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[ccarmock]

I have a line that used to run ADSL 2+ and achieved approx 17 Mb/s down.  The router used to report attenuation of 29 dB.  Since it was upgraded to VDSL it now reports an attenuation of 26 dB.

The Kitz speed calculator implies that would mean it's approx 1.9 km from the PCP?

However a BT line test on that line estimates it at around 1 km, so would I be right in thinking the attenuation should be lower and there is a possible high resistance joint?  On VDSL it achieves a banded 35 Mb/s down and a banded 6 Mb/s up.   I am hopeful the banding will be removed (it's be banded for over a year though!), as the router claims attainable of 41 Mb/s down and 7.9 Mb/s up.

[kitz]

Its much harder to calculate on vdsl because there are many more tones available.

As an example when you move from adsl1 to adsl2+ the opening up of the additional tones adds approx an additional 3dB of attenuation yet the line length is still exactly the same.   

[NewtronStar]

Do you get many errored seconds on your circuit and if so how many ES's are being counted in typical 24 period ?

With a 1Km VDSL2 line the attenuation can vary anywhere from 23 to 26 the type of metal conductivity & resistivity seems to play a big part on FTTC and even different VDSL modems may show higher or lower attenuations.

Would say a line @ 1Km a sync of 34Mbps to 38Mbps is normal and adding some crosstalk and other issues like RFI.

[burakkucat]

I have a line that used to run ADSL 2+ . . .  The router used to report attenuation of 29 dB.  Since it was upgraded to VDSL it now reports an attenuation of 26 dB.

Remember with a G.992.1/G.992.3/G.992.5 (ADSL) service, the reported attenuation is for the metallic pathway from your premises to the exchange based equipment. However for a G.993.2 (VDSL2) service, the reported attenuation is for the metallic pathway from your premises to the cabinet-based equipment. As the former involves both the D- & E-sides whilst the latter just involves the D-side, like is not being compared with like.

[ccarmock]

Thanks - all useful info - appreciate your help.

To confirm error rates - in the past 24 hours I've seen 22 ES downstream and 2 SES down.
Up I have seen 12 ES and 3 SES
107 CRC errors down and 0 FEC
28s UAS
SNR margin down is 7 dB

ReTX is on for upstream only, Trellis on in both directions, as is Bitswap.

[NewtronStar]

With 22 Downstream errored seconds in 24 hours that would be ok and Green on MyDslWebStats.
With just 7dB available on your DS SNRM the most you could gain with 6dB would be 2000Kbps taking your sync rate to 37Mbps.

Just a question if you only have Retransmission ReTX on the upstream then what happened to your downstream ?

[ejs]

ReTX is on for upstream only

I think that's unlikely to be correct, retransmission is probably on for downstream only, and it's displayed the wrong way around by some DrayTek devices.

[j0hn]

ReTX is on for upstream only, Trellis on in both directions, as is Bitswap.

I don't think that's even possible with the OpenReach FTTC DLM. Retx is enabled by default on the downstream (with compatible modems). It's only enabled on the upstream if there's sufficient errors.
I've never seen a line with upstream Retx without downstream Retx.

As ejs points out Draytek devices display some things backwards. The near end/far end is confusing enough without mixing up figures.  I know the DrayTek 2860 is 1 of the devices that mixes upstream/downstream Retx as can be seen in this post here.

[ccarmock]

I think that's unlikely to be correct, retransmission is probably on for downstream only, and it's displayed the wrong way around by some DrayTek devices.

You could well be right - this is a Draytek 2860.  I assume no way to get myDSLwebstats from a Draytek?

[PhilipD]

Hi

Thanks - all useful info - appreciate your help.

To confirm error rates - in the past 24 hours I've seen 22 ES downstream and 2 SES down.
Up I have seen 12 ES and 3 SES
107 CRC errors down and 0 FEC
28s UAS
SNR margin down is 7 dB

ReTX is on for upstream only, Trellis on in both directions, as is Bitswap.

ADSL and VDSL is designed to run with errors, it isn't designed to be error free, as if it were it would be chugging along at a fraction of the speed.  Other mechanisms further up the network stack deal with errors be re-requesting the data, so you don't get errors in downloads or in your emails etc.  Re-transmission helps to a certain degree but again it isn't designed to make VDSL error free, just fewer errors.

Your reported error rate are absolutely fine and nothing to worry about.

Regards

Phil