BRX-XLR User Guide
29
180-0145-001-R01
- Downstream and Upstream SNR values
- Line error status/counts (CES, ES, SES)
- Any error messages from the DSLAM and/or the
ADSL2+ test set
3. The user CPE loses synchronization
with the DSLAM when the phone
goes off-hook
You should have the following equipment to help you
troubleshoot the problem:
- Standard Telephone Test set and/or voltmeter
Verify the following measurements:
-
Voltage in ON-HOOK state on the pair from the
DSLAM and without the BRX-XLR installed
should be -40VDC to -60VDC
-
Voltage in ON-HOOK state on the pair from the
DSLAM with the BRX-XLR installed should be -
38VDC to -58VDC
-
Voltage in the OFF-HOOK state on the pair from
the DSLAM should be around 20VDC
-
Loop current in OFF-HOOK state on the pair
from the DSLAM should be at least 24 mA
-
Loop current in the OFF-HOOK state on the pair
toward the CPE should be at least 20 mA
If any of these measurements are not met, you
should make the corrections as per your corporate
standard procedure and re-verify.
B. Performance Problems: not achieving the expected bandwidth gains
4. With the BRX-XLR installed on the
copper loop, the downstream and/or
upstream performance is not
meeting the expected improvement
Verify the anticipated performance using the
BRX-XLR Calculator tool (makes sure to properly
specify the copper gauge)
Verify that the actual BRX-XLR location matches
(more or less) the recommended location from
the BRX-XLR calculator considering the mix of
various wire gauges
Verify the Min/Target/Max SNR settings and
Actual SNR values in the downstream and in the
upstream direction. A Min SNR that is too low or
a Max SNR that is too high may prevent SRA
from working properly.
Verify that SRA is enabled to allow rate adaptation to
take place and optimize the use of available
bandwidth
If any of the DSLAM settings are wrong, you should
adjust them as per your corporate guidelines and
retest.
5. The DSLAM and/or CPE is reporting
an unusually high number of CRC
errors or Errored Seconds (ES)
Enable Impulse Noise Protection (INP) and/or
increase the number of symbols in the DSLAM
impulse noise settings.
Enable G.INP if supported by the modem (CPE)
Increase target SNR by 2-3dB steps until error
