It is an absolutely superb feature. It gives me very very roughly the equivalent of another 3dB of SNRM and about another 5% downstream sync speed. The reliability improvement is absolutely spectacular, looking at the ratio of FEC error count to bad CRCs count when running at 3dB downstream target SNRM and drooping down to about 2dB during part of the day.
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I will do some number crunching for all the lines when I am a bit less tired, but here are some numbers for my line 1:
Since Link / Up-time = 5 days 6 min 23 sec = 432383 s
FEC downstream: 178704 CRC downstream : 15
FEC upstream: 46825 CRC upstream: 330
Downstream CRC / FEC = 8.3937684663E-05 = 1 / 11913.6
Upstream CRC / FEC = 7.0475174E-03 = 1 / 141.8939393939
This is with an upstream target SNRM of 6dB and target downstream of 3dB. The effectiveness of the combined error correction systems is spectacular, as too is the difference in effectiveness between downstream and upstream, especially given that the target SNRM difference is in the ‘opposite’ direction.
A question: can I work out how busy the line has been ? How much data has been going through it in both directions?
I thought about looking at the error counts per hour, but then I thought that a busy line and an idle line should not be placed side by side where counts are concerned.
For ADSL2 with ATM, can I take the modem’s reported "data cells" ATM stats figure and multiply by 53 bytes times 8 bits? There are several cell counters: there is that figure and a total ATM cells figure.