Kitz Forum

Broadband Related => ADSL Issues => Topic started by: 8062282 on June 23, 2019, 12:16:13 AM

Title: Modem Errors..
Post by: 8062282 on June 23, 2019, 12:16:13 AM
I used to get approx 7mb download & that's depreciated to 4mb. I had a BTOR engineer out on the 14th June due to widely fluctuating SNR & occasional disconnects. The line tested OK (at the time). He went & did some work at the cabinet & changed the D & E connections. He also had to get my ISP to remove a 4mb cap on my line, despite them telling me they don't cap lines. Not sure who's telling the truth..

In the early hours of the 15th, (I woke up early) the DLM had kicked in & my attainable rate had gone up to 8620 & my line rate was 7774. Great, I thought, I'm back to my normal speed. 1 & half hours later, the speed dropped to 4519. It's since dropped to 4059. The SNR is rock solid at 6dB.

I complained to my ISP about this drop, pointing out what I used to get & what I got (briefly) on the 15th. I've asked numerous questions about the DLM & the criteria it uses. All have gone unanswered. Every night my modem is reporting high ES but nothing during the day. When we go to bed there's maybe 6/7 ES, when we get up in the morning, there's roughly 200. According to the DLM calculator, that amount of errors shouldn't be problem. Despite this, the DLM isn't for increasing my speed. It's stuck at 4059. I'm wondering if they've capped my line at 4mb again despite them saying they don't..

I'm just banging my head against a brick wall getting any sense out of my ISP. They're answering my posts on their forum but conveniently not answering the questions about the DLM profiles they use or the criteria the DLM uses. All of a sudden after hitting a brick wall with them, my modem is no longer reporting any errors. I use a Billion BiPAC 7800DXL & in the xDSL there's not one error being reported.

HEC Errors         0   0
OCD Errors        0   0
LCD Errors         0   0
Total Cells          19852276   4612340
Data Cells          1290478   130359
Bit Errors           0   0
Total ES             0   0
Total SES           0   0
Total UAS           0   0

Can an ISP stop errors being reported?  I can't complain about errors, if I can't see them. I've decreased my SNR to 3dB just to see if any errors would start to appear, they haven't. My attainable rate is now 5800 & my line rate is still at 4059. Oddly the SNR is being reported as 5db even though I've set it at 3dB. I've only changed the SNR today so I will leave it overnight & see if anything changes by morning...

Any help or suggestions welcome..
Title: Re: Modem Errors..
Post by: burakkucat on June 23, 2019, 12:43:06 AM
Welcome to the Kitz forum.  :)

Having carefully read through the details of your post, I think I can fill in some of the gaps --
If interleaving has been applied to the circuit then there is the possibility that all errors are under control and, thus, there is nothing to report.

Does your Billion 7800DXL report CRCs and FECs? Ideally we would like to see the CRC, FEC, ES and SES counts over, say, a 24 hour period.
Title: Re: Modem Errors..
Post by: Weaver on June 23, 2019, 03:15:12 AM

    W E L C O M E   T O   T H E   F O R U M   !
         Very warmest welcome from me!

You wrote:
> Can an ISP stop errors being reported?

No. Those numbers,such as Errored Secs (over what period?), are just between your modem and the modem at the other end - the DSLAM, I assume in this case, because you havenít given full details of exactly what your service is.

An ISP doesnít generally interfere with modems although some modems are set up to allow remote control by the ISP. That remote control can be disabled though, so that the user is in total control of the modem. My modems are a perfect example, reprogrammed by me with a lot of help from learned members if the forum so that the ISP no longer has any control over them.
Title: Re: Modem Errors..
Post by: 8062282 on June 23, 2019, 07:41:13 AM
Thanks Weaver & Burakkucat for the responses & thanks for the welcome...

Yes it is TT.  I'm not that well up on internet stuff & modems so forgive me if I sound a bit vague at times. I am learning though..

The modem doesn't appear to report the FEC errors or CRC's in the xDSL part unless they're called something else. I did a soft reset of the modem at 23.26 to see if the modem had got 'stuck' & wasn't picking any errors up. There wasn't any ES an hour later.

I'm up now & have just checked the modem stats which only go from 00.30 this morning & this is what it's saying:

Super Frames               1556563   1406425
Super Frame Errors                23   1
RS Words                     202353181   4259735
RS Correctable Errors      624   3
RS Uncorrectable Errors       1729   0

After trying to find out for about 4/5 days what time these night times ES were occurring & getting nowhere, I resorted to downloading DSLstats yesterday, although I haven't left it running overnight yet..

This morning, after days of getting about 200 ES overnight, there's only been 12 ES since 00.30 last night.

It was only when I got NOW Tv to watch Game of Thrones did my problems start. My speed had slowed to a pitiful 1595 & of course, I couldn't watch GoT on the TV. Watching it huddled over an iPad didn't quite have the same enjoyment about it..

I just don't seem to getting anywhere with TT. I'm not on contract with TT as I was a transferred from Virgin when they decided they didn't want ADSL customers anymore. I just want them to help regards getting my speed back to where it was. I wasn't one for checking stats all the time & as long as I could do what I wanted to do, I was happy. Speed got a bit slow at times but a hard reset of the modem usually sorted that out. As I'm not on contract with TT, I don't know whether their 'guaranteed 2.6mb download' speed applies. If it does, I'm up the creek without a paddle..

The modem has been connected to the test socket since the 20th May as the extension where the modem was originally connected, was proving unreliable, which is why my speed had reduced. Now everything is stable on the test socket, TT don't seem the slightest bit interested about the speed I was getting, nor are they interested in helping me get that speed back. The last recorded measurement of the speed I used to get was July '16 & that was 7.18mb over wireless on an iPhone 4s. So, apart from a line rate of 7774 for about 1 & half hours on the 15th June after the engineer had been, my speed has slowly decreased to 4059..

Any views on why my modem is reporting the SNR as 5dB when I've reduced it to 3dB?   With congestion etc, could I have lost 3mb since July '16? 

Unfortunately my cabinet is full or I'd have been off to another ISP on fibre. I'm now looking at moving onto another ISP for broadband with the hope of upgrading to fibre with them when there's space in the cabinet. I can't believe I've been stupid enough to pay £24 a month for this & that doesn't even include line rental. What I don't want to do, is take a fault with me & have to start over again with another ISP.

Apologies for the long post  :)

Title: Re: Modem Errors..
Post by: parkdale on June 23, 2019, 11:40:18 AM
Do you have any wiring extensions off the Master socket, and is the bell (3) wire still connected?
Are you using the Telnet cli to look at your stats?

I'm using John Lewis as my ISP, they have a ADSL service which is unlimited for £20 (but upto 10Mb which is fairly common point for most ISP's)
I use them because it's "Plusnet with better customer service, and Plusnet is owned by BT"

Have you tried the https://www.dslchecker.bt.com to see what it available?
Title: Re: Modem Errors..
Post by: 8062282 on June 23, 2019, 11:57:25 AM
Hi - There is a extension off the master socket but it's disconnected at the moment. The modem is connected to the test socket & has been since 20th May. What do I need to be looking at in the Telnet data?

The cabinet is full so I can't get fibre at the moment. There was some slots available about a month ago but I spent too long faffing around deciding who to go with. When I'd decided, the cabinet was full again  :(



Title: Re: Modem Errors..
Post by: parkdale on June 23, 2019, 12:05:08 PM
adsl info --stats  :fingers:
Title: Re: Modem Errors..
Post by: 8062282 on June 23, 2019, 12:42:02 PM
Thanks...



adsl info --stats
adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    0
Last initialization procedure status:   0
Max:    Upstream rate = 972 Kbps, Downstream rate = 5260 Kbps
Bearer: 0, Upstream rate = 874 Kbps, Downstream rate = 4095 Kbps


Link Power State:       L0
Mode:                   ADSL2+ Annex A
TPS-TC:                 ATM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        5.3             7.5
Attn(dB):        41.5            21.6
Pwr(dBm):        19.7            10.4


                        ADSL2 framing
                        Bearer 0
MSGc:           59              66
B:              63              13
M:              1               16
T:              2               2
R:              16              16
S:              0.4961          7.9012
L:              1290            243
D:              64              2


                        Counters
                        Bearer 0
SF:             690247          626023
SFErr:          6               1
RS:             89732077                1336325
RSCorr:         116             6
RSUnCorr:       364             0


                        Bearer 0
HEC:            57              0
OCD:            2               0
LCD:            2               0
Total Cells:    107508739               23380971
Data Cells:     7219577         1189254
Drop Cells:     0
Bit Errors:     0               0


ES:             2               1
SES:            0               0
UAS:            0               0
AS:             11129


                        Bearer 0
INP:            3.00            0.50
INPRein:        0.00            0.00
delay:          8               4
PER:            16.12           17.77
OR:             32.25           32.40
AgR:            4111.93 903.67


Bitswap:        116/118         232/232


Total time = 3 hours 5 min 29 sec
FEC:            116             6
CRC:            6               1
ES:             2               1
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 15 minutes time = 5 min 29 sec
FEC:            0               0
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 15 minutes time = 15 min 0 sec
FEC:            8               0
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 1 day time = 3 hours 5 min 29 sec
FEC:            116             6
CRC:            6               1
ES:             2               1
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            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
LOM:            0               0
Since Link time = 3 hours 5 min 29 sec
FEC:            116             6
CRC:            6               1
ES:             2               1
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
 >
Title: Re: Modem Errors..
Post by: parkdale on June 23, 2019, 02:23:26 PM
Now post your stats again in about 24hrs + with no reboots....
Title: Re: Modem Errors..
Post by: Weaver on June 23, 2019, 07:04:56 PM
My friend, if you get truly fed up with your current ISP, Andrews and Arnold will guarantee to fix your line and they are superb. I use them. Superb doesnít usually come cheap for obvious reasons.
https://www.aa.net.uk/broadband/we-will-fix-your-line/
Title: Re: Modem Errors..
Post by: 8062282 on June 24, 2019, 04:25:29 PM
Now post your stats again in about 24hrs + with no reboots....


When I got up this morning, the attainable rate had increased to 7800 but the line rate was still stuck at 4059. Contacted TT as I thought my line might have been capped. They've restarted DLM & the sync speed went up & then it's gone down again:


Jun 24 10:56:27 daemon warn kernel: bcmxtmcfg: Connection UP, LinkActiveStatus=0x1, US=860000, DS=8189000
Jun 24 13:07:47 daemon warn kernel: bcmxtmcfg: Connection UP, LinkActiveStatus=0x1, US=885000, DS=4679000


Lots of errors today..



adsl info --stats
adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    1
Last initialization procedure status:   0
Max:    Upstream rate = 984 Kbps, Downstream rate = 5068 Kbps
Bearer: 0, Upstream rate = 885 Kbps, Downstream rate = 4679 Kbps


Link Power State:       L0
Mode:                   ADSL2+ Annex A
TPS-TC:                 ATM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        5.1             8.0
Attn(dB):        42.0            21.6
Pwr(dBm):        19.6            10.4


                        ADSL2 framing
                        Bearer 0
MSGc:           59              66
B:              146             13
M:              1               16
T:              1               2
R:              10              16
S:              0.9984          7.8049
L:              1258            246
D:              32              2


                        Counters
                        Bearer 0
SF:             729833          674370
SFErr:          26              15
RS:             47439024                1767624
RSCorr:         1206            90
RSUnCorr:       460             0


                        Bearer 0
HEC:            240             3
OCD:            4               0
LCD:            4               0
Total Cells:    130680418               26841091
Data Cells:     2816338         1174707
Drop Cells:     0
Bit Errors:     0               0


ES:             252             14
SES:            21              0
UAS:            68              48
AS:             11841


                        Bearer 0
INP:            1.00            0.50
INPRein:        0.00            0.00
delay:          8               4
PER:            16.22           17.56
OR:             32.05           32.80
AgR:            4693.15 914.82


Bitswap:        288/293         226/226


Total time = 1 days 6 hours 49 min 9 sec
FEC:            42912           131
CRC:            1402            26
ES:             252             14
SES:            21              0
UAS:            68              48
LOS:            2               0
LOF:            8               0
LOM:            0               0
Latest 15 minutes time = 4 min 9 sec
FEC:            38              0
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 15 minutes time = 15 min 0 sec
FEC:            1               0
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 1 day time = 6 hours 49 min 9 sec
FEC:            33500           99
CRC:            1309            16
ES:             204             7
SES:            21              0
UAS:            68              48
LOS:            2               0
LOF:            8               0
LOM:            0               0
Previous 1 day time = 24 hours 0 sec
FEC:            9412            32
CRC:            93              10
ES:             48              7
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Since Link time = 3 hours 17 min 21 sec
FEC:            1206            90
CRC:            26              15
ES:             15              6
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
 >


 
Title: Re: Modem Errors..
Post by: parkdale on June 24, 2019, 05:53:10 PM
Ok so... not too bad for CRC errors seen worse. I would watch the Attenuation closely as it appears to move up and down :-\ . I had this before on my line, turned to to be water on the u/g section of the line.
How much / quality of cable connecting the modem to the  wall socket do you have? if you can make it as short as possible, and using good screened interconnect. Mines 50cm and it does make a small difference, about 2db.

Like this https://www.ebay.co.uk/itm/Cat6-BT-Infinity-2M-Modem-cable-VDSL-RJ11-to-RJ11-High-speed-Broadband-router/323748698639?hash=item4b60ed1a0f:g:fgkAAOSwiZhcaF42

There are people better qualified than me, who will take a deeper look at lose stats, and hopefully give you a more detailed response  :fingers:


Added cable to comments
Title: Re: Modem Errors..
Post by: 8062282 on June 24, 2019, 06:59:41 PM
Hi - Thanks for the link to the cable. I may invest in one of those. The attenuation has ranged from 44 - 41.5.   When the DLM was reset the CRC's & FEC's went a bit crazy until the DLM reduced the speed. It's so frustrating. Getting TT interested in sorting this issue out is really hard.

I'll need to look at the graphs & see if there's any noticeable spikes & times...
Title: Re: Modem Errors..
Post by: 8062282 on June 28, 2019, 07:04:19 PM
Hi - Can anybody help in explaining this please? Every night between 22.30 & 05.30, there a big increase in errors. I don't really understand this graph. As you can see the bitswaps per minute go up at the time the errors start & finish approx 5.30. What is the scale on the left?  Do the bitswaps look normal till 22.30?



Title: Re: Modem Errors..
Post by: roseway on July 03, 2019, 03:53:39 PM
Hi - Does DSLstats show all errors up, including the CRC/FEC errors etc that are below the SNR threshold?  I have an issue with noise at night but my ISP is claiming there is noise as well during the day. All I can see is an occasional spike and the CRC/ES/FEC errors are low.  If I didn't have the huge spike in errors at night, I'm almpost sure the DLM wouldn't keep reducing my speed.

Did you mean to post that in an impossibly small font? Here it is in normal size:

"Hi - Does DSLstats show all errors up, including the CRC/FEC errors etc that are below the SNR threshold?  I have an issue with noise at night but my ISP is claiming there is noise as well during the day. All I can see is an occasional spike and the CRC/ES/FEC errors are low.  If I didn't have the huge spike in errors at night, I'm almpost sure the DLM wouldn't keep reducing my speed."
Title: Re: Modem Errors..
Post by: Weaver on July 03, 2019, 05:08:15 PM
Our user 8062282 asked:

Hi - Does DSLstats show all errors up, including the CRC/FEC errors etc that are below the SNR threshold?  I have an issue with noise at night but my ISP is claiming there is noise as well during the day. All I can see is an occasional spike and the CRC/ES/FEC errors are low.  If I didn't have the huge spike in errors at night, I'm almpost sure the DLM wouldn't keep reducing my speed.
Title: Re: Modem Errors..
Post by: burakkucat on July 03, 2019, 06:23:25 PM
Hmm . . . I found a report for the above post, reply no. 14 (and promptly fixed it), before noticing that both roseway and Weaver had posted subsequently.
Title: Re: Modem Errors..
Post by: kitz on July 03, 2019, 07:12:39 PM
Bit swap alone doesn't particularly prove anything.   It just tells us that your modem is working harder trying to keep bit rate sufficient to maintain sync.   Of more interest would likely be the SNRM graphs, as a reduction in SNR is usually what causes bit rate to drop.

I note from your last starts that the DLM has applied interleaving, which in itself will reduce the maximum attainable rate, but it should keep the errors under control. 

Quote
Does DSLstats show all errors up, including the CRC/FEC errors etc that are below the SNR threshold?

DSLstats will record all errors.  Check that you have the relevant boxes ticked under the Items to Monitor tab.
Title: Re: Modem Errors..
Post by: ejs on July 03, 2019, 08:11:07 PM
Does DSLstats show all errors up, including the CRC/FEC errors etc that are below the SNR threshold?

The question does not make sense. There is no such "SNR threshold" for errors. Either the FEC data was used to correct something, or it wasn't. Likewise the CRC either matches the value calculated for the data received or it doesn't.
Title: Re: Modem Errors..
Post by: 8062282 on July 07, 2019, 06:59:58 AM
I deleted this as I couldn't see any responses, apologies. 'Hi - Does DSLstats show all errors up, including the CRC/FEC errors etc that are below the SNR threshold?  I have an issue with noise at night but my ISP is claiming there is noise as well during the day. All I can see is an occasional spike and the CRC/ES/FEC errors are low.  If I didn't have the huge spike in errors at night, I'm almost sure the DLM wouldn't keep reducing my speed.'

The errors I can see during the day are minimal & using the DLM calculator, aren't anywhere sufficient to keep my speed down. TT just seem to be filling my head with rubbish & are extremely vague when responding & quite often don't answer the question at all.  Why can't I see this noise during the day?  Are TT telling porkies to keep me quiet.

I had the council out the other day to look at a street lamp outside my house as I thought it may have a faulty ballast. They've replaced the whole light fitting at the top. The 1st night afterwards, the errors didn't seem as high. The ES only went as high as 30 at points rather than the 45 before,
so I thought that might have been the issue.  Lo & behold in the early hours of Sat morning my SNR goes up to 16.6 & won't budge. The DLM then kicked in at 03.30 & the SNR stayed at 16.6. I've tried re-starting the router & switching it off for over half an hour.  With a SNR of 6dB my attainable is 8.5mb but my line rate is staying at 4095. Nobody on support at weekends & the tech peeps won't just optimise the line for you without having you jump through hoops.

Whilst the SNR is at 16.6, it's not showing up any errors, hence my question about DSLstats showing all errors. When the SNR is at 6dB, DSLstats shows significantly more errors. Below is the worst day in the last week..

Average error rates for 02 Jul 2019

CRC erors per hour:  46.1 Down,  0.38 Up
FEC erors per hour:  229 Down,  6.75 Up
HEC erors per hour:  400 Down,  0.21 Up
ES per hour:  12.3 Down,  0.25 Up
SES per hour:  0 Down,  0 Up

I have all the tick boxes checked. I'm new to monitoring my connection so apologies if I sound a bit dim  :)   
Title: Re: Modem Errors..
Post by: 8062282 on July 07, 2019, 07:50:04 AM
Did you mean to post that in an impossibly small font? Here it is in normal size:

"Hi - Does DSLstats show all errors up, including the CRC/FEC errors etc that are below the SNR threshold?  I have an issue with noise at night but my ISP is claiming there is noise as well during the day. All I can see is an occasional spike and the CRC/ES/FEC errors are low.  If I didn't have the huge spike in errors at night, I'm almost sure the DLM wouldn't keep reducing my speed."

Apologies, that was posted from my iPhone. No idea why it came out that size, sorry..
Title: Re: Modem Errors..
Post by: Chrysalis on July 07, 2019, 07:59:49 AM
im not convinced this is due to DLM, could easily be variable line conditions, if it ever syncs at 8mbit again please grab the line stats
Title: Re: Modem Errors..
Post by: 8062282 on July 07, 2019, 10:15:31 AM
This is what the Billion 7800DXL is reporting at 6dB
Title: Re: Modem Errors..
Post by: kitz on July 08, 2019, 11:27:03 AM
Bit swap alone doesn't particularly prove anything.   It just tells us that your modem is working harder trying to keep bit rate sufficient to maintain sync.   Of more interest would likely be the SNRM graphs, as a reduction in SNR is usually what causes bit rate to drop.

The SNRM is usually the most important graph to monitor when it comes to trying to understand what is happening to the line.   It can show if the line is suffering from regular night time patterns or if they are quick noise spikes.   I notice you mention getting the council out to the street light.   If it was the street lamp then you would normally expect the SNRM to dip by a few dB at dusk and the SNRM to increase again at dawn corresponding to when the light comes on and goes off.   Use the SNRM graphs over a period of time to see if you can see regular patterns occurring.  Dips in SNR(m) is what usually causes bitswap and errors to increase.

The DLM doesn't look at night and day independently, but takes into account what has happened over the course of the full 24hr period.    Therefore as far as it's concerned if you are breaching the error threshold at night, (even if it is just at night) it will class the line as having breached the full days limit and take action accordingly. 

 
Title: Re: Modem Errors..
Post by: 8062282 on July 08, 2019, 05:24:08 PM
Hi - Thanks for getting back to me. The SNRM doesn't really fluctuate that much at night. It probably fluctuates by 0.1 up to 0.3 of a dB at night. I've attached a SRNM graph of the 7th showing it to bit a bit wobbly & then about 3ish it shoots up to 16dB & then for the next two nights, there was no errors showing up at all. Hence my previous question about DSLstats showing up all errors irrespective of the SNR. Rebooting the router or switching it off for half an hour wouldn't budge the SNR.   TT optimised the line this morning & the line synced at 7.9Mb. DLM kicked in later that morning & my speed went back down to 3511.

The council changed the light fitting Friday morning & the ES errors didn't seem as high Sat morning when I checked. Unfortunately when the SNR shot up to 16, DSLstats didn't report any errors for the following 2 nights. I've just re-started the router & the speed has increased to 4165 with a SNR of 6dB. I will have to see what errors it reports tonight.

What I'm trying to get my head round is, why are such low errors causing a performance issue. I had an engineer out on the 14th of June as the SNR started to swing about all over the place causing disconnections etc. He did some work in the cabinet & changed the D & E round. That stopped the SNR swinging about but hasn't stopped all the ES at night nor has it stopped the DLM keep reducing my speed. The average ES for the previous 7 days is 125 with low CRC/FEC errors. Mostly accumulated between 22.30 & 05.30. I don't think that amount of errors should be an issue for DLM.   TT are a complete waste of time & just keep avoiding the issue.

I've tried 2 different modems, different filters, invested in a nice new solid copper RJ11 to RJ11 cable but nothing is stopping the problems. I want to move to fibre but I don't want the issue to cause me any problems, as I know you can't have the DLM reset like you can on ADSL.  All I can do is try to get to the bottom of it or hope that the problem is between the exchange & my cabinet.

Despite the SNR staying fairly constant up to 3am, the ES were going up till they dropped off about 4ish. No idea what the upstream ES was earlier. That was just a random one...
Title: Re: Modem Errors..
Post by: kitz on July 09, 2019, 07:13:55 AM
OK its kind of obvious now why you asked the question which didn't make sense.

Firstly DSLstats will record all errors, the reason why none were recorded after the SNRM shot up to 16dB is simply because there weren't any.

SNR Margin is a buffer zone above the true SNR.  The higher the SNR Margin, then the less likely there is to be any errors.   SNRM and Target SNRM is a way the DLM can help to stabilise a line.  The downside for you is by increasing the Target SNRM, this takes away a large chunk of sync speed.

Have a read of:
 ~ What is SNR? (https://kitz.co.uk/adsl/linestats.htm#SNR)
 ~ What is SNR Margin? (https://kitz.co.uk/adsl/linestats.htm#SNR_Margin)
 ~ What is Target SNR Margin (TNMR)? (https://kitz.co.uk/adsl/linestats.htm#target_SNR)
and you will perhaps understand why the DLM is using the Target SNRM on your line.



The big question now is what is triggering the DLM to increase the Target SNRM?

There are 2 main parameters which the DLM monitors to decide if it needs to take any action
1) The amount of Errored Seconds
2) The number of line retrains  (resyncs)

Looking at your line stats ~125 Err Seconds should not trigger the DLM and if you can confirm that the line didn't have a lot of disconnections the previous day then it becomes a bit puzzling why it should behave the way it is doing. 

One possibility that does spring to mind - especially when your target SNRM appears to shoot straight up to ~15dB - is that TT have you on a very harsh DLM profile.   There are many different profiles that TT use, but from memory 15dB is one of their maximum stability profiles.


I'm wondering if your DLM profile is too agressive.  - No matter how many times TT reset the DLM, if the actual profile is too high, then DLM could literally be kicking in just after a low rate of errors.

Try asking TT what your DLM profile is and can it be reduced.   
The profile will look something like SF_15_24M_1M.   With me not being on TT I'm not sure offhand what options are available to you, but try asking if your DLM profile can be changed to a lesser one now that the line fault has been fixed by the engineer to one of the 6dB profiles.    Perhaps b*cat can recall which profile he is on?
Title: Re: Modem Errors..
Post by: 8062282 on July 09, 2019, 06:05:04 PM
Hi Kitz - I had a period of 2/3 days where the SNR was up & down & going into the minus with the odd disconnect. This prompted me to get the engineer out on the 14th June. After he changed the D & E the SNR has been rock solid & has never really deviated from 6dB. The BTOR engineer also told me he had to get TT to take a cap off my line which TT denied was on there. The SNR dips a little at night but after googling for info, that's the norm. Apart from those disconnects, I never get any disconnects at all. The only time I get a disconnect is when the DLM kicks in.

I can't actually get TT to tell me what profile I'm on. I've asked numerous times & they just evade the question. None of what they're saying correlates with what the stats are showing. Now they've reset the DLM Monday morning, the ES that I'm worried about are now showing up. It seems like the street lamp that I thought was the problem, isn't the problem. I've attached a pic. TT aren't interested. When all these errors are occurring, there's no movement in the SNR. I've attached a pic of the SNR covering most of that period. I haven't seen a dip like that in the upstream before, that's a new one.

Today I have 2 steep downward SNR drops on the upstream & one downstream dip that caused a disconnect. You can see one of the upstream dips & the downstream dip in the attached pic. That's never happened before in all the time I've been monitoring my connection. Not sure what caused that.

As today hasn't yet finished, here's my average errors for yesterday. These surely can't be enough for the DLM to keep kicking in and reducing my speed or are they? Most of the errors have been accumulated during the period where I get all the ES at night. We live in a quiet avenue. I'm in bed for 10.15 as I'm up at 5.30 so it's not like there's anything on in the house at that time which would cause those errors.


Average error rates for 08 Jul 2019

CRC erors per hour:  43.6 Down,  0.58 Up
FEC erors per hour:  292 Down,  1.38 Up
HEC erors per hour:  75.9 Down,  0.63 Up
ES per hour:  3.71 Down,  0.50 Up
SES per hour:  0.46 Down,  0 Up

I will try asking for my profile again & see what they come back with. Can I demand to know what profile I'm on?

Thanks for your help & I will have a read of those links you sent. I've been googling for info all over the place & none of what TT are saying is making sense compared to what the stats are showing me. They keep telling me I have excessive noise during the day, not just at night. That would show up in the stats wouldn't it?  My errors during the day are minimal compared to those accumulated at night.
Title: Re: Modem Errors..
Post by: burakkucat on July 09, 2019, 10:51:07 PM
Perhaps b*cat can recall which profile he is on?

I can't say in TT-speak but in the ordinary words that we would use my circuit is provisioned with a DLM Off, target SNRM 6dB and interleaved profile.
Title: Re: Modem Errors..
Post by: 8062282 on July 10, 2019, 06:58:45 PM
Hi - TT did tell me my profile. The one Kitz thought it might be was their old system. My profile is 4096_1024_M6 (interleaved). I'm supposed to be on an 8mb line but it appears I'm capped at 4mb, They said my line isn't stable at higher speeds.  They keep going on about 'instability caused by the fluctuating background noise'.  My modem is connected to the master socket & I have a MK3 filtered face plate on there.  If there was noise, would this not make my SNR go down & how would I see the noise in DSLstats?   It's only started going up to 16dB in the early hours of the morning, since weekend. When it does that, I don't see any errors at all. The only way to get it back down to 6dB is to get them to optimise the line. This sorta defeats the training period if it keeps going up to 16dB. I will see what happens tonight.  Before that the SNR was always stable at 6dB.

Is any line completely error free? This is my error count for yesterday. Is that enough for the DLM to keep my speed down


Average error rates for 09 Jul 2019

CRC erors per hour:  39.3 Down,  11.9 Up
FEC erors per hour:  539 Down,  35.0 Up
HEC erors per hour:  271 Down,  88.1 Up
ES per hour:  10.8 Down,  1.54 Up
SES per hour:  0.83 Down,  0.17 Up

So far today


Average error rates for 10 Jul 2019


CRC erors per hour:  34.1 Down,  0.36 Up
FEC erors per hour:  429 Down,  1.58 Up
HEC erors per hour:  172 Down,  0.18 Up
ES per hour:  5.33 Down,  0.24 Up
SES per hour:  1.21 Down,  0 Up

They've had me disconnect everything for 2 hours tonight while they run some tests. I'll find out what the result is tomorrow.


Title: Re: Modem Errors..
Post by: kitz on July 10, 2019, 09:04:20 PM
5.33 E/S per hour (128 per day) is nothing...  although with a 15/16dB SNRM you wouldn't be expecting to receive many as the large margin would stop many from occurring in the first place - as would interleaving 

>> If there was noise, would this not make my SNR go down

Yes it would.   
If it were me, I would temp adjust the graph period to 24hrs and send them some screen shots over the course of a few days showing them how stable the SNRM is. 

(Change graph view from Configuration > Graphs > Time per page.)

I'm afraid I am not aufait with what their LLU DSLAM does these days - but the reps on their own forum used to be far more efficient at amending a line profile than going through their CS support desk.
Title: Re: Modem Errors..
Post by: 8062282 on July 10, 2019, 09:29:13 PM
Thanks. I've tried telling them till I'm blue in the face that there isn't enough errors showing at 6db for the DLM to intervene. They just aren't listening. This was their last response. Does it make sense to you? I'm getting no drops in SNR & the router isn't dropping connection. They also said that everything is automatic now & they don't have the ability to adjust anything.


If your router was constantly in sync at 8Mbps when you was with Virgin with no connection drops or performance issue then you won't have had the issue with fluctuating background noise that you have now, something has obviously changed somewhere

You can see the noise on the line yourself by checking your router stats. When I reset DLM earlier the router was in sync at 8.1Mbps with an SNR of 6.1db, the sync speed has now dropped to 4.4Mbps with a SNR of 6.1db (DLM hasn't changed your profile since I optimised earlier)

The drop in speed is due to the increase in background noise causing the router to lose sync and resync at a lower speed - the fact that your router is now in sync at half the speed but the same SNR shows the increase in background noise (if DLM had just randomly capped your speed at 4.4Mbps with no change in background noise then your SNR would now be 16db not 6db
Title: Re: Modem Errors..
Post by: burakkucat on July 10, 2019, 10:47:10 PM
They also said that everything is automatic now & they don't have the ability to adjust anything.

That is, unfortunately, a load of old hog-wash.  >:(

Somewhere, in TT-land, the script-writers have confused what is (& is not) possible for an LLU'd ADSL2+ circuit with what is (& is not) possible for a VDSL2 circuit. In the former case, an LLU'd ADSL2+ circuit, it is connected to a TT owned, a TT configured and a TT operated MSAN. In the latter case, a VDSL2 circuit, it is connected to an Openreach owned, an Openreach configured and an Openreach operated MSAN (operating as a DSLAM).  ::)
Title: Re: Modem Errors..
Post by: j0hn on July 11, 2019, 01:39:48 AM
Try the Talktalk community forums.

The OCE's (UK based Talktalk staff) are pretty good.

That is, unfortunately, a load of old hog-wash.  >:(

Somewhere, in TT-land, the script-writers have confused what is (& is not) possible for an LLU'd ADSL2+ circuit with what is (& is not) possible for a VDSL2 circuit. In the former case, an LLU'd ADSL2+ circuit, it is connected to a TT owned, a TT configured and a TT operated MSAN. In the latter case, a VDSL2 circuit, it is connected to an Openreach owned, an Openreach configured and an Openreach operated MSAN (operating as a DSLAM).  ::)

I think that for older customers the who had DLM off, it can remain that way.
They rolled out a new DLM a couple years ago and often claim no ability to disable the DLM.
Title: Re: Modem Errors..
Post by: kitz on July 11, 2019, 12:32:18 PM
Quote
The drop in speed is due to the increase in background noise causing the router to lose sync and resync at a lower speed - the fact that your router is now in sync at half the speed but the same SNR shows the increase in background noise (if DLM had just randomly capped your speed at 4.4Mbps with no change in background noise then your SNR would now be 16db not 6db

But your SNR Margin is 16dB.   What on earth are they looking at?
Title: Re: Modem Errors..
Post by: 8062282 on July 11, 2019, 05:18:36 PM
Try the Talktalk community forums.

The OCE's (UK based Talktalk staff) are pretty good.   I think that for older customers the who had DLM off, it can remain that way. They rolled out a new DLM a couple years ago and often claim no ability to disable the DLM.


I'm on the TT help & support forum & it's the OCE's that are responding.  I've asked if they can switch the DLM off & they said they can't. My interpretation of that is, they can, but won't  :lol:
Title: Re: Modem Errors..
Post by: 8062282 on July 11, 2019, 05:23:12 PM
That is, unfortunately, a load of old hog-wash.  >:(

Somewhere, in TT-land, the script-writers have confused what is (& is not) possible for an LLU'd ADSL2+ circuit with what is (& is not) possible for a VDSL2 circuit. In the former case, an LLU'd ADSL2+ circuit, it is connected to a TT owned, a TT configured and a TT operated MSAN. In the latter case, a VDSL2 circuit, it is connected to an Openreach owned, an Openreach configured and an Openreach operated MSAN (operating as a DSLAM).  ::)


They claim that the DLM is fully automated & the only thing they can do is optimise the line & restart the training period.  I did ask them who sets the profile up when they have a new customer as I didn't expect the DLM to guess the profile. I never got an answer.  If they have to set the profile up in the 1st place, I'm guessing it can be adjusted..
Title: Re: Modem Errors..
Post by: 8062282 on July 11, 2019, 05:42:13 PM

But your SNR Margin is 16dB.   What on earth are they looking at?


Good question. I have no idea. It's never done that before in all the time I've been monitoring my connection. It's happened on a couple of nights. The worst one being on the start of a weekend. Switching the modem off & leaving it off for 30 mins didn't make any difference nor did a quick re-boot. I had to wait until Monday when they optimised the line & that then brought the SNR back down to 6dB.  They're still maintaining I have unacceptable background noise which is why my speed isn't increasing. I can see the errors but to me, they look fine. I'm still getting a huge spike in ES at night which I'd like to get to the bottom of. Not sure what those daytime one's are. I'm at work so they could be anything. Some days are OK & other days I get bigger random spikes of ES. All in all the total never looks that bad.


My full tally of errors for yesterday is below. I would say they're OK:



Average error rates for 10 Jul 2019


CRC erors per hour:  33.4 Down,  0.46 Up
FEC erors per hour:  504 Down,  1.71 Up
HEC erors per hour:  245 Down,  0.23 Up
ES per hour:  7.45 Down,  0.28 Up
SES per hour:  0.93 Down,  0 Up