Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: c6em on May 23, 2013, 02:44:32 PM
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Here you are......................
as supplied in post No 28 in this thread
http://community.plus.net/forum/index.php/topic,115100.16.html (http://community.plus.net/forum/index.php/topic,115100.16.html)
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I assume Plusnet will not have any objections to that table being reproduced . . .
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:hmm: Interesting ...
So, Bald_Eagle_1's was: Profile Name 13.7M-27.4M Downstream, Interleaving High - 0.128M-0.8M Upstream, Interleaving On, which fits,
but mine is: 33M-67M Downstream, Interleaving Off - 10M-20M Upstream, Interleaving Off, which doesn't? ???
Looks like the min rates are often just half the max rates?
[Edit] BTW Chris Purvey of Plusnet volunteered (nice chap!) to research FTTC DLM as a result of a separate question I posed about it over there. This looks (possibly) like an early release of part of what he is finding out. As it was also him who provided my own Profile 'name' at my request, he missed an opportunity to spot the discrepancy. :) ;)
At post 40 on our own thread here http://forum.kitz.co.uk/index.php/topic,12463.30.html (http://forum.kitz.co.uk/index.php/topic,12463.30.html), Asbokid has tried to enumerate the possible (or at least potential, which is different) combinations
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http://community.plus.net/forum/index.php/topic,115100.16.html (http://community.plus.net/forum/index.php/topic,115100.16.html)
Having now read this post in its entireity, there seems to be a lot of confusion (probably lack of actual experience) with FTTC displayed on it. Perhaps some kind soul should point them in the direction of the wisdom available here on Kitz instead. :P
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It's understood there are nearly 200 different channel profiles.
Many combinations of downstream and upstream transmission rate bandings don't exist in the wild.
E.g. there is no channel-profile with [ 0.128 - 2 Mbps Downstream and 10 - 20 Mbps Upstream ]
cheers, a
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It's understood there are nearly 200 different channel profiles.
Many combinations of downstream and upstream transmission rate bandings don't exist in the wild.
E.g. there is no channel-profile with [ 0.128 - 2 Mbps Downstream and 10 - 20 Mbps Upstream ]
Sure A, I understand that, as I paid attention when you said it on the other thread... :) ;)
If I had a point it was that my band is 33-67 not the 37-74 (or even the 40-80) DS of the plusnet list!
BTW I hope you don't mind but it seemed they needed the clarity of your explanation of max rates in the channel profile vs the sync rate at home, so I paraphrased you over there (with due reference, of course ;))
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Just for info .......... (it really is a steep learning curve) !!!
My stats, taken direct from the DLM, show the 3 profiles since FTTC was enabled on my line .............
1 40M-80M Downstream, Interleaving Low - 10M-20M Upstream, Interleaving Off 2013-05-22T03:00:00
2 0.128M-80M Downstream, Interleaving Off - 0.128M-20M Upstream, Interleaving Off 2013-05-15T10:00:00
3 27M-54M Downstream, Interleaving Off - 10M-20M Upstream, Interleaving Off NA
The table obviously shows the latest profile change, as position 1
What is interesting, is that I myself reset the line on the 15/05, thus giving profile number 2 which is called an 'Open' profile 0.128Meg-80Meg. Whilst on this 'Open' profile, my circuit regularly showed the full 80Meg/20Meg synch speeds.
I'm guessing DLM must have seen errors, as we can see that I have now gone on a 40Meg-80Meg profile, with low Interleaving automatically applied. My synch speeds are now 72.9Meg/20Meg.
I suppose DLM is acting accordingly and doing its job on my circuit ??!!
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The more we all discuss this, the more we learn! :graduate:
First of all, is the profile timestamp the time of application of the profile, do you think? In other words, perhaps it starts a 14-day monitoring period? I'm assuming a 14-day monitoring period by the DLM, because it appears in the 'performance threshold' of >25% reduction in sync speed after 14 days. So, I'm guessing that perhaps someone somewhere thinks that if it was a transient condition that DLM would have backed-off again by then. If so, what does n/a mean (other than the obvious!)? Could it be an issue that if things don't materially change in those 14 days, as far as DLM is concerned, then whatever you're on now, becomes you're new 'baseline'? * :hmm:
I'm guessing DLM must have seen errors, as we can see that I have now gone on a 40Meg-80Meg profile, with low Interleaving automatically applied. My synch speeds are now 72.9Meg/20Meg.
Well that sounds right, but what was this then? 3 27M-54M Downstream, Interleaving Off - 10M-20M Upstream, Interleaving Off NA
and how long's your D-side? Is your DS attainable also now less than 80M (I guess it must be)? So, following Asbo's explanation elsewhere - if you went to the cabinet, you'd still get 80 there, but now only 72.9 at the NTE?
I suppose DLM is acting accordingly and doing its job on my circuit ??!!
I guess so, and neither of us would have a problem with that, I'm sure. However, the interesting thing is, if this was only a transient condition on your line (and so could be 'fixed' in some way), then perhaps your sync would rise back to the 80M profile band cap?
My own personal gripe atm is if my transient conditions have disappeared why am I still on a 33-67M profile when it's been a month now, and the attainables have been and still are in excess of 80/20 throughout? If the answer is something to do with CRCs/ES/what-have-you, it would be instructional to know. ;D
But whereas you have had some (low) interleaving applied, I still have none, and BE's had his removed! ???
:drink:
[EDIT]* I didn't really mean to use the word 'baseline' in the BTOR sense BS refers to below, i.e.what it originally synced at as recorded by WHOOSH. My fault. I should have said something like "your new 'best achievable' profile"
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The open profile is for ISPs and DLM testing to my knowledge... The Open Profile should always sync at 80/20 (from experience). It is used for ISPs to test connections, for example say if you was Infinity on 1 (40/10) and your speed was around the 40Mbps mark you can request the Open Profile. This allows the user to see if the throughput can be higher for their connection, it's normally forced to stay on 80/20 for 1/2 days similar to a 'light boost'. I've had this ran on my connection due to speed issues in the past, though I'm no where near the 40Mbps mark. This was essentially used as a diagnostic tool for my line. My sync speed was capped at 19Mbps for months, BT reporting my line couldn't handle any higher which I knew was a lot of c**p. The open profile was applied to my line and I was getting around 30Mbps throughput, then a full DLM reset was done and over time my line has settled at the 26Mbps mark.
I believe the DLM uses it when it considers previous data as 'inaccurate', I don't believe the DLM uses the Open profile a lot either...
P.S BT Didn't call it a Open profile but this sounds EXACTLY the same, they reported the same speed band so I assume it is the 'Open profile'
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The more we all discuss this, the more we learn! :graduate:
First of all, is the profile timestamp the time of application of the profile, do you think? In other words, perhaps it starts a 14-day monitoring period? I'm assuming a 14-day monitoring period by the DLM, because it appears in the 'performance threshold' of >25% reduction in sync speed after 14 days. So, I'm guessing that perhaps someone somewhere thinks that if it was a transient condition that DLM would have backed-off again by then. If so, what does n/a mean (other than the obvious!)? Could it be an issue that if things don't materially change in those 14 days, as far as DLM is concerned, then whatever you're on now, becomes you're new 'baseline'? :hmm:
I'm guessing DLM must have seen errors, as we can see that I have now gone on a 40Meg-80Meg profile, with low Interleaving automatically applied. My synch speeds are now 72.9Meg/20Meg.
Well that sounds right, but what was this then? 3 27M-54M Downstream, Interleaving Off - 10M-20M Upstream, Interleaving Off NA
and how long's your D-side? Is your DS attainable also now less than 80M (I guess it must be)? So, following Asbo's explanation elsewhere - if you went to the cabinet, you'd still get 80 there, but now only 72.9 at the NTE?
I suppose DLM is acting accordingly and doing its job on my circuit ??!!
I guess so, and neither of us would have a problem with that, I'm sure. However, the interesting thing is, if this was only a transient condition on your line (and so could be 'fixed' in some way), then perhaps your sync would rise back to the 80M profile band cap?
My own personal gripe atm is if my transient conditions have disappeared why am I still on a 33-67M profile when it's been a month now, and the attainables have been and still are in excess of 80/20 throughout? If the answer is something to do with CRCs/ES/what-have-you, it would be instructional to know. ;D
But whereas you have had some (low) interleaving applied, I still have none, and BE's had his removed! ???
:drink:
From the data I can see, the 'Baseline' remains what it was at the time of first connection. For me, that will be 54meg, as this is what No.3 profile is showing you in my post.
Also, we are told that DLM 'readjusts' the circuit every evening dependant on behaviours ?? I don't think the 14 day timescale has any other bearing other than that is how the data is presented to us on WHOOSH .... IE- 7days, 14days and 28days. I'm guessing that 14 days is probably a decent amount of time to gather averages for manual scrutiny, as I say, the DLM acts on its findings every single day.
I concur, learning from debate is the way forward, as DLM behaviours especially with VDSL are on a par with Quantum Physics. :)
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From the data I can see, the 'Baseline' remains what it was at the time of first connection. For me, that will be 54meg, as this is what No.3 profile is showing you in my post.
Ah, right! That was your baseline. Then you reset your own profile (lucky man!) and it opened it up to 40-80, from which you're now getting ~73. Sorry if it took a while for the penny to drop!
So, then my own 'baseline' will actually have been 80M, but because of what's happened since it's now on 33-67 but maxing out for want of a reset. At least I understand that. :)
I also take your point about the 14-days. It was just an entirely speculative suggestion on my part, now consigned to the dustbin of failed ideas.
I am sure that DLM may well intervene to readjust the circuit once a day if it thinks it merits it. Asbo's explanation of how the profiling thing works suggested that applying a different profile to the circuit will result in a resync, and my own experience is when that happens, it happens overnight in the early hours, say 3-6am, like you say. If this is actually the way it works, and it seems logical to me, then perhaps DLM reviews things once a day, and if on a given day it thinks a change is required, some new profile is applied (albeit this may change things other than max rate), and this resyncs the modem with the DSLAM under the 'readjusted' parameters. :-\
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My sync speed was capped at 19Mbps for months
The open profile was applied to my line and I was getting around 30Mbps throughput, then a full DLM reset was done and over time my line has settled at the 26Mbps mark.
This seems like a common factor. IIRC BS had an issue with a 'phantom' bridged tap, and perhaps that's why his baseline was set originally at 27-54M. But once he 'cleared' that and reset the line, it opened it up to 40-80, and now he's happily getting ~73.
Same with you, stuck on 19, the line was reset, perhaps getting the 15-30 profile, and your line settled at 26.
Mine was originally set at 40-80, and got 80. It had a problem, and so was changed to 33-67. The problem went away, but the line hasn't been reset, so my line is still maxing out at 67.
This leaves the suspicion though that DLM does not always allow a line to return fully to whatever it is actually capable of, following a 'fault' of some kind, without being given a bit of a nudge to think again.
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@ Colin,
I believe we can say that the new DLM logic for VDSL services (only ?) is specifically designed to apply a fixed cap on any line that underperforms for any reason. Howeve I've not seen any definitive documentation to that effect.
I am aware of 6 lines now that were capped at 15 Mbps due to sub-standard installation practices, but have eventually been released after the house wiring has been corrected. This has not always been as easy as one might hope. One had the cap raised from 20 to 30 Mbps on the day before an appointment was a no-show. That line eventually settled at around 40 Mbps after a second dialogue with Plusnet and a second appointment.
The question remains as to why those directing such operations consider these activities are acceptable and of benefit to either themselves or the EU.
Kind regards,
Walter
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@ Colin,
I believe we can say that the new DLM logic for VDSL services (only ?) is specifically designed to apply a fixed cap on any line that underperforms for any reason. Howeve I've not seen any definitive documentation to that effect.
Of course I agree Walter, and in the face of fault conditions on the line, I think that changing the profile to help manage that, is the right thing to do. But the max line sync rate is only part of that profile (see Asbo's explanations elsewhere), and not necessarily the sole most important parameter in managing line conditions. :( The debate (in which we are all learning, so your experience is most valuable :)) is about what it does if anything after those conditions are removed, i.e. when the status-quo-ante is restored or improved.
I am aware of 6 lines now that were capped at 15 Mbps due to sub-standard installation practices, but have eventually been released after the house wiring has been corrected. This has not always been as easy as one might hope. One had the cap raised from 20 to 30 Mbps on the day before an appointment was a no-show. That line eventually settled at around 40 Mbps after a second dialogue with Plusnet and a second appointment.
So, again this seems to be another example of a situation where, when the offending conditions have been removed, DLM has stubbornly maintained the existing banding, and it is only once the line was reset and opened up to a higher profile that it settled back to the natural rate that it was actually capable of - your point, or have I misunderstood that?
Sadly, problems with the the EUs internal wiring (which in many cases is a legacy from before 1983), while a fact, is a convenient excuse for what's actually happening. :(
I assert the proposition that a DLM that does not allow a line to return to a level of which it is capable of sustaining, is not really doing the job properly. It is a crude approach, and one that I think they will not be able to sustain in the long term. Well, at least I hope so for all our sakes. :(
The question remains as to why those directing such operations consider these activities are acceptable and of benefit to either themselves or the EU.
And I think it is only by the community becoming more informed about it through our collective experiences and debate, that we will amass sufficient evidence to have any chance of challenging this. :graduate: Nothing wrong with DLM per se, but that does not, to my mind, necessarily mean that its algorithms are incapable of challenge. ;) :)
Kind regards.
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Thought I would try to apply a Relative Capacity Occupation-type (RCO - actual sync rate divided by attainable sync rate) calculation to the profile max rates values of BS, Ryan and myself given above. Let's call it a Relative Profile Occupation RPO
BlackSheep before Actual 54 Max rate 54 Attain rate 80.7* RPO 100.0% RCO 66.9%
BlackSheep after Actual 72.9 Max rate 80 Attain rate 80.7* RPO 91.1% RCO 90.3%
Ryant705 before Actual 19 Max rate 19 Attain rate ? RPO 100.0% RCO ?
Ryant705 after Actual 26 Max rate 30 Attain rate 28 RPO 86.7% RCO 92.9%
ColinS before Actual 67 Max rate 67 Attain rate 88.6 RPO 100.0% RCO 75.6%
(the 622 attainable seems to be ~2.5M less for me than the 612 on the same line)
*taken from post 43 on BS's 'At long last' thread!
This might be a way of comparing how well the profile matches the capability a line might otherwise have if it wasn't banded?
If others want to PM me their values, then I would be happy to tabulate them here for us all to see.
If there is anything to see, that is. :-\
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Actual 26, Max 30, Attain 28
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Actual 26, Max 30, Attain 28
Thanks. :) Updated the above as:
Ryant705 after Actual 26 Max rate 30 Attain rate 28 RPO 86.7% RCO 92.9%
Suggests that you are now getting pretty much what is achievable for your loop length, within your current profile. How long is it, do you know?
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800-1000m
31 Attenuation
Just checked on google maps, looking at least 965m + up and down poles.
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I wonder, given sufficient data from many EUs, whether a sensible graph could be plotted? :-\
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I wonder, given sufficient data from many EUs, whether a sensible graph could be plotted? :-\
Sounds like a good idea - all it needs are more EUs and a decent programmer. Wonder where we might find one of them? :)
but with enough EU data, we might be able to identify some empirical rules of thumb ....
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Just checked on google maps, looking at least 965m + up and down poles.
In which case, your results might cause one of our feathered friends to lose even more feathers. :(
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Just checked on google maps, looking at least 965m + up and down poles.
In which case, your results might cause one of our feathered friends to lose even more feathers. :(
Hmmm.
December 2011 - 29430 Sync 34008 Attainable (DS Interleaving depth 467)
Now 20667 Sync 21116 Attainable (Interleaving OFF)
Line length 1000m to 1200m (max)
:( :( :(
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I'm going to make you lose a little more feathers... would you be annoyed if I told you I had 200m of Ali as well? :D
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I'm going to make you lose a little more feathers... would you be annoyed if I told you I had 200m of Ali as well? :D
I'm not quite sure how to phrase this, but the second word is OFF! :lol:
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I'm not quite sure how to phrase this, but the second word is OFF! :lol:
I've lost some speed so it isn't that bad, my original sync was 35Mbps though that dropped to 30Mbps the next day so... :)
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Also, we are told that DLM 'readjusts' the circuit every evening dependant on behaviours ?? I don't think the 14 day timescale has any other bearing other than that is how the data is presented to us on WHOOSH .... IE- 7days, 14days and 28days. I'm guessing that 14 days is probably a decent amount of time to gather averages for manual scrutiny, as I say, the DLM acts on its findings every single day.
Following one of Asbokid's posts 'in another place' :) here http://forums.thinkbroadband.com/fibre/4240841-dlm-fault-recovery.html?page=1#Post4240966 (http://forums.thinkbroadband.com/fibre/4240841-dlm-fault-recovery.html?page=1#Post4240966)
one of BT's patents confirms the 14 day monitoring period, and hence the profile timestamp:
In the present embodiment, each line is processed once every 24 hours to determine how the line should be
categorised, and thus if a new profile should be selected for that line. In order to avoid frequent oscillations between
adjacent profiles, a good and a bad delay counter are used to place a delay on how quickly a line is reprofiled. Thus,
every time a line is categorised as good a good delay counter is incremented (and a poor delay counter is decremented)
and only once the good delay counter has reached a good threshold (which in the present embodiment is set to 13) is a request made to the OSS for the profile to be increased by one step to a more aggressive level, and then the delay counters are reset.
So, in the absence of the events that provoked the reprofiling of the line, it should revert it back one profile level every 14 days ... or at least it would if it was following the mechanics set out in their own patent.
Clearly I'm 'stuck' on my current profile as a result of some subsequent improvement to that patent! :lol:
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An associated BT patent quoted by Asbokid at https://data.epo.org/publication-server/pdf-document?PN=EP2169980%20EP%202169980&iDocId=7293432&iepatch=.pdf (https://data.epo.org/publication-server/pdf-document?PN=EP2169980%20EP%202169980&iDocId=7293432&iepatch=.pdf) has this to say
The DEFAULT GOOD THRESHOLD is set in the present embodiment to 13 (i.e. equivalent to 14 days), the
DEFAULT POOR DELAY is set in the present embodiment to 3 (i.e. equivalent to 3 days) and the DELAY DOUBLER
is set to 0, thus the initial good delay is 13 but each time the line’s profile is transitioned to a less aggressive profile the DELAY DOUBLER is incremented until after 5 such transitions, each time the DELAY is reset it is reset to a value of 448 (i.e. equivalent to approx 14 months). :o In the present embodiment, if a user’s stability policy or level is changed the delay doubler is reset back to zero; furthermore, the delay doubler and even the delay counter may be manually reset by an operator to cater for exceptional circumstances.
But, what happened to me was it moved back in one transition from 80/20 to 35/20, and it subsequently moved forward again twice, every 3 days, before it stopped. That was on 14/04/2013 - over 6 weeks ago. :'(
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Credit goes to SevenLayerMuddle. It was he, way back in 2010, who first noticed that BT had patented its DLM system:
http://forum.kitz.co.uk/index.php/topic,7548.msg158076.html
I'm not 100% persuaded that the discovered patents represents the current state of play, i.e. the current embodiment(!).
Those patents describe a system that tweaks TSNRM. Yet Openreach's latest DLM algorithm rather than directly tweaking the noise margin, instead relies upon tweaks to interleaving/INP levels and to maximum and minimum data rates, in order to maintain stability and maximum speeds (I'll fetch my coat!)
cheers, a
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@ asbokid,
Surely we are dealing with a significantly different DLM VDSL algorithm now with additional "features" such as power cut-back and (almost) permanent cap on sub-standard lines.
Kind regards,
Walter
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Credit goes to SevenLayerMuddle. It was he, way back in 2010, who first noticed that BT had patented its DLM system:
http://forum.kitz.co.uk/index.php/topic,7548.msg158076.html
I'm not 100% persuaded that the discovered patents represents the current state of play, i.e. the current embodiment(!).
Those patents describe a system that tweaks TSNRM. Yet Openreach's latest DLM algorithm rather than directly tweaking the noise margin, instead relies upon tweaks to interleaving/INP levels and to maximum and minimum data rates, in order to maintain stability and maximum speeds (I'll fetch my coat!)
Well, thank you indeed 7LM. :clap: ;D
Yes, Walter I do agree that the stuff quoted above may not fully be the current embodiment. However, it does have a number of basic characteristics in common with it, which may explain a lot of things that have been debated at length here and elsewhere.
For example, it is probably the source of the debate around the 10-day period. In https://data.epo.org/publication-server/pdf-document?PN=EP2169980%20EP%202169980&iDocId=7293432&iepatch=.pdf (https://data.epo.org/publication-server/pdf-document?PN=EP2169980%20EP%202169980&iDocId=7293432&iepatch=.pdf) at [0063] it says In the present embodiment, the FTR is initially set at 2Mbs and is then re-set to 80% of the Maximum Stable Rate detected by the network during the first 10 days of operation of the DSL in its rate adaptive mode.
Now, I agree that this patent was for all flavours of DSL, and so that embodiment is probably only applicable to ADSL, but I think these patents can still give us all insights into how they thought it should work, and our collective experiences can shed light on how it appears to work now. In the absence of BT co-operating to fully publish it, what else can we do?
I am already aware that the patents to not fully describe the current behaviour for VDSL. I am merely suggesting that, using these as a starting point for discussion, it could assist us in trying to understand how it works now. Some things have undoubtedly changed, particularly the mechanisms as Asbokid and your good self have pointed out above, but others are still there. I doubt the basic framework has changed at all, merely the profile contents (i.e. the selected parameters of control).
Has anyone else found a better starting point yet? :-\ I advocate reading them fully and making your own minds up. ;) :)
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@ Colin,
I agree entirely !
Unless perhaps some very kind Ovis aries** can occasionally drop a few snippets in our direction ?
Kind regards,
Walter
** http://www.thefreedictionary.com/Ovis+aries
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Ha ha ........... thanks for the link, though I'd kinda guessed it was me !! ;D
Alas, you guys have found out more about the DLM's doings, than any documentation that I've personally seen !! I really can't seem to find anymore about DLM other than it's Layman's terms description. :-\
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Just for info .......... (it really is a steep learning curve) !!!
My stats, taken direct from the DLM, show the 3 profiles since FTTC was enabled on my line .............
1 40M-80M Downstream, Interleaving Low - 10M-20M Upstream, Interleaving Off 2013-05-22T03:00:00
2 0.128M-80M Downstream, Interleaving Off - 0.128M-20M Upstream, Interleaving Off 2013-05-15T10:00:00
3 27M-54M Downstream, Interleaving Off - 10M-20M Upstream, Interleaving Off NA
The table obviously shows the latest profile change, as position 1
What is interesting, is that I myself reset the line on the 15/05, thus giving profile number 2 which is called an 'Open' profile 0.128Meg-80Meg. Whilst on this 'Open' profile, my circuit regularly showed the full 80Meg/20Meg synch speeds.
I'm guessing DLM must have seen errors, as we can see that I have now gone on a 40Meg-80Meg profile, with low Interleaving automatically applied. My synch speeds are now 72.9Meg/20Meg.
I suppose DLM is acting accordingly and doing its job on my circuit ??!!
wooh.
so you was on a 27-54 profile (this before you swapped pair?)
then 0-80 basically DLM reset, but it didnt last.
now still a high sync but not full sync and interleaved. (this is on that perfect pair you found?)
you have the hg unlocked on your line?
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Basically yes to all the above, but not the unlocked modem. I am 0.6km from the PCP, but it is all 0.5 Cu cable. I can see my stats via logging into the DLM, but haven't looked for a while due to family commitments and that I'm currently sunning myself on a beach somewhere in Europe. Will take another look-see when I unfortunately have to go home.