ADSL installation and maintenance
Since the opening of the ADSL service on July 28, 2001, there have been more than 400 users in the three districts. In the process of installation and maintenance, some problems were encountered and some experience was summarized. In order to better carry out broadband services and other new services in the future, I Talk about your opinion on the installation and maintenance of ADSL.
Below I will briefly introduce the technology and characteristics of ADSL.
The PC uses a telephone line to access the Internet via Modem, and the transmission frequency band is 0 ~ 4kHz low frequency band. ADSL also uses a telephone line as a transmission medium. It uses a high frequency band above 26kHz to transmit data. The specific process is: the signal encoded by the ADSL Modem is transmitted to the telephone office through the telephone line and then passes through a signal recognition / separator. If it is a voice signal, it is transmitted to the PSTN, and if it is a digital signal, it is connected to the Internet. ADSL allows asymmetric high-speed transmission on the same twisted pair without affecting the telephone service. The system includes a high-speed downlink channel from the network to the user and a low-speed uplink channel from the user to the network. Therefore, there are three signals on the user's copper wire: voice signal, uplink data signal and downlink data signal.
ADSL has the following characteristics: ①has a high transmission rate. The up transmission rate supported on a pair of copper wires is 640kbit / s to 1Mbit / s, the down transmission rate is 1 ~ 8Mbit / s, and the effective distance is 3 ~ 5km. ②Internet and phone calls do not interfere with each other. ③ Easy to install and use. ④Provide a variety of advanced services. ⑤ Asymmetry of transmission rate.
General users send a small amount of commands and data information to the service source. When downloading files, the amount of data is large, so a high-speed downlink channel is required.
Some of the features and advantages of ADSL are introduced above, but many problems will be encountered during the actual installation and maintenance. Some of them are due to the reason of the line is too long; some are due to users such as no network card, no USB interface, and the system does not support ADSL. But no matter what kind of problems we encounter, we must find a solution, because our ultimate goal is to serve users. Occupy more markets. I have encountered some problems in the actual work of installing and maintaining ADSL in these months With the joint efforts of all of you and the assistance of the manufacturers, most of the causes have been found and resolved. Now we will summarize the common problems for your reference.
1. In the beginning of the installation process, it is reflected that the first port of the node is not available. It has been identified as a manufacturer software problem and has been resolved.
2. After connecting the outside line to the ADSL equipment, the Modem cannot be activated due to the following reasons:
(1) The quality of the line is not good, the wire is broken, the line is mixed, the insulation is not good, the ring resistance is too large, and the measurement room wiring is not equal. Because ADSL is bundled with voice, so during installation and maintenance, you must first listen to the phone for buzz. Check with the measurement room to see if there is any insulation problem and what is the ring resistance.
(2) The driver of the USB Modem is not installed correctly. Reinstall after uninstalling.
(3) If the backplane of the ADSL node dslam is connected to the terminal board of the measurement room, there is a problem. Just change the location.
(4) There is a problem with the modem.
3. After connecting the outside line to the ADSL equipment, the modem can be activated, but cannot access the Internet:
(1) The network management has not opened the port, you can contact the network management to find out the situation.
(2) There is a problem with the Usb Modem driver. Reinstall after uninstalling.
(3) Check whether the equipment in the composition structure in the properties of Beijing Broadband Communication dial-up software is compatible with the installed Modem.
(4) The network card of the user's computer is not a 10 / 100M adaptive network card.
(5) The server is malfunctioning.
4. In the actual installation process, I found that when the line resistance exceeds 700Ω, the rate will be slow, unstable, and often dropped, but this is not absolute. It depends on the quality of the line and whether there is interference in the line. When installing, use ADSL test instrument to see the upstream and downstream data of the line, and use the laptop to see the actual download rate.When the quality of the line is not good, it is best to replace the pair with the measurement room to find the best pair. .
5. ADSL has high requirements on line quality, so it is best to use it with ISDN and DDN and other data lines across the wire pair, because ISDN and other data lines will cause crosstalk on ADSL lines, affecting the normal use of ADSL.
6. The voice signal of ADSL is allowed to be connected with an extension when using a splitter, but it is best not to exceed 3, too many opportunities will affect the speed of Internet access, and it will seriously cause the Modem to not receive the data signal normally, so that users Internet access.
7. Win2000 server does not support Beijing Broadband Communication dial-up software, so it is recommended that users replace the system or download other pppoe dial-up software.
8. Users often report that the download speed of ADSL is slow, sometimes only a few kbit / s, which is related to the website. It is recommended that users try another website, such as Sohu, Sina and other relatively stable websites. If the speed of many websites has been changed slowly, it is necessary to consider the reasons of the Bureau. Poor line quality will cause slow network speed. At this time, it is best to test with ADSL meter and watch the download rate with a laptop computer, so that it can be judged whether it is a line problem or a user computer problem.
9. Some users report that the Internet is relatively normal, but they often go offline. There are many reasons for this obstacle, which can only be eliminated one by one:
(1) The line quality is not good, cooperate with the measurement room to test the line, replace the local line wiring or the user goes offline.
(2) The quality of the subscriber line is very good. At this time, check whether there is a data line such as ISDN near the subscriber line.
(3) Connect the user's line to your notebook and test to determine whether the user's computer has problems.
(4) You can also inform the network management to increase the signal-to-noise ratio of the user port and set a speed limit. Some users often get disconnected after adjusting the signal-to-noise ratio.
10. Some users cannot access the Internet normally due to incorrect LAN settings. This obstacle is easier to solve. Just connect the user's line to a laptop and prove that there is no problem with the Internet, but you must explain to the user that it is the cause of the LAN.
In order to better explain the common problems and solutions mentioned above. Let me give a few practical examples to illustrate.
1. The user of Cherry Garden Bureau 83532315 appeared to have slow network speed and frequent disconnection after one week of installation. The loop resistance of the line was tested to be 650Ω, and the line also had no insulation problems, which can be ruled out as the cause of line quality. When looking at the user's wiring table, it was found that there are multiple ISDN user pairs near the ADSL pair, so the ADSL pair was replaced and the distance from the ISDN pair was tried as far as possible to solve the problem of users dropping. This example shows that ISDN and other data line pairs interfere with ADSL line pairs. When installing ADSL, try to stay away from ISDN line pairs.
2. The user of Xidan Bureau 66076039 reported frequent disconnection, and it was very frequent. After inspection, it was found that the line loop resistance was 500Ω, the line was normal, there was no interference from ISDN and other data lines, and the user's computer was no problem. The ratio was adjusted from 40 to 60, and the problem was solved. This case shows that after eliminating the cause of the line and the user's computer, the problem of frequent disconnection can be solved by increasing the signal-to-noise ratio and limiting the speed.
3. After installing ADSL, the Langfang Toutiao Internet Café of Changdian Bureau often drops the line. After testing, the loop resistance is greater than 700Ω, so it is judged that the loop resistance is too large. I changed a lot of the local line loop resistance on the transfer box, which is 700Ω. After connecting to the modem, I still often dropped the line. Later, I decided to try the transfer box. There is also a transfer box at more than 100 meters away from this transfer box, which is not far away from the ionization users.The loop resistance of the local line is 400Ω on the new transfer box, and the ring resistance is 500Ω after the user is offline. . This case shows that the quality of the line is not determined by the distance. It must be tested in conjunction with the measurement room, and tested with an ADSL instrument. In fact, the effect of the net is checked with a laptop.
4. During the installation of Cherry Garden Bureau, there is a user line normal, Modem signal light is normal, but after dialing, it prompts that the server cannot be found, and the same is true when trying with a laptop. The network card modem was later replaced with a USB modem and the Internet was available. The problem occurred with the Ethernet card modem. After inquiry, the manufacturer did not set the pvc settings for the modem.
The problems and solutions mentioned above are relatively common and not very comprehensive. ADSL is a new business, and the problems that arise are also new.Therefore, problems can only be found and solved in actual work.To promote the ADSL business better, we all need to work together to provide users with high quality through our own technology Only in this way can ADSL and other new services be better marketed.
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