It all depends upon the type of noise experienced by your line, but I would fully expect G.INP to mostly remove CRC & E/Secs.
With the old way when data was lost through noise burst (if FEC wasn't enabled or the burst was too long for FEC) then a
CRC would be triggered. CRC is the indicator of a corrupt packet and an instruction is issued to re-request the data at a higher layer. A single CRC should also trigger an Err/Sec, although multiple CRCs in the same second time frame will only record 1 Err/Sec.
With retransmission if data is lost then detection and retransmission is done between the modem and dslam, if an error is detected then it attempts to retransmit from the buffer. I dont fully understand all the ReTX counters and need to do proper research when I get time, but my understanding is that its ETR/LEFTR where most of this goes on. LEFTRS would kind of be the equivalent to Errored Seconds, but its not and the two cant be directly compared because its not a count measurement of time when theres been a data error, but a ratio measurement of when LEFTR was below the ETR.
Unlike CRC, Retransmission doesnt keep trying and trying to send data (limited buffer size) and there are times when the noise burst may be too long for ReTX to be able to recover data, so it is still possible to see the traditional types of errors requiring higher level action.
However because you'd expect ReTransmission to catch most of the data defects, then its obvious that its now counters like LEFTRS are going to be the ones recording data errors first. I suspect (and again something I need to look further into before saying for certain) that with G.INP, the DLM may also be monitoring something like LEFTRS to determine line performance and if need be adjust DLM parameters.
What I was trying to say with my previous post to Alec is that just because a line isnt now showing any CRCs or Err/Secs it doesnt mean that the line is error free. We also need to be looking at the Retransmission counters.... and I suspect that DLM will also be monitoring them too.
ETR = Effective throughput Rate
LEFTR = Low Error Free Throughput Rate/Ratio
LEFTRS= Low Error Free Throughput Seconds
Even when pre-G.INP, my connection was on fastpath for DS & US, I saw a low level of FEC/RSCorr error correction.
Yes you are correct, DLM can and does indeed apply a low level of FEC protection without swinging into full Interleave and INP.
Im not G.INPed yet but you can clearly see from my
R value that my line is using RS encoding on the upstream, but Im not Interleaved.
R: 0 16Over the past decade we've got used to reading stats in a particular way and many forums (including here) got a bit loose with the term Interleaving when really we should have also been talking about Error Correction. I've already mentioned several times in this thread that since the advent of G.INP its now more important than ever that we make the distinction between Interleaving, Error Correction and Error Protection because they are 3 separate things that can be applied independently. In the past we lumped them all together because DLM used to switch them on at the same time.... whereas now the FTTC/NGA DLM doesnt.