Whilst I was away from the PC, this topic was still niggling at me.
I've been thinking about Spectral Management, yet Chrys said "
I also perhaps should clarify openreach themselves have told me this. "
Whilst I don't have this info, I was mulling it over whilst supposed to be doing something else, because I also have no reason to disbelieve why Chrys would say that when I know he has a pretty reliable source, yet it conflicts with how DSL is supposed to work.
Whilst traditionally Spectral Management profiles are set on the DSLAM and kind of hardwired into a profile - although complex, the base figure (Distance of cab to exchange) is straight forward, so then the DSLAM can make a fairly simple calculation for the later part. ie
IF (atten = 'x' DB) THEN (set profile 'A');.
This is totally separate from DLM.
Anyhow this is how the rest of my rambling thoughts went.
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Now they are using vectoring on some Huawei cabs, Spectral management will become a lot more complex for something which is already complicated. Although I havent seen any signs of dynamic SPM on the downstream for ECIs... thats not to say that they dont have something in place to cover the Huaweis cabs with Vectoring. Those cabs with vectoring would greatly benefit from DSM even non vectored lines in the area.
So back to DSM and DLM being separate. They will be separate parts of the system but it is possible that the RAMBO boxes could be used to calculate DSM. In a similar way that the RAMBO boxes also control RAP. Yet RAP is the bRAS control and different from DLM.
Trying to think of an easy way to explain it - try the following.
- RAMBO is like a powerful PC
- DLM is like a program that runs on the PC. This program is in charge of calculating which DLM parameters to set on the DSLAM. It then tells the DSLAM whether the EU's line should have Interleaving. (Lets pretend this is MS Access).
- RAP is a like a separate program that runs on the PC which is in charge of calculating the bRAS profile. It then sends that information over to the bRAS. (Lets pretend this is MS Excel)
2 completely separate programs but all running on one box. DLM is nothing to do with RAP.. but both are part of BTs DLM system because it's RAMBO doing the calculations based on the current sync speed to send over to the bRAS.
Got me so far?
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Now if Openreach are using DSM because of vectoring, then there could be some very intricate calculations to be made. Something will have to calculate the best Spectral profiles for all the lines in the area. Because we still have the legacy DSL systems in place this task becomes even more arduous. The DSLAM is relatively dumb, it mostly does what its told.. its basically a fancy modem handling a few hundred lines.
Something else will have to be calculating which DSM profiles to use... each and every cab will be different based on line lengths of all the users in that area. You'd need something which can access line stat data (such as atten) from the DSLAMs.
Why not use the RAMBO boxes to do the number crunching, it can already communicate with the DSLAM, it will already have access to line stat data. So now you just install another program which can take this data and calculate the relevant mask for each line which then sends that info back to the DSLAM.
Using my example above lets say its the equivalent of MS Word on that PC that already has Excel and Access.
All 3 are totally different programs that do their own thing, but they are all part of the MS Office suite running on one box.
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The more I think about it the more it makes sense. I'm certain I wrote on this very forum several months ago that BT was updating its RAMBO boxes.
It would explain why Openreach may call it part of the
DLM system... and yet why it is not part of DLM profiling which we see as things like INP, G.INP, target SNRM, Interleaving. Its just another program running on the RAMBO boxes which does its own thing separate to DLM.
Others thoughts are more than welcome