Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Pages: [1] 2 3

Author Topic: VDSL2 DLM entanglements / REIN  (Read 13074 times)

napalmdaz

  • Member
  • **
  • Posts: 34
VDSL2 DLM entanglements / REIN
« on: August 21, 2013, 03:49:54 PM »

Hi All,

Just signed up today but have been reading up a lot recently. I'll cut straight to the facts!

1. Signed up with Sky Fibre last year 40/10 and got the 38Mbps for 4-5 few months not a problem. I was provided with an ECI modem.
2. Started to get periods where interleaving was applied and sync was dropping to 28Mbps, but returning to 38MBps a few days later.
3. One day, sync dropped down and stayed at 18Mbps. After a week of this, I rung Sky to try and get on their fibre pro 76Mbps service. BT wholesale line checker was quoting me 55.1Mbps. Sky said they couldn't provide the Fibre pro so I changed over to BT Infinity2.
4. Received a text saying no engineer visit required as I already had a modem etc. They sent a Hub4 through the post.
5. On provisioning day, sync was..... 18Mbps!
6. Started to complain to BT retail.
7. Got an engineer eventually that reset DLM on the line. He used his J-something test device to confirm a 80Mbps sync with no errors on the line. He also did a pair test and that came. back all fine
8. A day later, I was down to 60ish
9. A day later, I was down to 55ish
10. Now I'm on 35ish :(... not the quoted 55.1 mbps.
11. I bought a HG612 off eBay and unlocked it. I then found out that my cab is not an ECI cab (examining the band plans).
12. I thought as the line was fine at the time the engineer was round, it must be REIN or another type of interference. Being a radio ham, I have some HF receivers, but setteled on using a basic AM radio to hunt out noisy power supplies / appliances in the house. I've switched most things off now and relocated the modem away from other electrical devices. I've also disconnected the extension cabling from the master socket.
13. I've started to log stats which I have attached here. I'm sure I should be getting a faster sync than what I've got. My DS signal margins are ~16dB so scope for more sync hopefully?
14. What should I do next? Contact BT and complain again? I guess I may now be banded and stuck at this speed without an engineer visit?

I'm in Sale, Manchester if that means anything.Any help appreciated thanks!

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Max:   Upstream rate = 31244 Kbps, Downstream rate = 87860 Kbps
Path:   0, Upstream rate = 14996 Kbps, Downstream rate = 34997 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):    16.3       14.6
Attn(dB):    0.0       0.0
Pwr(dBm):    13.5       6.6
         VDSL2 framing
         Path 0
B:      24      23
M:      1      1
T:      64      64
R:      16      8
S:      0.0227      0.0508
L:      14441      5038
D:      1964      631
I:      41      32
N:      41      32
         Counters
         Path 0
OHF:      27124095      1390456
OHFErr:      0      0
RS:      1825717140      960374
RSCorr:      49821      38877
RSUnCorr:   0      0

         Path 0
HEC:      0      0
OCD:      0      0
LCD:      0      0
Total Cells:   3995579070      0
Data Cells:   753607722      0
Drop Cells:   0
Bit Errors:   0      0

ES:      0      0
SES:      0      0
UAS:      84      84
AS:      59377

         Path 0
INP:      8.50      4.00
PER:      2.18      6.50
delay:      11.00      8.00
OR:      88.05      59.03

Bitswap:   2      279

Total time = 16 hours 31 min 21 sec
FEC:      49821      38877
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      84      84
LOS:      0      0
LOF:      0      0
Latest 15 minutes time = 1 min 21 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:      11      54
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
Latest 1 day time = 16 hours 31 min 21 sec
FEC:      49821      38877
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      84      84
LOS:      0      0
LOF:      0      0
Previous 1 day time = 0 sec
FEC:      0      0
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
Since Link time = 16 hours 29 min 35 sec
FEC:      49821      38877
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0

xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Max:   Upstream rate = 31244 Kbps, Downstream rate = 87860 Kbps
Path:   0, Upstream rate = 14996 Kbps, Downstream rate = 34997 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3959)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)

DS: (32,859) (1216,1963) (2792,3959)
       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:      31244 kbps         87860 kbps
Actual Aggregate Tx Power:        6.6 dBm          13.5 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB):    3.9    18.3    26.5     N/A    9.9    22.3    33.7   
Signal Attenuation(dB):    3.9    17.7    25.6     N/A    9.9    22.3    33.7   
        SNR Margin(dB):    14.8    14.7    14.6     N/A    16.1    16.3    16.3   
         TX Power(dBm):   -7.8   -27.1    6.3     N/A    10.8    7.8    6.8   
« Last Edit: August 21, 2013, 04:17:01 PM by napalmdaz »
Logged

kitz

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 33881
  • Trinity: Most guys do.
    • http://www.kitz.co.uk
Re: VDSL2 DLM entanglements / REIN
« Reply #1 on: August 21, 2013, 05:17:41 PM »

Hi and welcome :)


From a quick look at your graphs your SNRm looks relatively stable for the periods logged,  and at first glance it should be capable of much higher speeds.

The symptoms of the reduction in speed in stages would likely as you have already deduced be an effect of the DLM cutting in for some reason and increasing the target SNRm & interleaving.  As such that would infer that at times the line has been unstable with sparodic noise.

You are correct that the 16dB Target SNRm does give you a lot more scope for speed, but we need to find out why the DLM has kicked in at such a high rate 


You also appear to have lower than anticipated  bit loading in the first 500 tones.. this also mirrors the fact that your REAL SNR for some reason looks low in the first 400 tones - particularly around tone 250.   Im not familiar with the Huawei banding profiles (as Im on an ECI Cab) you mention so leave that to someone who has more experience in that field...  but it would appear you are seeing some sort of signal reduction/noise in that area.

It would be interesting to see the SNRm graphed over a longer period to see if there are any SNRm fluctuations..  but based on what Ive seen so far it looks like some sort of interference over those first 300 tones.

Is all your internal wiring ok.  Is your voice line quiet?

I'll await to see if someone with more FTTC spefific knowledge can add anything more.
Logged
Please do not PM me with queries for broadband help as I may not be able to respond.
-----
How to get your router line stats :: ADSL Exchange Checker

ColinS

  • Reg Member
  • ***
  • Posts: 529
Re: VDSL2 DLM entanglements / REIN
« Reply #2 on: August 21, 2013, 06:02:27 PM »

Hi and Welcome.  :)

Sorry to hear of your tribulations. :(

Here are some observations on the stats you provided, but hopefully our very own Bald_Eagle_1 will be along later with a more in-depth analysis.

Firstly, it looks as if DLM has put you on a banded profile of 35/15.
Secondly, the interleaving depth is very high at D=1964. R/N = 16/41 which means that the data is carrying almost a 40% overhead to correct bit errors. :'(
In addition Impulse Noise Protection (INP) = 8.5, which is quite high, giving rise to a delay of 11ms.

All of these things suggest that at some point DLM believes that it has seen a very noisy line, and is trying to protect the service with a combination of interleaving and INP.  :(

However, in the 16 hours or so since the last resync it seems to have been pretty much error free.  If it remains that way, there is at least a reasonable chance that DLM will relent in the coming days.  I'm not sure how many resyncs you saw or over what period, but at least 3 it looks like, and I am assuming that your last one was 16hrs before the stats you provided.

The good news is that your Hlog plot looks good, and the QLN plot shows a reasonable -120dB noise floor, although -140dB would be better.  So whatever it was it was more like REIN.  Perhaps the various things that you have done recently have helped, but the key thing now is to keep monitoring it with the stats.

Hope some of this helps.  :)
« Last Edit: August 21, 2013, 08:20:12 PM by ColinS »
Logged

Chrysalis

  • Content Team
  • Addicted Kitizen
  • *
  • Posts: 7382
  • VM Gig1 - AAISP L2TP
Re: VDSL2 DLM entanglements / REIN
« Reply #3 on: August 21, 2013, 07:16:05 PM »

my guess is that you have resolved the interference with the devices you turned off, moving the modem etc. so now its a waiting game for DLM to undo its changes.

Dont turn the modem off or resync it, just leave it connected.  This will probably take weeks as it will be done in steps but hopefully you will start seeing changes within a few days.
Logged

napalmdaz

  • Member
  • **
  • Posts: 34
Re: VDSL2 DLM entanglements / REIN
« Reply #4 on: August 21, 2013, 08:46:24 PM »

Awesome. Thanks for the replies so far, which concur with what I thought as well.

All the speed drops were with the ECI modem. The stats I have logged so far are with the HG612 I bought off eBay and set up last night. It hasn't resynced so far yet, but I'm going to continue to monitor, as suggested, in case noise returns. I noticed the HG612 had a choke on the power adapter and the ECI modem didn't. I've also performed the following:

1) Removed extension wiring from master socket so I only have the modem and a landline phone on there via the filtered faceplace.
2) Replaced a 15 year old Belkin multiway surge protector that was at the other side of the room feeding the HTPC, TV, amp, Xbox etc.
3) Relocated mobile phone power adapters, that were next to the phone extension socket upstairs, so that they are on extension leads higher up near the window.

Fingers crossed.

I've also got back to Tier-2 BT support to see if I can get a DLM reset pushed through to OR.

I'll keep this thread updated. Thanks again.
Logged

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2721
Re: VDSL2 DLM entanglements / REIN
« Reply #5 on: August 21, 2013, 10:51:25 PM »

I can't add anything other than to keep logging & look out for any bouts of errors that would point to some sort of electrical interference or perhaps a dodgy connection somewhere.

With a bit of luck there will be no more interference & DLM might eventaully relent & allow your connection to perform at its apparent capability level.

Logged

napalmdaz

  • Member
  • **
  • Posts: 34
Re: VDSL2 DLM entanglements / REIN
« Reply #6 on: August 22, 2013, 09:00:17 AM »

Thanks all.

Looks like the link went down and came back early this morning. The stats have certainly improved with a higher sync and lower interleaving. I had to reboot the HomeHub to get a new IP profile as the PPP session hadn't dropped during the resync. One thing for concern is the throughput on the upstream. The IP profile is 20Mbps and the sync is there abouts. I've attached the BTW wired speedtest. Nothing else was using the connection at the time. Good news overall I think?

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   2
Max:   Upstream rate = 30894 Kbps, Downstream rate = 87724 Kbps
Path:   0, Upstream rate = 19842 Kbps, Downstream rate = 47036 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):    12.4       6.9
Attn(dB):    0.0       0.0
Pwr(dBm):    13.4       6.7
         VDSL2 framing
         Path 0
B:      30      25
M:      1      1
T:      64      64
R:      16      16
S:      0.0210      0.0417
L:      17934      8064
D:      1682      505
I:      47      42
N:      47      42
         Counters
         Path 0
OHF:      8198055      3451268
OHFErr:      0      0
RS:      2623376982      2437272
RSCorr:      9875      12153
RSUnCorr:   0      0

         Path 0
HEC:      0      0
OCD:      0      0
LCD:      0      0
Total Cells:   1248491771      0
Data Cells:   17879949      0
Drop Cells:   0
Bit Errors:   0      0

ES:      5      0
SES:      5      0
UAS:      102      102
AS:      13806

         Path 0
INP:      6.00      4.00
PER:      1.67      4.00
delay:      9.00      6.00
OR:      95.39      48.00

Bitswap:   0      386

Total time = 1 days 13 hours 9 min 22 sec
FEC:      99380      80677
CRC:      2240      0
ES:      5      0
SES:      5      0
UAS:      102      102
LOS:      4      0
LOF:      5      0
Latest 15 minutes time = 9 min 22 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:      9      1035
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
Latest 1 day time = 13 hours 9 min 22 sec
FEC:      29166      27041
CRC:      2240      0
ES:      5      0
SES:      5      0
UAS:      18      18
LOS:      4      0
LOF:      5      0
Previous 1 day time = 24 hours 0 sec
FEC:      70214      53636
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      84      84
LOS:      0      0
LOF:      0      0
Since Link time = 3 hours 50 min 5 sec
FEC:      9875      12153
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0

xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   2
Max:   Upstream rate = 30894 Kbps, Downstream rate = 87724 Kbps
Path:   0, Upstream rate = 19842 Kbps, Downstream rate = 47036 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3959)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3959)
       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:      30894 kbps         87724 kbps
Actual Aggregate Tx Power:        6.7 dBm          13.4 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB):    4.0    18.3    26.6     N/A    9.9    22.4    33.8   
Signal Attenuation(dB):    4.0    17.6    25.8     N/A    9.9    22.4    33.8   
        SNR Margin(dB):    6.7    7.0    6.9     N/A    12.3    12.4    12.5   
         TX Power(dBm):   -8.4   -28.0    6.6     N/A    10.4    7.6    7.1   



« Last Edit: August 22, 2013, 09:32:03 AM by napalmdaz »
Logged

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2721
Re: VDSL2 DLM entanglements / REIN
« Reply #7 on: August 22, 2013, 08:34:08 PM »

That looks better & there's still scope for further improvement.


Has your bitloading graph improved now, particularly in the first 500 or so tones?

Logged

napalmdaz

  • Member
  • **
  • Posts: 34
Re: VDSL2 DLM entanglements / REIN
« Reply #8 on: August 23, 2013, 10:25:12 AM »

Hi Bald Eagle. Yes, it has improved; BT even sent me a text message this morning saying "oooh we see your speed has improved. let us know if it hasn't worked." although we all know they have not done anything!

Yesterday, around lunch to mid afternoon some noise hit the line. Nobody was in at home during this time and nothing would have switched on or off on a timer or anything. I'm suspecting it was somebody mowing their lawn, hedge trimming or similar. Unfortunately it caused a few uncorrected errors so no +ve change by DLM last night. Let's see if it does it again at the same time today.

Logged

napalmdaz

  • Member
  • **
  • Posts: 34
Re: VDSL2 DLM entanglements / REIN
« Reply #9 on: August 23, 2013, 10:31:49 AM »

Hmmm, the SNR on the first 500 or so tones looks pretty rubbish. Do you think it may be a dodgy faceplace? Maybe its worth getting another to try? Do they just low-pass filter - if so I guess not the faceplace to blame.
Logged

ColinS

  • Reg Member
  • ***
  • Posts: 529
Re: VDSL2 DLM entanglements / REIN
« Reply #10 on: August 23, 2013, 03:32:07 PM »

By comparison with my own SNR plot, I would say that you are ~15dB down in the first 100 tones, i.e. <~430kHz, although remarkably clear of MW radio interference.  You don't have some sort of REIN filter somewhere do you?
« Last Edit: August 23, 2013, 04:41:45 PM by ColinS »
Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: VDSL2 DLM entanglements / REIN
« Reply #11 on: August 23, 2013, 04:48:23 PM »

By comparison with my own SNR plot, I would say that you are ~15dB down in the first 100 tones, i.e. <~430kHz, although remarkably clear of MW radio interference.  You don't have some sort of REIN filter somewhere do you?

Are you thinking of an RF2, perhaps?
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

ColinS

  • Reg Member
  • ***
  • Posts: 529
Re: VDSL2 DLM entanglements / REIN
« Reply #12 on: August 23, 2013, 07:27:29 PM »

Are you thinking of an RF2, perhaps?
Yes, that had ocurrrrred 2 me!  ;)
« Last Edit: August 23, 2013, 07:36:40 PM by ColinS »
Logged

Chrysalis

  • Content Team
  • Addicted Kitizen
  • *
  • Posts: 7382
  • VM Gig1 - AAISP L2TP
Re: VDSL2 DLM entanglements / REIN
« Reply #13 on: August 23, 2013, 08:28:31 PM »

the lower tones are lower due to adsl crosstalk protection.

Different areas have diff masks applied, so not everyones cutback will look the same.
Logged

ColinS

  • Reg Member
  • ***
  • Posts: 529
Re: VDSL2 DLM entanglements / REIN
« Reply #14 on: August 24, 2013, 09:05:49 AM »

But not to that extent in tones below 100 ... The attached image shows its effect in those tones is limited to protection of the voice band, and does not extend beyond tone 6.
« Last Edit: August 24, 2013, 10:03:56 AM by ColinS »
Logged
Pages: [1] 2 3
 

anything