In reply to a post by RobertoS:

I think I'm right in saying that if the OR DLM applies banding, it is quite likely to remove it automatically after a while?

I think that's the theory. It certainly seems to be the case for day-to-day re-syncs.
However, if the banding was applied in definite steps such as 24999 k 29999 k due to serious problems requiring physical engineering repairs etc. it appears to take many, many days or even weeks before DLM increases sync speeds.

When that is the case (a "stuck" DLM profile) it can be reset/recalculated remotely, but currently this can only be requested via an engineer's visit.

I have had engineers carry out repair work who REFUSED to request a DLM reset & I have been stuck at low & rigid sync speeds for more than a couple of weeks at a time while I awaited a different engineer to arrive who did nothing but request DLM to be reset.

OP,
If you have run a BT speed test what was your IP profile???
If I understand what is being said here is that if you don't get the Full 40/10Mb speeds then you will not see speeds near the 80/20Mb profile??????? If I'm reading this wrong sorry.
I was getting 36-37Mb / 7-8Mb and am now getting 76/17-18Mb stable speed now after the uplift, At first they were lower but have picked up over the last several days, I'm about 140m+ from my cab.
iechyd da

In reply to a post by paul1360:

OP,
If you have run a BT speed test what was your IP profile???
If I understand what is being said here is that if you don't get the Full 40/10Mb speeds then you will not see speeds near the 80/20Mb profile??????? If I'm reading this wrong sorry.
I was getting 36-37Mb / 7-8Mb and am now getting 76/17-18Mb stable speed now after the uplift, At first they were lower but have picked up over the last several days, I'm about 140m+ from my cab.
iechyd da

I think you are confusing the sync speed with the IP Profile and/or speed test results. A 40Mbps sync has a 38.72 IP profile, delivering at full pelt the 36-37Mbps you quote on a speed test.

What is being said is that if you did not get 40Mbps sync on the 40Mbps product then you would get not get an increase by upgrading to the 80/20 one.

You were achieving the full 40/10 speeds.

RobertoS,
Ok lol story of my life of late getting confused and yes I was reading it wrong >>>>>giving himself a good kicking.
Best if I keep my mouth zipped shut.
iechyd da

After only one resync in 7 days, DLM thought it appropriate to decrease my downstream speed even further, and now has me capped at 47146 down, 18998 up (1mbps increase in UL). While it's clearly limiting me, the caps I have seem nothing like the ones you got.

Some people have mentioned 10-15 days, well after 7 it's just getting worse.

In reply to a post by qasdfdsaq:

After only one resync in 7 days, DLM thought it appropriate to decrease my downstream speed even further, and now has me capped at 47146 down, 18998 up (1mbps increase in UL). While it's clearly limiting me, the caps I have seem nothing like the ones you got.

47146 does not look like a banded speed cap.
It does look as though it was the best speed the connection could manage at the time it resynced.

You may have a connection with many errors of various types.
Interleaving, delay & impulse noise protection may be set at very high levels.
It is possible your connection suffers from bursts of REIN (interference).
If there are many users in the vicinity, it could even suffer badly from crosstalk.

Of course, it could be that the D-Side cable from the cabinet is full of dodgy corroded joints, aluminium sections, water in the cables, damaged cables etc. etc. etc.

Did the resync occur on its own (on the fly) or did you initiate it?

In reply to a post by Bald_Eagle1:

In reply to a post by qasdfdsaq:

After only one resync in 7 days, DLM thought it appropriate to decrease my downstream speed even further, and now has me capped at 47146 down, 18998 up (1mbps increase in UL). While it's clearly limiting me, the caps I have seem nothing like the ones you got.

47146 does not look like a banded speed cap.
It does look as though it was the best speed the connection could manage at the time it resynced.

You may have a connection with many errors of various types.
Interleaving, delay & impulse noise protection may be set at very high levels.
It is possible your connection suffers from bursts of REIN (interference).
If there are many users in the vicinity, it could even suffer badly from crosstalk.

Of course, it could be that the D-Side cable from the cabinet is full of dodgy corroded joints, aluminium sections, water in the cables, damaged cables etc. etc. etc.

Did the resync occur on its own (on the fly) or did you initiate it?

You'd think so at first, but that's not the case. It really is a DLM imposed cap. In fact, I thought so too, so I rebooted the modem a couple times but it always resynced at exactly 47146.

Initially, the resync occurred by itself at about 6am. Stats showed there were about 16 FEC and CRC errors at the time, in total, accumulated over 5 days. SNR margin was 13.5 and attainable rate over 92000.

20 hours later I forced a resync myself, and came back with exactly the same sync rate - SNR margin was 14.2 at the time, attainable rate ~94100. So it's not a static (high) SNRM, nor is it the max the line could do - it was stable (no resyncs) at 79,999 for a few weeks before I moved the cables excessively. xdslcmd info showed zero OHFErr and zero RSUnCorr, GUI showed zero FEC or HEC errors just before I resynced.

Right now after another 10 hours uptime, the GUI's showing zero CRC, FEC or HEC errors:

Attainable rate (kbit/s) 94076 32050
SNR margin (dB) 14.1 9.5
Line attenuation (dB) 0 0
Output power (dBmV) 12.6 5.7

I do a full reboot of the modem and it's still at exactly 47146.

Downstream Upstream Downstream Upstream
Line rate (kbit/s) 47146 18998 0 0
CRC errors 0 0 0 0
FEC errors 0 0 0 0
HEC errors 0 0 0 0

I know it does suffer badly from crosstalk - it's 90m from cabinet and should have an attainable rate well over 100 - but full modem stats here show quite high noise across the spectrum. I've done some investigation, and reducing attenuation simply increases the noise by the same amount, while shielded cable makes no difference - so I conclude it's crosstalk as it's coming from further up the line than my property and is surprisingly flat across the whole 30a spectrum.

Another trick I have up my sleeve is picking up the phone, which instantly reduces attainable rate by about 5mbps as follows:

Attainable rate (kbit/s) 89516 26890
SNR margin (dB) 12.9 8.4
Line attenuation (dB) 0 0
Output power (dBmV) 12.6 5.7

However, once again, a forced resync comes back again at exactly 47146/18998:

Downstream Upstream Downstream Upstream
Line rate (kbit/s) 47146 18998 0 0
CRC errors 0 0 0 0
FEC errors 0 0 0 0
HEC errors 0 0 0 0

(So exactly the same behaviour as when it was previously stuck at 60181 for 7 days - aside from when DLM changes my line speed cap, my line hasn't had a single unexpected resync/loss of sync since it's been installed)

Edited by qasdfdsaq (Sun 06-May-12 11:14:28)

In reply to a post by qasdfdsaq:

You'd think so at first, but that's not the case. It really is a DLM imposed cap. In fact, I thought so too, so I rebooted the modem a couple times but it always resynced at exactly 47146.

That's interesting & it can't be pure coincidence to achieve EXACTLY the same sync speed on rebooting the modem.

Initially, the resync occurred by itself at about 6am. Stats showed there were about 16 FEC and CRC errors at the time, in total, accumulated over 5 days. SNR margin was 13.5 and attainable rate over 92000.

Nothing really obvious then to have caused the resync.
Have you tried the ongoing stats that plot your connection stats minute by minute?
You may be able to see SNRM tailing off to zero (sometimes negative values) over a few minutes before the connection resyncs & puts SNRM back to usual levels.

I do a full reboot of the modem and it's still at exactly 47146.

Strange.

I know it does suffer badly from crosstalk - it's 90m from cabinet and should have an attainable rate well over 100 - but full modem stats here show quite high noise across the spectrum. I've done some investigation, and reducing attenuation simply increases the noise by the same amount, while shielded cable makes no difference - so I conclude it's crosstalk as it's coming from further up the line than my property and is surprisingly flat across the whole 30a spectrum.

I see from those stats that Interleaving depth (D) is quite high at 1686 DS & 527 US.
I imagine that Impulse Noise Protection (INP) & delay (delay) will also be quite high too.
INP & delay can be seen lower down the full Plink.log

How did you manage to reduce attenuation?
My connection suffers from really high attenuation that simply stops it syncing at anything higher than around 30 Mb.

Another trick I have up my sleeve is picking up the phone, which instantly reduces attainable rate by about 5mbps as follows:

Attainable rate (kbit/s) 89516 26890
SNR margin (dB) 12.9 8.4
Line attenuation (dB) 0 0
Output power (dBmV) 12.6 5.7

I occasionally see that phenomenon on my connection.
Attainable rates fluctuate in line with SNRM fluctuations.

I have seen SNRM dropping when dialling out to run the 17070 quiet line test etc.
My SNRM is usually only around 5dB or so, often dropping naturally to 3.5dB to 4dB overnight.
When the using the phone is especially bad, SNRM drops by 4dB or so which immediately forces the connection to resync (usually at a lower speed).

Dialling in to the phone sometimes causes SNRM to increase or lower.
Again, dialling in sometimes causes an immediate resync.

The last time dialling in caused a resync, the connection achieved a higher sync speed & then maintained stability for quite a few days, SNRM levels only dropping by 0.1dB or 0.2dB as should be expected.

It's almost as though the pulsed ringing tone voltages/current caused a dodgy connection somewhere in the D-Side cable to "fix itself".

Quiet line tests are always QUIET nowadays whenever I run them.

I have had many engineer visits due to my connection's instability & low(ish) speeds, "stuck" DLM profiles etc.

In attempts to permanently fix this particular phone issue, engineers have removed a double jumpered connection in the cabinet, replaced & rerouted my drop wire from the DP (approx 50m in length), replaced the master socket filtered faceplate, replaced just the filter pcb & replaced some slightly corroded cabinet jumper wires.

Each time, the connection seems to be fixed, but it usually only lasts for a few days.

More recently, I have noticed the phone issue appears to start as the weather changes to warm & dry periods for a few days.

April was supposedly one of the wettest & coldest on record.
It may be pure coincidence, but my connection was at its most stable during April.

The weather was quite warm & dry yesterday & my connection had resynced at only 23313 k at 20:12 while we were out last night.
My ongoing graphs show that SNRM had dropped from 4.5dB to -0.2dB (minus value) over around 1 hour, before causing the resync.

I tried the phone thing & noticed changes in SNRM levels while testing.

My connection resynced again at 29307 k at 07:02 this morning, while we were still in bed.
My ongoing logs do not show any particular issues for around that period.

Latest 24 hour ongoing stats here

Using the phone has gone back to only very insignificant changes in SNRM levels.
I'll see if that changes if the weather stays warm & dry for the next few days.

However, once again, a forced resync comes back again at exactly 47146/18998:

Downstream Upstream Downstream Upstream
Line rate (kbit/s) 47146 18998 0 0
CRC errors 0 0 0 0
FEC errors 0 0 0 0
HEC errors 0 0 0 0

Again, strange.

(So exactly the same behaviour as when it was previously stuck at 60181 for 7 days - aside from when DLM changes my line speed cap, my line hasn't had a single unexpected resync/loss of sync since it's been installed)

I wonder if your connection has started to develop an intermittent D-Side fault, possibly similar to mine?

One engineer in another forum has suggested that the plug in connection module at some DPs (known as a coffin lid DP due to its shape) can be a little unreliable. i.e. not always maintaining a solid connection on the relatively thin wires in use.
Apparently, a "fix" for this is to crimp some thicker wire to the thin wire & use the thicker wire for the actual plug in connection.

I wonder if Zarjaz and/or any other engineers would be able to comment on that as a "potential" cause of using the phone issues.

This is all ifs, buts & maybes & as these issues tend to be intermittent, it must be really hard for engineers to track them down as they may not be prevalent at the time of their visits.

In reply to a post by Bald_Eagle1:

In reply to a post by qasdfdsaq:

You'd think so at first, but that's not the case. It really is a DLM imposed cap. In fact, I thought so too, so I rebooted the modem a couple times but it always resynced at exactly 47146.

That's interesting & it can't be pure coincidence to achieve EXACTLY the same sync speed on rebooting the modem.

That's my thinking. If I get the same exact sync speed on several different days, under several different conditions, then the only explanation I can think of is an artificial cap. Incidentally, 6am today right on schedule, DLM reset my line again. It's now increased my upstream again to 19842, and reduced downstream even further, to 47036.

Nothing really obvious then to have caused the resync.
Have you tried the ongoing stats that plot your connection stats minute by minute?
You may be able to see SNRM tailing off to zero (sometimes negative values) over a few minutes before the connection resyncs & puts SNRM back to usual levels.

I had considered it, but my PC uses a good 200watts at idle and I'm not inclined to leave it on 24/7. Also, the resyncs do show at almost exactly 6am on my TBB charts, which matches with what other people have observed to be the time that DLM normally does its adjustments.

How did you manage to reduce attenuation?

My connection suffers from really high attenuation that simply stops it syncing at anything higher than around 30 Mb.

I replaced all the wiring within my house - including between the master socket and the junction box - with Cat 6 shielded. It dropped ~1.5dB off the attentuation but made no difference in speeds, so I put the old BT cable back. I also used a shorter modem lead and wired it straight into the socket (the filtered IDCs behind the bottom plate) which also cut off about 0.3-0.5dB.

The last time dialling in caused a resync, the connection achieved a higher sync speed & then maintained stability for quite a few days, SNRM levels only dropping by 0.1dB or 0.2dB as should be expected.

It's almost as though the pulsed ringing tone voltages/current caused a dodgy connection somewhere in the D-Side cable to "fix itself".

Curious. Something I did too makes me think there's something else going on. My modem cable is wired into the faceplate directly, leaving the modem socket unused. If I plug in a 15m long ADSL extension cable into the socket - while the modem is still wired in - and just leave it dangling off like a long unfiltered telephone extension, my SNR margin drops to negative, attainable rate drops to 40mbps, and my line disconnects and resyncs. But when it resyncs, it resyncs at "full" (capped) 47mbps and attainable rate shows as 85mbps again - and it stays stable this way.

If I then disconnect the ADSL extension again, the same thing happens - even though theoretically it should increase SNR margin and attainable rate from 85 to 95, it causes a line drop and resync. So it seems like a change in line characteristics (e.g. impedance, capacitance or frequency binning) can cause the line to drop, even if available headroom is still way above (even double) what it's synced at.

The weather was quite warm & dry yesterday & my connection had resynced at only 23313 k at 20:12 while we were out last night.
My ongoing graphs show that SNRM had dropped from 4.5dB to -0.2dB (minus value) over around 1 hour, before causing the resync.

What's the maximum speed your line's ever synced at? Gradually dropping over an hour would be a perfect case for SRA, if only anyone would sort out deploying that around here...

I wonder if your connection has started to develop an intermittent D-Side fault, possibly similar to mine?

It all started when I moved the cabling and modem several times in a day, and tested at least a dozen different extension cables (as well as having accidentally shorted the wires a few times). I'm hoping I haven't caused a fault and it's just DLM being paranoid from my deliberate resets.

Y'know I kinda wish DLM could just be turned off completely sometimes. Your issues and my old Be/O2 line problem would all benefit. I'd rather have 1-2 minutes of downtime a day while my line repeatedly resyncs than be constantly at half speed for weeks on end...

One engineer in another forum has suggested that the plug in connection module at some DPs (known as a coffin lid DP due to its shape) can be a little unreliable. i.e. not always maintaining a solid connection on the relatively thin wires in use.
Apparently, a "fix" for this is to crimp some thicker wire to the thin wire & use the thicker wire for the actual plug in connection.

I wonder if Zarjaz and/or any other engineers would be able to comment on that as a "potential" cause of using the phone issues.

This is all ifs, buts & maybes & as these issues tend to be intermittent, it must be really hard for engineers to track them down as they may not be prevalent at the time of their visits.

My only recommendation here is - have you considered just getting a completely new, seperate BT line installed? If they can't fix your old line, and you're out of contract, I'd just get a second line, move the service over to that, and disconnect the old one. BT are doing free installation of new lines if you order online right now.

In reply to a post by qasdfdsaq:

What's the maximum speed your line's ever synced at? Gradually dropping over an hour would be a perfect case for SRA, if only anyone would sort out deploying that around here...

When FTTC was installed last June (8c profile, but prior to access to unlocking firmware), sync speed must have been around 35Mb or so as I was actually downloading at up to 33Mb for almost a full month before everything started to go pear-shaped.

DLM was reset during a fairly recent engineer's visit (9th March). Sync speed was 35322 k for a short while before starting the usual downward journey.


I thought SRA was in place, hence "on the fly" resyncs that are so quick (16 seconds or so) that they do NOT initiate a new PPP session & therefore do NOT update the BT IP Profile/BRAS Rate.

My only recommendation here is - have you considered just getting a completely new, seperate BT line installed? If they can't fix your old line, and you're out of contract, I'd just get a second line, move the service over to that, and disconnect the old one. BT are doing free installation of new lines if you order online right now.

Yep, I have looked into that.
However, as spare pairs are available in the existing D-Side bundle, they would simply use those.
I have already had the D-Side pairs swapped in an effort to eliminate a single faulty pair.
My belief is that dodgy joints/connections are the root cause of my issues, perhaps only being noticed as my connection speed NEVER reaches the maximum for the capped 40Mb service, therfore my connection is already in a "delicate" condition.

It appears I may be the very last house on my STD code & have the option of a new line from a different exchange.
However, the closest fibre cab from that exchange is over 2km from my home!!!!!!