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[Chrysalis]

Ok yesterday my attainable jumped up from 72 to 102 and then it went down again from 102 to 73.  It went down at 8.40pm and I went to the cabinet immediatly when it happened as I noticed it live, and a engineer was there.

So basically people here have reported in the past having a lift and shift can fix problems with noise but that to me never made sense, unless the dslam circuit itself was faulty and leaking noise.  But after speaking to this engineer I think I know whats going on.

So the normal voice cabinet has pairs fed to the FTTC cabinet adjacent to it, the FTTC cabinet cannot be accessed by normal engineers.  So a lift and shift involves swapping the pair between the 2 cabinets.  My new theory is these fixes from lift and shift is that pairs between the 2 cabinets have variable noise whether its external noise or crosstalk.  This engineer told me he changed pairs on dozens of live cables so he could fit new customers in, and then he moved the pairs back again at the end of the day. He seemed very surprised that it had a huge impact on my attainable speed and unlike other engineers he didnt tell me to move on and go on my way he listened to me and promised to send feedback to the area manager, he even came back to my property and looked at my graphs.  Sadly since he had no idea which pair is mine he couldnt move it back and he didnt have time to move all the cables back again, he said otherwise he would have done it.  But his view is if there is a problem between the 2 cabinets since its such a small distance it has a moderate chance of been fixed as it should be cheap to do.  I told him about hoiw I lost tons of attainable sync twice within 3 weeks of my new install and asked him if its possible I was "lifted and shifted" on those 2 occasions, he said its very possible but couldnt say for sure as was so long ago now, he took my mobile number and said would ring me back next week to let me know if BT will fix it or not.

Also forgot to mention on both changes of speed I was disconnected, even when the attainable went up.

If we assume he either doesnt call back or says they wont fix, any advice on how to deal with this?

should I try and report a fault again? best way to go about it? or continue to accept I am not getting full performance from my line?

[kitz]

Not ignoring you, as I dont know and I was hoping that someone else may have some ideas.

>> I lost tons of attainable sync twice within 3 weeks of my new install

I'd normally expect routine crosstalk to build up over time...  for example like how it did on adsl2+ gradually decreasing speed as more users were put on the linecard/MSAN.  This type of background crosstalk (as yet) cant be avoided.  A sudden jump is more unusual.  The usual crosstalk we experience is  defined as NEXT and FEXT.  From the MSAN side PSD masks help with NEXT and vectoring will supposedly help with FEXT, but theres also something called Alien crosstalk thats seldom talked about. I know zilch about it though but perhaps may be worth having a look into?

[Chrysalis]

Yeah maybe, for now I am giving a chance for this guy to ring me back.  He might get somewhere by himself.

[Chrysalis]

I have had a call not long ago of the guy I met last week, I been informed I will have outages tommorow as they going to try and diagnose where the problem is.

Hopefully they will find the issue, my attainable is creeping down still more today.

[kitz]

hope it all goes well and they find out what it is

[Chrysalis]

nothing happened

[kitz]

Do you mean a no show...
or turned up and did nothing?

[Chrysalis]

he did show, he rang me up today.

They started moving the pairs but then had to stop because various lines were losing huge chunks of sync speed, he said it looks like about 2/3 of the pairs between the cabinets have significant noise injection/crosstalk.  So fault is confirmed but is no planned cause of action yet.  There is a 2nd cabinet he said its possible everyone will be moved to 2nd cabinet, or at least most people and then they can work on the 1st one, but he couldnt give me any estimate date.  He said the bad pairs some of them couldnt even get 80/20 at the cabinet they were so bad.   These pairs go underneath a traffic junction on a main road, the FTTC cabinets are across the road from the normal cabinet and that is a traffic lights junction.

[kitz]

So it at least seems like they know there is a problem.   Lets hope that it is soon resolved.

[Chrysalis]

yeah the guy sounds confident in what he is saying and wasnt dumbing it down talking to me, so I may have got somewhere.

[Chrysalis]

I think I just got swapped again, seem shifting live cabinet pairs is common in my area.

currently my attainable on the ds is 6mbit higher than my actual sync so I am guessing if I resync again I can recovery the ds sync speed back but the us snrm is now lower than before.  So line characteristics have changed.