It is a bit confusing in some circumstances as DLM might be just being slow to relent. I know interleaving got put on my line to a depth of 1235 DS and is off on US.
Remember that "banding" is just one of the tools that DLM can use - and it is often the last straw on very bad lines. In the past, the other alternative was to put interleaving in place - where DLM had the option of "low" and "high" settings; it would often try "low interleaving" as the first option, before trying "high interleaving", and finally attempting "banding" where the max speed is artificially limited (I thought the min speed was also artificially limited too, to stop the line achieving an accidental "really low" speed during bad moments).
Nowadays, "retransmission" has become another option for DLM too, with a variety of "high" and "low" settings to use, and has become the preferred option, even to an "open" profile.
In the past, DLM didn't seem to use banding much, and the idea of "relenting" was about getting it to remove interleaving. In fact, wasn't Walter on here fairly recently posting regular updates on one of his wheelbarrow-fixes? That line, which was in a sorry state before the fix, seemed to reband itself every few days on the road to improvement, but IIRC never got to its full possible potential.
Nowadays, with retransmission available, it appears to have become a more complicated beast. Banding looks to happen more often, and be much stickier, with little hope of relent. I don't know why, but I do wonder if the increased take-up (and increased crosstalk) is affecting BT's choices here.
Is 'banding' confined to FTTC?
It's a BT thing?
It is a BT thing, but it can happen on ADSL2+ too.
39973 is probably something to do with framing size.
Its why my line used to always sync at 79987, rather than 80000.
I think I half-discovered why recently, but have lost track of it now. It does indeed look to be a complicated relationship with the various elements of framing.
Can banding happen on the US too?
My US sync as always been 18999. Attainable rate is 21682.
Yes, banding can happen on the upstream too.
