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Modem Test at the NID

This procedure enables customers the ability to test DSL speeds, synchronization rates, and overall signal quality directly at the Network Interface Device (NID). By testing the modem directly at the NID all inside wiring and filters/splitters are eliminated from the circuit. Even if you have a Homerun (dedicated DSL wiring) you still must test at the RJ-11 test jack.

Extra Credit: You can also isolate and troubleshoot common telephone problems by connecting a phone directly at the NID. Reference the Telephone troubleshooting guide for more information.

NOTE: If you live in an apartment or multi-family building please see the Modem Test at the INI FAQ.

The best method for testing is to have both the modem and the PC as close to the NID as possible and using the shortest RJ-11 cable available between the NID and the modem. Since the PC is required to access the line statistics you may have to move the PC to another room closer to the NID and thread an Ethernet cable (or USB cable if you have a USB modem) through a window. If it is impossible or hard to move the PC, it is better to use the shortest possible RJ-11 cable to the modem then connect a long RJ-45 Ethernet cable to the PC. You do not have to log in to BellSouth to obtain the line statistics, you simply need the modem to synch with the DSLAM. Incorrect VPI/VCI settings will not effect your ability to synch with the DSLAM. Important Note: If you are using a separate router in conjunction with your modem you will have to connect the modem directly to a single PC in order to access the modem's interface.

    Required Equipment:
    -Flat Head Screwdriver (may not be required for all NIDs)
    -High quality RJ-11 modem cable (use the shortest length possible)
    -PC or laptop (located as close as possible to the NID)
    -Ethernet cable (if using an external Ethernet modem)

Step 1 - Baseline testing the modem
Important Note: Before testing at the NID you MUST establish an operational baseline reference. Pull your line stats and save/print all of your previous modem logs before you change anything or troubleshoot. Some modems have the ability to test attainable line rate, relative bandwidth capacity, power, attenuation, and signal-to-noise ratio. If available, these measurements and logs are the most accurate assessment of line quality. For more information about capturing line statistics and what the values and numbers mean please reference the following links:

Motorola 2210
Westell Line Statistics
SpeedTouch Home Line Statistics (Command Line Interface)
SpeedTouch Home Line Statistics using Alcatool (GUI Interface Alternative)
2Wire Line Statistics
Cayman Line Statistics
What do all the line statistics values mean? Are my numbers good?

Step 2 - Identify and locate your NID or Station Protector
The NID or Station Protector is the point where the telephone cable and service enter your house. Locations can include the side or back of the house, attics, or basements. They are usually about 8" to 12" tall and some common examples are shown in Figure 1. If you have a NID similar to the examples in Figure 1, proceed to Step 3.

Figure 1

Some homes (usually older) may only have a simple Station Protector as shown below. If you only have a Station Protector you will not be able to check the speed and synchronization rates and must call 611 (Service and Repair) and select the home telephone option (not DSL) to request a proper NID. Do not call BellSouth Internet Services. There is no charge to the customer for the new NID installation and it will be installed by a BellSouth technician. If you have a station protector as shown in Figure 2 do not proceed with this test.

Figure 2

Step 3 - Accessing the customer side of the NID
All NIDs have two labeled access panels. One is marked Customer Access and the other is marked Telco Access or something similar. The only panel needed to run this procedure is the one marked as Customer Access. Some NIDs may require a flat blade screwdriver to open the access panel. Do not try to access the Telco side of the NID. It requires a special tool and is illegal for the customer to open.

Step 4 - Finding and testing the RJ11 test jacks in the NID
Inside the NID you will find one or more (depending on how many phone lines your house has) Entrance Bridge Networks (EBN) or splitter. This is where the Telco network stops and your private house network begins. EBNs and internal spltters have an RJ11 test jack that will serve as the test point for this procedure. Depending on the style you may need to remove a small operational RJ11 plug wire to access the test jack. Other styles may require you to flip up a cover to access the RJ11 test jack. Some common EBNs and internal splitters are shown in Figure 3. Access the test jack and proceed to Step 5.

Figure 3

Step 5 - Testing the modem and reconnecting the wiring
Helpful Hint: To eliminate the modem cable itself being the problem, use a new or known good RJ11 cable (or a least a different one). Plug your test cable into the RJ11 test jack on the EBN or splitter and connect the other end into the line in jack on your modem as shown in Figure 4. All wiring within the house is now bypassed and there will be no dial tone on any phones inside while testing. Pull your line stats again (as described in Step 1) and log the results. Best advice ever: Run the test from the NID for as long as possible. You may have an intermittent issue that doesn't show up if you only check for a minute or two. If you are experiencing troubles at a specific time try and test in that time frame, if possible. Make sure you recheck the modem logs too.

Extra Credit: Remember you can also isolate/troubleshoot telephone issues by connecting a phone to the EBN's test jack.

Figure 4

Step 6 - Returning to your operational configuration
Once completed, disconnect the test cable from the EBN test jack and replace the operational wire and plug (or flip the test cover back down) depending on EBN style. Ensure that the inside phones have dial tone then close and secure the customer access panel of the NID. Connect the modem back to your standard operational configuration.

Step 7 - Analyzing the results:
Once you have pulled the modem/line statistics check the following link for detailed more information. What do all the line statistics values mean? Are my numbers good?

Your speeds or synchronization rates did not change or only slightly changed during test:

    One of two things may be wrong:

    1. The modem is bad.
    2. The local loop (wiring from your house to the Central Office/Remote DSLAM) has problems.

    Either way, please call the Help Desk at 1-888-321-2375 and request a line check. A simple line check can test the local loop for problems. Depending on the results of the line test, the Help Desk will either send a technician to fix the line or replace the modem

Your speeds, synchronization rates, or CRC errors changed dramatically during test:

    Several things may be at fault and will require further troubleshooting.

    1. The DSL filters are not installed properly, not present on all devices, or simply gone bad.
    Many times the issue is the filters have been installed incorrectly. The BellSouth supplied filters have two outputs, one for phones/faxes/etc and the for DSL. It is very important that all phones/faxes/etc have a filter installed. Filters can also go bad for various reasons so just because a filter is installed properly does not mean it is functioning properly. To eliminate the filters as a cause of problem remove all filters and POTS devices from every jack in the home. Replace the filters and POTS devices one at a time and test the modem for any speed or synchronization changes. If your speeds drop off dramatically then replace that filter.

    2. Bad inside wiring (substandard wiring, cuts/staples/nails through the wiring, improperly installed jacks, etc).
    Since inside wiring problems are extremely hard to track down we suggest that you install a Homerun. A homerun is a dedicated line that is strictly for data (DSL). It ensures that POTS devices and DSL do not conflict or be carried on the same lines. A homerun also eliminates the need for the individual filters on every POTS device. A BellSouth technician can install a homerun in most houses and it is an easy way to avoid the hassles of rewiring your house. There is a service charge for the install. Please call the Help desk at 1-888-321-2375 to schedule an appointment. Homeowners who have the aptitude and wish to do their own homerun wiring can find tutorials outlining a homerun installation online or here. Just remember, a splitter can go bad too, so don't discount it as a problem simply because you already have a homerun.

    3. You have an alarm or satellite system.
    Alarms and satellite systems (even if they are not active and you do not have service) can cause major problems. You will have to install a specialized alarm filter or install a completely separate homerun to isolate the alarm or satellite system as shown here.

    4. Interference from other electrical devices.
    Move any electrical devices such as monitors, TVs, intercoms, HAM radios, wireless devices, halogen or fluorescent lights, etc as far from the modem as possible. If such devices can not be moved disconnect all electronic devices and connect them one at a time and check your speed and synchronization rates after each device is turned on (much the same way you checked for bad filters). If your speed drops dramatically after a certain device is powered than that is causing your problems. A simple hand held AM radio can also be used to track down noisy electrical problems. Tune the radio to a lower frequency that is not used by a station so you hear only static. Pass the radio near the suspected device and if you hear a major change in the amount of static that device may be causing the problems.

    5. A bad or incompatible surge protector.
    Some telephone line surge protectors are not designed for DSL and will create connectivity issues. Even if the surge protector is rated for DSL it may have gone bad or been hit with a lightning surge. In either case, simply bypass the surge protector and test again.

Andy Houtz DSL

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by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2009-05-13 15:13:20