What quite doesnt tie up with me.. is how a full reset to open profile will give you a few days to supposedly download the updated ECI f/w.
Openreach appear to be forcing g.inp except on open profile.. so is it DLM forcing it rather than the DSLAM? Something is.
I thought the general principle was that DLM sets out what
ought to happen, with a variety of configuration property settings, including some minimums and maximums (and we don't get to see all of these), and the DSLAM follows a channel initialisation policy that attempts to maximise X, minimise Y (etc) within constraints set by those DLM configuration properties.
I think that a DLM reset, of either variety, fundamentally changes the set of DLM configuration properties to something that either a) turns G.INP off and turns interleaving off; or b) turns G.INP off, and turns interleaving on downstream. I haven't figured out why there might be two different starting points, or why they might be chosen.
When DLM "turns on G.INP", it makes another fundamental change to the configuration properties, that allows retransmission to activate (forced or optional? Interesting debate), but the DSLAM continues to follow a policy of minimisation/maximisation that gives it freedom to alter some of the detailed outcome. This freedom means that some chipset/modem implementations can end up with a different detailed outcome, even if DLM starts out asking for the same thing.
What gives DLM the ability to choose to "turn on G.INP" for a line?
I thought OR had said they run a process to enable G.INP on a regular basis and will continue to do so.
I think this is a process running "above" DLM - a new supervisor process whose job is to determine what options DLM is allowed to choose for an individual line. As far as G.INP/retransmission is concerned, it looks like the default setting here is: "don't consider" - that DLM (in it's nightly decision process) isn't allowed to even consider retransmission as one of the "solutions" to a line in ILQ-RED/CRIMSON/SCARLET.
The supervisor level might then take the responsibility of deciding whether the chipset/modem is one that requires a restriction of the retransmission options.
If there are two levels, then I wonder whether the two different kinds of DLM reset that we see depend on whether the reset is done at the lower (nightly) level, or the upper (supervisor) level.
I could see a reset at the lower level being one that removes retransmission as a "solution", and replaces it with interleaving. I could see a reset at the higher level being one that takes away all "solutions", so DLM (at the lower level) only has the option of an "open profile" left available.
Now, some of the behaviour we've seen over the last year - especially new lines being put to the back of the (long) queue before retransmission is even considered - suggests there is very much a second process involved. Whereas the original DLM worked every night, on every line, in parallel (and still looks to), the new aspects seem to work slowly, over some lines, in a nationwide pool. Something is definitely running to a bigger overview.
If there is a second "something" running, then it makes sense that it makes decisions very independently of the other, nightly, process.