Increase in BT profile

[#1]

I had the same issue in December, however my fibre kept losing connection. DLM intervened and enabled interleaving but didn't effect my sync speed. I opened a fault, i live 3hours away from my parents house and plusnet wanted me to do tests etc. I then had a power outage up on return a few hours later during the day (around 2-3pm) DLM removed interleaving but dropped my sync? Why I don't know... But I thought I ain't got time for OR to visit. I knew DLM would do it's job, and it has. I dropped 6-8mb during this time, and no one reboots the router nor gateway hops. Just keep that modem on and wait for DLM to do it's magic.
DLM done my changes during the day? This early morning seems a bit false
Good luck anyhow 

[#2]

DLM for FTTC s being constantly changed and improved. New changes have already been brought in this month with more profiles for each band.
In the coming months, it is planned that ISPs will be able to perform DLM re-assessments in certain scenarios (all subject to industry agreement).

[#3]

Quote from: Terranova667

@andy there is no evidence that there were errors or that my line couldn't handle the new Sync in fact the tests chris said he ran showed the line to be fine hence why reporting a fault wouldn't be an option, if DLM didn't think my line was capable it wouldn't have increased it at all it took almost two months to do the increase in the first place more than enough time and data to figure out if it was going to be problem so I'm sorry andy i dont believe your theory here.

Can I point out that, having read the entire thread, I have seen no evidence that DLM was involved in either increasing the speed, or in decreasing the speed. A lot of people are assuming both. They are certainly possibilities (and may even be the most likely ones), but they are not the only plausible explanations.
a) What AndyH is saying is perfectly plausible: DLM de-intervened early-morning, and then chose to re-intervene mid-afternoon. DLM *usually* makes adjustments overnight, but if it sees a bad enough stability problem, it can intervene immediately if it chooses.
BT do make changes to their DLM algorithm, and they don't send us nice emails to tell us: we have to observe the behaviour. If DLM has recently changed (a fair assumption), we don't know the impact of all the changes.
b) Another option is that your line resync'ed after midnight when a (usually present) noise source was missing. The reduced noise might then allow a high sync speed; when the noise source resumes, your line would suddenly look unstable - perhaps enough for SNRM to descend to 0dB, or for the modem to loose the remote signal. The modems could then choose to re-sync by themselves, with no intervention by DLM at all.
If I remember correctly Terranova, your line profile (as set by DLM) banded you to a maximum speed of 60Mbps, and your actual sync was around 51Mbps. The fact that, after the overnight resync, you appeared to be bounded by the 60Mbps limit still (a sync a few Kbps below the limit would be standard) suggests that the DLM limit was still in place, entirely unchanged. If DLM *had* made a change, the likely first alteration would be to increase the upper speed of the banding. This suggests to me that the overnight resync was NOT triggered by a DLM change at all, but nonetheless took advantage of a change in the noise environment. Perhaps your DSLAM restarted, and some other modems did not immediately resync.
c) It seems that BT are deploying G.INP and SRA as alternatives to FEC/interleaving, starting a rollout across the UK this week. Perhaps your line benefited from this for a while, but later BT withdrew the change from your DSLAM? Certainly there needs to be some interplay between the DSLAM and the set of profiles available to DLM for this to work, and we haven't seen enough evidence to know what happens. It is going to take months or years to figure things out as well as we understand the existing DLM.
Opinion:
To me, the fact that you seemed to be banded to 60Mbps, even after the resync, is the most telling bit of evidence - suggesting no DLM involvement here.
In future, the best way to be sure would be to run monitoring of the modem. With either a hacked modem, or a combined router/modem that the current monitoring software can work with. It is the only way to be sure about what is happening.
Final Note:
I agree that the co-incidence looks strange to you, but note this:
When a Plusnet employee changes your profile within their system, it only affects the edge routers within Plusnet's network (the ones that control the data flow-rate). There is no communication from Plusnet out to BTW or BTO at this point, either to their administration systems or to their operational equipment. Nothing is set manually or automatically - there is no pathway to send this information whatsoever.
When your line resyncs, it triggers changes through BTO and BTW, with information ultimately being sent to Plusnet. This information path is a one-way street - from BTO to BTW to Plusnet.
When Chris appears to ignore your suggestion that there is a problem with a cause-effect relationship there, he's working from knowledge that this one-way street exists; that there is no path whatsoever that can cause the effect observed. If he knows that to be true of the Plusnet systems, he equally knows there is no point asking BTW to investigate, because there is no possible pathway for them to investigate; there is no functionality that could be broken. The thing just doesn't exist.

[#4]

Quote from: thesawdust

I had the same issue in December, however my fibre kept losing connection. DLM intervened and enabled interleaving but didn't effect my sync speed. I opened a fault, i live 3hours away from my parents house and plusnet wanted me to do tests etc. I then had a power outage up on return a few hours later during the day (around 2-3pm) DLM removed interleaving but dropped my sync? Why I don't know... But I thought I ain't got time for OR to visit. I knew DLM would do it's job, and it has. I dropped 6-8mb during this time, and no one reboots the router nor gateway hops. Just keep that modem on and wait for DLM to do it's magic. DLM done my changes during the day? This early morning seems a bit false Good luck anyhow

thanks. yeah i never touch the Modem the only time it was ever messed with was when engineers visited to test my line, my first sync / profile dropped back in May a copper line fault was detected by support but the three engineers that were sent couldn't find anything wrong, i went from 64Mb BT profile down to 56Mb profile and my BT estimate was cut from 67Mb to 38Mb why i have no idea BTW / BTO / Plusnet wouldn't say.  
i never got that speed back was told it was due to cross talk and left it at that, i had the same line fault again back in august went from 56Mb BT profile down to 48Mb profile again engineer found nothing wrong with the line, although upon further investigation plusnet support found a bridge tap fault they wouldn't do anything about it because they said it wasn't causing any issues and i was still way over the estimate which of course i would be after it was cut by BTO.
i had a little increase by DLM in October that took me back up to the 51Mb BT profile, DLM at that time did both the Plusnet and BTW one, and then of course the increase that wasn't to last yesterday which went from 51Mb BT profile to 58Mb why DLM only did the BT profile that time and not the plusnet one as well i dont know it's why i asked for it to be adjusted by one of the CRT and of course it dropped when the plusnet one was adjusted taking me back down to a 50Mb BT profile.
any way i will see how it goes maybe in another 2 - 3 months it will increase it back up again.  
@ Andy interesting info i'll wait and see how these new profiles pan out if and when plusnet get the go ahead to utilise them, and of course if vectoring ever sees the light of day.
@ WWWombat thanks for all of that  sometimes i just dont know what is going on, one moment i'm told I'm banded the next i'm not, same goes with Interleaving, then crosstalk then something else,  all tests say my line is fine yet support find a bridge tap fault and deem that to be ok as far as i know it's still there maybe that had some part to play in the Sync drop It's all a little much to take in, i understood ADSL much more I didn't have DLM to contend with then as i was with UK online and then BE which didn't use it if sync dropped it went back up straight away no wating around for DLM changes, I was under the impression when i signed up for fibre back in March it was the same it just provided faster speeds due to the fibre cables to the cab i now know that to not be the case at all.      
thanks to all of you and to Chris and the rest of the CRT guys even if at times i get a little annoyed.    

[#5]

Quote from: Terranova667

any way i will see how it goes maybe in another 2 - 3 months it will increase it back up again.

Don't touch router/modem (avoid the temptation to gateway hop) You may see an improvement sooner than 2-3months 

[#6]

I do remember a long while back that Chris Pettitt told me that all isp's might able to perform a DLM reset for FTTC in the future but no time frame is yet agreement between isp's and openreach.

[#7]

Quote from: thesawdust

Quote from: Terranova667 any way i will see how it goes maybe in another 2 - 3 months it will increase it back up again.  Don't touch router/modem (avoid the temptation to gateway hop) You may see an improvement sooner than 2-3months

I won't hold my breath with that one, i didn't gateway hop or touch the modem after my last drop back in August and it took until October to do a small increase and then until Wednesday for the increase that didn't last I'm expecting the sme again if DLM this time does anything.
@goldenfibre yeah i remember something like that being said back when i joined in March but with anything involving BTO your more likely to see bigfoot have a party with the loch ness monster than ISP's having DLM control any time soon, although what Andy posted seems to be on some way there but again as always there is no time frame with it.   

[#8]

There are time frames - but there needs to be agreement amongst the ISPs about the changes.

[#9]

AndyH. I don't think it will never gonna to happen now. I doubt BTO will release DLM reset control to ISP's. No chance!

[#10]

Your assumptions are incorrect.

[#11]

Can i ask Andy, WWWombat or anyone else that may know if the TBB graphs are any indication of how a line is behaving ie would it show any indication that it would loose sync etc or is it primarily just a packet loss & latency thing that would have no baring, i ask because my graphs have always been pretty much flatline example below, even leading up to the sync drop on Wednesday there was nothing that showed anything untoward, Unfortunately I'm on a dynamic IP so I have to create a new one each time there is a session or sync drop, i'll have to get that remedied  sometime so i no longer have the graphs showing how things were leading up to Wednesdays afternoon Sync drop.
my ping has increased from it's usual 15ms to around 20ms after Wednesdays drop so i'm guess maybe a little interleaving has been applied ?

as you can see hardly a blip and this is how it is all of the time, there is a little increase during peek times but that's to be expected and it doesn't cause any issues, it has always been this way even back when DLM etc was happy with my full 65Mb BT profile before my first drop in late May. any way thanks for any info.

[#12]

For a resync, you would see a red spike descending from the top... it would sometimes drop almost all the way down to the bottom of the graph, sometimes only partway - it depends on the time taken to resync; I tend to think that it feels V-shaped (wider at the top than the bottom). Obviously you'd only see this if your IP was the same after the resync.
If DLM changes latency parameters, then the height of the green bar would be different after the resync.
Here's an old example of mine, with a couple of resyncs - one DLM-triggered.
Edit: there is actually a 3rd resync hidden in there, at around 2am. There is a small change in latency, probably due to hopping gateway to something slightly faster.

[#13]

Quote from: Terranova667

also according to the sticky thread on how DLM works it doesn't make adjustments until the early morning between 3am-5am when it's gathered enough data so why according to you did it make a change before the plusnet Profile was increased that shouldn't happen or is what is written there wrong.

FYI.  That info is now outdated.  BTw have been making changes to their core network and rather than the traditional 10 RAS's,  there are now >450 MSE bRAS locations and a lot of  re-routing occurred in Oct/Nov last year.    Since these upgrades weve seen many people experience DLM changes much later in the day, at any time up to mid-day.
For example  I had a line fault in late Oct which meant that DLM was changing my profile each day for the best part of a week.  Most days those changes occurred either at 10:20am or 11:20am 

[#14]

Also from this month, there have been more DLM profiles introduced (14 per sync rate). The idea being that there is more error correction available, before speeds are reduced. This should mean that lower level noise has a lower impact on speed compared to previously.

[#15]

@ kitz & andy thanks for that info I guess it's time that the DLM how it works thread should be updated so others like myself don't go off outdated info and such wonder why the hell things were happening that at the time we thought shouldn't, it  would save a lot of time and hassle.