

them. V.G. Shukhova

A. V. Glukhoedov, E. A. Fedotov

Infocommunication systems and networks

Approved by the Academic Council of the University as a textbook for undergraduate students 230400 "Information Systems and Technologies"

Belgorod 2012

UDC (Yu4.7 (07) BBK 32.973.2 () 2ya7 G55

Reviewers: Candidate of Technical Sciences, Associate Professor, Belgorod State Technological University named after V.I. V.G. Shukhova V.M. Polyakov

Candidate of Technical Sciences, Associate Professor, Belgorod State University A.I. Stifschuv

Glukhoedov A. V., Fedotov E. A.

G55 Infocommunication systems and networks: lecture notes: study guide / A.V. Glukhoedov, E.A. Fedotov. - Belgorod: Publishing house of BSTU, 2012. - 104 p.

The tutorial provides a comprehensive look at all of the critical network models, technologies, and protocols that define the functioning of modern information networks.

Tutorial Intended for undergraduate students 230400 "Information systems and technologies".

UDC 004.7 (07) BBK 32.973.202ya7

© Belgorod State Technological University (BSTU) named after V.G. Shukhova, 2012

Introduction 5

1. Application of information networks 6

Enterprise network 6

Home network 6

World Wide Web 7

Communication 1

Interactive entertainment 8

2. Classification of information networks 9

Fit to network 9

By network topology type 9

By type of functional interaction 13

By type of transmission technology 14

By type of transmission medium 15

By baud rate 15

3. Network Reference Models 16

Protocol and protocol stack 16

OSI Reference Model 17

TCP / IP Reference Model 20

Hybrid Reference Model 20

4. Network Devices 21

Network cards 21

Passive network devices 21

Active network devices 22

5. Lines and channels of communication 24

Cable communication lines 25

Wireless communication lines 32

6. Basic network technologies 35

Ethernet technology 35

Token Ring Technology 42

FDDI technology 43

7. Addressing in information networks 44

7.1. MAC address 44

IP address 45

Domain Name System 53

DHCP 61

ARP 64

8. Networking 66

Bridging Networks 66

Aggregating Networks Using Routers 71

9. Transport protocols TCP / IP 82

1. UDP 82

   TCP 84 protocol

10. Protocols of the application layer TCP / IP 92

FTP 92

HTTP 95 protocol

SMTP 98

1 1. Security in information networks 100

Classification of network attacks THEM)

Network Traffic Protection 101

Conclusion 102

Bibliography 103

Introduction

Information networks are the logical result of the evolution of information technology. The early computers of the 1950s — large, bulky, and expensive — were intended for a very small number of users. They were not intended to be interactive, but used in batch mode.

In the early 70s, with the advent of large-scale integrated circuits, personal computers began to appear. It was at this moment that the need arose to transfer information from one computer to another. This is how the first information networks appeared. At first, non-standard devices were used to connect computers with their own way of presenting data on communication lines, their own types of cables, etc.

In the mid-1980s, standard technologies for connecting computers to a network were approved. Standard networking technologies have greatly facilitated the process of building an information network. To create it, it was enough to purchase network adapters of the corresponding standard, a standard cable and connect the adapter to the cable with standard connectors.

This course is intended for students interested in a detailed study of the basic principles of building modern information networks. All materials of the textbook are prepared mainly for third-year students of the specialty "Information systems and technologies", but will also be useful for students of other specialties.