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From http://speedtest.btwholesale.com/
IP Profile for your line is - 39.73 Mbps
From HG612 stats
Max: Upstream rate = 10308 Kbps, Downstream rate = 41312 Kbps
What is the relationship between IP profile and max downstream rate?
I've just resynced the modem and I thought the IP profile should match the max downstream rate.
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96.8%
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The IP profile is a little less because of the way certain overheads are counted or not counted.
So they do 'match', but not as exact numbers.
I've seen 96.79% quoted ( http://forum.kitz.co.uk/index.php?topic=10514.0 ),
your is just under that at 96.17%
On the whole it is best not to resync the modem. That can be seen as errors by DLM and your speed can lower.
Resyncing the router (or disconnecting and reconnecting) is what reestablishes the PPPoE connection and updates the IP/BRAS profile to 'match' the sync speed.
Sometimes the modem resync will be quick enough that the higher level router->exchange connection is not broken; in that case you will get an out of date IP/BRAS profile.
--
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.
Edited by StephenTodd (Fri 17-May-13 09:19:10)
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Thanks. Hopefully the DLM will not be upset by a resync after 5 days.
From the HG612, my sync rate is 40793 which *.9679 = 39.48Mbps, close to my IP profile.
This connection seems to maintain an SNR of about 6.2. Another FTTC connect close by has a SNR of 4.4, sync rate of 46529 and IP Profile of 46.37. The SNR seems to be reducing over time. Is my SNR likely to reduce similarly over time, giving me an improved profile?
plusnet -> entanet -> Andrews & Arnold -> BE -> plusnet Fibre
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It might improve a little. They usually seem to want to make a connection at around 6db SNR, unless there is a history of problems on the connection.
Having said you don't want to fiddle with the modem too much, you could wait until you see a particularly high snr (eg the signal is particlarly good), and then force a resync.
That will probably give you 6db against the good signal, which will drop as the signal deteriorates.
However, doing that might increase the error rate and cause DLM to force extra error correction, so you would not necessarily win out long term.
My understanding from other posts (especially very helpful ones from WWWombat). Remember: my understanding is NOT 100% reliable ...
~~
The Max figures you get from the HG612 give you an indication of the very best you could possibly get accepting a significant amount of unreliability.
The main difference between Max and actual are partly due to SNR and partly due to the overheads of error correction.
The overheads of error correction are R/N (or R/I) (R,N,I from the modem figures).
If DLM dropped error correction on your line, you would see a speed of | Text | 1
| NOECCPath = Path/(1-R/I) |
I think that generally to losses due to error correction are greater than the losses due to too high an SNR.
DLM does not gratuitously force higher SNR and ECC; it does it because it sees (or thinks it sees) errors.
So you certainly can't expect miraculous changes.
~~~~~~~~~
If SNR decreases without forcing a new connection, that is because the actual signal is deteriorating. Once a modem connection is made, the sync speed will not change during the life of that connection. If SNR gets too low, the errors will build up so much that DLM will force a new connection, and that will be at a lower sync speed.
--
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.
Edited by StephenTodd (Fri 17-May-13 10:49:27)
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Ah, I misread your question. The Modem max downstream rate is just a calculated figure and has little to do with reality - reality being the actual sync rate.
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might it be the sync speed at 0 dB SNR margin ?
--
Phil
MaxDSL - goes as fast as it can and doesn't read the line checker first.
MaxDSL diagnostics |
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Mine is quite often below my sync speed 
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might it be the sync speed at 0 dB SNR margin ? That's my guess.
Mine is quite often below my sync speed What snr is it quoting when it is below sync speed?
I guess that at sync time max was above the sync; as time went on max wanders below sync, but the line quality is good enough it still manages to keep the connection.
--
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.
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Max: Upstream rate = 10308 Kbps, Downstream rate = 41312 Kbps
What is the relationship between IP profile and max downstream rate?
There is no relationship between IP Profile and max downstream rate.
The relationship is with the sync speed.
This connection seems to maintain an SNR of about 6.2. Another FTTC connect close by has a SNR of 4.4, sync rate of 46529 and IP Profile of 46.37. The SNR seems to be reducing over time. Is my SNR likely to reduce similarly over time, giving me an improved profile?
The settings for VDSL2 have a target SNR margin of 6dB, no matter what the DLM intervention level. When a re-sync happens, the resulting SNRM should always be at 6dB or above, and should only be above that level if there is more capacity on the line compared with the package speed (40 or 80Mbps) or a DLM-banding speed limit.
If the actual, current, SNR has reduced below this level, then noise levels have increased since the last sync.
A reduction in SNR on a live connection doesn't alter the IP Profile. When a resync happens later, the target will remain at 6, so the resync is likely to result in a lower sync speed and lower IP Profile.
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might it be the sync speed at 0 dB SNR margin ? That's my guess.
Mine is quite often below my sync speed What snr is it quoting when it is below sync speed?
I guess that at sync time max was above the sync; as time went on max wanders below sync, but the line quality is good enough it still manages to keep the connection.
I think it is the max speed estimated by the modem is based on the target SNRM (ie 6dB), and assumes that no FEC or interleaving is going on.
My line started with max attainable of 90Mbps and synced at 80 with a SNR higher than 6dB (not sure exactly what, though). As the max attainable dropped (I'm presuming because crosstalk has increased) so did the SNR value:
85Mbps - 7.3dB (Feb 2012)
84Mbps - 7.1dB (Mar 2012)
83Mbps - 6.9dB (Jun 2012)
82Mbps - 6.6dB (Jul 2012)
I don't have the later figures to hand, but it was very close to 6dB on the last resync (Dec 2012).
Right now, the max attainable is 72Mbps and the SNR is running at around 3.2dB. I don't want to resync it...
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If the actual, current, SNR has reduced below this level, then noise levels have increased since the last sync.
That's a bit of a worry. The uptime is 16 days at the moment but I did think it had retained that SNR over a 40min power cut that occurred 16 days ago.
Has anybody successfully used the SNR tweak available with DSLstats?
plusnet -> entanet -> Andrews & Arnold -> BE -> plusnet Fibre
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I've tried tweaking SNRM via telnet, which is all any of the tools use. It doesn't work. Gives wierd results. That isn't surprising, as sync speed is not set directly using it in the way it is on ADSLx.
Openreach SIN 498 FTTC DLM section specifically says it should not be tweaked. (At the time I tried, it didn't). Note : It is the DLM system that sets the line profile, and this should not be interfered with by CPs/users setting rates, SNR margins etc. at the modem.
My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 54.2/15.2Mbps @ 600m. - BQM
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
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There is no relationship between IP Profile and max downstream rate.
The relationship is with the sync speed.
Using an unlocked HG612 modem, we see this info:-
Max: Upstream rate = 4851 Kbps, Downstream rate = 21488 Kbps
Path: 0, Upstream rate = 4859 Kbps, Downstream rate = 20764 Kbps
Max: is the theoretical speed & actual Sync speed is Path: 0.
From a HG622 modem, we see this:-
Max: Upstream rate = 4940 Kbps, Downstream rate = 25300 Kbps
Bearer: 0, Upstream rate = 4947 Kbps, Downstream rate = 24894 Kbps
Actual sync speed is Bearer: 0.
IP Profile SHOULD be around 96.79% of sync speed.
Occasionally VDSL2 connections resync too quickly for a PPP session to be initiated & thus the reported IP Profile can remain stuck at a higher or lower level.
A means to refresh the reported IP Profile is to disconnect/reconnect the ROUTER/HUB, not the MODEM as doing it via the ROUTER will not make DLM see it as an 'unstable' connection needing remedial & usually negative action in terms of sync speeds..
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what is weird results?
bear in mind the hg612 cannot tweak vdsl snrm.
you need a device that can such as a fritzbox or draytek 2850.
BT Infinity 2 Since Dec 2012
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Attempting to tweak settings is against Openreach's specifications.
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what is weird results? The weird results he got when he tweaked the vdsl snrm on his HG612.
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I never said it wasnt.
whats your reason for trying to scare people of doing it hmmm.
BT Infinity 2 Since Dec 2012
Edited by Chrysalis (Sat 18-May-13 17:34:53)
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the hg612 can only tweak adsl snrm not vdsl snrm.
BT Infinity 2 Since Dec 2012
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I don't know about the ADSLx aspect. I said I got wierd results when I tried it on VDSL2. I meant "I got wierd results when I tried it on VDSL2". Strange variations in sync and other stats. I don't remember as it was something like a year ago and clearly an unwise and useless thing to be doing.
My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 54.2/15.2Mbps @ 600m. - BQM
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
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the hg612 can only tweak adsl snrm not vdsl snrm. This is patently untrue. Maybe you mean you can't do it because of DLM?
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I havent tried to do it, but its clear on the telnet layout its an adsl command only.
Plus a few have tried it on the kitz forums and had no affect but then when tried on a fritz worked fine.
DLM would only stop the adjustment if someone tried to overcome banding (an actual min/max speed cap). FTTC defaults to a 6db snrm with cap of the product spec.
BT Infinity 2 Since Dec 2012
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I havent tried to do it Figures but its clear on the telnet layout its an adsl command only. Clear? How? It's called xdslcmd rather than adslcmd for the obvious reason that the command applies to both.
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I tried the tweak on my VDSL2 connection a long time ago & I can confirm it had no effect whatsoever.
I have tried both increasing & decreasing SNRM, just for testing purposes, but mainly to see if I could achieve sync at a lower SNRM (say 3dB) to try to increase sync speeds as my SNRM doesn't usually drop much below 6dB.
It seems that 6dB is the minimum 'target' SNRM that DLM on a VDSL2 connection will allow.
e.g. my conection is too far from the cabinet to get anywhere near the 40Mb cap for my 40/10 service.
Even though my DS sync speed has now dropped from around 30Mb in December to currently just over 20Mb, SNRM is still around 6dB or so, occasionally increasing to 7dB or so in the D2 band.
However, users much closer to the cabinet, where their attainable rates exceed the 40Mb or 80Mb caps, do see higher SNRM values when in sync at the 40Mb or 80Mb cap (as high as 30dB in some extreme cases - Attainable rate around 130Mb on a 40Mb capped service):-
| Text | 1
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
2627
| Retrain Reason: 0
Max: Upstream rate = 41318 Kbps, Downstream rate = 129700 KbpsPath: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps
Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783) DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band PlanUS: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939) VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 41318 kbps 129700 kbpsActual Aggregate Tx Power: - 8.6 dBm 13.3 dBm
============================================================================ VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 2.2 7.8 10.0 N/A 4.4 9.2 13.8 Signal Attenuation(dB): 0.0 N/A 7.2 N/A 4.4 9.2 13.8
SNR Margin(dB): 30.7 N/A 30.8 N/A 31.4 31.2 31.4 TX Power(dBm): -25.1 -128.0 -10.2 N/A 10.5 7.7 6.2
Down UpSNRM(dB): 31.4 30.8
LATN(dB): 0.0 0.0SATN(dB): 0.0 0.0
TxPwr(dBm): 13.3 -8.6ATTNDR(Kbps): 129700 41294 |
The HG612 SNRM tweak does work on ADSL connections, but it does appear that DLM blocks the tweak on VDSL2 connections.
I have seen comments that the tweak does work via a Fritz!Box, but I can't personally confirm the validity of those comments.
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debate settled, I tested on the fritz 3370, both 9db and 3db work fine. Bear in mind can reduce snrm on the fritz by editing the config file manually as the gui only allows adjusting it upwards.
BT Infinity 2 Since Dec 2012
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debate settled, I tested on the fritz 3370, both 9db and 3db work fine. In what way do they "work fine"?
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I believe he means it successfully changed the target margin.
Edited by deleted (Sun 19-May-13 14:46:56)
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Did anything else change?
I had in mind something relating to the Subject of the thread - FTTC IP Profile, Sync speed or even Modem max downstream rate?
Edited by deleted (Sun 19-May-13 15:14:03)
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debate settled, I tested on the fritz 3370, both 9db and 3db work fine. Bear in mind can reduce snrm on the fritz by editing the config file manually as the gui only allows adjusting it upwards. Anyone know if it works with the Billion routers - either the 7800 connected as a router to the modem [if that would work?] or the newer 8200 VDSL modem/router, assuming it still supports the facility? You can drop the target SNR Margin by up to 15dB if you are really in trouble (at least with the 7800)...
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well yes of course.
the sync speed changed and the noise margin changed.
I know how to see if it works thank you.
I didnt need to test it tho as someone else on kitz forum had already proven it works. But I did it just to be sure.
Note I am on a ECI dslam, there is a chance HG dslams react different, but the only time I think a adjustment will be blocked is if the line is banded and the banding overides the target snrm.
BT Infinity 2 Since Dec 2012
Edited by Chrysalis (Sun 19-May-13 19:48:23)
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There's no facility on the 8200 to "tweak" the SNR either directly or via the config file.
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I didn't get any joy either, using a Planet VC-230N. The Planet VDSL2 modem-router has the same Metanoia MT2301/3301 chipset that powers the Draytek 2750 / 2850.
The web UI options for tweaking TSNRM (and line rates) in CPE mode are greyed out when synced with a Huawei DSLAM.
IIRC, the Kitz contributor was Ixel, who reported that he couldn't directly change the data rates with his Fritz!Box (7390). Only the TSNRM was tweakable, and only tweakable in a downwards direction. [1]
And, worse yet. Just like the "X-Factor brat" who couldn't help pulling funny faces (see Daily Mail [2] !), when the wind blew, things just stuck!
Ixel found himself irrevocably banded on dramatically lower data rates than he initially enjoyed. As StephenTodd has already lamented, it's all part of The Plan! 
cheers, a
[1] http://forum.kitz.co.uk/index.php/topic,12398.msg233...
[2] http://www.dailymail.co.uk/tvshowbiz/article-2322403...
edit: wrong way round..
Edited by deleted (Sun 19-May-13 22:18:07)
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luckily I havent upset DLM doing that test.
I of course undid the change. But yes whilst the fritz can adjust the snrm the affects of the FTTC DLM system on a tweaked CPE is unpredictable and if the DLM sees it as a fault condition it may change line settings in reaction making things worse.
I think you guys know I dont like the new FTTC DLM in my eyes its worse than the adsl versions, as it seems openreach are taking the position we are in control, we know best and tough luck if you dont like what we give you.
BT Infinity 2 Since Dec 2012
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as it seems openreach are taking the position we are in control, we know best and tough luck if you dont like what we give you.
I think that is the way that DLM is going to have to go...
That's because the future direction is far more than just DLM applied to one single line. It is far more than trying to get one line at the maximum speed, and hang everyone else.
No more "I'm alright, Jack". It will includes spectrum management over multiple lines. Reducing power where it can, to make room for other subscribers. Altering frequency usage for some people, so more distant users get a reasonable look-in.
Eventually, vectoring plays its part too - but it looks like one aim there is to reduce power rather than a massive increase in speed.
In such circumstances, there is no option other than to be fully in control. No one user can know better what is needed for all lines.
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Very sensible comment. I wonder if you could explain it to some of the users on the BT Infinity forum, though?
--
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.
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There's no facility on the 8200 to "tweak" the SNR either directly or via the config file. Thanks. I did find the user manual a little later and a conspicuously absent facility as you say.
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I agree when it comes to power masking.
But not when it comes to noise margins and interleaving levels.
they both two different bits of management.
Power masking configuration to make lines play nice with each other although its a poor brother to full vectoring.
Interleaving/banding to control fault calls and engineer callouts.
BT Infinity 2 Since Dec 2012
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On power and noise (and by "power", I'm not restricting things to just the power masking):
The problem is that, once you have brought power into the equation, it seems that *everything* is related to it. Once you have the aim of reducing power (either to reduce the impact on other lines, or just to be green), every variety of DLM can be determined to have a subtly different effect on power.
For example, when using a fixed 6dB margin without variation. Under this system, you could be forcing those on very good lines to transmit at higher power than necessary. They could get the same speed, at lower power, using a 3dB margin - and have less crosstalk impact on other lines.
A better DLM/DSM process might be changing both the noise margin and the power settings at the same time.
An even better one might be making those decision differently for different parts of the spectrum, for different lengths of lines.
The Broadband Forum's document on various DLM/DSM/DQM techniques gives a good idea, as it tends to describe the interplay between methods, and describes the impact on power.
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On FEC/interleaving:
This is a totally different issue, though obviously it reduces throughput for the same notional power setting.
It is interesting to see that SIN 498 requires a modem to support PHY re-transmission, alongside this statement:
Note: Openreach do not currently enable PHY Layer retransmission as defined in
G.998.4 but expect to do so in due course. It is therefore strongly recommended
that the CPE modem should support PHY layer retransmission to minimse errors and
retrains.
Note: Openreach do not currently support Virtual Noise (VN) requirements as defined
in G.993.2. This SIN will be updated if at a later date Openreach decide to offer
this feature.
Perhaps FEC and interleaving are to be consigned to the scrapheap.
The only downside is that interleaving had a quantifiable effect on sync speed, reducing the throughput expectations of the susbcriber. PHYR isn't quite so quantifiable.
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the question is have you ever seen snrm or interleaving levels adjusted by DLM as part of managing a batch of lines? probably not, I think those 2 variables only get adjusted to manage a single lines instability.
BT Infinity 2 Since Dec 2012
Edited by Chrysalis (Wed 22-May-13 12:50:11)
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No, but I'm not talking about what *is* done now. I'm talking about where we're going with this over the next few years.
Almost every future direction for DLM/DSM/DQM requires the central system to be in more and more control of every line, more and more dynamically, with less and less control over an individual line.
If that is the near future, then I'm not surprised that Openreach started with the position that no CP could fiddle with the details of DLM.
It is easier to never give control to the CP than it is to have to wrest it away in the future. Even easier than to explain why to Joe Public end-user.
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Hi all,
I came across this thread by Googling, pure accident, but it's lucky I did as I can say exactly what happened.
Many months ago I had a Fritz!Box 7390 and I discovered I was able to change the target SNRM (well, offset it anyway), but further to that I could also set my own maximum sync rates on the downstream and upstream. This worked fine, and somehow I'm certain through my fiddling I managed to either confuse DLM or freeze it, as I've been stuck on a speed band of no interleaving for months now (60/20). No matter how many times I disconnect and reconnect modems/VDSL2 routers DLM doesn't do anything to my line now, always 60/20 with no interleaving. I prefer no interleaving so I'm happy with the accidental result. Whether I could do that again is another question, my experimentation was a result of trying to increase SNRM to turn off interleaving at the time.
My original thread on Kitz can be found at http://forum.kitz.co.uk/index.php/topic,11659.0.html.
Edited by Ixel (Tue 04-Jun-13 01:12:37)
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Sounds like it has been "banded". Stop messing for a few weeks and it might sort itself out.
My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 53.4/16.8Mbps @ 600m. - BQM
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
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Indeed it's banded, 30000 min, 60000 max, it's been like this since around December last year. The most uptime I've had in a single connection is around 29 days. Otherwise the average has been between 10-15 days a time, on the most part. A few months ago I had an apparent line fault (battery contact or something), engineer fixed that and checked his JDSU noticing I was speed banded with no interleaving applied and was going to request a reset, unfortunately he didn't have an OGEA or whatever number it was that identifies my circuit. I rung BT Business instead and tried getting them to sort it out based on what the engineer suggested and told me to do, they were most unco-operative though in the fact that my line is achieving 1-2 megabits above the original estimate, despite the fact it can currently achieve up to 91 megabits downstream.
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mine is set to min 37000 max 74000 its been like that since my fault and shows no signs of budging. However its not actually currently capping my sync due to the insane levels of crosstalk I am suffering from.
My modem will be turned off likely in the next week or so for a while as I have to start investigating a weird electric meter issue so will be turning everything off. I am hoping I dont get any new banding if the modem is turned off for a long time.
BT Infinity 2 Since Dec 2012
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