Global network Internet: protocols, access systems. Internet World Wide Web: network access and communication channels Communication channels and internet access methods
Data link - these are means of two-way data exchange, which include communication lines and equipment for transmitting (receiving) data. Data transmission channels connect information sources and information receivers.
Sample graphical depiction of links between Internet networks
Internet connection
As we have already said, computers permanently connected toInternetand traffic controllersonline information(permanent connection), called servers Internet .
The temporary connection of a computer to a network server is calledswitched connection. If this connection is made remotely (using telephone lines), then the connection is calledremote access connection.
To connect toInternet, you need to connect your computer to another computer that has a permanentIP-the address. Each network server has a permanentIP - a d pec - This internet protocol (InternetProtocol, IP) responsible for addressing.
In addition to havingIP-addressesconnection requires a modem. It must be connected to a computer for a dial-up connection to the ISP's server. Modems provide transmission of digital computer data via analog telephone channels at speeds up to 56 Kbps.
The remote access connection can be clearly seen in the figure
digital signal
Phone line ( analog signal)
You also need to buy time from the Internet(orservice provider) . Organizations granting the right to such connection are called service providers.Internet. Usually these organizations are commercial and provide connection services under a contract.Internet Service Providers (ISPs) provide telephone lines that you must call to access the Internet.
When concluding a service contract, the provider provides the following information.
1. Phone number, according to whichdial-up connection using a telephone line and a modem.
2. Username ( login), which must be entered for registration at the time of connection.
3. Password ( password), entering which confirms the username.
Internet providers have high-speed connections of their servers to the Internet (1 Mbps and higher) and therefore can provide Internet access via telephone channels to hundreds and thousands of users at the same time. It is important that the phone number remains free. Regular and ADSL modems connect to the computer's USB port and to the telephone jack.
ADSL modem example Example regular modem
Many providers as additional service provide an electronic mailbox, and you can receive messages from anywhere on our planet. If this organization is scientific or educational, it can provide its employees and partners with a free connection, but at the same time control the nature of their work on the Web.
Large organizations connect their local networks to the Internet on an ongoing basis, and become part of the Internet themselves.
There are a lot of ways to connect to the provider's equipment. This is a connection via dial-up telephone line, leased line, digital telephone connection, cable television network, satellite channels, radio channel.
Data channels
Depending on the physical medium of data transmission, communication channels can be divided into:
wire communication lines without insulating and shielding braids;
cable, where such communication lines as twisted pair cables, coaxial cables or fiber optic cables are used for signal transmission;
wireless (radio channels of terrestrial and satellite communications), using electromagnetic waves that propagate through the air to transmit signals.
Wired communication lines
Wired (overhead) communication lines are used to transmit telephone and telegraph signals, as well as to transmit computer data. These communication lines are used as trunk communication lines.
Wired communication lines can be used to organize analog and digital channels data transmission. The transmission speed over wired lines is very slow. In addition, the disadvantages of these lines include noise immunity and the possibility of a simple unauthorized connection to the network.
Cable communication channels
There are three types of cables used in computer networks.
Twisted pair
The cable is used for data transmission at 10 Mbps and 100 Mbps.Coaxial cable
Bandwidth– 50-100 Mbps. The permissible length of the communication line is several kilometers.
Fiber optic cable (fiber optic)
Data transfer rate 3Gbps.
Wireless (terrestrial and satellite radio channels)
Use in cases of connecting inconveniently located or remote computer networks when cabling is difficult or impossible.
radio channels
Radio relay communication channels consist of a sequence of stations that are repeaters. Communication is carried out within the line of sight, the range between neighboring stations is up to 50 km. Digital radio relay lines (CRRS) are used as regional and local communication and data transmission systems, as well as for communication between cellular base stations.
satellite channel
AT satellite systems Antennas are used to receive radio signals from ground stations and relay those signals back to ground stations. Satellite networks use three main types of satellites, which are in geostationary orbits, medium or low orbits. Satellites are launched, as a rule, in groups. Separated from each other, they can provide coverage of almost the entire surface of the Earth. The operation of the satellite data transmission channel is shown in the figure
It is more expedient to use satellite communications to organize a communication channel between stations located at very large distances, and the possibility of servicing subscribers in the most inaccessible points. The throughput is high - several tens of Mbps.
Cellular communication channels
Cellular radio channels are built on the same principles as cellular telephone networks. Cellular communication is a wireless telecommunication system consisting of a network of ground base transceiver stations and a cellular switch (or mobile switching center).
Internet access technologies
WiFi
Notebook users can connect to the Internet using Wi-Fi wireless technology. At stations, airports and other public places, wireless access points connected to the Internet are installed. Within a radius of 100 meters, a laptop equipped with a wireless network card automatically accesses the Internet at speeds up to 54 Mbps.
PLC
PLC is a new telecommunications technology based on the use of power networks for high-speed information exchange (Internet from a socket). Allows you to transfer data high voltage lines power lines, without additional communication lines. Computer connects to electrical network and accesses the Internet through the same outlet. No additional cables are required to connect to your home network. Various equipment can be connected to the home network: computers, telephones, burglar alarms, refrigerators, etc. In this technology, based on the frequency division of the signal, a high-speed data stream is divided into several low-speed ones, each of which is transmitted on a separate frequency, followed by their combined into one signal. At the same time, Internet devices can “see” and decode information.
Bluetooth
Bluetooth is a technology for transmitting data over short distances (less than 10 m). The data transfer rate does not exceed 1 Mbps.
WiMAX
WiMAX (Worldwide Interoperability for Microwave Access), similar to WiFi - broadband Internet access technology. WiMAX, unlike traditional radio access technologies, also works on the reflected signal, outside the line of sight of the base station. Information can be transmitted over distances up to 50 km at speeds up to 70 Mbps.
WiMAX partially satisfies the conditions of 4G networks based on packet data transfer protocols. The 4G family includes technologies that allow data to be transmitted over cellular networks at speeds above 100 Mbps. and improved voice quality. VoIP technology is provided for voice transmission in 4G.
Radio Ethernet
Radio Ethernet - technology of broadband access to the Internet, provides a data transfer rate from 1 to 11 Mbps, which is shared among all active users. For the operation of the RadioEthernet channel, direct visibility between the antennas of the subscriber points is required. Radiusactionsbefore 30 km.
MMDS (Multichannel Multipoint Distribution System)
MMDS (Multichannel Multipoint Distribution System).These systems are capable of serving an area within a radius of 50-60 km, while the direct visibility of the operator's transmitter is not necessary. The average guaranteed data rate is 500 Kbps - 1 Mbps, but it is possible to provide up to 56 Mbps per channel.
Mobile GPRS - Internet
Mobile GPRS - Internet. To use the "Mobile Internet" service using GPRS technology, you must have a telephone with a built-in GPRS modem and a computer. GPRS technology provides data transfer rates up to 114 Kbps. When using GPRS technology, it is not the time of connection with the Internet that is charged, but the total amount of transmitted and received information. You will be able to view HTML pages, download files, work with e-mail and any other Internet resources.
Mobile CDMA-Internet
MobileCDMA-Internet.The CDMA standard network is fixed and mobile communications, as well as high-speed mobile Internet. To use the "Mobile Internet" service using CDMA technology, you must have a telephone with a built-in CDMA modem or CDMA modem and a computer. CDMA technology provides data transfer rates up to 153 Kbps or up to 2400 Kbps - using EV-DO Revision 0 technology.
Currently, CDMA technology provides third-generation mobile communication services. 3G mobile communication technologies (third generation - third generation) - a set of services that provides both high-speed mobile access to the Internet, and organizes videotelephony and mobile television. Mobile communication of the third generation is built on the basis of packet data transmission. Third-generation 3G networks operate in the 2 GHz band, transmitting data at speeds up to 14 Mbps.
Conclusion: each method of connecting to the network depends on several indicators, namely, on the financial situation, locality and from the needs of the consumption of Internet resources.
Definition 1
Internet- a worldwide information computer network, which is an association of numerous regional computer networks and individual computers that exchange information with each other using public telecommunications channels (leased analog and digital telephone lines, optical communication channels and radio channels, including satellite communication lines).
Structure and basic principles of building the Internet
Almost all services provided by the Internet operate on the principle client-server.
Information on the Internet is stored on servers, which have their own addresses, and specialized programs manage them. With their help, mail and files are sent, databases are searched, and other tasks are performed.
Network servers exchange information with each other through high-speed communication channels or backbones (leased telephone lines, fiber optic and satellite channels connections).
Servers, which are connected by high-speed backbones, are the basic part of the Internet.
General user access - clients– information on the Internet is most often provided by a provider (network service provider) or a corporate network.
Definition 2
Provider(Internet Service Provider, ISP) - individual or an organization that provides connection services to computer networks.
A smaller-scale (regional) provider connects to a larger national provider that has nodes in various parts of the country. The networks of national providers are combined into networks of transnational providers (providers of the 1st level). The association of networks of providers of the 1st level makes up the global Internet.
Local networks are the main cells of the global network. When connected local network to the global each of its computers can connect to the Internet.
Host computers(host) are directly connected to the global network.
Definition 3
Host- any computer that is a permanent part of the Internet, that is, connected via the Internet Protocol to another host, connected in turn to another, and so on.
To connect a communication line to a computer, use network boards, network adapters, modems etc. – special electronic devices.
Each computer connected to the network is assigned a unique IP address.
TCP/IP protocol stack
The main family of network protocols used on the Internet is TCP/IP stack. A set of network protocols ensures the interaction of different types of network computers that run under different operating systems.
Network protocols support multiple levels:
- ducted and physical layer supports Ethernet technology, FDDI, etc.
- network layer- the basis of a family of protocols, represented by the IP protocol and routing protocols. At this level, the movement of packets through the network and the control of their routing are ensured.
- transport layer manages packet sizes, transmission parameters, integrity control.
- On the application layer all services provided to the user by the system are combined. Main application protocols: TelNet - Remote Access Protocol, FTP - File Transfer Protocol, HTTP - Hypertext Transfer Protocol, SMTP, IMAP, POP, MIME - protocols Email.
Ways to access the global Internet
There are several ways to access the Internet:
- dial-up- connection of the user's computer to the provider's server via telephone, data transfer rate up to 56 Kbps.
- xDSL(ADSL, VDSL, etc.) access technology over an analog telephone network via a cable modem, data transfer rate up to 50 Mbps (actually up to 2 Mbps). The main advantage is the possibility of a significant increase in the speed of data transmission through telephone wires without changing the subscriber telephone line. When connected to the Internet, the user can use telephone communications.
- ISDN– technology of dial-up access via digital telephone network. Provides a high speed of information transfer in comparison with Dial-Up. The data transfer rate when using one communication channel is 64 Kbps, when using two communication channels - 128 Kbps.
- Leased line access(analog and digital) - a method of connecting to the Internet, in which the user's computer has a permanent connection (non-switched) with the provider's server via a cable (twisted pair). Data transfer rate up to 100 Mbps.
- Internet access via local network(Fast Ethernet) - connection via a network card (10/100 Mbps), transfer rate for the user is 100 Mbps.
- satellite access to the Internet (DirecPC, Europe Online). Real data transfer rate up to 3 Mbps.
- Access in Internet through cable TV channels. The data reception rate is 2–56 Mbps.
Wireless technologies:
- mobile CDMA Internet;
- mobile GPRS Internet;
- Radio Ethernet;
- WiFi;
- WiMax;
- LMDS;
- MMDS.
Communication channels and methods of Internet access 1.Dial-UpDial-Up 2. Using a cable modem Using a cable modem 3. Via digital telephone network Via digital telephone network 4. Via dedicated lines Via dedicated lines 5. Via local network Via local network 6. Satellite Internet access Satellite Internet access 7. Via cable TV network Via cable TV network 8. Wireless technologies Wireless technologies 1
Via local network data transfer rate up to 100 Mbit/s Connection is carried out using a network card. To connect the user's computer to the Internet, a separate cable (twisted pair) is connected to the apartment, while the telephone line is always free. Back 6
Satellite Internet access data transfer rate up to 52.5 Mbps There are two ways to exchange data via satellite: one-way when a satellite channel is used for receiving data, and available terrestrial channels for transmission. Two-way when satellite channels are used for both reception and transmission. Back 7
World Wide Web: Network Access and Main Communication Channels
Yu.S. Berdov,
Assistant of the Department of Business Informatics and Mathematics, Tyumen State Oil and Gas University (625000 Russia, Tyumen, Volodarskogo str., 38; e-mail: [email protected])
Annotation. The article discusses the most popular types and methods of Internet access, the main communication channels. The most promising methods of connecting to the Internet are presented.
abstract. In article the most popular types and ways of Internet access, the main communication channels are considered. The most perspective methods of connection are presented to the Internet.
Key words: local network, satellite access, wireless technologies.
Keywords: local network, satellite access, wireless technologies.
AT modern world the worldwide Internet is widely used not only to get acquainted with a million news or to communicate, the Internet contributes to the development own business, that is, there is not only communication with various people who are often in different cities, but also trade in goods, services, exchange of experience, etc.
Currently, there are many ways to connect to the Internet from connecting a computer via an analog modem to connecting using high-speed technologies.
The method of connecting a computer to the Internet depends on the level of services used by the user, which he wants to receive from the provider (service provider), on the speed and quality of data transfer. The services provided by the Internet include: E-mail, WWW, FTP, Usenet, IP-telephony, streaming video, etc.
Ways to connect to the Internet can be classified into the following types:
Dial-up access;
Access via leased lines;
Access via broadband network (DSL -Digital Subscriber Line);
Internet access via local network;
Satellite Internet access;
Access to the Internet using cable TV channels;
Wireless technologies.
Dial-up access typically uses an analog modem and an analog telephone line, but dial-up access over the ISDN (Integrated Services Digital Telephone Network) is also used. An ISDN adapter is used to connect a PC to a digital network with integrated ISDN services. In addition, dial-up access to the Internet can be carried out using wireless
technologies: mobile GPRS - Internet and mobile CDMA - Internet.
Access via dedicated communication channels implies a permanent communication channel from the premises with a computer to the switch owned by the ISP (provider). This access method ensures that the computer is connected all 24 hours a day. There are several connection options: via leased lines with speeds of 2400 bps - 1.544 Mbps. and via permanent virtual frame switching channels with speeds of 56 Kbps - 45 Mbps. For large organizations, this method of connecting a local network to the Internet is the most efficient.
A promising method of connecting to the Internet, both for individuals, and for companies is a DSL broadband network. Digital Subscriber Line - a family of digital subscriber lines designed to organize access over an analog telephone network using a DSL / cable modem. This method provides data transfer up to 50 Mbps.
Access to the Internet over a local area network with Fast Ethernet architecture provides the user with access to the resources of the global Internet network and the resources of the local network. The connection is made using a network card (10/100 Mbit/s) with a data transfer rate of up to 1 Gbit/s on trunk sections and 100 Mbit/s for the end user.
Satellite Internet access (DirecPC, Europe Online) is popular for users in remote areas. The maximum data reception rate is up to 52.5 Mbps (real average speed is up to 3 Mbps).
Cable TV users can use cable TV network channels to connect to the Internet, while the data reception speed is from 2 to 56 Mb/s. For
organization of connection to a cable television network, a cable modem is used.
Recently, wireless methods of connecting to the Internet have become more and more popular. Last mile wireless technologies include: WiFi, WiMax, RadioEthernet, MMDS, LMDS, mobile GPRS-Internet, mobile CDMA-Internet.
The Internet (Internet) is a global computer network covering the entire territory of the globe and operating on the TCP / IP protocol. However, this is only part of the answer to the question - "what is the Internet?". The Internet today is not only a huge number of computers, but also an incredible number of people for whom the network is a fundamentally new way of communication, almost unparalleled in the world.
Man is a social being, and communication with his own kind is one of his primary needs. Perhaps, until now, not a single technical invention (except for the telephone) has made such a revolution in this ancient as the world occupation - communication between man and man.
Of course, what exactly will interest you in the Internet in the first place - people or computers, depends only on you, but it will not be an exaggeration to say that by accessing the Internet, you make the whole world accessible to you.
The invention and improvement of modems - special devices that allow a computer to send information over a regular telephone line, opened the doors to the Internet for a huge number of people who do not have any special network equipment, but only a personal computer and a telephone socket nearby.
All computers on the Internet can be divided into two types: servers and clients. Your computer is an Internet™ client computer. you use Internet resources. Server computers form the backbone of the network and provide their resources for use by other computers.
When they say that a computer is connected to the Internet, this means that this computer, using one of the main means of communication - a modem (Dial-Up connection) or a network card, is connected to a provider (Internet access service) and can access any computer on the network Internet.
And the term Internet in this case is understood as a set of servers to which your computer has access and whose resources it can use.
Getting access to Internet, you connect to various servers and get the information you need. "Inside" the Internet is a complex structure of connected
among themselves computer networks, allowing them to have access to all computers on the network.
The Internet started out like most modern technologies, as a military program aimed at increasing the resilience of the US defense system. Nearly 30 years ago, after the launch of the first Soviet artificial Earth satellite, the RAND Corporation, America's famed Cold War think tank was confronted with the difficult strategic problem of managing a country after a nuclear war.
A country that could experience nuclear strike, we needed a reliable data transmission network that would function properly even with the loss of a significant part of the equipment of this very network. In 1964 RAND published its proposals, which were that:
The network does not have to be centralized;
From the very beginning, it should consist of separate segments (tatters - literally, “rags”).
Thus, each network node will be independent of other nodes and can independently be responsible for receiving / transmitting messages. The basis of information exchange was the principle of packet switching: any information message is divided into parts called packets, each packet is supplied with an address. Packets are sent over the network and assembled into a message at the destination node. Some of the packets may be lost, but the message as a whole has a good chance of finding the addressee. From the very beginning, it was assumed that any communication channels (radio, telephone, leased lines, etc.) can be used to receive / transmit information.
In the early 1960s, a packet-based network brought together RAND, the Massachusetts Institute of Technology, and the University of California. In 1968 The UK National Physical Laboratory has joined the network. In 1969 The US Department of Defense Advanced Research Agency decided to unite the supercomputers of defense, scientific and control centers into a single network, which was given the name ARPANET. In 1969 There were only four computers on the network, in 1971 there were fourteen, and in 1972 there were already thirty-seven.
The 1970s was a process of growth and debugging of the Internet technology! It soon became clear that the main load on the network was made up of communication messages (mail and news). This led to the development of electronic mail and teleconferencing systems.
Initially, it was assumed that the specialized computer network ARPANET would unite the internal networks of a number of research laboratories and US universities working for defense. Within this project
American researcher Vinton Ser-fom ^ tkt SeI) also developed the initial version of the TCP (Transmission Control Protocol, transmission control protocol) and IP (Internet Protocol, internetwork protocol). The first one describes how the data message is divided into packets and transmitted, and the second one controls the addressing in the network. These two protocols gave their name to the entire family of internetworking protocols developed within the Internet TCP/IP family of protocols.
In 1977 TCP / IP began to use other computer networks to connect to the ARPANET, but until 1986. The Internet didn't exist yet. Since 1984 The US National Science Foundation has begun investing significant money in the scientific computer network NSFNET. This network united the scientific centers and universities of the USA. The protocols of the TCP / IP family were chosen as the basis of the network. At that time, NASA, DOE and the National Institutes of Health joined NSFNET.
REUTOV EVGENIY VIKTOROVICH, TRISHINA TATYANA VLADIMIROVNA - 2015
Nagirnaya A.V. - 2014
The Internet is a worldwide system of interconnected computer networks. Often referred to as World Wide Web and Global network, and just Network. It is built on the basis of the IP protocol and IP packet routing.
The Internet is based on the World Wide Web (WWW) and many other data transmission systems.
By the end of 2011, the number of users who regularly use the Internet amounted to about 2.3 billion people.
Key principles
The Internet consists of many thousands of corporate, scientific, government and home computer networks. The combination of networks of different architectures and topologies became possible thanks to the IP protocol (English Internet Protocol) and the principle of routing data packets.
The IP protocol was purposely designed to be agnostic about physical links. That is, any digital data transmission system (network), wired or wireless, for which there is a standard for encapsulating IP packets into it, can also transmit Internet traffic. IP protocol agnosticism, in particular, means that a computer or router must know the type of networks to which it is directly connected and be able to work with these networks; but it doesn't have to (and in most cases can't) know which networks are behind routers.
At the junctions of networks, special routers (software or hardware) automatically sort and redirect data packets based on the IP addresses of the recipients of these packets. The IP protocol forms a single address space throughout the world, but each individual network may have its own address subspace, which is selected based on the network class. This organization of IP addresses allows routers to uniquely determine the forward direction for each data packet. As a result, there are no conflicts between individual Internet networks, and data is transferred seamlessly and accurately from network to network throughout the planet and near space.
The IP protocol itself was born in discussions within the IETF (Internet Engineering Task Force; Task force - a group of specialists to solve a specific problem), whose name can be loosely translated as "Internet Engineering Task Force". The IETF and its working groups are still developing the World Wide Web protocols to this day. The IETF is open to public participation and discussion. The organization's committees publish what are known as RFCs. These documents provide technical specifications and precise explanations on many topics. Some RFCs are elevated by the IAB (Internet Architecture Board) to the status of Internet Standards. Since 1992, the IETF, IAB, and a number of other Internet organizations have been members of the Internet Society (ISOC). The Internet Society provides the organizational framework for the various research and advisory groups involved in the development of the Internet.