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Stinger® ADSL 48-Port Annex C LIM Guide
Configuring an ADSL 48-Port Annex C Line Interface Module (LIM)
Configuring ADSL Annex C interfaces
admin> read al-dmt {1 2 1}
AL-DMT/{ shelf-1 slot-2 1 } read
admin> set interleave-path-config max-bitrate-up = 1280
admin> set interleave-path-config max-bitrate-down = 12480
admin> set interleave-path-config min-bitrate-up = 32
admin> set interleave-path-config min-bitrate-down = 32
admin> write
Margin-Config subprofile
The bit-error rate (BER) is the percentage of erroneous bits in the total number of transmitted
bits. The noise margins can be controlled to ensure that the line provides a BER of 10
-7
or
better, as required by DMT standards.
Noise margins are defined in decibels (dB). A BER of 10
-7
represents 0dB. The line tolerates a
certain level of random frequency voltage (noise) with respect to its received signal. If the
maximum noise level is exceeded, the ADSL transceiver unit (ATU) attempts to reduce the
far-end output power. If the noise drops below a minimum margin, the ATU attempts to
increase the far-end power output until the noise level is at or above the configured minimum.
Although the noise-margin settings can be from 1dB through 31dB, the modem software limits
the maximum noise margin to 15dB. If you specify a setting greater than 15, the modem
software uses 15dB. Figure 1-2 illustrates the relationship of margin parameters to power
adjustments.
Figure 1-2. Relationship between noise margin parameters and power adjustments
Following are the Margin-Config subprofile parameters shown with default values for
configuring the noise margins on the ADSL-DMT line for the ADSL 48-port Annex C LIM:
[in AL-DMT/{ any-shelf any-slot 0 }:margin-config]
target-noise-margin-up = 4
target-noise-margin-down = 4
min-noise-margin-up = 0
min-noise-margin-down = 0
max-add-noise-margin-up = 30
max-add-noise-margin-down = 30
Reduce output power
Increase output power
Steady-state operations
Target noise margin
Minimum noise margin
0dB margin
Maximum additional
noise margin
