Curriculum Computer Networks and Telecommunications. General information about the Internet Basic information about Internet

Literally translated into Russian, the Internet is an inter-network, i.e. it is a pooling of networks. Now the Internet is the world's COP.

The Internet is a unique collection of LAN, MAN, WAN that are connected together.

The basis of the Internet is the ARPANET network, developed in 1969 with funds from the Defense Advanced Research Projects Agency (DAPRA). The ARPANET is the result of research to create a COP that is robust enough to function in wartime. Despite the fact that the ARPANET was created with military money, it was developed mainly in universities. Some of its parts were classified, but most of it was open because maximum opportunity and ease of use of the network d. make it more stable, more reliable, more stable, more accessible, more useful.

One of the earliest standardized services was e-mail, followed by a standard for file transfers and then a standard for newsgroups. None of these services were developed for commercial or private use. All of this was done by people interested in creating open standards that anyone could use.

The main group that oversees the development of the Internet is the Internet Society ISOC. ISOC oversees many volunteer groups: the Architect Group, Engineering Force, Research Force, Digital Access Control Group, Disaster Relief Committee, Internet Action Forum, and more. But there is no single authoritarian figure on the Internet, senior officials may be ... from networks connected to the Internet. Nobody pays for the Internet in general. Everyone pays for their share.

Host (Host) - a host PC that performs the centralized functions of supporting this network, makes programs and data files available to other PCs on the Internet.

Protocol is a set of semantic and syntactic rules and procedures that determine the operation of functional devices in the communication process.

Dedicated channel - a communication channel to which terminal data processing devices are permanently connected, does not require switching.

Dial-up channel is a communication channel of subscribers, to which connection is made through general-purpose telephone channels by dialing the subscriber's number on the telephone dialer. This creates a temporary connection.

The real birthday of the Internet is 1983, when there was a revolutionary change in computer communications software. In 1983, the TCP / IP communication protocol was standardized.

TCP / IP (Transmission Control Protocol over Internet Protocol) is a transmission control protocol over the Internet protocol. It is a common protocol for all PCs. Internet. It is software that allows individual parts of the Internet to work together to form a single network. TCP / IP is independent of the hardware and cabling of the networks.

TCP / IP is a combination of two standards (stack): TCP and IP, which play different roles in the process of communication over the Internet. IP defines a low-level method for moving information from one PC to another, TCP provides a high-level method for determining if information is present and validating it for correctness (I-book, IP pages, and TCP language).

TCP Tasks:

1) Ensuring guaranteed passage of information through the Internet without data loss;

2) Prevention of accidental or unauthorized intentional distortion, changes in information during the passage;

3) Retransmission if received in an incorrect form;

4) Providing methods for splitting long messages into smaller sections of their transmission and then combining them into a single whole;

5) Providing the possibility of extended communication between two subscribers simultaneously with other subscribers.

IP includes:

1) Methods for uniquely identifying each PC on the Internet so that users can always determine where this or that information came from;

2) Methods for determining the availability of received information;

3) A system that divides information into small portions that could move without interference through any Internet switches.

Each host computer has two addresses:

1) PC friendly digital IP address;

2) User-friendly DNS (Domain name system) address.

The IP address consists of 4 numbers separated by dots. Each number is 1 byte long, i.e. takes a value from 1 to 255.

123 refers to the top-level network, 89 directly to the corresponding host PC. The first two numbers are the address of the network and the last two are the address of the host PCs within that network.

The domain name system assigns PCs literal names, domain names, which are the symbolic form of the address of a networked PC. For example, to find out the conditions for connecting to NTV + satellite television, you can try to contact the www / ntv / ru server (ru at the end of the name indicates that the company's server belongs to the Russian Internet sector).

Domain names are translated into their associated IP addresses by DNS domain name servers.

The domain name system is a method of assigning names by assigning responsibility to different groups of users for subsets of names. Each level in this system is called a domain. Domains are separated from one another by dots. In the name of m. any number of domains, but five are rare. Each subsequent domain (as viewed from left to right) is larger than the previous one.

Initially, there were six organizational top-level domains: commercial organizations - edu, educational institutions - gov, military institutions - mil, other organizations - org, network resources - net.

In order for foreign countries to control the names of the systems located in them, a two-letter domain was created.

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What is the Internet in a modern interpretation

In general, when it comes to the modern Internet, quite often the concept of the World Wide Web or the Network is used instead, which brings together computers from all over the world.

In general, it is true, but one clarification should be made here. As you know, no computer directly connects to the Internet, only through a service provider to which God knows how many other terminals or mobile devices are connected. It turns out that they are all united into one network. And in this sense, the Internet is called a "network of networks".

Indeed, the structure of the Internet is based on the association, so to speak, of subnets and has a high-tech hierarchy. In addition, it is impossible to imagine access to a particular resource without a router that is able to choose the optimal path for faster access to a given resource.

And here's what's interesting. The Internet as such has no owner, and the network itself is more of a virtual space, which every day affects a person more and more, sometimes even replacing reality. Good or bad, it's not for us to judge. But let's dwell on the main aspects of the construction and functioning of the World Wide Web.

The structure of the global Internet: the history of emergence and development

The Internet was not always the way we know it today. If you dig into history, it should be noted that the first attempts to create a unified information network that could not only transmit data, but also serve as a kind of "translator" of many programming languages \u200b\u200bfor the perception of information, were undertaken back in 1962, in the very the height of the "cold war" between the USA and the USSR. Then came the program based on the theory of packet switching for Leonard Kleinrock, led by Joseph Licklider. The main direction was not only but also its "indestructibility".

On the basis of these developments, in 1969 the first network arose, called ARPANet, which became the progenitor of the Internet, or the World Wide Web. In 1971, the first program for sending and receiving e-mail was developed, by 1973, when the Euro-Atlantic cable was continued, the network became international, in 1983 it switched to the unified TCP / IP protocol, in 1984 IRC technology appeared, which allowed chatting ... And only by 1989 at CERN the idea of \u200b\u200bcreating a global web, which is now commonly called the Internet, matured. Of course, it was far from the model used now, nevertheless, some of the basic principles that the structure of the Internet includes, have remained unchanged to this day.

Infrastructure of the World Wide Web

Now let's see how it was possible to combine individual computer terminals and networks based on them into a single whole. The key principle was the use of packet data transmission using routing based on a universal protocol that would be understood by any machine. That is, the information is not presented as separate bits, bytes or characters, but is transmitted as a formatted block (packet), which can contain rather long combinations of different sequences.

However, the transfer itself does not happen at random. Moreover, the resources of the Internet have several main levels:

Backbone (system of high-speed servers interconnected).
Large networks and access points connected to the main backbone.
Regional networks are of a lower rank.
Internet access service providers (ISPs).
End users.

The Internet is such that the terminals on which it is stored are called servers, and the user machines (reading or receiving it, as well as sending back responses and streams) are called workstations. The transfer of the information itself, as mentioned above, is carried out on the basis of routers. But such a diagram is presented solely for ease of understanding the issue. In fact, everything is much more complicated.

Basic protocols

Now we come to one of the key concepts, without which it is impossible to imagine what the structure of the Internet is. These are universal protocols. Today there are quite a few of them, but TCP / IP is the main one for the Internet.

In this case, it is necessary to clearly distinguish between the two terms. Internet Protocol (Internet Protocol) is one of the routing means, that is, it is solely responsible for the delivery of data packets, but is in no way responsible for the integrity and security of the transmitted information. TCP, on the other hand, is a means of providing a session communication between a sender and a receiver based on a logical connection between two points with the so-called guaranteed packet delivery, and absolutely intact.

Today TCP / IP is the de facto standard for the Internet, although many other protocols exist, such as UDP (transport), ICMP and RIP (routers), DNS and ARP (network address authentication), FTP, HTTP, NNTP, and TELNET (application ), IGP, GGP and EGP (gateway), SMTP, POP3 and NFS (mail and file access protocols on remote terminals), etc.

Domain Name System

The universal approach to access to resources should be noted separately. It is clear that writing a page address like 127.11.92.785 in order to get to the required resource is not so convenient (and even more so remembering all these combinations). Therefore, at one time a unique domain name system was developed, which allowed entering the address as we see it today (in English).

But here, too, there is a hierarchy of its own. Several levels are also distinguished in it. For example, international top-level domains include resources that are independent of the country identifier (GOV - government, COM - commercial, EDU - educational, NET - network, MIL - military, ORG - general organizational, not related to any of the above types) ...

This is followed by resources that explicitly indicate the country identifier. For example, US - USA, RU - Russia, UA - Ukraine, DE - Germany, UK - Great Britain, etc. In addition, such domains have their own sublevels like COM.UA, ORG.DE, etc. turn, and here you can find a clearer binding at the levels below the rank (KIEV.UA, KIEV.COM.UA, etc.). In other words, when looking at the address, you can immediately determine not only the country, but also the territorial affiliation of the resource within it.

Basic Internet services

As for the services that can be found on the Internet today, in their categories they are divided into e-mail, news and mailings, file exchange networks, electronic payment systems, Internet radio and television, web forums, blogs, social networks, online stores. and auctions, educational projects "Wiki", video and audio hosting, etc. Since social networks have become the most popular lately, let us dwell on their structure.

The structure of the social networks of the Internet

A common feature of such an online community is independence from territorial status or citizenship. Each user creates his own profile (image, place of residence on the Web, whatever you call it), and communication is carried out using the instant messaging system, but not through chat, but in private mode. The only thing comparable to chat is the commenting system. In addition, any registered resident of such a community can leave so-called posts, share with the public some materials or links to other publications, etc.

The structure of the Internet is such that when using certain protocols, such as TCP / IP and IRC, all this is done quite simply. The main condition is registration (creating a login and password for entering), as well as indicating at least minimal information about yourself.

Not surprisingly, personal sites and chats are slowly but surely fading into oblivion. Even the once popular “dialers” like ICQ or QIP cannot withstand any competition, because social networks have much more opportunities.

Laboratory work No. 4

Lesson topic:Global computer network Internet. Power Point Presentation Software

Lesson objectives:

1. To master the skills of browsing Web-pages and Web-sites, finding the necessary information on the Internet.

1. To master the skills of working with the program-browser MS Internet Explorer.

2. Master the skills of receiving and sending messages by e-mail.

3. Become familiar with the Power Point interface.

4. Learn to create, edit, format, customize and show slide multimedia presentations in Power Point.

5. Learn to independently study the material in preparation for laboratory work.

6. Develop technical thinking.

Time: 180 minutes ... A place: computer class

Equipment:

1. Personal computers

2. Assignment for laboratory work (handout)

1. Informatics. Basic course. Textbook for universities. Ed. S.V. Simonovich. 2nd ed. - SPb .: Peter, 2009.

2. V.G. Olifer, N.A. Olifer. Basics of data transmission networks. Lecture course. Tutorial. 2nd ed. M .: Internet University of Information Technologies (www.intuit.ru), 2005.

3. Laboratory workshop in informatics. Textbook for universities. 2nd ed. Ed. V.A. Ostreykovsky. M: Higher School, 2008.

General information about the Internet.

Global computer network INTERNET can be viewed from two points of view: physical and logical.

From a physical point of view, the INTERNET is a huge collection of individual computers and computer networks that unite hundreds of millions of computers around the world.

From a logical point of view, INTERNET is a global world information system - a huge information space covering the entire globe.

Since its inception (1960s), the global computer network INTERNET has been steadily expanding both quantitatively and qualitatively.

At present, the global computer network INTERNET provides users with the following basic services:

Search and selection of information for its further use (service WWW-World Wide Web);

Work with e-mail (E-Mail service);

Working with an electronic newspaper - so-called. conference (Usenet service);

Real-time communication (IRC service).

In general, the INTERNET exchanges information between any two computers included in the network. For this, the INTERNET uses two basic concepts - concepts addresses and protocol.

Each computer connected to the network has its own unique address. This address consists of four parts, each of which is one byte, i.e. eight binary digits. This means that each of the four parts of the address written in the decimal system can take a value from 0 to 255. These parts are combined into a record, where each part is separated from the other by a point. For example, record 129.102.83.94 can be a unique address of a computer connected to the INTERNET, i.e. an address that is no longer repeated.

Such addresses on the INTERNET are called IP addresses (IP- Internet Protocol). Each computer that has its own unique digital address on the INTERNET is called a "host" (from the English word Host).

However, the use of the system of digital IP-addresses is not always convenient, therefore there is another on the INTERNET - the domain-based address system or abbreviated system DNS (DOMAIN NAME SYSTEM - domain name system).

Domain address of the computer Is a unique name, usually meaningful and much easier to remember than a digital IP address. For instance.

LECTURE 3. Global computer network Internet

3.1. General information about the Internet

At that time, personal computers did not yet exist, and large American universities could afford 1-2 large computers. Computer time was a precious resource and was pre-recorded for it. People worked at night so that not a minute of this time was wasted.

Finally, the idea came up to connect computers from different universities to make it possible to remotely use any computer that is currently free. This project was named ARPANET. By the end of 1969, the computers of four universities were connected and the first computer network appeared.

It was soon discovered that the network was mainly used not for computing on a remote computer, but for exchanging messages between users. In 1972, when the ARPANET was already connecting 23 computers, the first program was written to exchange e-mail over the network. E-mail was appreciated, which prompted a number of government organizations and corporations to create their own computer networks. These networks had the same disadvantage as the ARPANET: they could only connect a limited number of computers of the same type. Moreover, they were not compatible with each other.

In the mid-70s, new standards for data transmission were developed for ARPANET, which made it possible to interconnect networks of arbitrary architecture, at the same time the word "Internet" was coined. It was these standards, later called the TCP / IP protocol, that laid the foundation for the growth of the global computer network by combining existing networks. Their important advantage was that the network was considered, in principle, not one hundred percent reliable, and means of dealing with errors in data transmission were provided. In 1983, ARPANET switched to a new protocol and split into two independent networks - military and educational. By this time, the network united over a thousand computers, including those in Europe and the Hawaiian Islands. The latter used satellite communication channels.

The development of the Internet received a new impetus thanks to the initiative of the US National Science Foundation (NSF) to create a global network infrastructure for the higher education system (1985-88). NSF created a high-speed backbone network and allocated funds to connect American universities to it, provided that the university provided access to the network for all trained users. The Internet remained predominantly a university network until the early 1990s, but NSF immediately took a course to make it independent of government funding in the future. In particular, NSF encouraged universities to seek commercial clients. By 1988, the Internet already numbered about 56,000 connected computers.

The real heyday of the Internet began in 1992, when a new service was invented, which received the strange name of the World Wide Web (or WWW, or simply "the Web"). The WWW allowed any Internet user to publish their text and graphic materials in an attractive form, linking them with publications of other authors and providing a convenient navigation system. Gradually, the Internet began to go beyond academic institutions and began to transform from a means of correspondence and file exchange into a giant repository of information. By 1992, the Internet had over a million connected computers.

Nowadays, the Internet continues to grow at the same breakneck speed. According to experts, the amount of transmitted information ( traffic) on the Internet is increasing by 30% monthly. In 1999, the Internet connected about 60 million computers and more than 275 million users, and every day one and a half million new Web documents appeared on it. These estimates are rather rough because there is no central administrative body on the Internet that would register new users and new computers.

The Internet first entered Russia in the early 90s. A number of universities and research institutes began at this time to build their own computer networks and acquired foreign communication channels. Of particular note is the Institute of Atomic Energy. Kurchatov. On the basis of the IAE, two largest commercial companies have emerged that provide services for connecting to the Internet - Relcom and Demos, as well as the Russian Institute for the Development of Public Networks (ROSNIIROS). The latter later became the parent organization coordinating the development of the Russian part of the Internet.

According to available estimates, in 1999 the number of Russian Internet users exceeded 5 million. Now on the Internet there are already many interesting materials in Russian, but knowledge of the English language is desirable - the pioneering role of the countries of the English language in the development of the Internet has consolidated the role of the language of interethnic communication for English.