Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: xreyuk on February 09, 2015, 01:22:07 AM
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Hey,
I had to reset my modem a couple of times over the past couple of weeks due to power work at my house. I've left it disconnected for over 30 minutes to try and avoid DLM intervention.
The past 2 times I've resynced, I've synced at exactly 44,000Kbps downstream, with a D value of 861, and the other stats very similar, including SNR.
Would this suggest a banded profile or just a big coincidence?
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Checking the value of your SNR Margin immediately at sync would be an indicator.
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Checking the value of your SNR Margin immediately at sync would be an indicator.
Thanks. What would I be looking for?
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Checking the value of your SNR Margin immediately at sync would be an indicator.
Thanks. What would I be looking for?
The downstream SNRm will be much higher than your previous SNRm after the line was banded.
IE: lower downstream rate = higher SNRm
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FTTC seems to stick with a target margin of 6dB, both upstream and downstream.
Immediately after a sync, the modem stats will be in one of two states:
a) The modem synchronised with an actual margin of 6dB - which shows that it very likely negotiated the speed relative to a target margin of 6dB
b) The modem synchronised with an actual margin above 6dB - which shows that it is very likely the sync speed was capped artificially.
The artificial cap could be the top speed of the package you are paying for (so 40/2, 40/10 or 80/20), or it could be a lower "banded" value.
This is true for both upstream & downstream independently.
(The above is how FTTC line profiles are currently understood; however note that someone just posted with a case where they saw 3dB. We have no evidence whether this is a change to the FTTC line profiles, or something else going on).
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bear in mind allow for some variance, I dont think I have ever seen 6.0db on a new sync, so I would say anything up to about 6.7db is within variance.