Plusnet "current line speed" v2 - modem stats

In reply to a post by Brookzy:

Here's the first batch of stats

# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:	0
Max:	Upstream rate = 15019 Kbps, Downstream rate = 57708 Kbps
Path:	0, Upstream rate = 15142 Kbps, Downstream rate = 58157 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783) 
DS: (32,859) (1216,1963) (2792,3971) 
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783) 
DS: (32,859) (1216,1963) (2792,3971) 
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 15019 kbps 57708 kbps
Actual Aggregate Tx Power: 7.4 dBm 13.9 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB):	 5.5	 25.4	 37.4	 N/A	 14.2	 31.2	 46.9	
Signal Attenuation(dB):	 5.5	 24.6	 36.7	 N/A	 14.2	 31.2	 46.9	
SNR Margin(dB):	 5.6	 5.7	 5.7	 N/A	 5.9	 5.9	 5.9	
TX Power(dBm):	 0.6	-17.9	 6.4	 N/A	 11.2	 8.2	 6.8

Can you also post the output with the "--stats" option? That will tell us what DLM has been up to.

Then just for comparison, here are my stats. Line between 350 and 400m.

# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Last initialization procedure status:   0
Max:    Upstream rate = 25501 Kbps, Downstream rate = 82188 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 79987 Kbps

Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3970)
Medley Phase (Final) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3970)
                  VDSL Port Details               Upstream                Downstream
Attainable Net Data Rate:           25501 kbps              82188 kbps
Actual Aggregate Tx Power:             6.9 dBm               13.1 dBm
====================================================================================
        VDSL Band Status                U0              U1              U2              U3              U4              D1              D2              D3
  Line Attenuation(dB):  4.3     21.6    32.5     N/A     N/A    11.3    27.1    41.3
Signal Attenuation(dB):  4.3     20.7    31.5     N/A     N/A    15.8    26.8    41.4
                SNR Margin(dB):  15.5    14.8    14.8     N/A     N/A    6.9     6.9     6.9
                 TX Power(dBm): -2.9    -21.7    6.5      N/A     N/A    9.8     7.9     6.9
#

Thanks for making a v2!!!

Here you go...

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:	0
Max:	Upstream rate = 14877 Kbps, Downstream rate = 57280 Kbps
Path:	0, Upstream rate = 15142 Kbps, Downstream rate = 58157 Kbps

Link Power State:	L0
Mode:			VDSL2 Annex B
VDSL2 Profile:		Profile 17a
TPS-TC:			PTM Mode
Trellis:		U:ON /D:ON
Line Status:		No Defect
Training Status:	Showtime
		Down		Up
SNR (dB):	 5.8		 5.6
Attn(dB):	 0.0		 0.0
Pwr(dBm):	 13.9		 7.4
			VDSL2 framing
			Path 0
B:		239		237
M:		1		1
T:		64		64
R:		0		16
S:		0.1313		0.5000
L:		14619		4064
D:		1		1
I:		240		127
N:		240		254
			Counters
			Path 0
OHF:		46885559		1878115
OHFErr:		682		110
RS:		0		1014017
RSCorr:		0		3590
RSUnCorr:	0		0

			Path 0
HEC:		1397		0
OCD:		0		0
LCD:		0		0
Total Cells:	2466201817		0
Data Cells:	251364723		0
Drop Cells:	0
Bit Errors:	0		0

ES:		470		107
SES:		0		0
UAS:		75		75
AS:		98911

			Path 0
INP:		0.00		0.00
PER:		2.10		8.00
delay:		0.00		0.00
OR:		91.36		31.00

Bitswap:	12421		10435

Total time = 1 days 3 hours 30 min 6 sec
FEC:		0		0
CRC:		682		0
ES:		470		107
SES:		0		0
UAS:		75		75
LOS:		0		0
LOF:		0		0
Latest 15 minutes time = 6 sec
FEC:		0		0
CRC:		0		0
ES:		0		0
SES:		0		0
UAS:		0		0
LOS:		0		0
LOF:		0		0
Previous 15 minutes time = 15 min 0 sec
FEC:		0		0
CRC:		2		0
ES:		2		1
SES:		0		0
UAS:		0		0
LOS:		0		0
LOF:		0		0
Latest 1 day time = 3 hours 30 min 6 sec
FEC:		0		0
CRC:		114		0
ES:		84		14
SES:		0		0
UAS:		0		0
LOS:		0		0
LOF:		0		0
Previous 1 day time = 24 hours 0 sec
FEC:		0		0
CRC:		568		0
ES:		386		93
SES:		0		0
UAS:		75		75
LOS:		0		0
LOF:		0		0
Since Link time = 1 days 3 hours 28 min 31 sec
FEC:		0		3590
CRC:		682		110
ES:		470		107
SES:		0		0
UAS:		0		0
LOS:		0		0
LOF:		0		0
#

OK, I can see the following about DLM:

- It has ordered no intervention for FEC or interleaving in either upstream or downstream.
INP=0 and delay=0.

- Interleaving is off in both direction
D=1

- FEC is off downstream, but turned on upstream
R=0 downstream, R=16 upstream

- The FEC overhead upstream is about 6%
(R=16, N=254, R/N=0.063)

- The error rate seems to be OK
CRC over last 24 hours is 568, and ES is 386

For comparison, the DLM settings are identical on my line (which is 80/20, but 82/25 attainable).

I'm currently getting the same rate of ES as you (averaging 400-500 per day over the last month), but it was averaging around 650 per day for the 2 months before that.

However, my CRC rate is about 10x the ES rate, which means that when I get errors, they come in bigger bursts. Thankfully, it appears to be the ES rate that DLM looks at.

Conclusion:
Those settings suggest that your line is running as fast as it can, so doing anything to the DLM profile, right now, would be pointless.

^{Edit: add conclusion}

Edited by deleted (Fri 28-Feb-14 11:09:42)

Thanks very much for your analysis.

I thought the CRC figures were a bit high but I guess not!

So DLM can be eliminated as a factor. Still disappointing that the BT Wholesale Availability Checker estimates up to 70 mbps (recently revised down from 72), yet realistically it is a good 25% slower than that.

Just out of curiosity, is it possible to "walk" your line, i.e. make a guess at actual line length back to the cabinet?
I have a line that is probably about 320m as you walk the route but the dsl checker isn't confident of full speed.
Have many people got estimated / accurate line length figures, checker estimates and corresponding real speeds for their own connections, would be useful to start a database for comparison.
flipdee

Hi Flipdee,

Here's a graphic showing a couple of routes I think the cable could take and distances taken from Google Earth
http://f.cl.ly/items/2V430X3G1V243Q0I1A1m/Phonecable...

I'd say my home line is about the same length as your worst case, maybe a tiny bit longer and I'm getting a stable 67.3 download 20Mbps upload.
Obviously two lines can't quite be compared side by side without a lot more details.
I'll see if I can dig out the line stats for my line.
Cheers,
flipdee

Edited by deleted (Sat 01-Mar-14 00:04:24)

Hmm... Just picked up the landline phone and noticed a bit of noise. So did a quiet line test and there seems to be some sort of interference.

Here's a four second recording of the sound. It's quiet, but I didn't want to boost the volume as it would distort its comparative loudness on the phone.

(Download link for browsers that do not play the file automatically. Approx. 30 KB.)

Okay,

Line 1:

Text
1 23 45 67 89 1011	VDSL2 framing                         Path 0B:              239             237 M:              1               1T:              23              42 R:              0               16S:              0.0956          0.3781 L:              20080           5374D:              1               1 I:              240             127N:              240             254

Text

1 23 45 67 89 1011 12

Max:    Upstream rate = 22919 Kbps, Downstream rate = 74432 Kbps Path:   0, Upstream rate = 19999 Kbps, Downstream rate = 79891 Kbps         VDSL Port Details       Upstream        DownstreamAttainable Net Data Rate:      22919 kbps         74432 kbps Actual Aggregate Tx Power:        7.1 dBm          14.1 dBm============================================================================   VDSL Band Status        U0      U1      U2      U3      D1      D2      D3  Line Attenuation(dB):  4.3     22.5    33.4     N/A    11.8    27.2    42.3 Signal Attenuation(dB):  4.3     21.5    32.4     N/A    11.8    27.2    42.3        SNR Margin(dB):  14.5    13.7    13.7     N/A    4.5     4.4     4.4          TX Power(dBm): -1.7    -20.7    6.5      N/A    11.6    7.7     7.1

This line, when it was the first connection on the cabinet, had attainable rates of 98020 kbps downstream and 29421 kbps upstream, it has had a single resync since then to the numbers above. That's the impact of 4 full cards worth of crosstalk.

Line 2:

Text
1 23 45 67 89 1011	VDSL2 framing                         Path 0B:              239             237 M:              1               1T:              21              42 R:              0               16S:              0.1044          0.3781 L:              18384           5374D:              1               1 I:              240             127N:              240             254

Text

1 23 45 67 89 1011 12

Max:    Upstream rate = 21650 Kbps, Downstream rate = 71544 Kbps Path:   0, Upstream rate = 19999 Kbps, Downstream rate = 73133 Kbps         VDSL Port Details       Upstream        DownstreamAttainable Net Data Rate:      21650 kbps         71544 kbps Actual Aggregate Tx Power:        7.1 dBm          14.1 dBm============================================================================   VDSL Band Status        U0      U1      U2      U3      D1      D2      D3  Line Attenuation(dB):  4.7     22.7    34.1     N/A    11.8    27.5    42.3 Signal Attenuation(dB):  4.7     21.8    33.3     N/A    11.8    27.5    42.3        SNR Margin(dB):  14.6    14.1    14.2     N/A    5.5     5.5     5.5          TX Power(dBm): -1.9    -20.7    6.5      N/A    11.6    7.9     7.0

So essentially a 25% loss in attainable downstream. Staggering.

Come on BT... get the vectoring rollout going!

I wonder how effective vectoring is? Does it wipe out the crosstalk or only mitigate it?