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A modern system of general secondary education, all the teaching directions that are within it, one way or another, are aimed at the formation of skills in schoolchildren to work with information. It is no coincidence that in most government programs that determine the priority directions for the development of education in the Russian Federation, special attention is paid to the formation of general educational and communal skills of students with information and means of its processing, which becomes the main rod of professional activities of graduates of educational institutions in the conditions of the information society, the necessary component of information culture . In turn, the desire to form information culture in future graduates leads to the orientation of general education for the acquisition of knowledge of knowledge about telecommunications and the media, the use of telecommunications to acquire various knowledge and creative expression, assessment of the reliability of information, the development of critical thinking, the correlation of information and Knowledge, the ability to properly organize the information process, evaluate and ensure information security.

Telecommunication systems are of paramount importance not only in the general secondary education system, but play a fundamental role in almost all spheres of society. At the level of development of the telecommunications information space, the most significant imprint impose a level of development of primary communication networks and the level of development of network information technologies, which can be considered as information transfer technologies.

Under communication networkunderstand the combination of wired, radio, optical and other communication channels, specialized channel-forming equipment, as well as centers and communication sites, ensuring the operation of this network. In almost all modern communication networks used in the creation of information telecommunication systems are simultaneously present and together several different network sections in their characteristics. These circumstances largely determine the strategy and tactics of the creation and use of network information technologies.

Network information technologies have developed simultaneously with the development of communication channels. At the beginning of the last century, the basis of telegraph and telephone communication networks was analogue wired and telecommunication radio channels, which, then with the development of microelectronics, became increasingly replaced with digital fiber-optic communication lines, which have significantly higher characteristics in terms of quality and information transmission rate. The concept of telecommunication technologies occurred, which unites the methods of rational organization of the work of telecommunication systems.

Telecommunication systems used today in the general secondary education system are usually based on different compounds of computers among themselves. Committed computers can be viewed from different points of view. On the one hand, the combination of computers is computer network. On the other hand, it is a means of transmitting information in space, a means of organizing people's communication. It is thanks to this property that computer networks are increasingly called telecommunications networks, emphasizing, thereby, their purpose, and not the features of their device.

Distinguish local and global telecommunication networks. As a rule, the local is called a network connecting computers located in one building, one organization, within the area, city, countries. In other words, the local is the network, limited in space. Local networks are distributed in education. Most schools and other educational institutions have computers related to the local network. At the same time, modern technologies allow you to bind separate computers that are not only in different rooms or buildings, but located on different continents. It is no coincidence that you can meet educational institutions that have branches in different countries whose computers are combined into local networks. Moreover, local networks can combine computers of different educational institutions, which makes it possible to talk about the existence of local networks of education.

Unlike local, global networks have no spatial restrictions. Any computer can be connected to the global network. Anyone can gain access to information posted in this network. The most famous example of a global telecommunications network is the Internet (Internet) network, access to which appears in an increasing number of high schools. The Internet is not the only global telecommunications network. There are other, such as FIDO or Sprint Network.

Thus, the majority of schools and other educational institutions of the general secondary education system have both local networks and the ability to use global networks.

With all the diversity of informational and telecommunication technologies, as well as methods of organizing data when sending them to communication channels, the World Information Computer Network is central. Moreover, today, this is almost the only global telecommunications network, universally used in the general secondary education system. This largely contributes to high speed and reliability of transmission over the Internet data of various formats (text, graphic images, sound, video, etc.). The Internet provides the possibility of collective access to educational materials that can be represented both in the form of simple textbooks (electronic texts) and in the form of complex interactive systems, computer models, virtual learning environments, etc.

The number of users and sources of Internet information is continuously increasing. In addition, there is a constant improvement in the quality of the provisions of telecommunication services. Thanks to this, high-quality access to the Internet receive not only enterprises and organizations working in the economic and other areas, but also the institutions of general secondary education.

Modern Internet is characterized by the presence of a serious problem of organizing global information search. Described, so-called search engines, which, according to the desired word or a combination of words, find references to those pages on the network, in which this word or a combination is presented. At the same time, despite the presence of existing search engines, the user has to spend a large amount of time both on the process of finding information and the processing and systematization of the data obtained.

In education, this problem is felt particularly sharp: educational information resources if they are presented on the network, then, as a rule, are submitted non-system. The lack of a systematic approach to the placement of such resources, as well as the absence of uniformity in solving the psychological and pedagogical, technological, aesthetic, ergonomic, and a number of other problems in the design and operation of educational resources of the Internet, leads to practical non-use of telecommunication funds in order to improve the quality of the educational process.

The most common communication technology and the relevant service in computer networks has become the technology of a computer method for shipping and processing information messages that ensures the operational relationship between people. Email (e-mail) - System for storing and sending messages between people having access to a computer network. Through email, you can transmit any information on computer networks (text documents, images, digital data, recording, etc.).

Such a service service implements:

· Editing documents before transfer,

· Storage of documents and messages,

· Shipment of correspondence,

· Check and correct errors that occur during transmission,

· Issuance of confirmation of contact with the recipient

· Getting and storing information

· View received correspondence.

Email can be used to communicate participants in the educational process and forwarding educational materials. An important property of email attractive for general secondary education is the possibility of implementing asynchronous information exchange. To use email, it is enough to master several mail client commands to send, receiving and processing information. Note that when communicating through email there is more psychological and pedagogical problems than technical. The fact is that with direct human communication, information is transmitted not only with speech, other forms of communication are included here: Mimic, gestures, etc. Of course, "emoticons" can be used to transmit emotions when corresponding to correspondence, but this does not solve the problem of solidifying communication. However, the transition to a written speech raises such positive features as accuracy, brevity of the expression of thought and accuracy.

Email can be used by teachers to consult, send tests and professional communication with colleagues. It is also advisable to use its use for electronic classes in asynchronous mode, when the text of classes in electronic form, excerpts from the recommended literature and other training materials, and then consult on e-mail are also pre-sent.

A distinctive feature and convenience of email is the ability to send the same message at once a large number of recipients.

Similar distribution principle used by another Internet service called mailing lists. This service is running in subscription mode. By subscribing to the mailing list, a subscriber with a certain periodicity receives a selection of emails on its chosen topic to its mailbox. Mailing lists perform on the Internet of the function of periodic publications.

In the general education system, using mailing lists, you can organize the so-called "Virtual training classes". In the school students created, the rules and ways to subscribe are explained, and it starts work. Each message addressed to the Group by any Participant is automatically sent to all member of the group. One of the participants in such a group may be a teacher.

The main didactic possibilities of using mailing lists are the automatic mailing of educational materials and the organization of virtual training classes.

Another popular service provided by modern telecommunications networks and the exchange of information between people, the combined common interests, are teleconference.

Teleconference It is a network forum, organized for the conduct of discussion and sharing news on a certain topic.

Teleconference allow you to publish posts on interests on special computers on the network. Messages can be read by connecting to the computer and choosing a topic for discussion. Further, if desired, the answer to the author of the article or sending his own message is possible. Thus, a network discussion is organized, which is a newspaper, since messages are stored a short period of time.

The presence of audio and video equipment (microphone, digital video camera, etc.), connected to the computer, allows you to organize computer audio and video conferencing, are increasingly widely distributed in the general secondary education system.

Unlike mailing lists based on e-mail, some teleconferences and newsgroups work in real time. The difference lies in the fact that in the case of the distribution list, the exchange of information is carried out in the OFF-LINE mode by automatically distributed electronic letters. The news server publishes all messages on a common board immediately, and saves them for some time. Thus, teleconferences allow you to organize a discussion both in ON-LINE mode and in deferred mode. When organizing training sessions, it is advisable to use newsgroups modified by the teacher.

With the development of technical means of computer networks, the data transfer rate increases. This allows users connected to the network not only to share text messages, but also to transmit sound and video to a significant distance. One of the representatives of the programs implementing communication via the network is the NetMeeting program, which is part of the Internet Explorer set. MS NetMeeting is a means of informatization that implements the possibility of direct communication over the Internet.

It should be noted that appropriate technical equipment is needed to implement sound communication: sound card, microphone and acoustic systems. To transmit video, you need a video card and camera, or only a camera that supports the Video for Windows standard.

The main directions of using MS NetMeeting in the educational process are:

· Organization of virtual training sessions and consultations in real time, including voice communication and transmission of video photographs;

· Information exchange in text and graphic mode;

· Organization of collaboration with curriculum in On-Line mode;

· Forwarding educational and methodical information in the form of files in real time.

One of the most important telecommunication technologies is distributed data processing. In this case, personal computers are used at the occurrence and application of information. If they are connected by communication channels, this makes it possible to distribute their resources on the individual functional areas of activity and change the data processing technology towards decentralization.

In the most difficult distributed data processing systems, a connection is connected to various information services and general-purpose systems (news services, national and global information and databases, databases and knowledge banks, etc.).

Extremely important for general secondary education, the service implemented in computer networks is automated search for information. Using specialized funds - information and search engines, it is possible to find information about the world information sources as soon as possible.

The main didactic objectives of using such resources obtained by telecommunication channels, in schoolchildren's training are the message of information, formation and consolidation of knowledge, formation and improvement of skills and skills, assimilation and generalization.

The use of the educational information resources available today, most of which are published on the Internet, allows:

· Organize a variety of forms of schoolchildren's activities on self-extracting and idea of \u200b\u200bknowledge;

· Apply the whole range of opportunities for modern information and telecommunication technologies in the process of performing various types of training activities, including such as registration, collecting, storage, information processing, interactive dialogue, modeling objects, phenomena, processes, laboratories (virtual, with remote access to real equipment) et al.;

· Use in the educational process the possibility of multimedia technologies, hypertext and hypermedia systems;

· Diagnose the intellectual opportunities of schoolchildren, as well as the level of their knowledge, skills, skills, the level of preparation for a specific lesson;

· Manage training, automate the control processes of learning activities, training, testing, generate tasks, depending on the intelligent level of a particular trainee, the level of its knowledge, skills, skills, features of its motivation;

· Create conditions for the implementation of independent learning activities of schoolchildren, for self-study, self-development, self-improvement, self-education, self-realization;

· Work in modern telecommunication environments, ensure management of information flows.

Thus, computer telecommunications are not only a powerful learning tool, allowing to train work with information, but, on the other hand, computer telecommunications is a special environment of people with each other, the interactive interaction environment of representatives of various national, age, professional and other groups. Users regardless of their location.

Unfortunately, many existing techniques for the efficient use of telecommunication technologies in the process of studying schoolchildren are still not fully used by teachers. A modern teacher must be in addition to the ability to work with the latest computer technologies to have an idea of \u200b\u200bthe possible ways of using them in the educational process. The experience of theoretical and practical development of teachers of various methods of using telecommunication technologies in the learning process could be the basis for improving the efficiency and quality of training, formation and further improvement of their professional skills.

Topic 4.2. Internet Information Resources

Informatization is one of the main factors forcing the formation of improving. The content and methods of learning change, the role of a teacher is changing, which gradually from a simple knowledge translator turns into an organizer of the activities of students to acquire new knowledge, skills and skills. An essential means of informatization are educational information resources published on the Internet. It is no coincidence that their correct, timely and appropriate use by all specialists working in the system of general secondary education is the key to the effectiveness of schoolchildren's training.

Consider working with distributed information resources of computer networks in more detail.

Similar ICT funds allow you to bring to work a general secondary education institution:

· Use of information posted on educational and scientific sites of the Internet (Web sites) to prepare educational and methodological materials. Abstracts and messages;

· Organization of a representative office of educational institution in the network of inetrnet;

· Creating a site dedicated to the content of school discipline and place it on the Internet;

· Placement of personal web sites of teachers and schoolchildren.

Most of the network information resources are submitted by the so-called Web pages organized by the principles of hypermedia.

Web page is a document containing:

· Formatted text;

· Multimedia objects (graphics, sound, video clips);

· Active components capable of performing work on the computer on the program laid in them.

As a rule, the Web page is a rather complicated document consisting of a whole group of files.

Within one page, it is difficult to set out all the necessary information, therefore, most often information is in the form of a set of several dozen or hundreds of Web pages associated with a single topic, a common design style and mutual hypertext links. Such a set is called Web Site or Web node.

Each Web site has its own start page, which is called initial or home.

The usual WEB node sends the requested document only to handle the client. There are Web nodes capable of independently transferring updated information, subject to registration and subscription client.

Numerous Web sites and web pages are stored on a huge set of so-called WWW servers, that is, computers on which special software has been installed.

Users have access to the network receive and view information from Web pages using customer client software for World Wide Web, which received the specific name of web browsers (browsers, observers).

To receive the page, the browser sends a request to the WEB server on a computer network, which stores the desired document. In response to the request, the server sends the viewing program to the desired Web page or a refusal message if it is not available for any other reasons. The client-server interaction occurs according to a specific rules, or, in other words, on the application protocol.

The Web document may contain formatted text, graphics and hypertext links to various Internet resources. To implement all these features and ensure the independence of information resources from the system software of a personal computer on which they will be viewed, a special language was developed. It was named Hypertext Markup Language (HTML) or a hypertext markup language.

Each file on the Internet also has its own unique address. It is called URL. URL (Universal Resource Locator, universal resource pointer) - address of any file in the network. The URL contains the name of the protocol for which you need to access the file, the address of the computer with an indication of which program server is running on it, and the full path to the file.

Until recently, two major firms were the main competitors for the release of client software for working with information resources of the Internet - Netscape Communications and Microsoft. The product of the first company is called Netscape Communicator, its composition includes a popular Netscape Navigator browser program. The client software for the Internet from Microsoft is called Internet Explorer. The browser in this kit received the name of the same name.

As the Internet development and increasing the number of information resources published in it, the problem of finding the necessary resources is becoming increasingly important. For a general secondary education system, it lies in the search for such information resources published on the network, which in practice would improve the efficiency of the school training system.

Such a search is based on interaction with information resources published in the World Telecommunications Internet.

The path to the huge informational baggage of mankind stored in libraries, phonethek, filmmakers lies through the catalog cards. On the Internet there are similar mechanisms for finding the required information. We are talking about search servers serving a starting point for users. From a meaningful point of view, they can be said about them as another special Internet service.

Search servers are quite numerous and varied. It is customary to distinguish search indexes and directories. Server-indexes regularly read the content of most web web pages ("index" them), and put them in whole or in part in the common database. Separator users have the ability to fulfill full-text search on this database, using keywords related to the topic of interest. The issuance of search results usually consists of excerpts of the recommended toe of the user's user and their addresses (URL) decorated in the form of hyperlinks. Work with search servers of this type is convenient when you imagine well what you want to find.

Catalogs have grown from lists of interesting links, bookmarks (Bookmarks). In essence, they are a multi-level semantic classification of references built on the principle of "from common to particular". Sometimes references are accompanied by a brief description of the information resource. As a rule, it is possible to search in the names of the headings (categories) and descriptions of resources by keywords. The catalogs use when they do not quite clearly know what it is looking for. Turning from the most common categories to more privately, it is possible to determine which multimedia resource network should be familiar with. Search directories is appropriate to compare with thematic library catalogs, tezaurus dictionaries or biological classifications of animals and plants. Maintaining search directories is partially automated, but so far the resource classification is mainly manually.

Search directories are common and specialized. Outlook search directories include the information resources of the most different profile. Specialized catalogs combine only resources dedicated to certain topics. It is often possible to achieve a better coverage of resources from their field and build a more adequate rubrication.

On the Internet there are quite a few catalogs and portals that collect resources whose use would be appropriate in the general secondary education system.

The use of such catalogs and network information resources is suitable for:

· Operational support of teachers, trained and parents of relevant, timely and reliable information that meet the goals and the content of education;

· Organizations of various forms of students' activity related to independent mastering knowledge;

· Applications of modern information and telecommunication technologies (multimedia technologies, virtual reality, hypertext and hypermedia technologies) in educational activities;

· Objective measurement, assessment and forecast of the performance of training, comparing the results of schoolchildren's learning activities with the requirements of the State Educational Standard;

· Training management of the student, adequately its level of knowledge, skills and skills, as well as the peculiarities of his motivation to teaching;

· Creating conditions for individual independent schoolchildren training;

· Permanent and operational communication of teachers, trained and parents aimed at improving learning efficiency;

· Organizations of effective activities of general education institutions in accordance with the regulatory provisions adopted in the country and meaningful concepts.

Appropriate to use in general middle education may be a variety of information resources of the Internet. Among such resources, educational Internet portals can be distinguished, which themselves are directory resources, service and instrumental computer software, electronic presentations of paper editions, e-learning tools and instruments for measuring the results of training, resources containing news, announcements and means to communicate participants in the educational process .

The greatest amount of information resources aims to use by teachers and schoolchildren during the educational process. Part of such resources is intended for use in the traditional system of training in accordance with government educational standards and exemplary programs for each academic discipline. Other educational resources are intended for extracurricular and extracurricular work of schoolchildren, deepening knowledge and independent study (for schoolchildren and applicants). The resources of the reference and encyclopedic nature are allocated, as well as measuring instruments, control and evaluation of the results of training activities.

Using information resources of the Internet, teachers will be able to more effectively manage the cognitive activities of schoolchildren, to quickly monitor the results of training and education, take reasonable and appropriate measures to improve the level of training and quality of students' knowledge, purposefully to improve pedagogical skills, have operational address access to the required educational information, methodological and organizational nature. Teachers engaged in the development of their own information resources acquire an additional possibility of using fragments of educational resources published on the network, making the necessary links and observing copyright.

Accessing students to the information resources of the Internet will provide schoolchildren with the main and additional educational material necessary for school training, the fulfillment of the tasks of the teacher, independent training and leisure organization. Thanks to such resources, schoolchildren have the opportunity to quickly get acquainted with the news, learn about the competitions held by the Olympics, competitions, consult, communicate with teachers and peers. Applicants will find in the information resources of the Internet information needed to continue education - information about institutes, universities and academies, deadlines and conditions of admission, educational and methodological materials necessary to prepare for introductory tests.

Parents of schoolchildren and representatives of the public, using the information resources of the Internet, will be able to learn more about the development and functioning of federal and regional education systems, to get acquainted with curricula, programs and recommendations of teachers, to provide an intention on improving the quality of general secondary education.

Using information resources of the Internet, the administration of educational institutions will be able to make effective management decisions, correlating them with current legislation and regulatory documents, to objectively assess the activities of teachers, to interact with colleagues to quickly, increasing the overall level of planning and administration of the educational institution.

The main part of the information resources is advisable to use to increase the efficiency of schoolchildren's training in all disciplines of the educational program of general secondary education.

It is important to understand that the use of information resources of the Internet should be previously correlated by teachers with the main components of the methodological training system - targets, contents, methods, organizational forms and applied learning. The resources used should fit into this system, do not contradict and correspond to its components.

Special attention should be paid to the selection and development of training methods using the Internet information resources. Among such methods, the search and the use of schoolchildren of educational information, significant from the point of view of learning objectives, design activities of students based on interaction with the Internet resources, the use of communication components of such resources for educational communication of students and teachers.

Topic 4.3. Educational Internet portals

Connecting schools to the Internet generates a number of problems requiring immediate resolution. Among them, training and retraining of teachers for professional activities using telecommunications, ensuring the education system with qualitative information resources published on the Internet, as well as informing teachers and trained on access to such resources.

In this direction, a lot has already been done. A system for training teachers in the field of informatization of education has been formed, educational portals have been created, electronic educational resources are developed and published on the network for almost all school disciplines.

Educational portals created on the Internet have an increasing impact on improving the efficiency of using ICT to teach schoolchildren.

In the previous sections of this electronic publication, it was already noted that the lack of a systematic approach to the placement of information resources on the Internet, as well as the absence of uniformity in solving psychological and pedagogical, technological, aesthetic, ergonomic and a number of other problems in the development and use of educational information resources leads to practical Non-use advantages of telecommunications tools in order to improve the quality of the educational process in the general secondary education system.

Partially resolving this problem can be carried out on the basis of the development and implementation of integrated information educational portals (integrated Web systems). In this case, such portals, Combining the main information resources with high educational value, could become a "entry point" in modern telecommunication systems for all individuals, one way or another related to education.

Using the portal system allows you to more effectively organize the work of teachers, since the most popular resources are collected on portals. Using them, teachers, students and parents will be able to access high-quality educational and methodological materials, reduce the time to search for the required information, learn the features of the classification of information resources of the Internet.

Useful references to resources containing contact information on educational institutions and individual teachers, education news, announcements about the competitions, competitions, conferences and other events, in which teachers and schoolchildren regularly take part regularly.

Most of the highest quality information resources whose use would increase the effectiveness of general secondary education catalog into educational Internet portals. Currently, the organizational scheme for creating a system of educational portals has already been developed in Russia, which has its own characteristics. The organizational scheme for creating a system of educational portals includes:

· Horizontal portal "Russian Education" (www.edu.ru),

· Profile vertical portals by knowledge areas: Humanitarian, economic and social, natural-scientific, engineering, pedagogical, medical, agricultural, etc.,

· Specialized vertical portals: book publishing, uniform exam, education news, etc.

Horizontal portal "Russian Education"provides:

· Navigation for all vertical portals;

· Search for multimedia information in the field of education on the Internet;

· Personification and personal adaptation of the interface as by selecting a user of its own category (trainee, teacher, administrator, portal developer) and an indication of the level of education and by constructing its own interface;

· Formation and provision of cuts of vertical portals for education levels;

· Storage and provision of information in the field of education (legislation, orders, regulatory documents, standards, lists of specialties, federal textbooks, university database, etc.);

· Publication of the daily press review on education issues;

· News feed in the field of education;

· Organization of forums, discussion groups, mailing lists.

Profile vertical portals Must contain materials for all levels of education: elementary school, high school, primary vocational education, secondary vocational education, higher education, additional education, postgraduate education.

Almost any modern company has a need to improve the efficiency of networks and technology of computer systems. One of the necessary conditions for this is the unobstructed transmission of information between servers, data warehouses, applications and users. It is how the data transfer method in information systems often becomes a "bottle neck" in terms of performance, nullify all the advantages of modern servers and storage systems. Developers and system administrators are trying to eliminate the most obvious bottlenecks, although they know that after eliminating a bottleneck in one part of the system it occurs in another.

Over the years, bottlenecks over the years have occurred mainly on servers, but as the functions and technological development of the servers, they began to move on the network and network storage systems. Recently, very large storage arrays have been created, which transfers bottlenecks back to the network. The growth of data volumes and their centralization, as well as the requirements of the new generation applications to bandwidth often absorb the entire bandwidth.

When the information manager is faced with the task of creating a new or extension of the available information processing system, one of the most important issues will be the choice of data transmission technology. This problem includes a selection of not only network technology, but also a protocol for connecting various peripheral devices. The most popular solutions that are widely used to build SAN storage networks (Storage Area Network) is Fiber Channel, Ethernet and InfiniBand.

Ethernet technology

Today, Ethernet technology occupies a leading position in the high-performance local network sector. Worldwide, enterprises are investing in cable systems and equipment for Ethernet, in personnel training. The widespread dissemination of this technology allows you to hold low market prices, and the cost of implementing each new generation of networks tends to reduce. A constant growth of traffic in modern networks makes operators, administrators and architects of corporate networks to look closely to faster network technologies in order to solve the problem of bandwidth deficiency. Adding 10-Gigabit Ethernet to the Ethernet family allows you to maintain new resource-intensive applications in local networks.

Appearing for more than a quarter of a century ago, Ethernet technology soon became dominant in building local networks. Due to the simplicity of installation and maintenance, reliability and low cost of implementation, its popularity has grown so much that it can be safely argued today - almost all traffic on the Internet begins and ends in Ethernet networks. The IEEE 802.3ae 10-Gigabit Ethernet standard, approved in June 2002, has become a turning point in the development of this technology. With its appearance, the Ethernet use area expands to the scale of urban (MAN) and global (WAN) networks.

There are a number of market factors that, according to sectoral analysts, contribute to the output of the 10-Gigabit Ethernet technology to the fore. The development of network technologies has already become the traditional developer alliance, the main task of which is to promote new networks. It did not exception and 10-Gigabit Ethernet. The origins of this technology was the organization of 10-Gigabit Ethernet Alliance (10 GEA), which included such giants of the industry as 3com, Cisco, Nortel, Intel, Sun and many other (all more than a hundred) companies. If in the previous versions of the Fast Ethernet or Gigabit Ethernet, the developers borrowed individual elements of other technologies, the specifications of the new standard were created with almost zero. In addition, the 10-Gigabit Ethernet project was focused on large transport and main networks, such as the scale of the city, while even Gigabit Ethernet was developed exclusively for use in local networks.

The 10-Gigabit Ethernet standard provides for the transmission of the information flow at a speed of up to 10 Gb / s for a single and multimode optical cable. Depending on the transmission environment, the distance can be from 65 m to 40 km. The new standard was to ensure the following basic technical requirements:

• bidirectional data exchange in duplex mode in point-point topology networks;
• support for data rates of 10 Gbps on the MAC-level;
• specification of the physical level of the LAN PHY to connect to local networks operating on the MAC-level with a data transfer rate of 10 Gb / s;
• wAN PHY physical level specification To connect to SONET / SDH networks operating on the MAC-level with a data rate compatible with the OC-192 standard;
• determination of the mechanism for adapting the MAC level data rate to the WAN PHY data rate;
• support for two types of fiber optic cable - single-mode (SMF) and multimode (MMF);
• specification independent of the XGMII interface transfer medium *;
• reverse compatibility with previous versions of Ethernet (save the package format, size, etc.).

* Xg Here means 10 Gigabit, and MII - Media Independent Interface.

Recall that the 10/100 Ethernet standard defines two modes: half duplex and duplex. The half-duplex in the classic version provides for the use of a shared transmission medium and CSMA / CD (CARRIER-SENSE Multiple Access / Collision Detection). The main disadvantages of this regime are the loss of efficiency with an increase in the number of simultaneously working stations and remote restrictions associated with the minimum length of the package (64 byte component). In Gigabit Ethernet technology, a carrier expansion technique is used to preserve the minimum package length, which complements it to 512 bytes. Since the 10-Gigabit Ethernet standard is focused on point-point trunk connections, half-duplex mode is not included in its specification. Therefore, in this case, the length of the channel is limited only by the characteristics of the physical environment used by the receiving / transmission devices, signal power and modulation methods. The necessary topology can be ensured, for example, using switches. Duplex transmission mode also gives the ability to save the minimum saute package size 64 without applying the carrier expansion technique.

In accordance with the reference model of interaction of open systems (OSI), network technology is determined by two lower levels: physical (Layer 1, Physical) and channel (Layer 2, Data Link). In this scheme, the level of physical Ethernet devices (PHY) corresponds to Layer 1, and the level of access control (MAC) - Layer 2. In turn, each of these levels, depending on the technology being implemented, may contain several sublevels.

The MEDIA ACCESS CONTROL level is the level of access to the environment) provides a logical connection between MAC-clients of peer-to-peer (equal) workstations. Its main functions are initialization, control and maintenance of a connection with a peer node network. Obviously, the normal data transfer rate from the MAC-level to the physical level of PHY for the 10 Gigabit Ethernet standard is 10 Gb / s. However, the WAN PHY level to match the SONET OC-192 networks should transmit data with a slightly lower rate. This is achieved using the mechanism of dynamic adaptation of the intercadron interval, which provides its increase on a predetermined period of time.

The RECONCILIATION SUBLAYER RECORDING RECORDING (Fig. 1) is an interface between the sequential flow of the MAC-level data and a parallel stream of XGMII sublayer. It displays the Ochatts of the MAC-level data into parallel XGMII paths. XGMII is a 10 Gigabit independent of the medium. The main function is to provide a simple and easy-to-implement interface between the channel and physical levels. It isolates the channel level from the specifics of the physical and thereby allows the first to work on a single logical level with various implementations of the second. XGMII consists of two independent reception and transmission channels, each of which 32 data bits in four 8-bit paths are transmitted.

Fig. 1. Levels 10-Gigabit Ethernet.

The next part of the protocol stack refers to the physical level of 10 Gigabit Ethernet. Ethernet architecture breaks the physical level into three sublevels. PCS physical encoding sublease (Physical Coding Sublayer) performs encoding / decoding of the flow of data coming from the channel level and to it. PMA Physical Media Attachment Connection Subject is parallel-serial (direct and reverse) converter. It performs the conversion of a group of codes into bits stream for serial bit-oriented transmission and reverse transformation. The same sublevel provides receiving / transmission synchronization. The data dependent on the PMD sublayer (Physical Media Dependent) is responsible for transmitting signals in this physical environment. Typical functions of this sublevel - formation and amplification of the signal, modulation. Different PMD devices support various physical transmission media. In turn, the medium-dependent MDI interface sets the types of connectors for different physical environments and PMD devices.

The 10-Gigabit Ethernet technology provides low compared to alternative cost of ownership, including both the cost of acquiring and support, since the existing Ethernet network infrastructure easily interacts with it. In addition, 10 Gigabit Ethernet attracts administrators of the already familiar management organization and the ability to apply the accumulated experience, as it uses processes, protocols and management tools already deployed in the existing infrastructure. It is worth recalling that this standard provides flexibility when designing connections between servers, switches and routers. Thus, Ethernet technology offers three main advantages:

• ease of operation
• high bandwidth,
• low cost.

In addition, it is easier for some other technologies, because it allows you to associate networks located in different places as part of a single network. Ethernet bandwidth increases with steps from 1 to 10 Gbit / s, which makes it possible to efficiently use the network capacity. Finally, Ethernet equipment is usually more cost-effective compared to traditional telecommunication equipment.

To illustrate the capabilities of the technology, we give one example. Using the 10-Gigabit Ethernet network, a group of scientists working on the Japanese Data Reservoir project (http://data-reservoir.adm.su-tokyo.ac.jp) passed data from Tokyo to the elementary physics research center located in Geneva CERN particles. The data transfer line crossed 17 time zones, and its length amounted to 11,495 miles (18,495 km). The 10-Gigabit Ethernet line connected computers in Tokyo and Geneva as part of the same local network. The network used optical equipment and Ethernet switches from Cisco Systems, Foundry Networks and Nortel Networks.

In recent years, Ethernet has become widely used and telecom operators - to connect objects within the city. But the Ethernet network can stretch further, covering entire continents.

Fiber Channel

Fiber Channel technology makes it possible to fundamentally change the architecture of the computer network of any major organization. The fact is that it is well suited for the implementation of the centralized SAN data storage system, where disc and ribbon drives are located in their separate network, including geographically quite highly removed from the main corporate servers. Fiber Channel is a standard consecutive compounds intended for high-speed communications between servers, drives, workstations and concentrators and switches. Note that this interface is almost universal, it is used not only for connecting individual drives and data warehouses.

When the first networks appeared, designed to combine computers for collaboration, convenient and efficient to bring the resources to the working groups. Thus, in an attempt to minimize the network load, the information drives were evenly divided between multiple servers and desktop computers. The network simultaneously there are two data channels: the network itself is to exchange between clients and servers, and the channel for which the data is exchanged between the system bus and the storage device. It can be a channel between the controller and the rigid disk or between the RAID controller and the external disk array.

Such separation of channels is largely due to various data transfer requirements. In the first place there is a delivery of the desired information to one client from a variety of possible, for which it is necessary to create certain and very complex addressing mechanisms. In addition, the network channel involves considerable distances, therefore, here is preferably a serial connection here. But the storage channel performs an extremely simple task, providing the possibility of exchanging with a previously known data storage device. The only thing that is required of it is to do it as quickly as possible. The distances here are usually small.

However, modern networks are faced with processing tasks of increasing and large amounts of data. High-speed multimedia applications, image processing require a much greater I / O speed than ever before. Organizations are forced to store all large amounts of data in online mode, which requires an increase in external memory capacity. The need for insurance copying of huge amounts of data requires the separation of secondary memory devices for all long distances from the processing servers. In some cases, it turns out that combine the resources of servers and drives to a single pool for the information processing center using Fiber Channel is much more efficient than when using the Ethernet network. Plus SCSI interface.

The ANSI Institute has registered a working group to develop a method for high-speed data exchange between supercomputers, workstations, PCs, drives and display devices back in 1988 and in 1992 the three largest computer companies - IBM (http://www.ibm.com ), Sun Microsystems (http://www.sun.com) and HP (http://www.hp.com) created the Fiber Channel Systems Initiative (Fiber Channel Systems Initiative), in front of which the task was to develop a devote method of digital data . The group has developed a number of preliminary specifications - profiles. Since the physical environment for sharing information was to become fiber-optic cables, the word fiber appeared in the title of technology. However, a few years later, the ability to use copper wires was added to the relevant recommendations. Then the ISO Committee (International Standard Organization) proposed to replace the English writing Fiber French Fiber to somehow reduce associations with a fiber-optic environment, while maintaining almost initial writing. When the preliminary work on profiles was completed, further work on the support and development of the new technology assumed the Association of Developers of the Fiber Optic Channel FCA (Fiber Channel Association), which entered the ANSI Committee. In addition to FCA, an independent FCLC Working Group (Fiber Channel Loop Community) was also created, which began to promote one of the Fiber Channel ARBITRATED LOOP (Fiber Channel Arbitrated Loop). Currently, the Fiber Channel Industry Association (Fiber Channel Industry Association, http://www.fibrechannel.org) has been on all coordination work on promoting Fiber Channel technology. In 1994, the FC-PH standard (physical connection and data protocol) was approved by the T11 ANSI committee and received the designation X3.203-1994.

Fiber Channel technology has a number of advantages that make this standard convenient to organize data exchange in computer groups, as well as using mass media devices, in local networks and when choosing access tools to global networks. One of the main advantages of this technology is a high data transfer rate.

FC-Al is just one of the three possible Fiber Channel topologies, which, in particular, is used for data storage systems. In addition to it, the point-point topology and a star-shaped topology, built on the basis of switches and hubs, are possible. The network that is based on switches connecting a plurality of nodes (Fig. 2), in Fiber Channel terminology is called Fabric.

Fig. 2. FIBRE CHANNEL factory.

In the "loop" FC-AL can be included up to 126 devices with the possibility of hot replacement. When using a coaxial cable, the distance between them can reach 30 m, in the case of a fiber-optic cable, it increases to 10 km. The basis of the technology is the method of simple movement of data from the transmitter buffer to the receiver buffer with the full control of this and only this operation. For FC-Al, it does not matter how data is processed by individual protocols before and after the room in the buffer, as a result of which the type of data transmitted (commands, packets or frames) does not play any role.

The Fiber Channel architectural model in the details describes the parameters of the connections and the exchange protocols between individual nodes. This model can be represented as five functional levels that define the physical interface, the transmission protocol, signal protocol, general procedures and the display protocol. The numbering comes from the lowest hardware level of the FC-0, which is responsible for the parameters of the physical connection, to the top program FC-4, which interacts with higher-level applications. The Display Protocol provides communication with I / O interfaces (SCSI, IPI, HIPPI, ESCON) and network protocols (802.2, IP). In this case, all supported protocols can be used simultaneously. For example, the FC-Al interface that works with IP and SCSI protocols is suitable for the exchange system and the peripheral system. This eliminates the need for additional I / O controllers, significantly reduces the complexity of the cable system and, of course, the total cost.

Since Fiber Channel is a low-level protocol that does not contain I / O commands, the connection with external devices and computers is provided by a higher level protocols, such as SCSI and IP, for which the FC pH is transported. Network protocols and I / O protocols (for example, SCSI commands) are converted to FC-PH protocol frames and delivered to the addressee. Any device (computer, server, printer, drive), having the ability to exchange data using Fiber Channel, is called N_PORT (Node Port), or just a node. Thus, the main purpose of Fiber Channel is the ability to manipulate high-level protocols using a different transmission medium and already existing cable systems.

High Reliability Exchange When using Fiber Channel is due to the two-port architecture of disk devices, the cyclic control of the transmitted information and the replacement of devices in the hot mode. The protocol supports almost any cable systems applicable today. However, two carriers were the greatest distribution - optics and twisted steam. Optical channels are used to connect between Fiber Channel network devices, and twisted pair - to connect individual components in the device (for example, disks in the disk subsystem).

The standard provides several bandwidth and provides the exchange rate of 1, 2 or 4 Gb / s. In view of the fact that two optical cables are used to connect devices, each of which operates in one direction, with a balanced set of operations "Record-reading" the rate of data exchange is doubled. In other words, Fiber Channel works in full duplex mode. In terms of megabytes, the passport speed of Fiber Channel is respectively 100, 200 and 400 MB / s. Really, with a 50% relationship of operations "Record-reading", the interface speed reaches 200, 400 and 800 MB / s. Currently, the most popular solutions of Fiber Channel 2 Gb / s, as they have better value for money.

Note that equipment for Fiber Channel can be consecrated to four main categories: adapters, hubs, switches and routers, and the last widespread spread has not yet received.

Fiber Channel-based solutions are usually intended for organizations that need to maintain large volumes of information in Online mode, accelerate exchange operations with primary and secondary external memory for networks with intensive data exchange, as well as when removing external memory from servers over long distances than Allowed in the SCSI standard. Typical areas of applying Fiber Channel solutions - databases and data banks, analysis and decision support systems based on large amounts of data, storage systems and processing multimedia information for television, film studios, as well as systems, where discs must be removed at considerable distances from servers For security reasons.

Fiber Channel makes it possible to separate all data streams between the enterprise servers, data archiving, etc. from the local network of users. In this embodiment, configuration features are huge - any server can access any system-enabled disk resource administrator, access to the same disk of several devices simultaneously, and at a very high speed. In this embodiment, data archiving also becomes a light and transparent task. At any time, you can create a cluster, freeing the resources for any of the Fiber Channel storage systems. Scaling is also quite clear and understandable - depending on what features there is not enough, you can add either the server (which will be bought on the basis of its computational capabilities), or a new storage system.

One of the very important and necessary features of Fiber Channel is the possibility of segmentation or, as they say, zoning the system. Separating the zones like division into virtual networks (Virtual LAN) on the local network - devices located in different zones cannot "see" each other. Separation to zones is possible either using a switched matrix (Switched Fabric) or based on the WWN address indication (World Wide Name). The WWN address is similar to the MAC address in Ethernet networks, each FC controller has its own unique WWN address that the manufacturer assigns it to it, and any correct data storage system allows you to enter the addresses of those controllers or ports of the matrices with which this device is allowed to work. The division into zones is intended primarily to improve the security and performance of data storage networks. Unlike the usual network, it is impossible to access the device closed for this zone.

Technology Ficon. Fiber Connection technology provides enhanced performance, extended functionality and long-distance communication. As a data transfer protocol, it is based on the ANSI standard for Fiber Channel systems (FC-SB-2). The first-developed IBM standard for communication between mainframes and external devices (such as discs, printers and tape drives) was based on parallel connections, not too different from stranded cables and multiscultuous connectors that were used in those years to connect desktop printers to PC . The set of parallel wires served to transfer longer data "at a time" (parallel); In Mainframes, it was called Bus and Tag. Connectors and cable layout are huge in physical dimensions were the only way to communicate until the market appeared in the market in the 1990s. ESCON technology. It was a fundamentally different technology: in it for the first time instead of copper, fiber was used and the data was not transmitted in parallel, but consistently. Everyone perfectly understood that Escon is much better and much faster, at least on paper, but to universal technology adoption, many tests and efforts on the conviction of buyers took place. It is believed that ESCON technology appeared during the stagnation in the market; In addition, the device supporting this standard has been presented with a noticeable intake, so the technology has met the cool reception, and for its widespread distribution it took almost four years. With Ficon, the story was in many respects repeated. For the first time, IBM introduced this technology on S / 390 servers back in 1997, many analysts were immediately clear that this is largely a technically more advanced solution. However, for several years, FICON was used almost exclusively to connect tape drives (a significantly improved solution for creating backup and recovery) and printers. And only in 2001, IBM finally equipped Ficon its Enterprise Storage Server storage system under the code name Shark ("Shark"). This event again coincided with a serious economic recession when the introduction of new technologies at the enterprises was slowed down. Literally in a year, a number of circumstances arose, which contributed to the accelerated adoption of Ficon. This time the wholesale fiber concept was no longer new, but technology storage networks (SAN) were widespread both in the world of mainframes and beyond. Now the steady growth of the storage device market continues. Today's devices called directors (Director), from the very beginning, developed to support ESCON, now support the Fiber Channel standard, based on the same devices deploy FICON solutions. According to developers, Ficon provides significantly greater functionality compared to Fiber Channel.

InfiniBand.

InfiniBand architecture defines a general standard for processing I / O operations of communication, network subsystems and data storage systems. This new standard led to the formation of the InfiniBand Trade Association Trade Association (IBTA, http://www.infinibandta.org). Simply put, InfiniBand is the standard of the new generation I / O architecture, which uses a network approach to connecting servers, storage systems and network devices of the information center.

Infiniband technology was developed as an open solution that could replace all other network technologies in various fields. This concerned the common technologies of local networks (all types of Ethernet and storage networks, in particular, Fiber Channel), and specialized cluster networks (Myrinet, SCI, etc.), and even connection of I / O devices in a PC as a possible replacement PCI tires and I / O channels, such as SCSI. In addition, InfiniBand infrastructure could serve to unite into a single system of fragments using different technologies. Advantage of InfiniBand in front of specialized, high-performance clusters-oriented clusters is consisting of its versatility. Oracle Corporation, for example, supports InfiniBand in its cluster solutions. A year ago, HP and Oracle installed the performance record in TPC-H tests (for 1 TB databases) in the InfiniBand-cluster based on Proliant DL585 using Oracle 10G DBMS in the Linux medium. In the summer of 2005, IBM reached record indicators for TPC-H (for 3 TB databases) in the DB2 and SUSE Linux Enterprise Server 9 in an InfiniBand-cluster based on XSERIES 346. At the same time, the cost of one transaction was almost twice as much as the cost. For the nearest competitors.

Using a technique called a switched network structure, or a switching grid, InfiniBand transfers the traffic of I / O operations from the server processors to the peripherals and other processors or servers throughout the enterprise. A special cable (link) is used as a physical channel that provides 2.5 Gb / s data transfer rate in both directions (InfiniBand 1x). Architecture is organized as a multi-level, it includes four hardware levels and upper levels implemented software. In each physical channel, you can organize many virtual channels, assigning different priorities to them. To increase the speed, there are 4-fold and 12-fold InfiniBand versions that use 16 and 48 wires, and the data transfer rates are equal to 10 Gbps (InfiniBand 4x) and 30 Gb / s (InfiniBand 12x).

Infiniband architecture solutions are in demand in four main markets: corporate data centers (including data warehouses), high-performance computer clusters, embedded applications and communications. InfiniBand technology allows you to combine standard servers to cluster systems to provide data centers. Performance, scalability and failure resistance - features, usually provided only by top-class platforms in millions of dollars. In addition, the InfiniBand repository can be connected to server clusters, which allows you to associate all storage resources directly with computing resources. The high-performance cluster market has been aggressively looking for new ways to expand computational capabilities and therefore can extract huge benefits from high throughput, low latency and excellent scalability offered by inexpensive InfiniBand products. Built-in applications, such as military systems, real-time systems, processing video streams, etc., will receive huge benefits from the reliability and flexibility of InfiniBand connections. In addition, the Communication Market constantly requires an increase in connection throughput, which is possible to achieve due to 10- and 30-Gbit / with InfiniBand connections.

At the physical level, the InfiniBand protocol defines electrical and mechanical characteristics, including fiber optic and copper cables, connectors, parameters that specify the hot replace properties. At the bond level, the parameters of the transmitted packets, operations connecting the point with a point, the features of switching in the local subnet. On the network level, the rules for routing packets between subnets are determined, this level is not required inside the subnet. The transport level provides for an assembly of packets to the message, multiplexing channels and transport services.

We note some key features of the InfiniBand architecture. For I / O and Clustering, the only InfiniBand board is used in the server, which eliminates the need for individual charges for communications and data storage systems (however, in the case of a typical server, it is recommended to install two such cards configured to provide redundancy). Just one connection with the InfiniBand switch to each server, the IP network or SAN system (redundancy is reduced to a simple duplication of the connection with another switch). Finally, the InfiniBand architecture permits the problems of connections and restricting the band inside the server and at the same time provides the required strip and the ability to communicate for external storage systems.

The InfiniBand architecture consists of the following three main components (Fig. 3). HCA (Host Channel Adapter) is installed inside the server or workstation that performs the function of the main (host). It acts as an interface between memory controller and the outside world and serves to connect host machines to network infrastructure based on InfiniBand technology. The HCA adapter implements the messaging protocol and the main mechanism of direct memory access. It connects to one or more InfiniBand switches and can exchange messages with one or more TCA. The TCA adapter (target channel Adapter) is designed to connect to the InfiniBand network of devices such as drives, disk arrays or network controllers. It, in turn, serves as an interface between the InfiniBand switch and the input-output controllers of peripheral devices. These controllers do not have to be one type or belong to one class, which allows you to combine different devices into one system. Thus, TCA acts as an intermediate physical layer between InfiniBand structure data and more traditional I / O controllers for other subsystems, such as Ethernet, SCSI and Fiber Channel. It should be noted that TCA can interact with HCA and directly. Infiniband switches and routers provide central docking points, and several TCA adapters can be connected to the HCA control. InfiniBand switches form the core of the network infrastructure. With the help of a set of channels, they are connected to each other with TCA; In this case, mechanisms such as channel grouping and load balancing can be implemented. If the switches are functioning within the same subnet formed directly connected devices, then InfiniBand routers combine these subnets by setting the connection between multiple switches.

Fig. 3. The main components of the InfiniBand SAN-Network.

Most of the developed logical capabilities of the InfiniBand system are built into the adapters that connect nodes to the I / O system. Each type of adapter unloads the host from the transport task execution, using the InfiniBand channel adapter, which is responsible for organizing I / O messages to the data delivery packages. As a result, the OS on the host and the server processor is exempt from this task. It is worth noting that such an organization is radically different from what is happening when communications based on the TCP / IP protocol.

InfiniBand defines a very flexible set of communication lines and transport level mechanisms, which provides accurate configuration of the SAN network characteristics based on InfiniBand, depending on the application requirements, including:

• variable size packets;
• maximum gear unit size: 256, 512 bytes, 1, 2, 4 KB;
• level 2 level 2 headers (LRH, LOCAL ROUTE HEADER) to direct packets to the desired port of the channel adapter;
• additional level 3 header for global routing (GRH, Global Route Header);
• group transfer support;
• various and invariant checksums (VCRC and ICRC) to ensure data integrity.

The maximum amount of the transmission unit defines such characteristics of the system as the instability of packet synchronization, the magnitude of the overhead costs for encapsulation and the delay duration used in the development of systems with multiple protocols. The ability to lower information about the global route when sending to the local subnet destination reduces the cost of local data exchange. The VCRC code is calculated again each time when the next link of the communication channel is passed, and the ICRC code is received when a package is received, which guarantees the integrity of the link and throughout the communication channel.

Infiniband defines a permission-based flow control - to prevent the head of the head of the head of Line Blocking and the packet loss - as well as the flow control on the channel level and through flow control. By your capabilities, the channel-based management based on permission is superior to the widespread Xon / Xoff protocol, eliminating the limit on the maximum range of communication and ensuring the best use of the communication line. The receiving end of the communication line sends the transmitting device to the resolution indicating the amount of data that can be obtained securely. Data is not transmitted until the receiver sends permission indicating the availability of free space in the receiving buffer. The mechanism for transferring permissions between devices is built into the connection protocols and communication lines to guarantee the reliability of flow control. The flow control at the channel level is organized for each virtual channel separately, which prevents the distribution of transmission conflicts inherent in other technologies.

Using Infiniband Communication with remote storage modules, network functions and connections between servers will be carried out by connecting all devices through the central, unified framework of switches and channels. The InfiniBand architecture allows you to place an I / O device at a distance of up to 17 m from the server with a copper wire, as well as up to 300 m using a multimode fiber optic cable and up to 10 km with a single-mode fiber.

Today InfiniBand is gradually gaining popularity as a highway technology for server clusters and storage systems, and in data processing centers - as a basis for connections between servers and storage systems. The organization called Openib Alliance (Open InfiniBand Alliance, http://www.openib.org) is a great job in this direction. In particular, this alliance aims to develop a standard InfiniBand support software with open source for Linux and Windows. A year ago, InfiniBand technology support was officially included in the Linux kernel. In addition, at the end of 2005, OpenIB representatives demonstrated the possibility of using InfiniBand technology at large distances. The best achievement during the demonstration was the transmission of data at a speed of 10 Gb / c to a distance of 80.5 km. The experiment participated in the data processing centers for a number of companies and scientific organizations. At each of the end items, InfiniBand protocol encapsulated into the SONET OC-192C, ATM or 10 Gigabit Ethernet interfaces without reducing bandwidth.

1. Introduction

Telecommunication concept

Elements of the theory of information

1.3.1 Definition of information.

1.3.2 Number of information

1.3.3 entropy

1.4. Messages and signals

Topic 2. . Information networks

2.2. LAN configuration.

Topic 3.

3.2. Reference Model (OSI)

Topic 4.

4.1. Wired lines

4.2. Optical communication links

Topic 5.

Theme 6 ..

Topic 7.

7.2. Addressing in IP networks

7.3. IP protocol

Lecture 1.

Telecommunications. The concept of information. Information transmission systems. Measuring the number of information

Telecommunication concept

Before considering information transfer technologies, consider networks (systems) in which various types of information are transmitted. Information (sound, image, data, text) transmitted in telecommunication and computer networks.

Telecommunications (Greek Tele - distance, far and lat. Communication - Communication) is a transmission and reception of any information (sound, images, data, text) for a distance of various electromagnetic systems (cable and fiber optic channels, radio channels and other wired and wireless communication channels).

Telecommunication system - Collapse technical Objects, Organizational Measures and Subjectsimplementing the processes of connection, transmission, access to information.

Telecommunication systems together with the data transfer medium Form telecommunication networks.

Telecommunication networks It is advisable to divide the type of communications (telephone network, data network, etc.) and consider if necessary in various aspects (technical and economic, technological, technical, etc.).

Examples of telecommunication networks:

- Postal Communications;

- Community telephone connection (TFP);

- Mobile telephone networks;

- Telegraph Communication;

- Internet - global network of interaction of computer networks;

- network of wired broadcasting;

- network of cable broadcasting;

- network of television and broadcasting;

and other information networks.

To implement communication at a distance, telecommunication systems use:

- switching systems;

- data transmission systems;

- access systems and transmission channels;

- Information conversion systems.

Data transfer system - This is a combination communication channels, centers switching, Television Processors, Multiplexers data transmission and software establishment and communication.

Under data transfer system (SPD) It is understood as a physical environment (FS), namely: the medium on which the signal is distributed (for example, cable, fiber optic (light guide), radio ester, etc.).

This lecture course is devoted to the study of information transfer technology on physical, channel and network levels.

The most important aspect of the course is the concept of information. Currently, there is no single definition of information as a scientific term.

Here are some definitions of information:

1. Information (from lat. informatio. - "Clarification, presentation, awareness") - this is information (messages, data), regardless of the form of their presentation.

2. Information - information about persons, subjects, facts, events, phenomena and processes, regardless of the form of their presentation.

Information reduces the degree of uncertainty, incoming knowledge About faces, subjects, events, etc.

In the theory of information measure of uncertainty any experience (test), which can have different outcomes, so, the amount of information is called entropy.

In a broad sense, in which word is often used in everyday life, entropy means the measure of the unforgettable system; than lesselements of the system subordinate to any order, the higher the entropy.

The more information, the greater the ordering system, and vice versa than less information, the higher chaos system the higher her entropy.

Communication: Information - Message - Signal

Message- this is information expressed in a certain form. and intended for transmission from the source to the user ( texts, Photo, Speech, Music, Television Imageand etc.). Information is a part of the message representing the novelty, i.e. What has not previously known.

Signal- This is a physical process that spreads in space and time, the parameters of which are capable of displaying (contain) a message.

For information transfer use signalwhich is the physical size and with its parameters anyway information is connected.

In this way, the signal is a variable physical value.. Telecommunication systems and networks use electrical, optical, electromagnetic and other types of signals.

Telephone networks

First stage Telephone network development - public telephone networks (TFE or PSTN). TFOP is a combination of PBX, which are combined with analog or digital communication lines (highways) or connecting lines, and user (terminal) equipment connected to the subscriber lines. Tfop use channel switching technology. The advantage of channel switching networks is the ability to transfer audio information and video information without delay. The disadvantage is a low channel utilization factor, a high cost of data transfer, an increased time of expectation of other users.

Second phase - ISDN telephone networks. Modern generation of a digital telephone network - ISDN. ISDN (INTEGRATED SERVICES DIGITAL NETWORK) - Digital network with integrated servicesIn which only digital signals are transmitted on the telephone channels, including by subscriber lines.

As a line of ISDN BRI, the telephone company more often uses a copper cable of the public telephone network (TSOP), due to which the final cost of the ISDN line is reduced.

Digital networks with ISDN service integration can be used to solve a wide class of information transfer tasks in various fields, in particular: telephony; data transfer; Union of remote LAN; access to global computer networks (Internet); Transfer of traffic sensitive to delays (video, sound); Integration of various types of traffic.

The end device of the ISDN network can be: a digital telephone, a separate computer with an ISDN-adapter installed, a file or specialized server, a bridge or a LAN router, a terminal adapter with voice interfaces (for connecting a conventional analog phone or fax), or with serial interfaces (for data transmission).

In Europe, the actual ISDN standard becomes euroisdn, which supports most European telecommunication providers and equipment manufacturers.

Currently, TFE and ISDN networks are connected cellular communication centers(Cellular networks of different operators are interconnected), which provides calls from cell phones to stationary phones (TFP or ISDN) and vice versa.

To communicate the Internet (IP network) with TFP Special are used analog VoIP gateways, and ISDN apply digital Voip Gateways. The voice signal from the VoIP channel can directly enter an analog telephone connected to a regular telephone network TFE or a digital telephone, connected to a digital network with the integration of ISDN services.

Copper cable and PDH / SDH are used as primary networks in fixed telephony to combine PBX.

cellular

Cellular communication is a wireless telecommunications system, consisting of 1) network of ground-based base receiving-transmitting stations, 2) small mobile stations (cellular radio phones) and 3) of a cellular switch (or mobile switching center). GSM (Global System for Mobile Communications)

Cellular communication: 1G, 2G, 2.5G, 3G, 4G, 5G.GSM (Global System for Mobile Communications)

Television networks

Television networks (essential, cable, and satellite,) are designed to transfer video. Cable television uses non-commutable communication channels. At first, the video was in analog form, then the cable and satellite television was translated into digital signals. Currently, the analog television has ceased to exist, and all types of broadcasting will transmit signals in digital form.

Digital television is based on open standards and develops under the control of the DVB consortium.

Systems obtained the greatest distribution:

· Digital satellite broadcasting - DVB-S (DVB-S2);

· Digital cable broadcasting - DVB-C;

· Digital essential broadcast - DVB-T (DVB-T2);

· Digital broadcasting for mobile devices - DVB-H.;

· Television on ip - DVB (IPTV);

· Internet television or streaming broadcast (Internet-TV).

Concerning DVB-H, DVB-IPTV and Internet-TVThis is the result of integration (convergence) of various networks, as well as terminal devices.

Mobile television DVB-H is a mobile broadcast technology that allows you to transmit a digital video signal over the Internet to mobile devices, such as PDAs, a mobile phone or a portable TV.

It is important to note that IPTV (IP via DVB or IP on MPEG) is not a television that broadcasts via the Internet. IPTV reminds usual cable television, only to the terminal of the subscriber it comes not by a coaxial cable, but on the same channel as the Internet (ADSL modem or Ethernet).

IPTV is a broadcast of channels (usually obtained from satellites), mainly in MPEG2 / MPEG4 formats over the provider's transport network, followed by viewing on a computer using one of the video players - VLC-Player or IPTV - Player or on TV using a special specialized SET device Top Box.

Streaming video broadcast ( Internet-TV.). The broadcast model in Internet-TV is significantly different from other concepts. Streaming video (Streaming Video) is called compression technology and data buffering technology that allow you to transfer real-time video via the Internet.

Computer networks

Primary networks

Currently, on the Internet, almost all known links from low-speed telephone lines to high-speed digital satellite channels are used.

Communication channels of global networks are organized by primary networks of FDM technologies, PDH / SDH, DWDM (Didabl Diem).

Since IP traffic today is an indispensable attribute of any data network and not support it is simply impossible, then to provide quality services most large global networks, especially network operator networks, are built on a four-level scheme.

Fig. 10. Four-level structure of the modern global network

Two lower levels do not belong to the actual packet networks - these are levels of the primary network.

Primary, or supporting, networks are designed to create a switched infrastructure. Based on channels formed by primary networks, secondary ( computer or telephone) Network.

At the lower level, the most high-speed today is Dense Wavelength Division Multiplexing technology (dense multiplexing with a wavelength division) DWDM forming spectral speeds 10 Gb / s and higher. Wavelength Division Multiplexing ( WDM.) - technology of optical spectral sealcalled usually multiplexing with a division of wavelength. To WDM (DWDM, CWDM), almost any equipment can be connected to the Multiplexer: SONET / SDH, ATM, Ethernet.

The next level works SDH technology ( synchronous digital hierarchy). SDH / PDH standards are designed for high-speed optical communication networks - first PDH (PLESIOCHRONOUS DIGITAL HIERARCHY, plesiOhron digital hierarchy), and then more perfect SDH (Synchronous Digital Hierarchy, synchronous digital hierarchy) Common in Europe and its American analogue SONET. SONET / SDH Ensures use method of temporary multiplexing and synchronizing the time intervals of traffic between network elements and determines the levels of data rates and physical parameters.

The third level is formed by the ATM network, the main purpose of which is to create the infrastructure of permanent virtual channels connecting IP router interfaces operating in the third, upper level of the global network.

IP levels forms a composite network and provides services to end users transmitting their IP traffic transit on the global network or interacting on IP with an Internet.

On the Internet, the "clean" IP networks are used, called so due to the fact that under the IP level there is no other network switching packages, such as atm.

The structure of the "clean" IP network is presented in Fig. below.

Fig. 11. Structure "Clean" IP Network

In such a network, digital channels are still formed by the infrastructure of the two lower levels, and these channels directly use IP router interfaces, without any intermediate layer.

The development of communication networks showed the need to integrate sound, images and other data types for the possibility of their collaborative transmission. Since discrete channels of communication of reliable and economical analog communication channels, they were taken as the basis. In this regard, the number of analog networks is quickly reduced and they are replaced by discrete.

Softswitch.

SoftSwitch (Software Switch) - Flexible Software Switch, one of the main elements of the Next Generation NGN Communication Network

Fig. 15. Softswitch in general use network

SoftSwitch is a NGN network management device designed to separate connections from switching functions capable of servicing a large number of subscribers and interact with application servers by supporting open standards. SoftSwitch is a carrier of the intellectual capabilities of the IP network, it coordinates call service management, alarm, and functions that ensure the establishment of a connection through one or more networks.

Also, an important function of the program switch is the connection of the next-generation NGN networks with existing traditional TFP networks, by means of signaling (SG) and media gateways (MG).

Information transfer technologies

Topic 1. Basic concepts of information transmission systems

1. Introduction

Telecommunication concept

Elements of the theory of information

1.3.1 Definition of information.

1.3.2 Number of information

1.3.3 entropy

1.4. Messages and signals

1.5. The main directions of development of telecommunication technologies

Topic 2. . Information networks

2.1. Characteristics and classification of information networks

2.2. LAN configuration.

2.3. Basic network topologies

2.4. Network technology local networks

2.5. Methods for building information networks

Topic 3. Architecture of information networks

3.1. Multi-level information network architecture

3.2. Reference Model (OSI)

Topic 4. Communication lines and data channels

4.1. Wired lines

4.2. Optical communication links

4.3. Wireless communication channels

4.4. Satellite data channels

Topic 5. Data transmission technologies at the physical level

5.1 Basic Functions of the Physical Level

5.2. Methods for converting discrete signals (modulation and coding):

5.2.1. Analog modulation of discrete signals (AM, FM, FM)

5.2.2. Digital Discrete Signal Coding (Pulse and Potential)

5.3. Pulse-code modulation of analog signals

5.4. Multiplexing methods:

5.4.1. Frequency multiplexing method FDM

5.4.2. TDM time division multiplexing

5.4.3. By WDM wavelength (in fiber optic communication channels)

Theme 6. Data transmission technologies on channel level.

6.1. Data transmission technologies on channel level in LAN and highlighted lines (Ethernet, token Ring, FDDI; Slip, HDLC, PPP)

6.2. Data transmission technologies on channel levels in global networks or road transport technology (X.25, Frame Relay, ATM, MPLS, Ethernet; ISDN, PDH, SDH / SONET, WDM / DWDM)

Topic 7. Information transfer technologies on a network level in composite networks (IP networks)

7.1. Network-based networks

7.2. Addressing in IP networks

7.3. IP protocol

7.4. Routing in data transmission networks.

7.5. Data flow management.

The curriculum of the course of 108 academic watches consists of one content (academic) module of 3 loans (the volume of the ECTS loan is 36 academic hours) and consists of audit classes and independent work of students.