ADSL(Asymmetric Digital Subscriber Line - Asymmetric Digital Subscriber Line) is one of the high-speed data transmission technologies known as DSL (Digital Subscriber Line) technologies and having general designation xDSL. Other DSL technologies include HDSL (High data rate Digital Subscriber Line), VDSL (Very high data rate Digital Subscriber Line), and others.

The common name for DSL technologies originated in 1989, when the idea first appeared to use analog-to-digital conversion at the subscriber's end of the line, which would improve the technology for transmitting data over twisted-pair copper telephone wires. ADSL technology was developed to provide high-speed (one might even say megabit) access to interactive video services (video on demand, video games, etc.) and equally fast data transfer (Internet access, dial-up LAN and other networks).

ADSL technology - so what is it?

First of all, ADSL is a technology that allows you to turn a twisted pair of telephone wires into a high-speed data transmission path. ADSL line connects two ADSL modem that are connected to each end of the twisted-pair telephone cable (see Figure 1). In this case, three information channels are organized - a “downstream” data transfer stream, an “upstream” data transfer stream and a conventional telephone communication channel (POTS) (see Figure 2). The telephone communication channel is allocated with the help of filters, which guarantees the operation of your phone even if the ADSL connection fails.

Picture 1

Figure 2

ADSL is an asymmetric technology - the speed of the "downstream" data stream (that is, the data that is transmitted towards the end user) is higher than the rate of the "upstream" data stream (in turn transmitted from the user to the network). It should immediately be said that one should not look for a cause for concern here. The data transfer rate from the user (the "slower" data transfer direction) is still significantly higher than when using an analog modem. In fact, it is also significantly higher than ISDN (Integrated Services Digital Network - Integrated Digital Communications Network).

ADSL technology uses digital signal processing and specially designed algorithms, advanced analog filters and analog-to-digital converters to compress the large amount of information transmitted over twisted-pair telephone wires. Long distance telephone lines can attenuate a transmitted high frequency signal (for example, at 1 MHz, which is the normal transmission rate for ADSL) by up to 90 dB. This forces the analog ADSL modem systems to work with a large enough load to have a large dynamic range and low noise. At first glance, the ADSL system is quite simple - high-speed data transmission channels are created over a regular telephone cable. But, if you understand in detail the work of ADSL, you can understand that this system belongs to the achievements of modern technology.

ADSL technology uses a method of dividing the bandwidth of copper telephone line into multiple frequency bands (also called carriers). This allows multiple signals to be transmitted simultaneously on a single line. Exactly the same principle underlies cable television, when each user has a special converter that decodes the signal and allows you to see a football match or an exciting movie on the TV screen. With ADSL, different carriers simultaneously carry different parts of the transmitted data. This process is known as Frequency Division Multiplexing (FDM) (see Figure 3). With FDM, one band is allocated for the transmission of the "upstream" data stream, and the other band for the "downstream" data stream. The downstream range is in turn divided into one or more high speed channels and one or more low speed data channels. The upstream range is also divided into one or more low-speed data channels. In addition, Echo Cancellation technology can be used, in which the upstream and downstream ranges overlap (see Figure 3) and are separated by local echo cancellation.

Figure 3

This is how ADSL can provide, for example, simultaneous high-speed data transmission, video signal transmission and fax transmission. And all this without interrupting the normal telephone connection, which uses the same telephone line. The technology provides for the reservation of a certain frequency band for conventional telephone communication (or POTS - Plain Old Telephone Service). It is amazing how quickly telephone communication has become not only "simple" (Plain), but also "old" (Old); it turned out something like "the good old telephone connection." However, one should pay tribute to the developers of new technologies, who still left telephone subscribers with a narrow band of frequencies for live communication. Wherein telephone conversation can be driven simultaneously with high-speed data transmission, rather than choosing one of the two. Moreover, even if your electricity is turned off, the usual “good old” telephone service will still work and you will not have any problems calling an electrician. Making this possible was part of the original ADSL development plan. Even this capability alone gives the ADSL system a significant advantage over ISDN.

One of the main advantages of ADSL over other high-speed data transmission technologies is the use of the most common twisted-pair copper wire telephone cables. It is quite obvious that there are much more such pairs of wires (and this is still an understatement) than, for example, cables laid specifically for cable modems. ADSL forms, so to speak, an "overlay network". At the same time, costly and time-consuming upgrades of switching equipment (as is necessary for ISDN) are not required.

ADSL connection speed

ADSL is a high speed data transfer technology, but how fast? Considering that the letter "A" in the ADSL name means "asymmetric" (asymmetric), we can conclude that data transfer in one direction is faster than in the other. Therefore, there are two data rates to consider: "downstream" (transferring data from the network to your computer) and "upstream" (transferring data from your computer to the network).

Factors affecting the data transfer rate are the condition of the subscriber line (ie, the diameter of the wires, the presence of cable outlets, etc.) and its length. The signal attenuation in the line increases with increasing line length and signal frequency, and decreases with increasing wire diameter. In fact, the functional limit for ADSL is a subscriber line 3.5 - 5.5 km long with a wire thickness of 0.5 mm. ADSL currently provides downstream data rates ranging from 1.5 Mbps to 8 Mbps and upstream data rates from 640 Kbps to 1.5 Mbps. The general trend in the development of this technology promises to increase the data transfer rate in the future, especially in the "downstream" direction.

In order to evaluate the data transfer speed provided by ADSL technology, it is necessary to compare it with the speed that may be available to users using other technologies. Analog modems allow you to transfer data at speeds from 14.4 to 56 Kbps. ISDN provides a data rate of 64 Kbps per channel (typically a user has access to two channels, for a total of 128 Kbps). Various DSL technologies allow the user to transfer data at speeds of 144 Kbps (IDSL), 1.544 and 2.048 Mbps (HDSL), "downstream" 1.5 - 8 Mbps and "upstream" 640 - 1500 Kbps s (ADSL), downstream 13 - 52 Mbps and upstream 1.5 - 2.3 Mbps (VDSL). Cable modems have a data transfer rate from 500 Kbps to 10 Mbps (it should be taken into account that the bandwidth of cable modems is divided among all users who simultaneously have access to this line, so the number of simultaneously working users has a significant impact on real speed data transmission of each of them). Digital lines E1 and E3 have data rates of 2.048 Mbps and 34 Mbps, respectively.

When using ADSL technology, the bandwidth of the line through which the end user is connected to the backbone network belongs to this user always and entirely. Do you need an ADSL line? It's up to you, but in order for you to make the right decision, let's look at some of the benefits of ADSL.

First of all, the data transfer speed. The numbers were given two paragraphs above. And these figures are not the limit. The new ADSL 2 standard implements 10 Mbps downstream and 1 Mbps upstream speeds at a range of up to 3 km, and the ADSL 2+ technology, the standard of which is due to be approved in 2003, features downstream speeds streams of 20, 30 and 40 Mbps (respectively for 2.3 and 4 pairs).

Internet via ADSL

In order to connect to Internet via ADSL, no need to dial a phone number. ADSL creates a broadband data link using an already existing telephone line. After installing ADSL modems, you get a permanently established connection. The high-speed data link is always ready to go - whenever you need it.

The bandwidth of the line belongs entirely to the user. Unlike cable modems, which allow bandwidth sharing among all users (which has a significant impact on data transfer speed), ADSL technology allows only one user to use the line.

ADSL connection technology allows full use of line resources. Conventional telephony uses about one hundredth bandwidth telephone line. ADSL technology eliminates this "flaw" and uses the remaining 99% for high-speed data transmission. In this case, different frequency bands are used for different functions. For telephone (voice) communication, the lowest frequency region of the entire line bandwidth (up to approximately 4 kHz) is used, and the rest of the band is used for high-speed data transmission.

The versatility of this system is not the last argument in its favor. Since different frequency channels of subscriber line bandwidth are allocated for different functions, ADSL allows simultaneous data transmission and telephone conversation. You can make and receive phone calls, send and receive faxes, while being on the Internet or receiving data from a corporate LAN. All this on the same telephone line.

ADSL opens up completely new possibilities in those areas in which it is necessary to transmit a high-quality video signal in real time. These include, for example, videoconferencing, distance learning and video-on-demand. ADSL technology allows service providers to provide their users with services that are more than 100 times faster than the fastest analog modem (56 Kbps) and more than 70 times faster than ISDN (128 Kbps) ).

ADSL technology allows telecommunications companies to provide a private secure channel for the exchange of information between the user and the provider.

Internet connection via ADSL

We should not forget about the costs. The technology of connecting to the Internet via ADSL is effective from an economic point of view, if only because it does not require the laying of special cables, but uses existing two-wire copper telephone lines. That is, if you have a connected telephone at your home or office, you do not need to lay additional wires to use ADSL. (Although there is a fly in the ointment. The company that provides you with the possibility of a regular telephone service must also provide an ADSL service.)

Not much equipment is needed to make an ADSL line work. At both ends of the line are installed ADSL modems: one on the user side (at home or in the office) and the other on the network side (at the ISP or at the telephone exchange). Moreover, the user does not have to buy his own modem at all, but it is enough to rent it from the provider. In addition, for the ADSL modem to work, the user must have a computer and an interface board, such as Ethernet 10baseT.

As telcos gradually enter the untapped field of video and multimedia data transmission to the end user, ADSL technology continues to play a large role. Of course, after some time, the broadband cable network will cover all potential users. But the success of these new systems will depend on how many users will be involved in the process of using new technologies now. By bringing movies and television, video catalogs, and the Internet to homes and offices, ADSL makes this market viable and profitable for both telephone companies and other service providers in various fields.

Hello Irina!

Basically, you can watch movies online at any speed.

Another question is how much it will cost nerves and health at very low speeds.

I will give an example specifically for your reception speed in numbers. Do not delve into the numbers, the main thing is the meaning.

Judging by the designation 1.55 M b/s, you have a speed of 1.55 Megabyte per second. The capital letter "M" indicates this.

Movies online, depending on the format (in my "Additional Materials" there is a link to my lesson on this topic, on films, in particular) and quality, the size of an average-quality online movie can be from 300 megabytes to 5000 megabytes.

Let's take something in the middle, for example, the size of a movie is 1000 megabytes.

How is watching a movie online?

When you enter the page for watching a movie, a player appears on your screen for viewing with the buttons "Pause", "Playback", "Stop".

When you click "Play", the movie starts downloading to your computer.

As soon as a very small part of the movie, which the player is already capable of playing, is downloaded to your computer, the player (after a few seconds) starts showing you the movie.

And the rest of the movie continues to swing in the background.

It turns out that the whole movie has not yet been downloaded, and you are already watching it.

So the problem with low reception speeds is that while you are viewing the first downloaded part, the next one does not have time to download to your computer. Then the Brakes begin. What hits the nerves.

But in this case, there is a way out. The truth takes some time. You put the player on "Pause" and do other things. After 5-10 minutes, turn on playback and watch the movie normally.

Now for your speeds.

Roughly speaking, a 1000 megabyte movie should be downloaded for

1000Mb / 1.55Mb/s = 645 seconds = 10 minutes

Judging by my observations, this is a fairly comfortable viewing of an average quality movie.

Now a little fly in the ointment.

The reception speed of 1.55 Mb/s does not mean at all that the movie will be downloaded at that speed.

1. In addition useful information(of the film itself) there is a lot of service information in the communication channel.

2. A lot depends on the workload of the site from which you are watching the movie.

3. Much depends on the workload of the channels through which you receive information.

4. A lot depends on how loaded your computer is directly - how many programs and processes are loaded and how much they “eat away” the memory and resources of the processor itself.

5. What is the quality of the movie you are watching - low, medium or high.

In general, we make discounts for factors on which we do not depend and it turns out (according to experience) somewhere around 20 - 40 minutes.

But, that's also acceptable. After all, the player has a "Pause" button.

And finally. The whole movie, in fact, is not downloaded to the computer. Parts only. Viewed parts are automatically deleted.

Regards, Oleg

ADSL is an asymmetric Internet access technology. It is an asymmetric system in its structure and allows you to work with connections at speeds up to 8 Mbps. ADSL-technology, the transmission speed of which is calculated up to 1 Mbps, operates on average at a distance of more than 5 km. Today we will look at what this type of connection is and how it works.

History of appearance

Before answering the question: "ADSL - what is it?", we bring to your attention some historical data. For the first time, they started talking about creation in the late 80s, when even the Internet in its modern form was only its main task in 1989 was to improve and modernize the technology of data transmission over copper telephone wires. Analog-to-digital conversion was created mainly for the rapid transfer of information between various interactive services, video games, video files, as well as for obtaining instant remote access to LAN and other network systems.

Modern ADSL technology: how it works

The operation of the network is based on the subscriber's digital line, which provides access to the Internet through telephone communication channels. But telephone lines use an analog signal to carry voice messages. An ADSL connection is designed to convert an analog signal into a digital one and transfer it directly to a computer. At the same time, unlike already outdated Dial-up modems, ADSL-based devices do not block the telephone line and allow you to use digital and analog signals simultaneously.

The essence of the technology (asymmetry) lies in the fact that the subscriber receives a huge amount of data - incoming traffic, and transmits a minimum of information from himself - downstream traffic. As an input, various kinds of content are meant: video and media files, applications, objects. Downstream sends only important technical information - various commands and requests, emails and other secondary elements. The asymmetry is that the speed from the network to the subscriber is several times higher than the speed from the user.

The most important advantage that ADSL technology has is its budget and economy. The fact is that the same copper elements are used for the operation of the system. The number in them, of course, significantly exceeds the number of similar elements in cable modems. But at the same time, no modernization of switching equipment and complex reconstruction is necessary. ADSL connects quickly, and modern types of modems are intuitive to manage and configure.

What equipment is used for this connection?

In order for the technology to work, special types of modems are used, which differ in their structure, design, connection type:

• PCI modems (internal computer devices).
• External modems with USB connection type.
• Devices with Ethernet type interface.
• with Ethernet scheme.
• Profile types of modems (for security companies, private telephone lines).
• Router with internal Wi-Fi hotspots.

Additional equipment: splitters and microfilters

We must not forget that to connect such a gadget as an ADSL modem, you will need splitters and microfilters. Devices are selected in accordance with the design of the telephone cable. In a situation where a cable outlet is made (or can be done) to separate the modem and telephone channel, a splitter is used. In another case, the purchase of a microfilter is required, which is installed on each telephone present in the room.

The main task of the splitter is to separate frequencies - voice (0.3-3.4 kHz) and those used directly by the modem itself (25 kHz-1.5 MHz). It is in this way that the simultaneous operation of the modem and the telephone is ensured, which do not interfere with each other and do not interfere. Splitters are compact and will not cause unnecessary inconvenience. The miniature box is equipped with three connectors and is light in weight.

ADSL - what is it? Stages of connecting high-speed Internet

1. Provider choice. To date, each provider offers to use this technology. Different kinds and tariffs depend on the region, as well as on the technical capabilities of the company, the coverage area of ​​\u200b\u200bwhich may be limited.
2. Purchase of equipment. Currently, it is not necessary to buy a modem, splitters and microfilters. When drawing up a connection agreement, the provider offers to rent the necessary equipment, including an ADSL modem. In the future, upon termination of the document, the equipment is returned back. The client pays exclusively for the Internet connection. Modern Internet ADSL - what is it? This is a fast, cheap and high-quality connection method.
3. Account activation. For each client, the provider reserves an account, the activation of which can take up to 12 days. However, in most cases, with normal network coverage, the procedure does not require more than a few hours. First, the provider checks the phone number for the possibility of connecting ADSL. If the technology access zone is not enough, then high-speed Internet will not work.
4. Equipment setup. At this stage, devices are connected to the telephone line, splitters and microfilters are installed, modem drivers are installed on the computer, and the modem's network parameters are set in the Internet browser.

pros

What are the advantages of ADSL technology? Here are a few of them:

• High ADSL allows you to easily transfer files of any size without a long wait. The technology is constantly being improved, and the speeds are growing, significantly expanding the capabilities of the subscriber.
• Wireless connection. To use an ADSL system, you do not need to stretch the cable to the subscriber and install a large amount of equipment. The reliability, quality and functionality of the network is improved.
• No interference on the telephone line. The ADSL router operates in independent mode and does not create any problems for the phone to work. You can call and surf the virtual space completely freely.
• Permanent Internet access ADSL. What it is? This means that the network will not fail during operation. The technology does not require reconnection. The user gets access to the Internet constantly and can be online around the clock.
• Reliability and stability. Today, ADSL is the most reliable type of Internet connection.
• Profitability. The cost of connecting ADSL and installing a modem with a router is minimal and will not hit the family budget.

disadvantages

1. Lack of crosstalk protection. If several dozen clients are connected to one channel, you won’t have to rely on high speed. The more subscribers on one ADSL, the lower the quality of data transmission.
2. Although ADSL technology has disadvantages, they are not numerous. This also includes the minimum speed from the subscriber. The asymmetry of ADSL has an obvious minus - the transfer of files from the subscriber will be long and inconvenient. But the technology is intended, first of all, for quick access to the Internet, for surfing. In addition, the information transmitted from the subscriber takes up a minimum of space and does not require a large resource.

Speed ​​and factors affecting it

ADSL is a technology high speed internet, but there is no universal meaning and formula. For each individual subscriber, the speed is individual and is determined by a whole set of factors. Including some of them can affect the reliability and quality of equipment. Therefore, it is best for professionals to install modems and routers.

The main reason for the low speed of an ADSL connection is the quality of the subscriber line. We are talking about the presence of cable outlets, their condition, the diameter of the wires and the length. Signal attenuation is a direct consequence of increasing the length of the subscriber line, and interference can be reduced by expanding the diameter of the wire. The standard length of an ADSL channel does not exceed 5 km - the optimal range for high-speed data transmission.

Speed ​​characteristics

Compared to other Internet connection technologies, ADSL has a significant speed advantage. An analog modem will give a maximum of up to 56 Kbps, while ADSL at the dawn of its appearance already allowed information to be transmitted at speeds up to 144 Kbps.

ADSL technology, maximum speed which is also determined by the characteristics of the modem and can reach 2048 Mbps, optimizes the process of information transfer. Digital lines greatly increase the user's capabilities, taking him beyond the limits even if there are several connected computers, mobile phones, tablets and other gadgets.

Technology Perspectives

The possibilities and resources of ADSL technology are far from being exhausted. Even the ADSL2 and ADSL2+ standards, introduced back in the mid-2000s, still retain their relevance and capabilities. This is, in fact, the only technology that can provide wide Internet access without failures and software problems, therefore it is a competitor to many other methods of connecting to the Internet.

The minimum technical equipment is complemented by modern types of modems. Manufacturers annually release new devices designed for continuous operation without the need for maintenance and service. In addition, ADSL speed is constantly growing and is not limited to megabits. The connection becomes relevant both for the home and for the whole office company with several dozen computer clients.

Conclusion

So, we found out what ADSL technology is, what is its essence and principle of operation. As you can see, this is one of those technologies that practically does not fail during operation (even if several dozen users are connected to the network). At the same time, it does not require constant reconnections and speed limits.

Test Methodology for ADSL

The testing methodology is designed to evaluate and visualize the results of testing in case of problems when working on the Internet.
How to take a "screenshot" can be read .

We draw your attention to some features of working on the Internet:
1) When the Subscriber is connected to its Data Transmission Network, the Provider is not responsible for the quality of communication outside the terminal subscriber device (if any) connected to the Provider's equipment.
The provider guarantees the speed of Internet access only if there is a direct connection, i.e. The Provider's cable connects directly to a laptop or personal computer. You can read more about the Procedure for the provision of services.
2) You can familiarize yourself with the division of areas of responsibility between the Provider and the Subscriber.
3) When using technology ADSL speed data transfer is always less than the connection speed by at least 13-15%. This is a technological limitation, which we will discuss in more detail below. It does not depend on the provider or the modem used.
Under ideal conditions, with a connection speed of 12 Mbps, you can expect a maximum real speed of ~ 10 Mbps.
Note! You can read more about the factors affecting the data transfer rate when using ADSL technology.

Attention! If you are using wireless WiFi networks, It will be useful for you to read the information below.
1. Sources of interference that affect the operation of wireless Wi-Fi networks can be as follows:
- material of walls and partitions in your apartment or office;
- the location of the Wi-Fi hotspot of your neighbors. For example, if the neighbor's point is near the wall adjacent to your apartment, and your point, in turn, is located near this wall, then the signals of both points will interrupt each other;
- Wi-Fi module in your PC or other mobile device. A mobile device may not have the most modern module installed, which has a maximum speed limit;
- simultaneous downloading from different devices, both inside your apartment and at neighboring points outside your apartment;
- Bluetooth devices operating in the coverage area of ​​your Wi-Fi device;
- various Appliances, which, when operating, uses the 2.4 GHz frequency band operating in the coverage area of ​​​​your Wi-Fi device.
You can read more about possible sources of interference that affect the operation of Wi-Fi wireless networks.

2. To speed up the work on the Internet and make it more stable, you must:
- configure the router to work with mobile devices. How to do this on a TP-Link router, see ;
- choose a more free channel;
- choose the optimal location of the Wi-Fi point;
- purchase an external Wi-Fi adapter;
- use a dual-antenna wireless access point operating in the 2.4 GHz band;
- use a wireless access point operating in the 5 GHz band;
- work through an Ethernet cable.

You can learn more about ways to increase connection speed and Wi-Fi throughput.

Test Methodology

Attention! If you are connected via optional equipment or use wireless networks Wi-Fi, you must first connect the Internet cable directly to your laptop or personal computer without additional devices, and then perform the speed test method.

To obtain adequate results during each of the points of the test, NO work on the Internet should be conducted!

For Windows OS
Downloading the archive. Unzip it to any folder on your computer. The file should appear in the same folder TEST.bat. We launch it and wait from 10 to 20 minutes (depending on the quality of the DSL connection).
Attention! For Windows 7 and Windows 8, you need to run the file as an administrator (right-click on TEST.bat and select "Run as Administrator"). When the BAT file performs all the actions, you will see the following window.

Press any key on the keyboard - the window will close. After that we go to Disk C and find text files there PING.txt, PATHPING.txt and CONFIG.txt . We attach these files to the results.

For Mac OS X
Downloading the archive. Unzip it to any folder on your computer. After unpacking, a file should appear in the same folder test.app. We launch it and wait from 10 to 20 minutes. After completing the test, press any key on the keyboard - the window will close.
Upon completion of testing, three text files will appear on the desktop - CONFIG, PING, TRACEROUTE. We attach these files to the results.

• We measure the speed of the Internet.
  a) We go by link and press the button Begin Test. We are waiting for the completion of the test.

  When the test is completed, you will be presented with a window similar to the following. Let's make it" screenshot” and attach to the results.

  b) Download the file (about 75 MB in size) from here: http://www.apple.com/itunes/download/
  Start downloading by clicking on the button "Download Now".
  During the upload process, do "screenshot"
  Attention! To display the download speed in the browser, go to the Downloads section by pressing the Ctrl + J key combination.

  with) Download a large file (about 2.3 GB) from here:
  ftp://ftp.freebsd.org/pub/FreeBSD. During the upload process, do "screenshot" Your download manager or browser and attach to the test results.
  Attention! You don't have to download the whole file! It is enough to wait a minute or two until a stable speed is established, then do 2-3 " screenshot» with an interval of 20-30 seconds and stop the download.

  d) Download the file using a torrent client. For correct speed testing it is necessary to exclude local retrackers. How to do this, you can see.
  Attention! It is necessary to test the connection speed when downloading 3-4 files at the same time, in which the number of distributors is more than 100. During the download process, do " screenshot» of your torrent client and attach it to the test results.

• We measure the speed from internal resources. For this Minsk subscribers go to the next link .

  On the site click on "Change Server".

  In the search bar write Atlant Telecom and select it as the server.

  Then we press the button "GO".
  We are waiting for the testing to be completed.

  As a result, a window with the results should appear.

  We take a screenshot and attach it to the general results.

  Regional subscribers go to the following links and download the file:
  - link for Brest;
  - link for Vitebsk;
  - link for Grodno;
  - link for Gomel;
  - link for Mogilev.
  During the download process, we take a “screenshot” of your download manager or browser (except for Internet Explorer) and attach it to the test results.

• Download the program and install it (for modems of the D-link brand - the program).

  Zyxmon is a free Windows program for managing and monitoring the status of Zyxel routers.

  Unpack the zip folder using some archiver. For example, WinRAR or winzip. Run the executable " ZyxMon". The program window will open. Click on the button " Settings(circled in red).

  

  The following window will appear. Fill in the fields Router IP and router password. Press " OK».

• After pressing " OK» we will return to the Main window of the program. We activate the connection with the modem. To do this, press the button " Telnet Router Connections” (circled in pink), while the indicators “ Telnet connection status" and " PPPoE session status» should change color from red to green .

  Description of bookmarks:
  telnet: Modem connection status and PPPoE status.
  Log: Modem text log;
  SyslogD: Messages received from modem by Syslg Daemon;
  SNMP: RealTime channel filling statistics;
  DynDNS: Dynamic DNS state (not used);
  line: Data required for line testing: noise margin , attenuation . To get the data, you need to press the button “ Get ”.

  Doing " screenshot» of the result and attach it to the test results.

We check at what speed the modem receives / gives data.

a) telnet.
We go to the command line: Start -> Run -> cmd -> Ok . In the window that appears, write the command telnet (for example, telnet 192.168.1.1) and press the key Enter. The next step will ask for a password. password , enter the password (by default - 1234 ) and press the key Enter.
From the main menu of the modem, go to the menu 24.1 - System Maintenance - Status . To do this, press on the keyboard 24 - "Enter", 1- "Enter". Take screenshots of this window:




Explanations to the fields of interest to us in this menu:
Tx B/s - transmission speed in Bytes per second;
Rx B/s [Receiving speed, Byte/s] - receiving speed in Bytes in seconds;
Up Time [Connection time] - the duration of the connection between the modem and the provider;
My WAN IP (from ISP) [my ip address in global network(from provider)] - ip-address received by the modem from the provider;
line status [Line state] - current state of the xDSL line: Up - up, Down - not up;
Upstream Speed [Outgoing speed] - transmission speed of outgoing traffic in Kbps;
downstream speed [Incoming speed] - transmission speed of incoming traffic in Kbps;
CPU Load [CPU load] - percentage of modem CPU load.

b) For modems ZyXel 660R, ZyXel 660R-T1, ZyXel 660RU-T1, ZyXel 660HT1, ZyXel 660HW-T1 via WEB interface.

192.168.1.1 and press the key Enter. 1234 and press the button "login". Ignore.
In the main menu of the modem, select System Status. In the window that opens, find the button "Show Statistics" and press it. Doing " screenshots» last window:
- first: during download from the Internet;
- second: during download from internal resources.
We name the files accordingly and attach them to the results.

c) For modems ZyXel 660R-T2, ZyXel 660RU-T2, ZyXel 660HT-2, ZyXel 660HW-T2.

Type in the address bar of your Internet browser (Chrome, Mozilla Firefox, etc.) address 192.168.1.1 and press the key Enter. Next, a window will appear asking for a password. Prescribe 1234 and press the button "login". A window will appear in which you are advised to change the password for logging into the modem. Click the button Ignore.
In the main menu of the modem, press Status, and in the window that opens, click the link Packet Statistics.
As a result, a statistics window will open, do it " screenshot»:
- first: during download from the Internet;
- second: during download from internal resources.
We name the files accordingly and attach them to the results.

d) For D-Link modems 2500/2540/2600/2640U v.2

Type in the address bar of your Internet browser (Chrome, Mozilla Firefox, etc.) the address 192.168.1.1 and press the " Enter ". Next, a window will appear asking for a username and password. We register the user - admin and password - admin , press the button " Ok ».
Next, go to the menu Device Info -> Statistics -> WAN
As a result, a window will open, do it " screenshot»:
- first: during download from the Internet;
- second: during download from internal resources.

We diagnose the connection of the DSL channel.
For this we go: Start -> Run -> cmd -> Ok.
In the window that appears, write commands one by one (after each press the key "Enter" ):
netsh("Enter")
ras("Enter")
set tracing ppp enable("Enter")
exit("Enter")
Next, go to the Windows folder (usually c: Windows) and create a folder there tracing . If you are told that such a folder already exists, do not be alarmed. We go into it (the path for the example: c: Windowstracing) and copy the ppp.txt file from there with the results of the commands we entered earlier. We attach this file to the results of the methodology.

We analyze the DSL channel on the modem.

a) For modems ZyXel 660R, ZyXel 660RT1, ZyXel 660RU1, ZyXel 660HT1, ZyXel 660HW-T1
We go to the modem configurator, as shown in paragraph 6-a, go to the menu - modem command line. We write commands one by one (after each press the key "Enter" ):
wan adsl chandata ("Enter")
wan adsl opmode("Enter")
wan adsl linedata far("Enter")
wan adsl linedata near("Enter")
wan adsl perf("Enter")
wan hwsar disp ("Enter")
Doing " screenshots» obtained results. First of all, the state of the 1st (physical) level is analyzed. This information is retrieved by the commands "xdsl state", "wan adsl linedata far", "wan adsl linedata near". Link for information: http://zyxel.ru/kb/1543.
The main parameters for monitoring are "SNR margin value", "Loop attenuation" for 782 and 791, and "noise margin downstream", "attenuation downstream" for 642, 650, 650, 660. Both values ​​are measured on the receive channel of the transceiver. The first universally characterizes the noise immunity margin of the line. Level 6 db roughly corresponds to an error rate of 10E-6 and is the threshold for reliable communication. This parameter obviously depends on the speed, i.e. the higher the speed, the lower the margin. It is also worth noting that the measured values ​​at each end of the line may differ. This indicates that the source of interference is located closer to one of the ends of the line.
Attenuation downstream - signal attenuation in the line and clearly depends on the active resistance of the wire. The influence of noise on the quality of communication and the maximum speed is higher than that of attenuation. You need to do this several times at different times of the day. Attach the results to the results of the methodology.

b) For modems ZyXel 660RT2, ZyXel 660RU2, ZyXel 660HT2, ZyXel 660HW-T2, ZyXel 660RT3, ZyXel 660RU3, ZyXel 660HT3
When entering the modem settings through telnet (as shown in paragraph 6-a), you will immediately be taken to the modem's command line, where you need to enter the commands indicated above.

c) For ZyXel 700 series modems (782 and 791)
In a similar way, go to the modem configurator (see paragraph 6-a) and go to the menu 24.8 - Command Interpreter Mode.
We write commands one by one (after each press the key "Enter" ):
xdsl cnt disp("Enter")
wan hwsar disp ("Enter")
xdsl state("Enter")
Doing " screenshots» obtained results and attach to the test results.

d) For D-Link 2500/2540/2600/2640U v.2 modems
We go into the modem configurator, as shown in paragraph 6-d, go to the menu Device Info -> Statistics -> ADSL .
We take a screenshot and attach it to the results.


We save all the results of the testing methodology in one archive and send it to the e-mail address technical support [email protected] indicating client data (personal account number/organization name, contact phone number/address Email) for feedback.

04. 09.2017

Blog of Dmitry Vassiyarov.

What is ADSL - an old but relevant connection method

Hi all.

No internet now. Therefore, any modern person should know about the different options for connecting it in order to choose the right one for themselves. From these motives I will tell you about what ADSL is. Suddenly you will like this way of connecting with world wide web? If not, you will simply be more aware of Internet technologies. In any case, after reading the article, you will win;).

Introduction to the xDSL family

In the mid-90s, a new family was born, and not just a simple one, but digital technologies that use a telephone line to connect to the Internet. It is called DSL, which means "digital subscriber line" (digital subscriber line). The abbreviation is usually preceded by the letter "x", hiding a specific member of this family.

There are a lot of them, but one of the most popular nowadays is Asymmetric. So our further conversation will be about ADSL. As the name implies, its feature is asymmetry. This is an uneven distribution of downstream and upstream traffic.

The second one is slower. Practice shows that the first digit is more important for users. Because the amount of incoming traffic always exceeds the amount of outgoing traffic.

Physical ADSL

To understand the essence of our conversation, you must understand what ADSL really is. Connection to the network using this technology is carried out through a telephone line and 2 modems (1 is located at the subscriber, the other at the provider).

Between the socket for the telephone cable and the user's modem, there is usually an intermediary - a splitter. It has 1 input for connecting a telephone line and 2 outputs - for the telephone itself and the modem. Also, the splitter eliminates communication interference and ensures the safety of devices from high-voltage impulses thanks to its inductors and electrical protection circuits on varistors.

By the way, there are modems that allow you to additionally connect, distributing Wi-Fi.

Modem phone - not a hindrance

Representatives of the "old school", remembering how the 1990-2000s were connected to the Internet through the phone using cards, do not rush to write off ADSL. For those who do not remember this, I will explain: in those days you could either go online or talk on the phone - one of the two.

But in asymmetric technology, this drawback is eliminated. The fact is that talking on the phone takes on a meager percentage of the line's capabilities. Smart people guessed to use the rest of the channel to access the network so that one does not interfere with the other.

For undemanding voice communication, the lowest frequency band is used, for the Internet - everything else. In particular, the phone uses a range of 400 - 3500 Hz, incoming traffic - 26000 - 138000 Hz, outgoing - from the last digit to 1.1 MHz.

Which line is suitable for internet?

Connecting to the network via ADSL is cost-effective. Since you can not buy a modem, but rent it from a provider, and you do not have to lay new cables. But this is only if the telephone company provides Internet service. In addition, not every line is suitable for this case. It must meet the following requirements:

• loop resistance - no more than 1200 ohms, and insulation - no less than 40 ohms;
• loop capacity - maximum 300 nanofarads;
• capacitive asymmetry - maximum 10 nF;
• signal attenuation: good - 5-20 decibels, in the range from the last digit to 30 dB there are failures, and at 31-40 dB synchronization may disappear;
• noise level: from -65 dB to -55 dB - excellent, up to -35 dB - good, up to -21 dB there may be failures, and if lower - the equipment will not work.

Cable quality also matters. It is best to use shielded twisted pair cable. Often the phone is connected through a single-pair distribution wire (SDP), especially in old houses. Which, of course, is not suitable for new technologies.

Transfer rate

The primary question when choosing a method of connecting to the Internet - what is its speed? Compared to other modern types of connections, ADSL "smokes on the sidelines", although it is considered high-speed. Compare yourself.

The latest generation of this technology is 2++. Its maximum input speed is 48 Mbps, output - 3 Mbps. While the currently popular family can offer customers an incoming traffic speed of 5 Gb / s, although 1 Gb / s remains more affordable, and, nevertheless, this is much more than the ADSL maximum.

For these reasons, the leased line enjoys in great demand than modem technology. However, ADSL is still showing its ability to compete. For example, in public institutions and other enterprises where fixed phones are indispensable, it is convenient and profitable to use their lines for the Internet, because high speed not needed in this situation.

You are always welcome on my blog page.