New SNR Margin On FTTC Line Connected To Huawei Cabinet

Hi guys,

Just noticed that the line has resynced and there have been several changes made to it by DLM.

Here's the line stats before and after.

Just wondering if it looks like the new implementations announced by Openreach have been activated on the line?

Before:

xDSL
Mode VDSL2
Traffic Type PTM
Status Up
Link Power State L0
Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 6.8 6.0
Attenuation (dB) 26.0 0.0
Output Power (dBm) 12.2 5.5
Attainable Rate (Kbps) 42250 8748
Rate (Kbps) 40844 8748
B (# of bytes in Mux Data Frame) 243 227
M (# of Mux Data Frames in an RS codeword) 1 1
T (# of Mux Data Frames in an OH sub-frame) 0 0
R (# of redundancy bytes in the RS codeword) 10 10
S (# of data symbols over which the RS code word spans) 0.1902 0.8289
L (# of bits transmitted in each data symbol) 10682 2297
D (interleaver depth) 8 4
I (interleaver block size in bytes) 254 238
N (RS codeword size) 254 238
Delay (msec) 0 0
INP (DMT symbol) 48.00 46.00
OH Frames 0 0
OH Frame Errors 0 0
RS Words 80201240 1295108
RS Correctable Errors 102067 111
RS Uncorrectable Errors 0 0
HEC Errors 0 0
OCD Errors 0 0
LCD Errors 0 0
Total Cells 300831147 0
Data Cells 3517590 0
Bit Errors 0 0
Total ES 0 0
Total SES 0 0
Total UAS 30 30.

After:

xDSL
Mode VDSL2
Traffic Type PTM
Status Up
Link Power State L0
Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 5.2 6.4
Attenuation (dB) 26.0 0.0
Output Power (dBm) 12.0 4.8
Attainable Rate (Kbps) 45875 8531
Rate (Kbps) 45327 8531
B (# of bytes in Mux Data Frame) 227 227
M (# of Mux Data Frames in an RS codeword) 1 1
T (# of Mux Data Frames in an OH sub-frame) 0 0
R (# of redundancy bytes in the RS codeword) 10 10
S (# of data symbols over which the RS code word spans) 0.1600 0.8500
L (# of bits transmitted in each data symbol) 11901 2240
D (interleaver depth) 4 4
I (interleaver block size in bytes) 238 238
N (RS codeword size) 238 238
Delay (msec) 0 0
INP (DMT symbol) 55.00 47.00
OH Frames 0 0
OH Frame Errors 585 0
RS Words 48041396 495669
RS Correctable Errors 29141 21
RS Uncorrectable Errors 0 0
HEC Errors 0 0
OCD Errors 0 0
LCD Errors 0 0
Total Cells 168230857 0
Data Cells 2244583 0
Bit Errors 0 0
Total ES 14 0
Total SES 11 0
Total UAS 68 57.

Edited by deleted (Sat 21-Jan-17 20:07:28)

In reply to a post by WilliamGrimsley:

Just wondering if it looks like the new implementations announced by Openreach have been activated on my line?

Do you mean the lower allowed sync-time noise margins? Doubtful. The only way to be sure is to read the stats within seconds of a re-sync.

The changes in your figures overall look to me look like your first set were due to sync'ing at a relatively noisy time and the noise went away. The re-sync at a less noisy time and at the time you read the stats the noise level was a fraction higher than at sync-time.

The only noticeable change I see is that DLM has slightly reduced the downstream interleaving depth. (And associated parameters). Both sets suggest that G.INP is active, but your modem does not displaying Bearer 1 figures. Only Bearer 0. I'm saying this because interleaving at these very low levels is typical of "with G.INP". Without G.INP downstream interleaving is normally in the high hundreds or a few thousands.

Upstream interleaving is quite rarely seen on these forums. Is it a Draytek modem?

Edited by RobertoS (Sat 21-Jan-17 14:33:59)

Hi Bob,

Yes, I have to admit, the first set of stats were at a noisy time, but the second set were taken just minutes after the resync and with such an increase in the downstream rate, I thought something had changed, which, as you can see is true by what you've explained.

No, I'm using a Billion 8800AXL router, I was also surprised to see Upstream G.INP too, this made me also think something had changed, though I have noticed that more Huawei lines are now using Upstream G.INP.

Thanks for your help!

Edited by deleted (Sat 21-Jan-17 15:23:16)

You could possibly now be on a 5dB downstream profile, it is going to have to start somewhere. I guess the only way to be sure will be to check your SNRM at the next resync.

Hi underzone,

It's nice to see you on the forum, I hope you're well.

I should think so, here's an update:

xDSL
Mode VDSL2
Traffic Type PTM
Status Up
Link Power State L0
Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 5.1 6.5
Attenuation (dB) 26.0 0.0
Output Power (dBm) 12.0 4.8
Attainable Rate (Kbps) 45867 8531
Rate (Kbps) 45327 8531
B (# of bytes in Mux Data Frame) 227 227
M (# of Mux Data Frames in an RS codeword) 1 1
T (# of Mux Data Frames in an OH sub-frame) 0 0
R (# of redundancy bytes in the RS codeword) 10 10
S (# of data symbols over which the RS code word spans) 0.1600 0.8500
L (# of bits transmitted in each data symbol) 11901 2240
D (interleaver depth) 4 4
I (interleaver block size in bytes) 238 238
N (RS codeword size) 238 238
Delay (msec) 0 0
INP (DMT symbol) 55.00 47.00
OH Frames 0 0
OH Frame Errors 585 0
RS Words 306802436 2136261
RS Correctable Errors 260564 97
RS Uncorrectable Errors 0 0
HEC Errors 0 0
OCD Errors 0 0
LCD Errors 0 0
Total Cells 1073890647 0
Data Cells 23613584 0
Bit Errors 0 0
Total ES 14 0
Total SES 11 0
Total UAS 68 57.

Unless he is on a trial cabinet on a trial exchange, then nope. General release isn't scheduled until March.

Oh, I thought it was in February. I wonder why this is the case then. I'll keep monitoring over the next few days and report back if there's any changes.

Edited by deleted (Sat 21-Jan-17 16:12:07)

I concur with one of the other reports ... your new INP level has changed, but both old and new are values that go with G.INP. The small level of interleaving depth (8 before, 4 after) are also both indicative of G.INP

I note too that G.INP is active in both the upstream and downstream. Both before and after.

Your new sync looks suspiciously like it is targeting 5dB. The current SNRM level is at 5.1dB and the actual & attainable speeds are close enough to not worry about.

That would make me wonder, and monitor...

In reply to a post by RobertoS:

Unless he is on a trial cabinet on a trial exchange, then nope. General release isn't scheduled until March.

From Kitz, we know what exchange William is on ... and it is one of the trial exchanges.
It is therefore plausible that this is indeed step 1 of the trial ... to shift a line to a 5dB profile.

In reply to a post by WilliamGrimsley:

I'll keep monitoring over the next few days and report back if there's any changes.

It is very worthwhile monitoring. Can you turn your MDWS logging back on?

In particular, watch the error rates in a few different forms
- Errors fixed by correction: the FEC counters
- Errors fixed by retransmission, the RTX_TX, RTX_Corr and LEFTRS counters
- Errors not fixed - CRC, ES and SES rates

Hi WWWombat,

Thanks for your help, I hope you're well.

Sure, I'll turn MDWS back on once I get it all set up, I should be back on within the next hour.

Cheers!

Uploading now as requested. Should be interesting to watch.