Complete ADSL Technical Manual

ADSL is the mainstream form of broadband Internet access. Next we will introduce some maintenance methods that often encounter faults when using ADSL for Internet access, hoping to help you.

I. Why is the ADSL indicator normal?
The most important indicator of ADSL is "ADSL. When there is no problem with the ADSL line, the light should be green.
However, some users will also be disconnected when the "ADSL" indicator is normal, and restart the MODEM. This often happens to network users who do not have a proxy server or a firewall or router. Why?
There is a "10Base-T" port on the MODEM, which is connected to the LAN and is actually a HUB port. Although it is a 10 m port, the upstream bandwidth of ADSL is only several hundred Kbit/s. If the user's LAN is directly connected to the HUB through ADSL and the HUB is connected to the following clients, many data packets irrelevant to ADSL in the network will occupy the ADSL uplink channel, ADSL cannot control the broadcast storms in the LAN. If the uplink transmission capacity of ADSL is exceeded, data packets are loaded into the ADSL cache. If the data volume continues to increase, the cache overflows, causing ADSL to "Sleep. In this case, only the MODEM is restarted.
Solution: users with insufficient funds can build a proxy server with dual NICs and must have dual NICS). In this way, the MODEM can communicate directly with the LAN to avoid the above problems.
You are advised to use a firewall or router.

2. Why is the error sometimes caused by virtual dialing?Failed
1) The ADSL virtual dialing software has the following error messages:
1. "Begin Negotiation" is displayed in the dial-up window, and then waits. The "time out" menu is displayed ".
This indicates that the network is disconnected. Cause: 1) the network cable on the 10 BaseT port on ADSL is not properly connected. 2) The ADSL Network is disconnected. You can restart ADSL and try again.
2. "Begin Negtiation" is displayed in the dialing window, and "Authenticating" is followed by "Authentication Failed ".
This situation indicates that your account or password is incorrect, and sometimes it may be caused by PPPOE software problems. Close the PPPOE software and re-open it.
3. the dial-up window displays "Begin Negotiation", "Authenticating", and "processing Network Parameter". The "time out" menu is displayed ".
This indicates that the dial-up address is full. Please try again later.
2) Why does the "ADSL" lamp on the ADSL Modem disappear? How can we avoid it as much as possible?
The "ADSL" lamp (the front light) on ADSL is the most important indicator light on ADSL. It is the first step to determine whether ADSL can communicate.
"ADSL" lamp has several statuses ":
If the "ADSL" lamp is green, it indicates that the MODEM on the user end has established a physical connection with the MODEM on the telecom Bureau end-this is called "synchronization", which is the first step for normal operations of ADSL, is the most important step.
If the "ADSL" light is not on, it indicates that the physical connection between the MODEM of the user end and the MODEM of the Telecommunications Bureau has been disconnected ----- This is called "out of step ".
If the "ADSL" light is flashing, it indicates that the MODEM on the user end is trying to establish a connection with the MODEM on the telecom Bureau end, that is, synchronization is in progress.
After the user adds the adsl modem to the power supply for dozens of seconds, the "ADSL" lamp changes from "not on" to "green flashing" to "long green". This is the synchronization process.
If the adsl modem is in use and the "ADSL" indicator light is not on, it indicates that there is a strong interference on your telephone line at this moment. A connection on the telephone line is not properly connected and loose. The line is faulty.
Solution and precautions:
1. No extension is available on the ADSL line. The PHONE number can only be obtained from the PHONE port of the separator; otherwise, ADSL may fail.
2. The connection on the line must be well connected, especially the connection within the user's house.
3. If the telephone line is too long, replace the parallel lines with twisted pair wires to improve the line anti-interference capability.
4. ADSL is sometimes affected by weather conditions, such as heavy rain. Users can recover naturally in just a few hours.
Iii. main fault sources and solutions:
Hardware
O. The connector is loose, the network cable is disconnected, the hub is damaged, and the computer system is faulty. For the above faults, you can observe the Modem, Hub, or computer indicators to help locate and replace suspected devices.
O the voltage is not normal, the temperature is too high, lightning strikes-the voltage is unstable, it is best to configure the Modem with a small power UPS uninterruptible power supply); Modem should be kept dry and ventilated; avoid water shower; keep clean. During thunderstorms, you must disconnect the Modem power supply from all connections to avoid damage caused by lightning strikes. If the Modem is damaged, if the indicator is not on, or only one light is on, or if the network cable is changed, or the 10BaseT light is still not on after the NIC is changed, the Modem is damaged. Contact the service provider.
O line quality-the distance is too long; the line quality is poor; the connection line is unreasonable; the result is frequent loss of synchronization, difficult synchronization, or a slow inertia speed.
Solution: place the devices that need to be connected with each other, such as Phone extensions, faxes, and common Modem, to the Phone port of the splitter. check whether all the connections are in good contact, the customer line with poor quality should be transformed or replaced; if the above work still cannot solve the problem, please contact the data center in time and cooperate with the data center to adjust parameters. After consulting the IDC room, you can consider replacing the bearer phone or trunk line.
Software
Restart-Restart Modem power), computer, or HUB is a very effective solution. However, frequent disconnection and recovery after the Modem is restarted may be caused by an unreasonable network structure. This problem occurs easily in the LAN of a single Nic proxy server. The solution is to use a dual Nic proxy or a vro, in short, enable the Modem to directly connect to the server Nic or vro port instead of the HUB. Some NICs are also connected to the Modem. Change the NIC.
Troubleshooting
The general principle is: Pay attention to the indicators and error messages, First hardware and then software, first internal and external, first local and then Internet, first try the host and then check the customer, and then report. Fault reporting should be accurate and concise, and user problems should be matched to the faults mentioned in the user manual whenever possible. When a fault is reported to the IDC, the port number and user name should be first reported in accordance with the user manual. For regular faults, the user shall record them and mention them during the declaration.
Software fault examples

If the four status lights are green,
① The system prompts "Time out while ........ "Check the network connection between the computer and ADSL Modem. Check whether the 10BastT light is flashing when dialing. If the light is not flashing, it indicates that the computer has not transmitted the data to the Modem. If the computer's software is faulty, restart the computer, or reinstall the virtual dialing software.
② "Authentication Failed" indicates that the entire ADSL line is normal, but the user account and password do not match, you should fill in again. If you confirm that your account and password are correct, contact the business office.
③ If the dial-up connection of the virtual dialing software is normal, but the connection fails. As long as the dial-up connection is normal, ADSL is normal under normal circumstances. Otherwise, it is a problem with the user's computer system.
4. Other problems
1. What is the simplest troubleshooting method for ADSL?
Answer: The problem can be preliminarily identified based on the signal light displayed on the ADSL Modem panel. Currently, there are four types of adsl modem available for users in Zhanjiang, the following describes the standard MODEM for the NOKIA Bridge Ethernet interface, and the rest will be introduced later), as follows:
"ADSL" Light: used to display the synchronization status of the Modem. A green light indicates that the Modem and the local terminal can be normally synchronized. A red light indicates that the Modem is not synchronized. A flashing green light indicates that synchronization is being established; when the light is on, it indicates it may be affected by the indoor phone extension.
"LAN (10 M-100 M)" light, used to show whether the Modem is connected to the NIC or Hub normally. If the light is not on, the Modem and the computer are definitely disconnected, when there is data transfer in the network cable, the light will flash slightly.
"SYS" light, which is related to remote management, usually on.
"POW" light, power display ..
2. Will using ADSL to access the Internet Cause the quality of telephone services to decline? In addition, will a call result in a decrease in the Internet access rate?
Answer: The ADSL device has already taken this into consideration. The technology of frequency division multiplexing is used to separate telephone and data streams without interfering with each other. In the test of the actual line, there is no difference between the phone number that installs ADSL and the voice of a common phone: When transmitting data information, bring up the phone number, stop the phone number, and make a casual call, the transmission rate remains unchanged.
3. Why is the access speed of ADSL faster than that of common dial-up MODEM?
A: The access speed of ADSL is slow as follows:. if you visit a site outside China, the access will be affected by factors such as Outbound bandwidth and the configuration of the site of the other party; B. because ADSL technology has high requirements on the quality of telephone lines, and currently uses a RADSL [speed-adaptive ADSL], if the telephone line from the telephone building to the user is disturbed by external factors for a certain period of time, RADSL dynamically adjusts the user's access speed based on the quality of the line and the distance between transmission.
4. Why does ADSL sometimes fail to access the Internet normally?
Answer: ADSL is a Transmission Technology Based on twisted pair wires. Twisted Pair wires wrap two insulated copper wires together with each other according to certain rules, so as to effectively resist external electromagnetic interference. However, most of the telephone lines on the market are parallel lines. Many of the lines from the telephone company's junction box to the user's telephone are parallel lines, which is very unfavorable for ADSL transmission, too long non-twisted pair wires may cause unstable connection, DSL light flashing, and other phenomena, thus affecting Internet access. Because ADSL overlays high-frequency digital signals on the base-frequency voice of a common telephone line, the addition of any device in the connection from the telephone company to the ADSL filter will endanger normal data transmission, therefore, do not use phone or phone anti-theft devices before filters.
5. The ADSL speed is generally kb for users, and 2-8 Mbit/s for conditional Users)
Answer: The unit of speed. The maximum download speed of a 56 K modem is 5-6 K. The unit of 56 K is bit, And the download speed is byte. 1 byte = 8bit. Therefore, when the download is kb, it has actually reached 416bit, which is already quite fast. Because of the hard drive speed of the server and client, the local download speed cannot take full advantage of ADSL. We also expect a faster server.
6. Why is the ADSL indicator normal?
Answer: The most important indicator of ADSL is "ADSL. When there is no problem with the ADSL line, the light should be green. However, some users will also be disconnected when the "ADSL" indicator is normal, and restart the MODEM. This often happens to network users who do not have a proxy server or a firewall or router. Why? Because there is a "10Base-T" port on the adsl modem, which is connected to the LAN and is actually a HUB port. Although it is a 10 m port, the upstream bandwidth of ADSL is only several hundred Kbit/s. If the user's LAN is directly connected to the HUB through ADSL and the HUB is connected to the following clients, many data packets irrelevant to ADSL in the network will occupy the ADSL uplink channel, ADSL cannot control the broadcast storms in the LAN. If the uplink transmission capacity of ADSL is exceeded, data packets are loaded into the ADSL cache. If the data volume continues to increase, the cache overflows, causing ADSL to "Sleep. In this case, only the MODEM is restarted. The solution is that users with insufficient funds can build a proxy server with dual NICs and must have dual NICS). This way, the MODEM can communicate directly with the LAN to avoid the above problems. You are advised to use a firewall or router.
7. Why sometimes virtual dialing fails?
A: The ADSL virtual dialing software has the following errors:
A. the dial-up window displays "Begin Negotiation" and then waits. The "time out" menu is displayed ". This indicates that the network is disconnected. The reason is: The network cable on the 10 BaseT port on ADSL is not properly connected; the ADSL Network is disconnected. You can restart ADSL and try again.
B. the dial-up window displays "Begin Negtiation", "Authenticating", and "Authentication Failed ". This indicates that your account or password is incorrect.
C. the dial-up window displays "Begin Negotiation", "Authenticating", "processing Network Parameter", and "time out ". This indicates that the dial-up IP address is already full. Please try again later.
8. Why is the "ADSL" lamp on the ADSL Modem red? How can we avoid it as much as possible?
A: The "ADSL" lamp [front light] on ADSL is the most important indicator light on ADSL. It is the first step to determine whether ADSL can communicate with each other.
"ADSL" lamp has several statuses ":
If the "ADSL" lamp is green, it indicates that the MODEM on the user end has established a physical connection with the MODEM on the telecom Bureau-this is called "synchronization", which is the first step for normal operations of ADSL, is the most important step.
If the "ADSL" light turns red, it indicates that the physical connection between the MODEM on the user end and the MODEM on the telecom bureau has been disconnected-this is called "out of step ".
If the "ADSL" light is flashing, it indicates that the MODEM on the user end is trying to establish a connection with the MODEM on the telecom Bureau end, that is, synchronization is in progress.
-- After the user adds the adsl modem to the power supply for dozens of seconds, the "ADSL" lamp changes from "red-green". This is the synchronization process.
If the "ADSL" indicator turns red when the adsl modem is in use, it indicates that there is a strong interference on your telephone line at this moment. A connection on the telephone line is not properly connected, and there is looseness. The line is faulty.
　Solution and precautions:
A. No extension is available on the ADSL line. The PHONE number can only be obtained from the PHONE port of the separator; otherwise, ADSL may fail.
B. The connection on the line must be well connected, especially the connection within the user's house.
C. If the telephone line is too long from the branch box of the Telecommunications Bureau, replace the parallel lines with twisted pair wires to improve the line anti-interference capability.
D. ADSL is sometimes affected by weather conditions, such as heavy rain. Users can recover naturally in just a few hours.
9. Does ADSL support LAN access?
A: Yes. There are three methods:
A. set the host directly connected to the Internet through ADSL as a proxy server, and then the client on the local LAN accesses external information resources through the proxy server, the advantage of this method is that you need to apply for an account or an IP address, the local client can use the reserved IP address; B. the physical connection is used to apply for one IP address from the telephone Bureau for each computer on the LAN. The advantage of this method is that you do not need to set up a dedicated proxy service gateway. The defect is due to the limitations of the current technology, the telephone board can only provide up to 16 IP addresses to the LAN;
C. Connect A vro behind ADSL and apply for an IP address from the telephone Bureau for the local area network. After the telephone Bureau sets a route for the IP address, you can access the Internet. The advantage of this method is that the number of LAN computers is unlimited, but you need to add more routers.
D. what is exciting is that we are about to launch an ADSL Modem with routing and firewall functions on the client. We Can Do either of the above three methods without adding any proxy server or router.
10. What is "Internetwork "?
A: "internetworking" refers to the interconnection of local networks distributed in different locations through virtual or actual leased lines. Currently, DDN, ISDN, and satellite are the most commonly used leased lines, while ADSL can be either a common leased line or a on-demand virtual leased line, in addition, the cost of internetworking with ADSL is lower and more reasonable than that of DDN.
11. Do users need to apply for a dedicated telephone line to install ADSL? What are the requirements for users' computers?

A: To install ADSL, you can modify the existing telephone line or apply for a second telephone line dedicated for Internet access. There is no difference in installation and use. If you use an existing phone line, the previous phone number remains the same.
For users who apply to install ADSL, the basic hardware and software requirements of the user side are as follows:
> One common Linear phone
> An adsl modem has a built-in PCIe card, a USB interface, and an Ethernet interface)
> One computer is configured as follows ):
> CPU: INTEL Pentium II or above and same-grade CPU
> Memory: 16 MB or more
> Hard Disk: 80 m available space
> Operating System: WIN98, WIN NT
> Software: PPPOE virtual dialing software
> Network adapter: ethernet card 10 M/100 M baseT, provided by the user)
Note: you do not need to use an Ethernet card when using the PCI Card internal and USB interfaces external adsl modem .)
12. Will I change my phone number if I change my ADSL number on my current phone?
A: Generally, this will not change. Because the ADSL signal is completely independent of the phone signal and does not affect each other, the ISDN is completely different. There is an ISDN signal in the line. When the telephone and data are together, the ISDN must change the number, which is also a small advantage of ADSL.
13. Can I use a dial-up Modem as an ADSL Modem?
A: No. The ADSL Modem is different from the current dial-up Modem. The modulation method and network structure are different, in addition, the interface to the PC is 10BaseT Ethernet interface or USB interface, instead of RS232 serial port or parallel port.
14. Do I need to buy new parts for my computer?
Answer: depending on the type of adsl modem you selected: 1) if you use the USB interface's adsl modem or PCI plug-in adsl modem, no new components are required. 2) if you use the adsl modem of the Ethernet interface, you only need to buy a single network card, you can use an ordinary 10/100 M Ethernet Card, the market price is about one hundred yuan, 10 M network card must have RJ45 interface ).
15. Can I use 10 M/M network cards for ADSL?
A: Yes. ADSL external Modem has a 10Base-T interface and supports 10 m Nic. Currently, the vast majority of M NICs also support 10 M, so they can be used.
16. Will ADSL reduce the quality of telephone calls, and will phone calls lead to a decrease in the Internet access rate?
A: ADSL uses the frequency division multiplexing technology to separate voice and data. Although it is on the same telephone line, the voice and data run on different frequency bands, so they do not interfere with each other. Even if you use a phone call to access the Internet, the speed of the Internet access will not decrease, and the quality of the call will decline.
17. How do I install an extension number or other devices on my ADSL line?
Answer: It is best to connect the ADSL filter splitter to the Telephone Line bus, and then expand the telephone extension from the telephone port separated by the splitter. Of course, it can also be connected to the extension port theoretically, however, if other electronic devices (telephones) are incorporated between the bus entry, that is, the Telecommunications Board) and the separator, these devices will interfere with the communication between ADSL, because ADSL has high requirements on the line quality, it may affect the normal operation of ADSL, so it is generally necessary to install the extension after the separator line.
18. Why is PPPoE unavailable on computers on the LAN when the ADSL connection uses 10 M/100HUB?
Answer: The 10 BASE-T standard (10 M) is used for ADSL. It can connect to a 10/100 m hub, however, if the connection speed between your computer and the HUB is 100 MB, The HUB's 10/100 switching module does not currently support PPPOE well, therefore, PPPoE may not be able to locate the ADSL signal at a speed of M, so it cannot be used. The solution is to create a 10 m network cable using a 10 m wiring method for the PPPoE dial-up computer, or use the NIC setup program to forcibly set the speed of the network card to work at 10 m.
19. Why is my ADSL data traffic too high?
A: We generally think that this is a poor quality or compatibility of NICs, especially for 10 m NICs of the old ISA bus. Because PPPoE is a relatively new technology, such NICs may have compatibility problems and are slow, cause the final line of the conflict to be deadlocked or even crashed.
Is the speed of 10 M/M Nic used on ADSL different?
A: In general, the speed will not be different, because the ADSL Internet access speed is not limited by the NIC and less than 10 M, but for the 10 M Nic, A large part of ISA interfaces use the I/O addressing mode, and their CPU usage is very low in efficiency, which will have a slight impact on the speed, therefore, we recommend that you use the PCI interface 10 M/M dual-speed adaptive Nic.
21. My location is far away from the telecommunications machine room of the Telecommunications Bureau. Can I install ADSL?
A: currently, the distance between ADSL technology and telecom equipment buildings of the Telecommunications Bureau is less than 5 kilometers. Therefore, it depends on the situation. Because ADSL has high line requirements, therefore, in order to ensure the quality of communication, the website considers that the communication quality is better under 3KM.
22. Will ADSL be dropped like a 56 K Modem?
A: When any connected device fails, ADSL will also be dropped. However, as long as the line quality is good, the chance of disconnection is still very small.
23. ADSL does not mean to use the ADSL line. Why didn't I see the telecommunications company change the line after I installed it?
A: In fact, the physical media used by ISDN lines, telephone lines, and ADSL lines are common telephone lines, but the signal standards are different. The telecom company will not change the lines for you, you can only connect your telephone lines to different devices in the telecom data center, which is invisible to end users.
24. Will I generate telephone fees like ISDN and Modem if I use ADSL to access the Internet?
A: No. The channels used by ADSL for data communication do not enter the local switch, and no telephone fee is generated.
25. Do I need to dial data when using ADSL?
A: There are two ways to connect ADSL to the INTERNET: Virtual dialing and leased line access. Users using virtual dial-up methods use dial-up programs similar to MODEM and ISDN, which is similar to the original method in terms of usage habits. Users who use leased line access can access the INTERNET as long as they start up.
26. What is virtual dialing? What is the dial number?
A: When using ADSL to access the INTERNET, you must enter the same user name and password as the original MODEM and ISDN to access the INTERNET ), however, what ADSL connects is not a specific access number such as 163, but the IP address of the ADSL access of the Virtual Private Network VPN.
27. Do I have to purchase an ADSL Modem from a telecommunications company?
A: Basically speaking, because the technical standards adopted by ADSL are not widely used at present, the devices produced by various manufacturers cannot be fully compatible. However, if the ADSL Modem sold by the store is licensed by a local telecommunications company, you can also purchase it.
28. What is the price comparison between the leased line access method of ADSL and the ddnleased line?
Answer: the launch of ADSL is a supplement to the existing ddnleased line business. The group users it faces are small and medium-sized enterprises, and the charges are lower than those of ddnleased lines at the same rate, however, it is more stable than DDN.