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[licquorice]

A few rambling thoughts and questions about how DLM and banding operate using my Infinity 1 line for figures. Not particularly worried about getting my line unbanded, just trying to get my head around things.

 'The event' was a period of severe instability on my line that just came and went without any intervention, no idea what caused it.

Before 'the event' my Downstream actual sync was the Infinity 1 max of 40M with a max attain of 45/46M Snrm 8/9dB with G.Inp active. Upstream was 9/10M actual with max attain about the same, Snrm 6dB with G.Inp inactive. Subsequent to 'the event', my upstream had G.Inp applied and the actual didn't change but max attain went to ~11/12 with a Snrm of 7dB . Downstream was banded at 35M with max attain unchanged at 45/46 but with an increased Snrm of ~10 as you would expect with the lowered actual sync speed. About 2 weeks after 'the event', G.Inp was removed from my upstream and the figures went back to those of before, as expected. When my line was upgraded to the new Infinity1 speeds, my upstream saw no change as expected but my downstream had G.Inp removed and interleaving applied, my Snrm dropped from 11/12 to 7 but my max attain remained at 45/46 despite the lower Snrm and actual sync unchanged at 35M. I would have expected the max attain to drop in line with the drop in Snrm. Almost as if the max attain is calculated  unaware of the banding still in place and thinks actual is still 40M. Is DLM a part of G993.2 or is it a proprietary addition? How are the downstream stats reported back to the DSLAM in order for it to take action? Is it possible that unlocked modems and third party routers do not report the correct downstream information back to the DSLAM?

Grateful for any information or insight into what is happening.

[ejs]

DLM is proprietary, it is not detailed in the G.992.3 document, although the existence of some sort of "management entity" may be occasionally mentioned. The mechanisms for reporting the downstream stats to the DSLAM are covered in G.992.3 (and perhaps also G.997.1).

I suppose it's possible that if your modem reported the wrong values, the other end wouldn't necessarily know they were wrong, although I wouldn't have thought this kind of thing would be wisespread. I am aware of an issue with the old AR7 chipset based modems on ADSL2: mine does not include SES in the ES count (I think by definition, a Severely Errored Second is also an Errored Second), in the past this resulted in occasional issues with such high error rates to result a completely unusable Internet connection, but the connection didn't drop and the DLM appeared to be completely unaware of any problem, probably because the ES count was fairly low, because it was only being included in the SES count.