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[JustAnother]

I have recently gained a VDSL2 line, and courtesy of asbokid's work I have unlocked the modem and subsequently spent some time with it. One of the things I wanted a better understanding of was the stats available via '/bin/xdslcmd info', and rather than let my notes rot away I want to share them so that the next me coming along would not need to do the investigation work again.

If anyone knows better than this, please can they say (backed up with a source) and I will update this post.


For reference, the cabinet for my line is a few minutes walk away from my house (the BT technician did not know the distance), and the JSDU unit reported the maximum line synch at 36000 Kbit down, 10000 Kbit up – either it was provisioned on profile 17a or changed to that before I unlocked the modem.

Available Info Commands

Code: [Select]

xdslcmd info [--state] [--show] [--stats] [--SNR] [--QLN] [--Hlog] [--Hlin] [--HlinS] [--Bits]
[--pbParams] [--linediag] [--linediag1] [--reset] [--vendor] [--cfg]
xdslcmd info –state

This provides the most basic data available, which is included at the top of the output of all other stat commands:

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9106 Kbps, Downstream rate = 49912 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps

I have observed the following status values during testing (the states briefly mentioned here at the end):

Code: [Select]

Status: G.993 Started
Status: G.994 Training
Status: Showtime

Showtime indicates that training has been completed and the line is operating normally.

Max represents the maximum attainable rate the line is capable of under the current conditions, and Path 0 lists the rates the line is currently synched at. It appears that in order to use the max rates, you need to resynch with the DSLAM (there is a Seamless Rate Adaption option, but it is disabled by default and probably isn’t available even if it was enabled).

Path 0 refers to the fact that the firmware of the Openreach modem, properly known as the Huawei Echolife Home Gateway, supports multiple tagged VLANs  – 0 is the VLAN your normal connection is ran over and 1 is BT’s backdoor network.

‘It looks as though the “max attainable” figure is actually “max attainable at 6dB SNRM” thus it is possible for this figure to be lower than the current sync if the SNRM drifts below 6dB’ – source.

You can see my max downstream rate is far in excess of the rate I am synched at – this is the 40Mbit cap in action (the line is sold at 40/10Mbit).

xdslcmd info –show

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9124 Kbps, Downstream rate = 49912 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 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): 10.4 6.3
Attn(dB): 0.0 0.0
Pwr(dBm): 11.9 5.8

VDSL2 framing
Path 0
B: 239 223
M: 1 1
T: 64 35
R: 0 16
S: 0.1910 0.7805
L: 10054 2460
D: 1 1
I: 240 120
N: 240 240
Counters
Path 0
OHF: 26881481 1124041
OHFErr: 1492 140
RS: 0 1695887
RSCorr: 0 259
RSUnCorr: 0 0

Path 0
HEC: 4143 0
OCD: 0 0
LCD: 0 0
Total Cells: 2042409149 0
Data Cells: 114539597 0
Drop Cells: 0
Bit Errors: 0 0

ES: 409 130
SES: 4 0
UAS: 16 16
AS: 82459
Path 0
INP: 0.00 0.00
PER: 3.05 13.65
delay: 0.00 0.00
OR: 62.83 35.14
Bitswap: 3486 2599

Annex B: Suggestion that this represents a line that carries voice and broadband.

TPS-TC: Transport Protocol Specific Transmission Convergence sublayer.

The following single letter acronyms courtesy of npr (source pdf, see page 24):

B: Number of bytes in Mux Data Frame.
M: Number of Mux Data Frames in FEC Data Frame.
T: Mux Data Frames over sync bytes.
R: Number of check bytes in FEC Data Frame.
S: Ratio of FEC over PMD Data Frame length.
L: Number of bits in PMD Data Frame.
D; Interleave depth (1=fast path).

OHF and OHFErr: TODO – Unknown.

The following is also backed up by CT-5372 Multi-DSL Router User’s Manual (pdf):

RS: Reed Solomon codes.

RSCorr: Data corrected by Reed Solomon codes.

RsUnCorr: Data uncorrected by RS codes, must be retransmitted

ES: Errored seconds. “An Errored Second is a second in which one or more coding violations occurred OR one or more loss of signal defects occurred.

Again, as with CRC I am not aware of any standard formula which would indicate whether a given level of ES is acceptable or unacceptable. Anything other than a near perfect line will give some level of ES error. On really bad lines the ES number can actually equal the total seconds i.e. every second of connection experienced a coding violation or loss of signal.

In many ways, in my opinion, errored seconds are a better indicator of a line that is struggling than CRC. Severely errored seconds give an additional quantification” – source.

SES: Severely errored seconds. “As the name suggests, a severely errored second is worse than an errored second. To be counted as errored only one event needs to occur. A severely errored second quantifies this. Typically a severely errored second is one where a threshold number of events is passed. I am not aware of a standard for this threshold and so each manufacturer may set their own threshold for what constitutes a severely errored second.” – source.

OCD: Number of out-of-cell Delineation errors.

LCD: Number of Loss of Cell Delineation errors.

UAS: Number of Unavailable Seconds (presumably when synch was lost with the DSLAM).

AS: Number of Available Seconds. UAS + AS  = system uptime (see Data Problems, Router Uptime VS Link Uptime).

INP: “Electrical appliances and installations at customer premises often generate short bursts of noise of relatively high amplitude. These bursts, called impulse noise, are electromagnetically coupled into the digital subscriber line, degrading performance and in some cases disrupting service. The ADSL2/plus standard introduced a parameter (impulse noise protection, INP) that allows operators to select the maximum impulse length that the system can correct. VDSL2 uses this same parameter. In effect, an INP value of between 2 and 16 can correct errors from noise impulses ranging from 250µs to 3.75ms in length.” – source.

PER: Packets in ERror.

Delay: I think this is the delay introducted by interleaving on the line. As the interleaving level can be differed, the delay isnt just a set value. As I have no interleaving, this is currently 0. TODO: Can anyone confirm this?

OR: TODO: Unknown.

Bitswap: Changing the bit loading of the bins used when a bin’s usablility (SNR) falls below its original bit loading. Other bins that are not running at full capacity can take on the extra data – see kitz’s excellent article on how *DSL works.

xdslcmd info –stats

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9083 Kbps, Downstream rate = 49696 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 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): 10.3 6.2
Attn(dB): 0.0 0.0
Pwr(dBm): 11.9 5.8

VDSL2 framing
Path 0
B: 239 223
M: 1 1
T: 64 35
R: 0 16
S: 0.1910 0.7805
L: 10054 2460
D: 1 1
I: 240 120
N: 240 240

Counters
Path 0
OHF: 107332063 766680
OHFErr: 5712 584
RS: 0 3712854
RSCorr: 0 1029
RSUnCorr: 0 0

Path 0
HEC: 10580 0
OCD: 0 0
LCD: 0 0
Total Cells: 3828791842 0
Data Cells: 240466458 0
Drop Cells: 0
Bit Errors: 0 0

ES: 1738 530
SES: 4 0
UAS: 16 16
AS: 329237

Path 0
INP: 0.00 0.00
PER: 3.05 13.65
delay: 0.00 0.00
OR: 62.83 35.14

Bitswap: 8481 8801

Total time = 1 days 19 hours 27 min 34 sec
FEC: 0 0
CRC: 5712 0
ES: 1738 530
SES: 4 0
UAS: 16 16
LOS: 0 0
LOF: 0 0

Latest 15 minutes time = 12 min 34 sec
FEC: 0 0
CRC: 6 0
ES: 5 1
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0

Previous 15 minutes time = 15 min 0 sec
FEC: 0 0
CRC: 137 0
ES: 6 2
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0

Latest 1 day time = 19 hours 27 min 34 sec
FEC: 0 0
CRC: 2432 0
ES: 483 119
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0

Previous 1 day time = 24 hours 0 sec
FEC: 0 0
CRC: 793 0
ES: 391 142
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0

Since Link time = 3 days 19 hours 27 min 17 sec
FEC: 0 1029
CRC: 5712 584
ES: 1738 530
SES: 4 0
UAS: 0 0
LOS: 0 0
LOF: 0 0

LOS: Loss of signal (i.e. the line goes dead).

LOF: Loss of frame (ATM framing).

Total time: Presumably system uptime, however fails badly as the day count never passes 1 (...) - see Data Problems, Router Uptime VS Link Uptime.

Since Link time: Presumably time since the current synch to the DSLAM started.

xdslcmd info –SNR

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9091 Kbps, Downstream rate = 49696 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
Tone number SNR
0 0.0000
1 0.0000
< and so on for the thousands of [url=http://www.kitz.co.uk/adsl/adsl_technology.htm]tones/bins[/url] >
xdslcmd info –QLN

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9083 Kbps, Downstream rate = 49696 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
Tone number QLN
0 -160.0000
1 -160.0000

< and so on for thousands of [url=http://www.kitz.co.uk/adsl/adsl_technology.htm]tones/bins[/url] >

QLN: Quiet Line Noise (see Measuring Line Characteristics on the Huawei).

xdslcmd info –Hlog

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9098 Kbps, Downstream rate = 49576 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
Tone number Hlog
0 -96.0000
1 -96.0000
< and so on for thousands of [url=http://www.kitz.co.uk/adsl/adsl_technology.htm]tones/bins[/url] >

Hlog: Logarithmic channel characteristic function Hlog(f) (see Measuring Line Characteristics on the Huawei).

xdslcmd info –Hlin

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9095 Kbps, Downstream rate = 49576 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
Hlin scale factor: DS = 0 US = 0
Tone number Hlin
0 0 0
1 0 0
2 0 0
3 0 0
< and so on for thousands of [url=http://www.kitz.co.uk/adsl/adsl_technology.htm]tones/bins[/url] >

Hlin: Hlin(f) is a format providing complex values in linear scale (as compared to Hlog which is logarithmic – see Measuring Line Characteristics on the Huawei).

xdslcmd info –HlinS

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9098 Kbps, Downstream rate = 49696 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
0 0.000000e+00 0.000000e+00
1 0.000000e+00 0.000000e+00
< and so on for thousands of [url=http://www.kitz.co.uk/adsl/adsl_technology.htm]tones/bins[/url] >

HlinS: This should be a scaling factor applied to Hlin (see mention of the scaling factor in Measuring Line Characteristics on the Huawei).

xdslcmd info –Bits

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9106 Kbps, Downstream rate = 49576 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
Tone number Bit Allocation
0 0
1 0
< and so on for thousands of [url=http://www.kitz.co.uk/adsl/adsl_technology.htm]tones/bins[/url] >

Bit allocation per tone/bin (see Kitz ADSL Technology and DMT).

xdslcmd info –pbParams

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9098 Kbps, Downstream rate = 49696 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 9098 kbps 49696 kbps
Actual Aggregate Tx Power: 5.8 dBm 11.9 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 5.9 32.4 48.9 N/A 15.2 40.5 63.0
Signal Attenuation(dB): 10.9 31.5 48.0 N/A 15.2 40.5 63.0
SNR Margin(dB): 6.1 6.3 6.2 N/A 10.2 10.4 0.0
TX Power(dBm): -4.1 -12.7 5.3 N/A 9.7 7.8 -15.5

This lists the bins used in the band plan (numbers detailed in brackets) that correspond to the frequency bands used by the current VDSL2 profile (17a for me). With profile 8c, two bands are used for upload and download data. See Kitz for details about attenuation and SNR.

N/A indicates that the modem/DSLAM(?) decided that the band was too attentuated to even try to use.

xdslcmd info –linediag

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9083 Kbps, Downstream rate = 49576 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
Down Up
SNRM(dB): 10.3 6.2
LATN(dB): 0.0 0.0
SATN(dB): 0.0 0.0
TxPwr(dBm): 11.9 5.8
ATTNDR(Kbps): 49576 9083
Tone number SNR
0 0.0000
1 0.0000
< and so on for thousands of [url=http://www.kitz.co.uk/adsl/adsl_technology.htm]tones/bins[/url] >
xdslcmd info –linediag1

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9080 Kbps, Downstream rate = 49696 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 9080 kbps 49696 kbps
Actual Aggregate Tx Power: 5.8 dBm 11.9 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 5.9 32.4 48.9 N/A 15.2 40.5 63.0
Signal Attenuation(dB): 10.9 31.6 48.0 N/A 15.2 40.5 63.0
SNR Margin(dB): 6.3 6.2 6.2 N/A 10.2 10.4 0.0
Line 0 DS HLOG (dB) (grouped by 8 tones):
< data omitted >

Line 0 US HLOG (dB) (grouped by 8 tones):
< data omitted >

Line 0 DS QLN (dBm/Hz) (grouped by 8 tones):
< data omitted >

Line 0 US QLN (dBm/Hz) (grouped by 8 tones):
< data omitted >

Line 0 DS SNR (dB) (grouped by 8 tones):
< data omitted >

Line 0 US SNR (dB) (grouped by 8 tones):
< data omitted >

Line 0 DS HLIN (grouped by 8 tones):
< data omitted >

Line 0 US HLIN (grouped by 8 tones):
< data omitted >
xdslcmd info –vendor

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9109 Kbps, Downstream rate = 49576 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
ChipSet Vendor Id: BDCM:0xa1b7
ChipSet VersionNumber: 0xa1b7
ChipSet SerialNumber:
xdslcmd info –cfg

Code: [Select]

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 9098 Kbps, Downstream rate = 49696 Kbps
Path: 0, Upstream rate = 9113 Kbps, Downstream rate = 39997 Kbps
adslTrainingMarginQ4: -1
adslShowtimeMarginQ4: -1
adslLOMTimeThldSec: -1
adslDemodCapMask: 0090447a
adslDemodCapValue: 0010447a
adsl2Param: 00000000
adslPwmSyncClockFreq: 0
adslHsModeSwitchTime: 0
adslDemodCap2Mask: 00540200
adslDemodCap2Value: 00540200
vdslParam: 007f00ff
vdslParam1: 00000000
xdslAuxFeaturesMask: 00000003
xdslAuxFeaturesValue: 00000003
vdslCfgFlagsMask: 00000000
vdslCfgFlagsValue: 00000000
Continued in a later post.

[Bald_Eagle1]

Hi JustAnother,

Thank you for the detailed explanations & links.

I too am dabbling with an unlocked HG612 modem, but I'm afraid I am unable to answer your queries regarding TODO etc.

Incidentally, this link http://www.4i2i.com/reed_solomon_codes.htm appears to be broken, but I suspect your post included all the relevant detail anyway.

Paul.

[npr]

TODO: Unable to decode the single-letter acronyms under ‘VDSL2 framing path 0′ – anyone able to do this and provide a source?

This is what I understood them to stand for with ADSL:

B = Number of bytes in Mux Data Frame
M = Number of Mux Data Frames in FEC Data Frame
T = Mux Data Frames over sync bytes
R = Number of check bytes in FEC Data Frame
S = ratio of FEC over PMD Data Frame length
L = Number of bits in PMD Data Frame
D = interleave depth (1=fast path)

[JustAnother]

Thanks - do you have a source for this at all?

[npr]

A quick google search for "B = Number of bytes in Mux Data Frame" has found this.

http://wiki.aaisp.org.uk/images/d/dd/UM_AR-5382u_A1.0.pdf

See page 24  8)

[JustAnother]

Thanks, updated.

[JustAnother]

xdslcmd profile –show

Code: [Select]

Modulations:
G.Dmt Enabled
G.lite Enabled
T1.413 Enabled
ADSL2 Enabled
AnnexL Enabled
ADSL2+ Enabled
AnnexM Disabled
VDSL2 Enabled
VDSL2 profiles:
8a Enabled
8b Enabled
8c Enabled
8d Enabled
12a Enabled
12b Enabled
17a Enabled
30a Enabled
US0 Enabled
Phone line pair:
Inner pair
Capability:
bitswap On
sra Off
trellis On
sesdrop Off
CoMinMgn Off
24k On
phyReXmt(Us/Ds) Off/On
TpsTc AvPvAa
monitorTone: On
dynamicD: On
dynamicF: On
SOS: On
Training Margin(Q4 in dB): -1(DEFAULT)

sra: Seamless Rate Adaption as mentioned before.

trellis: Trellis Coded Modulation.

sesdrop: Some sort of functionality to stop all error correction stuff in order to reduce latency on the line? See Think Broadband thread. TODO: Anyone able to confirm what this is?

TODO: What are the rest of these for?

Data Problems

CRC And FEC Data

It appears the code behind the stats as obtained via xdslcmd and/or the web interface is either incomplete or poorly made. Bald_Eagle has highlighted a discrepancy in what exact data is returned for CRC and FECs from the sources:

From the web interface:

Code: [Select]

DS CRC errors 54391
DS FEC errors 1349
DS HEC errors 16063
From xdslcmd info --stats:

Code: [Select]

DS CRC errors 1349           (reported as FEC errors above & also reported as OHFerr in xdslcmd info --stats)
DS FEC errors 1377279      (No idea what this relates to, other than same value as RSCorr in xdslcmd info --stats)

FEC and CRC errors appear to be flipped around and some data is unaccountable.

Router Uptime VS Link Uptime

Bald_Eagle has also shown that the way the router reports the total (system) uptime and link (connection) uptime is suspect - selected output from my 'xdslcmd info --stats':

Code: [Select]

UAS:        17        17
AS:        251975

Total time = 1 days 21 hours 59 min 52 sec

Since Link time = 2 days 21 hours 59 min 33 sec
Clearly the link time cannot be greater than the time the system was up for. rhone has pointed out that the day count never goes past 1 on the Netgear DG834GT, and checking now I can indeed see that this is the case with this router! I enjoy the fact a machine processing ~5MB/Sec of data cannot count.

[JustAnother]

Any mods around? I have already hit up against the 20000 max for the first post, so have had to split the article. Please can this new post be moved after the main one?

Can I have some extra reservation posts inserted after this too?

Thanks

[roseway]

Posts are displayed in date order, and I don't think there's any way to change the dates. I could copy the relevant posts to another thread, but then you wouldn't be able to edit the copies. This is very valuable information, for which we're very grateful, so I would very much like to keep it in an ordered fashion. I think the best option (if you're agreeable) would be for you to complete the posts in this thread, then I can copy them in an ordered fashion to another thread.

[rhohne]

Clearly the link time cannot be greater than the time the system was up for, so the data must have been switched around

Don't believe that they are transposed.

If it's anything like the DG834GT then the display of the number of days in the Total time never increments above one.

[JustAnother]

Posts are displayed in date order, and I don't think there's any way to change the dates. I could copy the relevant posts to another thread, but then you wouldn't be able to edit the copies. This is very valuable information, for which we're very grateful, so I would very much like to keep it in an ordered fashion. I think the best option (if you're agreeable) would be for you to complete the posts in this thread, then I can copy them in an ordered fashion to another thread.

Shall I make another thread and copy over my posts then? At least that way I can add 'reserved' posts at the start.

[JustAnother]

If it's anything like the DG834GT then the display of the number of days in the Total time never increments above one.

Thanks - here is the situation now:

Code: [Select]

Total time = 1 days 22 hours 10 min 42 sec

Since Link time = 3 days 22 hours 10 min 23 sec
So clearly you are right. What POS code.

[roseway]

Shall I make another thread and copy over my posts then? At least that way I can add 'reserved' posts at the start.

I didn't like to ask, but if you're happy to do that, it would be the best solution. Thank you.

[JustAnother]

OK, I have now created the dupe thread at http://forum.kitz.co.uk/index.php/topic,10289.0.html - please can you lock this one? If it gets deleted then its harder to attribute the contributions.

[roseway]

Locked as requested.