Kitz Forum
Broadband Related => Broadband Technology => Topic started by: Weaver on September 21, 2016, 10:26:04 PM
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If I remember correctly, when you do an SNR margin reset it puts an ADSL line back into the training phase. Is this true for 21CN ADSL2+? How long before I should see a change in sync rate, and do I have to restart the modem to see the effect?
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Hmmm ?? On BT classic ADSL it certainly takes it back to a default 6dB/Fast profile, so I suppose dependant on what conditions/line length the DLM sees, it could be classed as a 'Training period' as it has to 're-learn' its MSR's and FTR's etc ....
No idea with LLU DLM though ??
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This is BTW, not LLU. I was trying to reset the downstream target SNRM from 6 dB to 3 dB on this line, as part of a test run that I mentioned some while ago. I have already done so with the other two lines.
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I am uncertain but perhaps a modem - DSLAM resynchronisation, at around 1100 hours tomorrow morning, might be a worthwhile experiment. :-\
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This is BTW, not LLU. I was trying to reset the downstream target SNRM from 6 dB to 3 dB on this line, as part of a test run that I mentioned some while ago. I have already done so with the other two lines.
I see. I was referring to the DLM SNR reset (default) that we perform, Weaver. I have no idea how it would behave with an EU applying their own parameters ?? :)
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I think what weaver is referring to is a specific option available to AAISP customers available from their Control Panel. I see no reason why it cant be available to adsl2+... just not VDSL.
As to how long it takes- I'm not sure as it would depend if they are batch processed and how long it takes them to put the request through to BTw... and then for BTw to act on it. Once its been acted upon it should be immediate - same as if it was done by the OR engineer.
>> I was trying to reset the downstream target SNRM from 6 dB to 3 dB on this line
AFAIK default is 6dB so performing a reset would take it back to 6dB. :-\
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Kitz is quite correct. I was using, and possibly misusing, the terminology used on the Andrews and Arnold ‘clueless’ server’s control panel. I don't know that hitting this AA button puts the line back into the training phase, that's just my guesswork. Maybe there's more than one way of changing the target SNR margin on a BTW 21CN line. I didn't have this ability before when I was on 20CN, and I would have had to ask tech support to find out whether they could change it or not.
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In fact, see
http://support.aa.net.uk/BT_ADSL_Line_Profiles
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Results before and after - the second snapshot was taken following a forced resync, eleven days after the change of downstream target SNRM was requested
Before: (when set at 6dB downstream target SNRM)
BT Test xDSL Status Check:Pass Standalone sub test passed successfully.Pass OK. Circuit In Sync
BRAS=2321kb/s FTR=1817kb/s MSR=2272kb/s ServOpt=1 I/L=I
A SERVICE OPTION CHANGE ORDER IS IN PROGRESS ON THIS LINE
Up Sync=402kb/s LoopLoss=43.2dB SNR=6.3dB ErrSec=0 HECErr=0 Cells=0
Down Sync=2631kb/s LoopLoss=66.1dB SNR=1.1dB ErrSec=0 HECErr=N/A Cells=0
After: (now set at 3dB downstream target SNRM)
BT Test xDSL Status Check:Pass Standalone sub test passed successfully.Pass OK. Circuit In Sync
BRAS=2321kb/s FTR=1817kb/s MSR=2272kb/s ServOpt=1 I/L=I
A SERVICE OPTION CHANGE ORDER IS IN PROGRESS ON THIS LINE
Up Sync=412kb/s LoopLoss=42.9dB SNR=5.9dB ErrSec=0 HECErr=0 Cells=0
Down Sync=2670kb/s LoopLoss=65.9dB SNR=3.2dB ErrSec=0 HECErr=N/A Cells=0
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Pretty unimpressive, a gain of 40 kbps downstream. Interesting that the upstream has improved too, slightly. And notice that the loop loss figures are different, for some unknown reason, presumably because the bits-to-bins allocation table is different. Not sure why, as these other numbers don't seem to change over time. However, maybe just taking repeated snapshots every so often isn't enough, and perhaps I need to force a resync more often in order to be able to see what's going on.
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It hasn't learned MSR/FTR, and looks like profile is unchanged
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