There are various ways to connect to the Internet.
● Local network access- this type of access is usually practiced in corporate and some home networks. There is no need to configure anything here - you just need to insert the network cable into the Ethernet connector of the computer. Despite the fact that the data transfer speed over the local network itself can reach 100–1000 Mbit/s, the speed of Internet access depends on the Internet channel connecting the local network gateway (a special computer that provides other computers with access to the Internet) with the provider. For example, if there are 20 clients on the network, and the Internet channel speed is only 2 Mbit/s, then your connection cannot operate at a speed of 100 Mbit/s.
● LAN + VPN- some providers, concerned about the security of data transmission, deploy a VPN - virtual private network - “on top” of the local network. This allows you to provide password access to the network (i.e., authenticate the user) and provide data encryption.
● Modem access- to access the Internet, a special device is used: a modulator-demodulator, or simply a modem. Data transmission is carried out via telephone line. This type of access is so outdated that the current generation of users probably doesn’t even know about it.
● DSL and its variations- we can say that this is an improved modem access. To implement it, you need a digital telephone line, a DSL modem and a splitter. The modem itself and a regular telephone are connected to the splitter. There are many advantages to this connection method. Firstly, it is cheap compared to modem access, where you had to pay a double tariff: to the telephone operator for a busy line and to the Internet provider for access to the Internet. Secondly, the speeds here are significantly higher. With modern ADSL connections, speeds can reach 100 Mbit/s versus 56 Kbit/s for a modem. Thirdly, the telephone line is free when working on the Internet. In a word, only advantages. As a rule, ADSL connections are very popular in home networks.
● Wireless connection via cellular operator network (3G/4G)- to access the Internet, use a mobile phone connected to a computer or a special 3G/4G modem made in the form of a USB flash drive. 3G/4G modules are also built into some tablets - you just need to insert a SIM card. This type of connection has gained popularity among mobile users who always need to stay connected.
● Wireless Wi-Fi connection- is also popular among mobile users, given the fact that free Wi-Fi points are installed in many establishments. And setting up a wireless network at home is not particularly difficult.
● Other ways to access the Internet- there are quite a few different types of connections: both RadioEthernet and satellite connections, but all of them, compared to those listed here, are used quite rarely.So, we can distinguish four most popular types of Internet access:
● Local network
● DSL
●VPN
● Wi-Fi
3G/4G Now no one sets it up: just connect the 3G/4G modem to the USB port, click the Connect button in the window that opens - and you are on the Internet. A RadioEthernet configured according to the principle DSL- created according to the protocol PPPoE. Other methods of connecting to the Internet are special cases. Not everyone has, say, a satellite connection. What about what's popular now? WiMax, then setting it up comes down to setting up the router and has nothing to do with setting up Windows itself.
Annotation: The Internet has penetrated extremely widely into modern technology - for example, its resources can be used not only from a desktop PC or laptop, but also from a cell phone and a pocket computer. In this lecture we will discuss methods of connecting to the Internet and choosing equipment.
7.1. Choosing a method to connect to the Internet
There are many ways to connect to the Internet, we will talk here about the most popular and common ones, and consider their advantages and disadvantages from the consumer’s point of view. It must be said that the advantages or disadvantages of this or that technology are to a certain extent conditional - it all depends on what goals you are pursuing, why you need the Internet and how you are going to work with it.
If you are new to the Internet, first it makes sense for you to use the most accessible and common method of accessing the Internet - a modem connection. With a little money and time, you'll understand what you need from the Web, and then you can decide which access method best suits your needs.
So, perhaps the most common and accessible way to access the Internet is a modem connection over a telephone line.
7.1.1. Modem connection
A modem connection (also called a Dial-UP connection) is the oldest, most accessible and most common way to access the Internet. To connect to the Network, you only need a regular telephone line, a modem, and a relationship with a provider - the organization that provides access to the Network. It should be noted here that conventional analog modems are now built into many motherboards of desktop PCs and laptops, which makes modem connection to the Internet even more accessible.
An Internet access session using a modem looks like this. The modem dials the provider's phone number, where another modem answers, after which the username and password associated with any tariff plan are checked and, if authorization is successful, the user is connected to the Internet.
During an Internet session, no one will be able to reach you - this is one of the disadvantages of modem access.
As for the relationship with the provider, several options are possible. To begin with, this is the purchase of an Internet card.
7.1.2. Access via Internet cards
When you purchase a card, you receive a username and password that you use to access the Internet. Cards come in different denominations and represent different tariff plans. Moreover, usually large providers provide users with a choice of several types of tariff plans (and sometimes from several dozen), among which everyone can choose one that is convenient for themselves.
For example, there are cards for 24/7 Internet access in various denominations. Let's say it could be 10, 20, 50 hours. The main difference between these cards is the cost of one hour of work. So, a card for 10 hours can cost 150 rubles, for 20 – 250, and for 50 – 500. It’s easy to calculate which card can be used to get the cheapest access to the Internet. That is, if you use the Internet quite a lot and want to save money, then 50-hour cards are created especially for you (this is if you don’t look at other typical tariff plans, which we will talk about below). But if the Internet is an occasional activity for you, and you know that 10 hours will last you for several months, it is quite possible that you will take a 10-hour card, not wanting to spend a large amount of money today on providing yourself with access to the Internet for a year forward.
Further, many providers offer card plans that provide unlimited Internet access for, say, a month. Such Internet access means that you are going to be online literally around the clock (otherwise, why pay for unlimited access?). Perhaps, you should resort to such a tariff plan only when you are unable to connect to the Network using some other technology, and, at the same time, have very high Internet needs.
In addition to unlimited access cards and cards for access at any time of the day, there are cards that give you access to the Network only at a certain time of day for a certain period of time (say, from 17.00 to 22.00 for a month, or from 22.00 to 6.00, etc.). d.). If you really only use this time of day to work on the Internet, such cards are created specifically for you, as they allow you to significantly save on the Internet. On the other hand, for those whose work with the Network is irregular, these cards are inconvenient.
7.1.3. Conclusion of an agreement
Another option for a relationship with a provider is to conclude a service agreement. It is quite possible that Internet services under the contract will be cheaper than card services. Otherwise everything is exactly the same.
Both when connecting using Internet cards, and when concluding an agreement, the provider, in addition to the username and password, can provide you with a number of additional parameters. For example, this could be the DNS server address, your IP address, etc.
7.1.4. Urgent Internet access
Many providers (sometimes telephone companies, which are often providers) offer the following service to users. They allocate a special telephone number through which you can connect to the Internet without a name or password. The cost of using the Network will be included in your telephone bill. This connection is convenient either for those who use the Internet very little, or as a backup connection in case you urgently need the Internet and your Internet card has run out. The main disadvantage of such a connection is the cost of access, which is usually 2-3 times higher than the price of the most favorable card tariffs.
7.1.5. About additional services
When purchasing an Internet card or concluding a service agreement at the provider’s office, you can count on some additional services. Let's look at some of them.
- Providing space for a website (hosting) and an email box on the provider’s website. This service should be used with caution. For example, if you are a user of an Internet card, then after it expires, you will not be able to work with your mailbox or WEB site until you activate a new one. In addition to the fact that, for obvious reasons, there may be long breaks between purchasing cards, you may decide to switch to another method of connecting to the Network, or to another provider. This means that your website and email address will be lost to you, which is very unpleasant, and sometimes even very undesirable - after all, dozens of business partners and friends may know your email address. Today there are a huge number of free (but very reliable) email services and website hosting services, so this service from providers is not as relevant as it was a few years ago.
At the same time, if you are confident that you will use the services of the provider for a long time, you can safely set up a website and email address with them.
- The introduction of time-based payment for telephone calls makes the call-back service relevant, when the provider’s modem, after calling it from your modem, breaks the connection and dials your number. Thus, the provider takes responsibility for paying for the connection time.
- 24/7 technical support. This service (or its variants) is present, perhaps, in all providers, but not all of them work properly. And this can be very important - to get timely help or advice.
7.1.6. Tariff schemes
Above we discussed options for accessing the Network using various schemes of interaction with the provider. All of them implied a fee for the connection time. That is, if you connected to the Internet and “sat” there for an hour, doing nothing, then you will pay for this hour. There are traffic pricing schemes - that is, you will pay only for the data sent and received, and not for the time. Tariffing based on traffic may be of interest to those who use the Internet for online communication.
7.1.7. Choosing a provider
If there are several providers in your city and you want to choose the one that is most suitable for you, ask friends and acquaintances who work on the Internet via modems what they think about certain providers. As a rule, the quality of Internet access services from different providers may vary. For example, some may have difficulty dialing because the provider’s modem pool is usually overloaded; also pay attention to the actual speed of Internet access using a particular provider. The fact is that not everyone can achieve the maximum (something around 5.5 Kb/s) - sometimes there is not even half of this speed. Also, the speed and quality of the connection greatly depends on the condition of your telephone line.
In any case, if you choose a provider, it is best to try to work with each of the applicants (preferably in test mode, or by purchasing cards of a small denomination) from exactly the place (that is, from the telephone line) from which you are constantly going work on the Internet. As you work, it will become clear to you how easy it is to reach this or that provider, you will see for yourself the speed and reliability of the connections.
As a rule, modem access is good only when the user does not feel the need to constantly work on the Internet, in particular, he does not need to download (or upload to the Network) large amounts of data, hours-long ICQ conversations and full-fledged Online games. Anyone who wants more, if technically possible, can choose other methods of accessing the Network. For example, ADSL access has recently become increasingly popular.
7.1.8. ADSL
ADSL (Asymmetric Digital Subscriber Line) is a technology that allows you to transfer data over regular telephone networks at speeds of up to 8 Mbit/s to the subscriber and up to 1.5 Mbit/s from the subscriber (hence the name of the technology).
Currently, ADSL access is “promoting” in many cities - and this is very good, since even if the user gets at his disposal a channel with a width 10 times less than the maximum for 8 Mbit/s technology, this will seriously improve the quality of work in Internet.
To connect to ADSL you will need an ADSL modem and a splitter (all of this is usually installed by the provider’s employees in a “transparent” mode for the user), and after installing the equipment you will be able to simultaneously use the phone and surf the Internet. The usual pricing scheme for ADSL is a fee for traffic, that is, you can surf the Internet all day and pay only for the information transmitted and received. As a rule, the cost of working on the Internet via ADSL is within the limits of “modem” Internet.
Perhaps ADSL today is the most convenient type of Internet access for home users and small offices.
7.1.9. Satellite Internet
Satellite Internet comes in two versions. The first, relatively cheap ($200-300), involves the use of a satellite dish to receive data, the request for transmission of which is sent using a conventional wired modem or some other connection. The operating diagram of this system looks like this: for example, to download a file, you transmit a request via a regular modem, after which this file is transmitted to you using a satellite communication channel. The speed of receiving data from a satellite can vary greatly - as a rule, it is several hundred Kbps, which is very good.
There is another type of satellite Internet, which involves the use of special equipment to transmit signals to and receive signals from a satellite. The cost of such a system amounts to tens of thousands of dollars, which few can afford.
Considering the widespread use of ADSL, the real need for satellite Internet may arise only where ADSL is unavailable for some reason. Among the advantages of this type of Internet connection, we can note the possibility of using a satellite dish not only to work with data, but also to receive satellite television.
The disadvantage of satellite Internet is the relatively long time between transmitting a request and receiving data, which makes it a dubious solution for those who are interested in online games.
Satellite Internet is characterized by a number of specific services. For example, pre-ordered files can be downloaded at very high speeds.
7.1.10. Leased line, home or city local network
Access via a leased line is relevant for private users when laying this same line does not require significant costs. Basically, for those who want to connect to the Internet via a high-speed channel and not spend significant money, the best option is to connect to home or city local networks, which, as a rule, provide shared access to high-speed Internet connections.
You can connect to such networks in various ways - in fact, these are ordinary local networks.
7.1.11. Mobile Internet: GPRS and others
GPRS (General Packet Radio Service) is one of the services of GSM networks that are extremely widespread in Russia..
Sometimes, when talking about generations of cellular communications, GPRS networks are called 2.5G networks. There are also 3G networks, that is, third generation networks (for example, these include the W-CDMA, CDMA2000, TD-CDMA, DECT, EDGE standards). These networks have been deployed in several locations in Russia and feature very high data transfer rates. However, in practice, it is not always possible to obtain noticeable benefits from using new generation equipment.
One of the features of GPRS is the possibility of using the principle of payment for services depending on the volume of transmitted information, that is, the mode of payment is used for traffic, and not for the connection time.
The user gets the opportunity to be online for as long as desired without paying for connection time. The maximum data transfer rate provided by the GPRS standard is 171.2 Kbps. The actual speed depends on many parameters - the load and capabilities of the operator’s network, the characteristics of a particular device, etc. For Russian operators it is usually around 30 Kbit/s.
Having discussed the different types of Internet access, we will conduct a comparative analysis of them. In table 7.1 collects information on all described types of access and draws an approximate “portrait” of the user of a particular technology.
| Type of access | Advantages | Flaws | User |
|---|---|---|---|
| Modem connection | Widely available, does not require major investment | Low speed and reliability of connections, unavailability of telephone communications | Anyone who does not need to transfer large amounts of data, or who rarely needs the Internet. Beginner user. |
| ADSL | High speed, low traffic cost | Quite a high cost of connection, although in general the technology is practically free of disadvantages | If the initial cost of $150 doesn't scare you and there are no restrictions on ADSL connections in your area, it will be the best solution for any use. |
| Satellite access | High speed of loading information, additional services ( digital television) | Quite high (about $300) connection cost, the need for an outgoing communication channel (modem connection, etc.), relatively long server response time | A user who is not able to use ADSL connections, leased lines, connections to home networks, etc., but wants to increase the speed of downloading data from the Internet. |
| Home or city local network with access to a dedicated line | Average speed, low cost | If there are a large number of subscribers, the speed drops, dependence on the provider’s equipment, which, in the case of home networks, can be supported “on a voluntary basis”, that is, long downtimes are possible | This method is very attractive for those who, in addition to working on the Internet, want to use local information resources. For example, download (for just a subscription fee, usually small) large amounts of information, play online games |
| Leased line | High speed and reliability, low traffic costs | High cost of connection and maintenance | A solution for professionals who desperately need reliable high-speed Internet access (although ADSL competes with leased lines here) |
| Mobile Internet | Internet access is available anytime, anywhere | High cost of traffic | As a rule, mobile Internet users do not transfer very large amounts of information, which means it does not cost them too much. Therefore, the mobile Internet is suitable for everyone who needs to work with Internet resources on the go. Also, a GPRS connection can become a good backup channel in case of problems with the main Internet communication channel. |
The Internet has long been included in the list of natural conveniences. It has turned from a luxury into a necessity that can make life much easier for each of us.
There is no longer any special need to buy magazines/books/newspapers, because as soon as you turn on your PC and launch your browser, hundreds of materials will appear in front of you, crowding into the columns of search results in the hope of attracting your attention.
The Internet is a collection of servers located around the world and connected by data transmission channels. Local network of enormous scale.
You might be wondering how it all works? Where and in what ways do all these tons of varied information end up on our PCs? There are many ways to connect to the global Internet. Surely, you are interested in learning about them with all the advantages and disadvantages.
So let's get started.
Dial up connection
The most “ancient” and accessible method of connection. Access to the Internet occurs through a telephone line channel and a modem. The phone is always busy while using it. The speed is ridiculous in our times - 56 kbit/s. In general, it is a relic of the past and is seen simply as a fragment of history.
Leased line
The most relevant and common type of connection today. Fast and relatively cheap Internet, with virtually no restrictions for the end user. Comfortable surfing, downloading large amounts of data, online games - everything, as they say, “flies”.
Most often in cities, it is implemented with FTTB technology: optics are installed in an apartment building, and twisted pair cables or also fiber optics (FTTH) are sent from the local switch to the users’ apartments. Speeds range from 1-1000 Mbit/s, traffic packages are usually unlimited.
Definitely a good option. No additional equipment is required - just a PC and a cable from the provider. Connection is also usually free or symbolically small. It’s just important for you not to make a mistake when choosing a provider - so that both the size of the monthly fee and the quality of the Internet/technical support please you.
ADSL connection
ADSL is a fast connection type. Not as popular as before, but still holds its place in the ranks. To implement communication, you need two modems - one from you, the other from the provider. The transmission channel is a telephone line, which is not very good. The capacity of the new telephone cable is 24 Mbit/s. And those that have been serving for 30 years will hardly exceed 10 Mbit/s. However, this is not a bad speed. In addition, while using the Internet, the phone continues to work, unlike Dial Up.
This connection is enough for high-quality voice and video communications, faxing and surfing. It is beneficial to use where FTTx providers have not reached (usually the private sector or small villages).
Satellite Internet
A relatively exotic thing for the average user. The high cost and small number of providers until recently made VSAT the choice of units.
The last few years have changed the situation in the communication services market, making satellite Internet, although not cheap, but accessible. It is used where there is nothing else. Roughly speaking, he can work in the desert or on the top of a mountain, where there are no communications.
Exists in 2 variations:
· One-way: signal transmission occurs through terrestrial channels, and reception through satellite;
· Two-way: signals travel in both directions via satellite channels.
The first connection method is more common and cheaper. The second is usually used by organizations for remote offices. The speed of such Internet can reach 20 Mbit/s. An obvious disadvantage is the high cost of equipment and the size of the monthly fee, as well as possible interference in bad weather.
Radio Internet
Access to the network is provided by connecting the antenna installed at the user’s location with a wireless access point organized by the service provider. The antenna is placed on a hill (pole, roof), and its horn must be precisely aimed at the signal source. Range – up to 50 km.
Like VSAT, this option is used as a last resort. Equipment costs are high and bad weather can cause interference. However, this approach provides mobility and excellent access speeds (up to 1 Gbit/s).
Mobile Internet
A type of communication implemented via a mobile phone using GPRS and EDGE technology. The only clear advantage of such a connection is good coverage of the territory by mobile providers and mobility.
The disadvantages include the relatively low speed and high cost. Can be used in conjunction with a PC. Again, this option is good if there is nothing else.
3G modem and GSM modem
Technologies are used to connect GSM and CDMA. Speed depends on the provider's equipment and tariff. The method is not much different from connecting via a mobile phone - the pros and cons are the same.
3G will be able to provide speeds of up to 3.6 Mbit/s. This modem is inserted into the USB port of a PC, and you can buy it from any mobile operator. There are limited and unlimited tariffs.
WiFi
A type of wireless connection based on the connection provided by the provider to a PC and a router - a multifunctional access point. This is a great option for covering small areas. High speed, low cost and convenience. The disadvantages include a strong dependence on the proximity of the access point and on the presence of obstacles in the path of radio waves.
Results
The most preferable for use in home/office environments are Ethernet networks implemented using FTTx technology. They provide users with inexpensive and very fast Internet. At the same time, the choice of providers is very wide.
If such a connection is not possible, you should take a closer look at wireless technologies (3G is a priority) or ADSL if a telephone line is available.
Types of Internet connection. Introduction
The Internet came to the masses only ten years ago, and during this time the ways to access it have proliferated, apparently and invisibly; however, most of the network devices were invented even before the popularization of the World Wide Web and were intended to receive completely different services. Be that as it may, now with regard to any means of communication the user has one question: how can this thing help me to access the Internet, to access a home or intra-apartment network? We will try to understand the variety of ways to connect to the Internet from home and home office.
The purpose of this series of articles is to consider the most well-known technologies from theoretical and practical points of view, but without taking into account their prevalence: the popularity of a particular technology does not mean its availability in your city, region, home. The proposed material should be considered as a small reminder when choosing from several real offers from local providers. Even if a provider of the right type is found, the last word remains with its technical specialists, who determine the possibility of connection specifically in your case.
The articles are divided into chapters, each of which is devoted to a separate type of connection to the Internet with a description of general points, types of this type of connection and the equipment necessary for this. The first publication will be of an introductory nature and will cover basic issues.
Classification of connection types
Subscriber connections to the Internet are divided into two main classes: individual and collective. With an individual connection, each subscriber uses a channel allocated personally to him to the provider’s point of presence located outside the building (Fig. 1a). An example here would be access to the Internet via a regular or DSL modem, via satellite.
Rice. 1. Classification of connections by mass use of channels
With a collective connection, a shared network is laid in the building, which is used not only for access to the Internet, but also for communication between neighbors without using the Internet (Fig. 1b). This class of connections includes all home networks and access via television cable. Simply put, the division is based on how many wires are connected to the house, and who will suffer if one wire malfunctions - an individual subscriber or an entire team.
Connections are also divided according to the distance of the subscriber from the provider’s point of presence (Fig. 2).
Rice. 2. Classification of connections by distance from the provider
In the case of home networks, the point of presence is located in the same house as the subscriber, or in the neighborhood. For DSL connections, the provider's equipment is usually located at the nearest telephone exchange. Classic access via a modem implies the presence of a provider somewhere within the city. And with satellite communications, a virtual channel is laid into earth orbit.
There are other classification methods based on technical characteristics. We won't go into details for now. Subsequent chapters will describe each type of connection in detail so that you can come up with the classification that you need.
Transmission speed
Perhaps this question seems to be the most confusing, so we will consider it one of the first.
The speed of information transfer between two devices is determined, first of all, by the channel speed, that is, the number of “raw” bits transmitted per unit of time over the transport channel. This set of bits is called “raw” because, in addition to useful information, it contains service information. The ratio of useful and service information depends on the specific technology, and sometimes on the size of the transmitted block. For example, when downloading a file from an FTP server on a local Fast Ethernet network with a channel speed of 100 Mbit/s, the payload will not exceed 96 Mbit/s. This efficiency can be considered almost ideal; in many technologies it is much lower: for example, for Wi-Fi it is less than 50%.
One of the common causes of misunderstanding between providers and their clients is confusion between bits and bytes. In the field of communications, as well as in other areas associated with low-level operations, the basic unit of information is the bit, and the unit of speed, accordingly, is the number of bits per second. For a user who operates with information at a high level, it is more convenient to count in bytes. But the speed expressed in bits/s is numerically higher than in bytes/s, so it is more profitable for the provider to indicate the former. To completely confuse a potential client, the word “bit” is shortened to one letter “b”, which many mistakenly decipher as “byte”. Things get even more confusing when it comes to kilobits and megabits. Computer specialists traditionally consider the prefix “kilo” to correspond to a multiplier of 1024, while communications specialists and many marketers who are far from knowledge of computer science use the decimal system in which a kilobit is equal to 1000 bits. Taking into account all of the above, the channel speed of 100 Mbit/s declared for Fast Ethernet in practice corresponds to 11.4 MB/s (in ideal conditions), but not 12.5 MB/s, as one might think. And certainly not 100 MB/s!
Electromagnetic interference and signal attenuation have a strong impact on speed. Some technologies, such as Ethernet LAN, operate at only one speed over a limited range of distances between the transmitter and receiver. Other technologies, such as telephone modems, allow you to adaptively adjust the speed depending on the channel condition: the worse it is, the lower the speed. For example, ADSL channel speed varies from 8 Mbit/s on a good line near the telephone exchange to 192 kbit/s at a distance of 5 km.
Channel speed minus all costs is not the speed of Internet access. Channel speed only determines the maximum throughput between your computer and the provider's point of presence. For example, the channel speed may be 100 Mbit/s, and the access speed according to the tariff you choose is 128 kbit/s towards you and 64 kbit/s towards you.
Whatever the connection of the subscriber - individual or collective - there are common channels from the provider’s point of presence to the Internet backbones (Fig. 3).
Rice. 3. Bandwidth of channels between client and server
The bandwidth of these channels is less than what would be required by all clients at the same time, because in the traditional model of Internet use only a small part of users simultaneously transmits and receives information. The skill of the provider lies precisely in having a channel with minimal bandwidth, and so that clients hardly feel the speed limit. Unfortunately, each provider understands the word “almost” in its own way, and sometimes it happens that the needs of subscribers significantly exceed the capabilities of the provider. The lightning-fast emergence of new high-speed subscriber connections, which global networks cannot keep up with, contributes to this. For the same reason, the model for using the network is changing: if previously downloading movies, music, and games seemed unrealistic, now many users download gigabytes of information around the clock.
When working with servers on the Internet, you need to understand that each server has its own provider, whose channels are also not rubber. Highways between cities, countries and continents also have their limitations, serving millions of users. Even if you are entitled to 1 Mbps according to the tariff, do not be surprised that the download speed from somewhere in Australia or South America will be 10 kB/s.
Transmission delay
By and large, high transfer speeds are only important for downloading large files. For web browsing, online gaming and Internet telephony, transmission latency is much more important. It is the delay that determines the comfort of work. Typically, providers rank tariffs by transmission speed, and therefore many equate speed and latency, but they are not the same thing.
Let's compare a satellite channel and a regular modem (Fig. 4).
Rice. 4. Time diagram of information exchange at different speeds and delays
In the first case, the speed can reach several Mbit/s, but you cannot get more than 56 kbit/s from the modem. But the modem has a delay of only a few milliseconds, and from a satellite it is more than a second. The first user can quickly download a large file, but the web page will not open until a couple of seconds after entering the address. In action games, this user's shooting at opponents will be unsuccessful, because it will seem to him that he is aiming, but the target has actually run away a long time ago. Conversely, the owner of a modem will need at least ten minutes to download a short song, pictures on web pages will load slowly, but the reaction to the user’s actions can be almost instantaneous.
The delay is determined not only by the time it takes for a signal to propagate through the transmission medium, but also by the time it takes to process signals and data by various network devices, which can be many times longer than the propagation time (Fig. 5).
Rice. 5. Increasing delay with passage of sections between the client and server
The delay is affected by channel congestion: in an overloaded area, data queues will appear, some of which may be lost, which requires additional time to detect losses and retransmit. Therefore, it is not a fact that a modem user will be more successful than a satellite user in games: if the game requires a higher frequency of data exchange than the modem can provide, the channel will simply become clogged with data, and the action in the game will occur in jerks.
Tariffication
To charge in proportion to the volume of service use, providers may take into account the connection time (for session access via a modem or satellite), may take into account the amount of information received or transmitted, may take into account everything at once, or may not take into account anything at all, limiting themselves to only a fixed subscription fee.
The user can control the connection time independently, and almost everyone has an idea of how much time they are going to spend on the Internet. It is much more difficult to control your traffic, because it is intangible without special technical means. The user simply does not realize that he is dealing with large amounts of information, especially if the speed is high and the loading time is correspondingly short. A classic joke on this topic: a subscriber who refuses to pay the bill motivates his refusal by saying that he did not download the movie, but just watched it (of course, this is the same thing).
Traffic accounting programs are not standard components of user operating systems; To choose the right program, you need to try many options, and this is not an amateur activity. In addition, the program on your computer only takes into account what came onto your computer while the program was running. And the provider takes into account everything that was intended for you, even if your computer was disconnected from the network at that moment. Particularly greedy providers even take into account traffic within the local network (between their subscribers), while other providers may not take into account traffic from some sites on the Internet or sell it at preferential rates. Caring providers create their own multimedia and game servers so that the user does not have to spend money on working with the same resources on an external network.
Tariff plans taking into account the volume of traffic have a constant component in the form of a subscription fee, which already includes a certain amount of traffic. A clear understanding of his needs allows a prudent subscriber to choose the optimal tariff, because even incomplete use of the traffic included in the subscription fee for a more expensive tariff can be cheaper than paying for overconsumption on a tariff with a lower subscription fee (Fig. 6).
Rice. 6. Selecting the optimal tariff based on the amount of traffic consumed
Unlimited tariffs seem more attractive to many users. Of course, you need to understand that nothing happens without restrictions. The provider bases its proposals for unlimited access on the assumption of an average traffic rate per person. If you constantly exceed a certain limit, you will either be offered to pay extra, or your access speed will be reduced, or the contract will be unilaterally terminated. For marketing reasons, this limit is rarely advertised in the contract, but rest assured: the provider will always find a legal justification for its actions. To prevent the user from getting the erroneous feeling of permissiveness, access speeds on unlimited tariffs are usually low: for example, the same provider may offer 2 Mbit/s for tariffs with paid traffic, but no more than 256 kbit/s for unlimited tariffs.
Authentication and data protection
The provider's equipment determines whether to allow access to the client using authentication. The basis for authentication can be a username and password, the network address used, or even the fact of a physical connection over a given cable. The common feature of all these methods is the ease of falsification: it is enough to connect to your wiring and/or intercept the necessary information.
Even if the provider does not count traffic, it is in the interests of it and legitimate users to make it difficult for unauthorized connections and tampering. Firstly, the traffic of illegal immigrants leads to additional costs for the provider, which are reimbursed by legal users. Secondly, any traffic loads public channels. Thirdly, pirated connections often have the goal of maliciously affecting subscribers’ computers and compromising them.
The basic level of security is provided by a point-to-point connection (Point-to-Point, PPP) between the subscriber’s computer and the Internet gateway with mandatory password encryption. The greatest confidentiality is achieved using virtual private network (VPN) technology, but to encrypt all traffic the provider would need powerful equipment, which would not have the most pleasant impact on the cost.
Subscriber network address
To exchange information over the Internet, each computer needs a network address called an IP address (Inter-network Protocol). In order to simplify local networks, some addresses are not part of the Internet address space. Such addresses are called internal, and, unlike external addresses, they are valid only within their local network, and the same internal addresses can be used in different local networks.
Rice. 7. Internal and external IP addresses
The subscriber’s computer with an internal address (“A2” in Fig. 7) works with the Internet not directly, but through address substitution, which is carried out by the provider’s gateway (“A3”). In this case, all subscribers of the local network from an external point of view look like one user, which is the gateway. An arbitrary computer from the Internet (“A4”) cannot directly access the subscriber’s computer, which, by the way, protects the subscriber from external hacker and virus attacks. This is the best option for users who require web and mail.
Some applications require direct access from the Internet. First of all, such applications include increasingly popular file-sharing networks and similar peer-to-peer communities (Peer-to-Peer, p2p), for example, distributed IP telephony. Peer-to-peer means that there is no division of network participants into clients and servers: any computer is both at the same time, and therefore must be accessible from the Internet (“A1” and “A4” in Fig. 7). An external IP address may also be required to work with some FTP servers and client-bank systems. You can’t do without it when creating your own game or web server. However, having an external address, the computer is accessible not only to the desired target audience, but also to a whole variety of attacks. Therefore, owners of external addresses must take special measures to prevent attacks, paying special attention to installing and configuring firewalls and antiviruses.
Some providers allocate external addresses at no additional cost, while others charge from $1 to $20 monthly for this pleasure. Moreover, on cheap tariffs, blocking of some incoming connections can be introduced to prevent the subscriber from creating any servers.
Regardless of whether the user has an external or internal address, it is technically possible to directly exchange information between subscribers of the same network. But the provider can block such exchange so as not to overload internal channels, or, as mentioned above, such exchange can be charged on the same basis as external traffic.
Connection cost
When reviewing each access technology, we will try to provide a rough estimate of connection costs. These costs consist of three main components: the cost of equipment, payment for the provider’s actions and your own labor costs. The latter includes, for example, cabling throughout the apartment, if it is required for this type of connection. The fee to the provider can be of very different amounts for the same type of connection: from free or discounted during a long-term advertising campaign to several hundred dollars. It is difficult to predict anything here, so we will limit ourselves to indicating the approximate cost of the equipment.
However, the equipment is different: there are simpler models, and there are sophisticated ones that can cost several times more. If a provider offers to purchase equipment from them, such a standard package, as a rule, includes a simple model with a minimum of necessary functions. It is this option that we will focus on, and advanced users themselves will always be able to choose a model to suit their taste and budget.
Access sharing
There are more and more users who have several computers in their home: desktop, mobile, pocket, refrigerator with automatic ordering of products via the Internet. Of course, they all need Internet access, and it would just be nice to combine them into one intra-apartment network.
Rice. 8. Home router - the center of the intra-apartment network
The optimal solution for most are specialized home routers - Internet Gateway Device, or, in common parlance, Broadband Router. Thanks to the development of electronics, it is now possible to implement many functions in one single chip. Therefore, several devices, previously offered as independent products, are easily combined in a small home router housing (Fig. 8, 9).
Rice. 9. Appearance of home routers
The simplest models with a built-in 4-port switch cost about $50. A multifunctional combine, which also combines an ADSL or cable modem, a wireless access point and a print server (or network storage), can be purchased starting from $150. Such a device provides almost Transparent sharing of one connection between several users protects them from attacks and can even scan traffic for viruses. VPN routers allow homeworkers to create a secure connection to their office network; Unlike simple gateways with the ability to pass VPN traffic (almost every modern router can pass-through VPN), real VPN gateways have a powerful encryption processor and take care of all the troubles of creating secure channels.
What I would like to warn against is purchasing equipment “for growth.” Current trends mean that by the time you finally need those features you overpaid for a couple of years ago, the technology used may have changed so much that it renders your supplies virtually useless. For example, if you don’t yet have wireless devices, but plan to have them, buy a router not with a wireless adapter installed, but with a PC Card slot, into which you can then install the most modern adapter. However, you shouldn’t go to the other extreme, limiting yourself to a minimum of functions without taking into account the prospects.
Internet access methods
The following methods of accessing the Internet are currently known:
Dial-Up(when the user’s computer connects to the provider’s server using a telephone) – dial-up access over an analog telephone network, data transfer speeds up to 56 Kbps.
DSL (Digital Subscriber Line)- a family of digital subscriber lines designed to provide access via an analog telephone network using a cable modem. This technology (ADSL, VDSL, HDSL, ISDL, SDSL, SHDSL, RADSL, collectively called xDSL) provides high-speed connections up to 50 Mbit/s (actual speed up to 2 Mbit/s). The main advantage of xDSL technologies is the ability to significantly increase the speed of data transmission over telephone wires without upgrading the subscriber telephone line. The user gains access to the Internet while maintaining normal telephone communication;
ISDN - dial-up access over a digital telephone network. The main feature of using ISDN is the high speed of information transfer, compared to Dial-Up access. The data transfer rate is 64 Kbit/s when using one and 128 Kbit/s when using two communication channels;
Internet access via dedicated lines(analog and digital). Leased line access is a method of connecting to the Internet when the user’s computer is connected to the provider’s server using a cable (twisted pair) and this connection is permanent, i.e. non-switched, and this is the main difference from regular telephone communication. Data transfer speed up to 100 Mbit/s.
Internet access via local network (Fast Ethernet). The connection is made using a network card (10/100 Mbit/s) with data transfer speeds of up to 1 Gbit/s on the backbone sections and 100 Mbit/s for the end user. To connect the user's computer to the Internet, a separate cable (twisted pair) is supplied to the apartment, while the telephone line is always free.
Satellite Internet access or satellite Internet (DirecPC, Europe Online). There are two types of satellite Internet access - asymmetric and symmetric:
The exchange of data between the user’s computer and the satellite is two-way;
Requests from the user are transmitted to the satellite operator's server through any available terrestrial connection, and the server transmits data to the user from the satellite. The maximum data reception speed is up to 52.5 Mbit/s (real average speed is up to 3 Mbit/s).
Internet access using cable television channels, data reception speed from 2 to 56 Mb/sec. Cable Internet (“coax at a home”). Currently, two data transmission architectures are known: symmetric and asymmetric architectures. In addition, there are two connection methods: a) a cable modem is installed separately in each user’s apartment; b) the cable modem is installed in a house where several Internet service users live. To connect users to a common cable modem, a local network is used and Ethernet equipment is installed common to all.
Last mile wireless technologies:
RadioEthernet, Mobile GPRS Internet
WiFi (Wireless Fidelity - accurate data transmission without wires) is a technology for broadband access to the Internet. The information transfer speed for the end subscriber can reach 54 Mbit/s. Their range of action does not exceed 50 - 70 meters. Wireless access points are used within an apartment or in public places in large cities. Having a laptop or pocket personal computer with a Wi-Fi controller, visitors to a cafe or restaurant (within the Wi-Fi coverage area) can quickly connect to the Internet.
WiMAX (Worldwide Interoperability for Microwave Access), similar to WiFi - broadband Internet access technology. WiMAX, unlike traditional radio access technologies, also operates on a reflected signal, outside the line of sight of the base station. Experts believe that mobile WiMAX networks open up much more interesting prospects for users than fixed WiMAX intended for corporate customers. Information can be transmitted over distances of up to 50 km at speeds of up to 70 Mbit/s.
RadioEthernet is a broadband Internet access technology that provides data transfer speeds from 1 to 11 Mbit/s, which is shared among all active users. For the RadioEthernet channel to operate, direct visibility between the antennas of the subscriber points is required. Range up to 30 km.
MMDS (Multichannel Multipoint Distribution System). These systems are capable of serving an area within a radius of 50-60 km, while direct visibility of the operator’s transmitter is not necessary. The average guaranteed data transfer rate is 500 Kbps - 1 Mbps, but up to 56 Mbps per channel can be provided.
LMDS (Local Multipoint Distribution System) is a standard for cellular networks for wireless information transmission for fixed subscribers. The system is built on a cellular principle; one base station allows you to cover an area with a radius of several kilometers (up to 10 km) and connect several thousand subscribers. The BSs themselves are connected to each other by high-speed terrestrial communication channels or radio channels (RadioEthernet). Data transfer speed up to 45 Mbit/s.
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 speeds of up to 114 Kbps. When using GPRS technology, it is not the time of connection to the Internet that is charged, but the total volume of information transmitted and received. You will be able to view HTML pages, download files, work with email and any other Internet resources.
Mobile CDMA - Internet. The CDMA standard network provides landline 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 a CDMA modem and a computer. CDMA technology provides data transfer speeds of up to 153 Kbps or up to 2400 Kbps - using EV-DO Revision 0 technology. EV-DO Revision A technologies will allow subscribers to receive mobile Internet access at a speed of 3.1 Mbps.
In general, the Internet exchanges information between any two computers (PCs) connected to the network, which are often called Internet nodes or sites.(site – location).
There are two concepts used on the Internet: address And protocol.
Protocol– these are the rules of Interaction – the language of communication on the Internet. There are several layers of protocols that interact with each other. At the lower level, two main protocols are used: IP – internet protocol and TCP – transmission control protocol. They are united under the same name TCP/IP. All other protocols are based on TCP/IP.
When transmitting information, the TCP protocol breaks information into portions (packets) and numbers all portions. Further, with the IP protocol, all packets are transmitted gradually. After receiving all the parts (packets), TCP places them in the right order and assembles them into a single whole.
Hardware The component is represented by computers of different models and systems, communication lines. All components operate in a single network, both permanently and temporarily. Physical failure or temporary shutdown of individual sections of the Network does not affect the functioning of the entire Network.
Program component. Coordinated and joint operation of technically incompatible equipment is achieved thanks to programs running on PCs included in the Network. They allow you to transform data so that it can be transmitted over any communication channels and reproduced on any computer (PC). Programs have many functions: storing information, searching it, collecting and reproducing it, they ensure interoperability of all components of the Network.
Informational the component is represented by network documentation of the following types: text, graphic, sound, video (recordings) and can be distributed: text can come from some sources, sound from others, graphics from others. A certain information space is formed, consisting of hundreds of millions of interconnected documents. It looks like a spider's web.
The difference between the physical space of the Internet and the virtual information space of documents is manifested in different addressing systems. Every computer on the Internet has an address of four blocks, for example 193.29.137.31. This address is called an IP address. Computers on the Network on a permanent basis have a permanent IP address, on a variable basis - a temporary IP address for the duration of a given session, a dynamic IP address.
URLs (Uniform Resource Locator) are used for the information space. Each Internet user has his own unique URL, for example, the address of the Teacher's Newspaper http://www.ug.ru
Internet addressing
In order for the IP protocol to deliver packets to their destination, you must specify the address of the computer to which the data is intended. All computers connected to the Internet have unique addresses consisting of four integers, each of which does not exceed 256. When written, the numbers are separated from each other by dots, for example, 195.34.93.10 or 200.5.79.175. These are the addresses that are added to packets when sent over the network. While digital addresses are easy for computers to use, people find it easier to work with names. On the Internet, along with digital addresses, symbolic addressing is used. In this case, the conversion of a symbolic address to a digital one occurs automatically.
The postal address always contains the symbol @ , and the site address never contains this character. Attempting to send mail to an address ivan.cornpany.ru or go to the address [email protected] will cause an error.
Sign @ often called a "dog", although its correct name is "commercial at". Word at pronounced "et" and translated from English as the preposition "in". That is, the email address [email protected] means that the mailbox with the name myname located at the post office company.com. It can be difficult to master all the Internet addressing options at once. However, as you study the programs and surf the Internet, you will get used to the existing system and it will seem extremely simple to you. Plus, in most cases you won't have to manually enter addresses, you'll just click and load the page you want or select an email recipient.
Internet resources
On the Internet, the three components correspond to the following types of resources: hardware, software and information.
Hardware resources
Hardware resources are represented by backbone networks (Figure 12.9). By connecting to the Network, we actually use the hardware resources of the computer that provides this connection, the exploited physical resources of the communication lines. When overloaded, the data encoding time slows down, i.e. each person makes the work of other Network participants more difficult.
Figure 12.9 Central European reference
Internet network
