Damn DLM

[#1]

Why oh why oh why cant the bloody ADSL2+ DLM leave things alone......  My line has been uber stable for months, with infrequent resyncs ( can go for over 1000hrs sometimes with no resyncs), and stable syncs of between 6900 and 7700 depending upon when the resync occured. (Attn down 46dB) Now noticed that my syncs are just below 9000 and the default margin has dropped to 3dB.  I KNOW full well, that my line will not hold this for any length of time, and indeed last night the SNRM was at 0.2dB, but luckily still managed to maintain sync, but throughput did become rather choppy.  I realise alot of people would kill for these syncs, but I much prefer stability to speed.  Whats eventually going to happen is more and more resyncs, and knowing my luck will end up with a margin of 9 or 12dB.  WHY CANT THINGS BE JUST LEFT ALONE....... if I wanted more speed i would have asked plusnet. 
Whatever happened to Daves Fixed SNRM trial, this was the BEST THING ever to happen, and should have been made a live product, but I presume BT will never want to give us a facility like this.....
Sorry for the rant

[#2]

Hi penfold,
Not heard from you for a while. There is no fixed DLM trial per se at the moment, however I should still be able to request a wide-open fixed profile which to yourself would mean no DLM at all.
Let me know if your OK with this and I'll get on the case, should take around 24 hours to sort out.

[#3]

Sorry for sounding thick.... whats  a wide open fixed profile...?

[#4]

Its not really a technical term I was trying to be descriptive, its no DLM effectively.

[#5]

Quote

its no DLM effectively

That's not available on the 20CN network i.e. G.DMT is it? 

[#6]

Quote from: _Adam_Walker_

Its not really a technical term I was trying to be descriptive, its no DLM effectively.

Thanks Adam.  Dont mean to sound disrespectful, but are you sure about this, are BT giving you this amount of control on 21CN?? If so, its not widely advertised, and I am sure lots more people would like the DLM removed completely......

Quote from: _Adam_Walker_

There is no fixed DLM trial per se at the moment, however I should still be able to request a wide-open fixed profile which to yourself would mean no DLM at all.

What I was referring to was Daves DLM trial a while back, where customers on the trial could either fix the SNRM, or fix to a banded profile.  I was rather conservative, as prefer stability to speed, and fixed at 9dB Down and Up.  had to come off the trial due to serious line issues, if you recall, fixed by D and E side pair swaps, repairs to the cable bundle to the Cab, and a lift and shift.
So...... correct me if I am wrong, i can fix my SNR to whatever I want up and down, or have I got the wrong end of the stick, so to speak

[#7]

Quote

Dont mean to sound disrespectful, but are you sure about this

None taken as I'm sure, just let me know if you want me to fix DLM for you. I can however perform an SNR reset too but I can't set the SNR specific values. Your router might let you do that though.

[#8]

Thanks Adam.  So just to be sure, this dosnt fix SNRM, but just removes the BT DLM.  So what will this do, will it just keep SNR at the levels they are at now, regardless of any resyncs.....
Can you also confirm what my surrent SNRM is, if you can....  I am sure its 3dB down, 12db up.
Currently my line has lost sync only once, at this higher level, and has stabalised at a lower level, but I am surrentl quite pleasantly surprised at how the router has coped with the less SNRM.
Current stats are
ADSL Link Downstream Upstream
Connection Speed 8253 kbps 888 kbps
Line Attenuation 45.5 db 23.0 db
Noise Margin 2.6 db 10.5 db
Any idea why upload is stuck like glue to 888?

[#9]

You can have your SNR fixed at different targets  and even your levels of interleave  
Mine for example is hard fixed at 6db up& down with interleave off (inp 0)
WBC 160K - 24M No delay (INP 0) 6dB Downstream, UC No delay (INP 0) 6dB Upstream (ADSL2+)

[#10]

I remember seeing somewhere that a "fixed" 888 upstream speed means you are one of the chosen ones. I think it's a 21CN DLM bug that caps upstream at 888 when interleaving is on - but only affects some users.
A target SNRM of 3dB is included in the 21CN DLM's armoury, but I guess only very good lines can cope with it.

[#11]

Quote from: spraxyt

I remember seeing somewhere that a "fixed" 888 upstream speed means you are one of the chosen ones.

I wish spraxt
My line is quite good now, but I have doubts on a 3dB margin, given my 45,5dB attenuation..... 
Adam, if poss can you fix me at 6dB up and down, with interleaving on and remove DLM.

[#12]

Has the DLM not raised the target back to 6dB already? If it's not suitable transmission error rates (CRC and HEC) would usually be high and cause the DLM to react quickly.

[#13]

@spraxt
The DLM has not altered anything, but the line has stayed remarkably stable..... Current stats
Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 61021 83426 0 84 517 48:19:47
LAN 10M/100M 1768303 801714 0 279 12 1833:28:51
WLAN 54M 262423 203403 0 722 116 94:50:48
ADSL Link Downstream Upstream
Connection Speed 8253 kbps 888 kbps
Line Attenuation 45.5 db 23.0 db
Noise Margin 1.8 db 10.6 db
Other stats
adslctl: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 8000
Channel: FAST, Upstream rate = 888 Kbps, Downstream rate = 8253 Kbps
Link Power State: L0
Mode:                  ADSL2+
Channel:                Fast
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):      1.9            10.7
Attn(dB):      45.5            23.0
Pwr(dBm):      0.0            12.6
Max(Kbps):      8216            888
Rate (Kbps):    8253            888
                        G.dmt framing
K:              129(0)          14
R:              10              16
S:              1              8
😧              64              8
                        ADSL2 framing
MSGc:          59              10
B:              128            13
M:              1              8
T:              2              9
R:              10              16
S:              0.4982          4.0000
L:              2232            256
😧              64              8
                        Counters
SF:            12108160                10892058
SFErr:          17168          0
RS:            1574060910              2783531
RSCorr:        46796648                22
RSUnCorr:      81288          0
HEC:            13648          0
OCD:            15              0
LCD:            0              0
Total Cells:    3816290171              1115228
Data Cells:    2283258        5128
Drop Cells:    0
Bit Errors:    0              0
ES:            64813          0
SES:            20706          0
UAS:            379            0
AS:            196057
INP:            1.14            2.00
PER:            16.19          18.00
delay:          7.97            8.00
OR:            32.11          7.11
Bitswap:        59888          7646
Total time = 1 days 9 hours 32 min 15 sec
SF  = 407719432
CRC = 1038302
LOS = 17
LOF = 72
ES  = 64813
Latest 1 day time = 9 hours 32 min 15 sec
SF  = 2120504
CRC = 269
LOS = 0
LOF = 0
ES  = 100
Latest 15 minutes time = 2 min 15 sec
SF  = 8362
CRC = 0
LOS = 0
LOF = 0
ES  = 0
Previous 15 minutes time = 15 min 0 sec
SF  = 55565
CRC = 12
LOS = 0
LOF = 0
ES  = 8
Previous 1 day time = 24 hours 0 sec
SF  = 5335952
CRC = 16175
LOS = 0
LOF = 0
ES  = 1731
15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
SF  = 55627
CRC = 41
LOS = 0
LOF = 0
ES  = 15
15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
SF  = 55564
CRC = 6
LOS = 0
LOF = 0
ES  = 5
15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
SF  = 55565
CRC = 5
LOS = 0
LOF = 0
ES  = 4
Showtime Drop Reason:  8000
Last Retrain Reason:    8000
unsure what these mean though.....  Also i was under the impression I was interleaved.....

[#14]

Quote from: penfold

Channel:                Fast Trellis:                U:ON /D:ON Max(Kbps):      8216            888 Rate (Kbps):    8253            888                         ADSL2 framing 😧              64              8                         Counters SF:            12108160                10892058 SFErr:          17168          0 RS:            1574060910              2783531 RSCorr:        46796648                22 RSUnCorr:      81288          0 HEC:            13648          0 OCD:            15              0 LCD:            0              0 unsure what these mean though.....  Also i was under the impression I was interleaved.....

Despite what the green text says there are a number of clues (marked in red) that suggest your connection is in fact interleaved. Having an upstream speed of 888kbps as the first - a 21CN DLM bug is believed to cause this "cap", though not everyone is affected. The next ones are firmer indications - Interleaving depth 64/8, and having RSCorrected errors (those are what Interleaving facilitates).
As far as uncorrected errors are concerned, they are a small fraction of those corrected and it looks like the DLM is happy with the measured rate of these.
Hope this continues for you.

[#15]

Removed.