Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: GigabitEthernet on April 09, 2017, 06:42:34 PM
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I had a line issue back in February 2017 which resulted in lots of drops and my FTTC line was (as far as I understand), banded. The issue has been resolved and I have had a period of 30+ days connection and I'm still banded.
How long do I need to stay connected for for the banding to be removed? Is it more a total time? How does it work?
I am GbEth on MDWS but I've only just recently started uploading again.
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I am interested in this too. I was banded within the first few days of going live but engineer came and did a soft reset which removed the banding and G.INP. But I notice you have a lot of ES on your upstream, maybe that is why and US sync pretty low.
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I have been banded for 10 months now with v low errors and stable sync. I am not sure once applied DLM lifts banding.
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I too am banded and have been since August 2016. According to my ISP's technical department I will stay that way until my line goes to Green status (check your status in MDWS) for an extended period or they agree to get a BTOR engineer out to reset it and they wont in my case do that, they have point blank refused as they say the attainable speed is not much above my banded speed. My only hope is that when/if G.INP is re-instated on ECI cabinets and my attainable goes back to where it was prior to G.INP was removed (over 71000kbps). I was banded to try to resolve an issue which it did not fix but that makes no difference and I'm stuck.
Stuart
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all depends on your ISP
I was banded for 2 months, my ISP (zen) agreed it was banded and got OR to visit and DLM reset at no cost.
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Banding is extremely hard to get rid of. Weve seen people stuck on it for months.
Getting an engineer to do a full DLM reset appears to be about the only successful way of clearing it.
Ive only had a quick look at your stats but I notice you are showing amber for upstream for the profile which your ISP uses.
Also there doesn't seem to be much surplus SNRM atm to give you that much more speed. In fact your daily swing goes between 5.3 & 6.3 so nothing much to play with :(
G.INP is active and INP & Interleave aren't on so its not as problematic as it would be for someone on an ECI cab.
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Kitz, my DS SNRM is currently at 12dB...
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oops sorry, my bad. I looked at the graph on MDWS and you can see why I made that mistake. :doh:
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Just joined the banded club after a faulty modem caused several re-sync while I was away and could not rectify.
Problems now solved an my line is pretty clean and I'm now sat at 43998 Down whilst my attainable is 54MB approx. SNRM = 9.6db
I'm guessing from all the posts on this forum that I'm going to be suffering this fate for some time
Has anyone actually had theit banding removed by DLM and not needed an Engineer visit ?
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Just joined the banded club after a faulty modem caused several re-sync while I was away and could not rectify.
Problems now solved an my line is pretty clean and I'm now sat at 43998 Down whilst my attainable is 54MB approx. SNRM = 9.6db
I'm guessing from all the posts on this forum that I'm going to be suffering this fate for some time
Has anyone actually had theit banding removed by DLM and not needed an Engineer visit ?
Short answer is no. The vast majority are stuck on banding forever, or until an engineer does a full DLM reset.
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Had a BTO visit - thank you Zen
Problem removed back to 55MB sync
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Had a BTO visit - thank you Zen
Problem removed back to 55MB sync
Did the engineer have to visit your house? What did they do?
I wonder if I can get TalkTalk to do a DLM reset for our line.
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I wonder if I can get TalkTalk to do a DLM reset for our line.
My experience of TalkTalk is that they are not interested unless your attainable is significantly above the cap and your SNRM has enough in it to cope. Also they say unless your stats show green for both U/S and D/S they are unlikely to comply.
Stuart
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We've opened a request on the TalkTalk Community forum anyway - hopefully we might get a response at least.
Just a thought but I'm assuming going to the slower FTTC product (up to 38Mbps), won't undo the banding?
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We've opened a request on the TalkTalk Community forum anyway - hopefully we might get a response at least.
Just a thought but I'm assuming going to the slower FTTC product (up to 38Mbps), won't undo the banding?
I tried the same. They basically told me as long as line was within operating tolerance they won't raise a fault even though the banding was clearly unnesecary.
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I tried the same. They basically told me as long as line was within operating tolerance they won't raise a fault even though the banding was clearly unnesecary.
I got a reply which said the same. I've told them I'd like it removed again because the line doesn't need it - we'll see what they say.
I've researched this a little bit and the consensus is still not completely clear as to whether DLM ever removes banding itself. Some users on thinkbroadband seem to have had it removed automatically but I haven't seen any reports of that here.
There is something strange going on with my line though: the power on the upstream is often negative?
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There is something strange going on with my line though: the power on the upstream is often negative?
A negative value is perfectly acceptable. Please remember that you are looking at units which display the power relative to 1 mW.
So positive values indicate powers greater than 1 mW whilst negative values indicate powers less than 1 mW. (And when 0 dBm is displayed, the power is exactly 1 mW.)
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But it never used to be negative. It's only since this banding incident that this has happened.
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I can understand your logic in querying the power level but the setting is dynamic. The appropriate power levels are set by the two transceivers negotiating in the discovery phase. So there really is nothing to be concerned about. :)
If it would help assume, as an experiment, the absolute power was initially 1.01 mW and now it is 0.99 mW. The difference between those two power levels is just 0.02 mW. Now calculate those two powers in terms of dBm and look at the difference.
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Doing the calculations myself (as a result of a moment of doubt -- which seems to become more frequent with age) . . .
The equation is: n dBm = 10 x log10(p mW / 1 mW)
When p = 1.01 mW, 10 x log10(1.01 / 1) = +0.043 dBm (to three decimal places).
When p = 0.99 mW, 10 x log10(0.99 / 1) = -0.044 dBm (to three decimal places).
Difference in absolute powers is 1.01 - 0.99 = 0.02
Difference in the relative powers (to 1 mW) is +0.043 - (-0.044) = 0.043 + 0.044 = 0.087
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Urgh
Hi
The predicted A Range for this line, thats under optimal conditions is 35 - 54mb
Your router is in sync at 49mb and this is within that range. As such we or BT would not see this line at fault as it is behaving as predicted.
If unhappy with this, please follow our Complaint Process
Thanks
Karl.
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Presumably talktalk are been tight on engineer expenses.
I assume talktalk sell the service as "best efforts", that usually means lowest tier service, however it also should mean not artificially restricted.
I would send a polite reply stating that you simply want the service as is sold, basically for the line to run at the highest adapted sync rate, it is artificially capped excessively (12 db snrm with g.inp) and if they are not willing to follow due process of what is needed for a DLM reset then you want to leave your contract penalty free as they failing to fulfil those basic conditions.
Of course the question is are you prepared to change isp to get this resolved? and I havent personally read the t&c's for talktalk, just made assumptions based on what I expect to be in there.
There is naturally a conflict in the way the service is sold, it is sold as a rate adaptive service, but also sold with estimated speed's, and its a question of which one overcomes the other, as the latter allows an isp to only consider a fault if the estimated speed is not achieved.
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We've got an exceptional deal with TalkTalk and so would not be willing to change.
The frustrating thing, is that my understanding is DLM won't even consider unbanding the line (if it ever does) until all counters are green, which the upload is not (it's yellow). G.INP would resolve this but DLM won't add it and so we're stuck in a vicious circle!
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Just a few quick observations . . .
- An xDSL based service is provided as a "best effort".
- Perhaps WWWombat may be able to make use of the concept of the reduction in power as another empirical indicator of a circuit that is banded?
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I assume talktalk sell the service as "best efforts", that usually means lowest tier service, however it also should mean not artificially restricted.
I would send a polite reply stating that you simply want the service as is sold, basically for the line to run at the highest adapted sync rate, it is artificially capped excessively (12 db snrm with g.inp) and if they are not willing to follow due process of what is needed for a DLM reset then you want to leave your contract penalty free as they failing to fulfil those basic conditions.
I don't think that's what "best efforts" means. I think it's just wishful thinking that you've got a contractual right to the highest sync speed free of whatever things restricting it that you don't like.
I expect the terms and conditions will allow you to get the best speed that you line can achieve subject to all manner of things including the DLM.
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I have to say a DLM system that never unbands a line that no longer needs intervention is broken and not fit for purpose.
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I have to say a DLM system that never unbands a line that no longer needs intervention is broken and not fit for purpose.
Agree ............. which is one like that doesn't exist.
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I have certainly had enough consecutive green days to lift any other intervention - yet nothing. If it lifts at all (not convinced it does) then the settings are ludicrously conservative. It is pretty frustrating for anyone stuck on it.
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Agree ............. which is one like that doesn't exist.
Can you shed any light on the conditions for DLM to unband the line then?
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It's all been documented before on this forum ...... maybe someone else can provide links to said info, I haven't got the time or wherewithal to go looking.
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My observations on this, from looking at MDWS...
- The power reduction is on the upstream only, and kicked in sometime between May 7th and May 9th;
- The upstream ES rate approximately tripled
- The upstream noise margin hasn't changed much
- The change in power is roughly from +3.9 to -0.9dBm. Does that make the new power about one third of the original?
I'll throw in a reminder that UPBO will be in play here; we can expect it to adjust things to try to keep power lower in the lower frequencies, depending on the line length.
I wonder why, if the transmission power dropped so much, didn't the SNRM drop much?
My further observations on surrounding line conditions
- Hlog is similar on both 7th and 9th (but D3 looks iffy)
- QLN looks similar on both 7th and 9th
- SNR/tone looks similar downstream. Upstream shows data on the 7th (mostly U1, but a few tones in U2), but nothing on the 9th (or after the resyncs on the 10th).
- Bits/tone looks similar on both upstream & downstream.
I can't get sufficient data on the framing parameters to know if they changed at all (eg changing FEC settings), which could affect the way in which quality is determined.
So, ultimately, I can't fathom why the drop in power is not seen with a drop in SNR per tone, and a consequent drop in bits per tone.
In which case, I wonder whether there really has been a drop in power. Instead, I wonder whether we are seeing a bug in the presentation of power data; the only other anomaly I can see is that, in the "after" case we also see no tones measured in U2. I therefore wonder if this is a fault in calculating (or displaying) the aggregate power, when that aggregate no longer includes U2.
- Perhaps WWWombat may be able to make use of the concept of the reduction in power as another empirical indicator of a circuit that is banded?
As I see it, the line isn't banded in the upstream. Or it isn't hitting that limit.
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wombat I do believe US power does vary from sync to sync, as I see from one sync to the next changes on my US snrm, however the changes are minor in terms of the overall snr, I do see huge differences in US ES rate from one sync to the next as well.
I have observed after power cuts I tend to get very favourable treatment from the dslam on the US and have extremely low US ES rates, dslstats is currently reporting 0.2 ES/hour on my US for the previous day. However I suspect if I were to do a resync now, it would increase to over 5 ES/hour.
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- The change in power is roughly from +3.9 to -0.9dBm. Does that make the new power about one third of the original?
Doing the arithmetic --
10+3.9/10 ~ 2.46 mW
10-0.9/10 ~ 0.81 mW
2.46 / 0.81 ~ 3
Confirmed! ;)
As I see it, the line isn't banded in the upstream. Or it isn't hitting that limit.
Ah, I see. So let's scratch that idea. :-[
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I think it's just wishful thinking that you've got a contractual right to the highest sync speed free of whatever things restricting it that you don't like.
[rant]
I think BT have subtly changed the goalposts over time.
In ADSL and ADSL2+ days, BT/Openreach set their thresholds WRT engineer involvement, but ISPs had some flexibility over the line relating to DLM.
In original FTTC days, Openreach worked to similar thresholds WRT engineer involvement, and gave ISPs no flexibility relating to DLM. The attitude to the former says that BT are willing to investigate and fix physical faults, but they are forcing (some) ISPs to ignore unprovable faults. The attitude to the latter says that BT consider DLM to be vitally important, *and* that it is perfect in the decisions it makes.
[As a software engineer, I can say this: it is rather hard to make software perfect. If you can't make it perfect, then make it self-correcting]
The older variants of DLM weren't perfect. But they did relent, slowly. So, even if DLM made a bad choice sometimes, and got involved when it didn't need to, it would eventually remove itself. Thankfully.
The ability to self-correct meant that DLM's failure to be perfect was not a fatal flaw.
In current FTTC design, Openreach continue to make (some) ISPs ignore those unprovable physical faults. But as a consequence, they are also forced to ignore faults that DLM has latched on to and not let go.
The current variant of DLM seems to make bad choices - including being far too prone to using banding. It compounds this problem by having removed (or, at least, reduced) the self-correction. Banding, sometimes, is sticky.
To me, that looks like DLM is fatally flawed software that has inherited an ego problem from its designers: it cannot cope with its own flaws. DLM believes itself to make perfect decisions, and to have no need for a human nudge that says "Are you sure?" DLM is now the all-powerful arbiter that, sometimes, stops you getting the speed you ought to, but cannot see it.
And, because ISPs like TalkTalk aren't willing to get an engineer involved, you've lost any manual backstop.
If the Openreach platform had a button labelled "Please ask DLM to try relenting", TalkTalk would hardly refuse to press it.
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It's all been documented before on this forum ...... maybe someone else can provide links to said info, I haven't got the time or wherewithal to go looking.
We have this example of the opposite case, presented by Walter a year ago:
http://forum.kitz.co.uk/index.php/topic,16804.msg311500.html#msg311500
It involves a line that had been banded, and was recovering in 2.5Mbps steps every couple of days. Recovery then just stopped (at 27.4Mbps), with SNRM at 15dB, with no indication *why* it stopped. Certainly the error rates don't seem to have increased.
The post I link to is Walter reporting the freeze; two posts later we can see a graph of the line, from BaldEagle.
In that case, DLM ought to have continued to reduce banding (and increase the allowed speed).
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wombat I do believe US power does vary from sync to sync,
Yes. I think upstream handling is purposefully different, because it can make a difference to people on longer lines.
Here, you need something dynamic and flexible. DLM can be dynamic, but not always flexible.
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While re-connecting to MDWS, my screen updated @gbeth's data, and I noticed it had undergone a couple of resyncs earlier today (13th).
In particular, it was clear that the upstream power had, for a couple of hours, gone back up again. All with little change to the sync speed or much difference to the SNRM.
However, like I noticed here:
In which case, I wonder whether there really has been a drop in power. Instead, I wonder whether we are seeing a bug in the presentation of power data; the only other anomaly I can see is that, in the "after" case we also see no tones measured in U2. I therefore wonder if this is a fault in calculating (or displaying) the aggregate power, when that aggregate no longer includes U2.
The brief period today (between 2 resyncs) show measurements for U2 in the "SNR per tone" graph, which aren't present in the periods of low power before the first resync or after the second resync.
Note that while there is a difference in the upstream data in the "SNR per tone" graphs, there isn't really a difference in the consequent "bits per tone" graph.
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Well my line has been green on MDWS for a couple of days now after I made some cabling changes. If it stays like that, in theory I should be looking at around 10 days before DLM does something I think?
Sent from my iPhone using Tapatalk
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Something curious happened tonight. My line resynced and the sync speed is the same but the SNRM has dropped from 12 to 8? In one go, that's too much to put down to interference so what is going on here?
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Ah! Upstream power has gone up significantly and I've gained almost 500Kbps of upload sync.
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Is your DS still banded?
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Is your DS still banded?
It is :(
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Would migrating to a slower product remove the banding?
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I feel lonely in here :(
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Dont feel too lonely, my line was banded in August 2016 and it still is banded! My ISP refuses to do anything about it.
Stuart
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But in regards to my question, does migrating to a slower product reset DLM and so remove the banding? I am going from LLU to BTW.
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the answer is yes sometimes.
It used to be the understanding was it would do a full dlm reset, now we have seen instances where banding has not been removed and the emergence of a "soft" dlm reset which doesnt remove banding.
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the answer is yes sometimes.
It used to be the understanding was it would do a full dlm reset, now we have seen instances where banding has not been removed and the emergence of a "soft" dlm reset which doesnt remove banding.
Thanks for the information. Let's hope I get lucky :fingers:
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Changing product with the same ISP on the same DLM profile will NOT remove banding.
You can only be sure banding will be removed with a change in DLM profile, a change of ISP, or a manual reset by an OpenReach engineer.
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But in regards to my question, does migrating to a slower product reset DLM and so remove the banding? I am going from LLU to BTW.
I am almost 100% certain that for your case, as described above, the circuit will be set to a "wide open profile" with the DLM process beginning to monitor it from the second day after the migration.
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Thanks all. It will be interesting to see how the line performs as I've never actually had it unbanded since I had a fault some months ago. Before that it was stable at around 52Mbps.
I'm not switching until the 6th July so quite some time yet.
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Well due to TalkTalk's cock-up and BT's lack of communication, I am having to get a new line installed as TalkTalk aren't releasing my number.
At least the DLM will be "reset". I will be curious to see how the two lines compare as there will be a bit of overlap.
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It happened to me when moving from EE to Vodafone my telephone number was changed but after 3 days it then returned back to the original number, just give your gaining ISP/voice a call to say you want to keep your old telephone number.
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It happened to me when moving from EE to Vodafone my telephone number was changed but after 3 days it then returned back to the original number, just give your gaining ISP/voice a call to say you want to keep your old telephone number.
That's what BT is doing but they've said TalkTalk keep it for 14 days (from CEO's team).
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TT maybe thinking you will return back to using their service before the 14 day cooling off period ends or something like that but TBH it's a bit harsh though ISP's will try any trick in book to keep you as their customer.