DLM QUESTION

I have been having a few problems with my sky fibre line since I switched to the 80/20 package from the 40/10 package.
A bit of back ground, my line even on ADSL was quite good, got a ping of about 38-42ms, I then switched to fibre and got a ping of 12-15ms on the 40/10 product. I upgraded to the 80/20 and synced at the full 80mb and had a ping of 15-18ms then all of a sudden my ping jumped to 25ms then to 34ms and the sync stayed the same. I logged a line fault and after three visits OR finally found a bit of corrosion on the line. I phoned sky yesterday to ask them if they would request a DLM reset and they said the engineer would have requested one already. I woke up this morning and my line speed has dropped to 62mb and the ping has gone to 42ms I phoned sky and they said this proves the DLM was reset and in about 8 days a new speed would be set, I thought if my DLM was reset my line would go back to 80mb and my ping back to 15-18 ms they are adamant that that is incorrect and the line gradually speed up. Which is the right answer I'm livid at the minute because I'm sure they are taking bull.

here are my line stats

Broadband Link Downstream Upstream
Connection Speed 62920 kbps 20000 kbps
Line Attenuation 16.9 dB 0.0 dB
Noise Margin 9.3 dB 6.6 dB

Edited by deleted (Tue 24-Jun-14 20:11:55)

The Openreach DLM generally starts high and then lowers speed or raises latency to compensate for errors or does both. It is possible that the work done was nothing to do with the errors.

The Openreach DLM does give back latency and speed if left alone and the errors do go away, I've seen my line speeds go up and down.

In reply to a post by MrSaffron:

The Openreach DLM generally starts high and then lowers speed or raises latency to compensate for errors or does both. It is possible that the work done was nothing to do with the errors.

The Openreach DLM does give back latency and speed if left alone and the errors do go away, I've seen my line speeds go up and down.

So it generally is a full reset back to the top speed and then adjusts down, and not what it has done this morning? Ie dropped 18mb and added 8ms of ping without going back to top speed. That now takes my below BTs est of between 80-63mb

When I spoke to sky last night they said between 11.00 and when I spoke (2100)there had been 0 errors on the line and was perfect

Edited by deleted (Tue 24-Jun-14 18:39:09)

Not aware that providers are fed the CRC/FEC and other error counters, they have limited visibility with the Openreach DSLAM - unless the Sky modem/hub is also sending them figures to them.

An ISP saying no errors often really just means no resyncs

I don't think any provider has access to the DLM data as yet - and If I remember any change to your DLM requires an engineer visit and is chargeable, but most providers won't even let you raise a ticket.

No control over interleaving settings either...

Sorry - till BT pull there finger out your stuck with whatever the system *thinks* is best for your line...

In reply to a post by IamQ:

I don't think any provider has access to the DLM data as yet - and If I remember any change to your DLM requires an engineer visit and is chargeable, but most providers won't even let you raise a ticket.

No control over interleaving settings either...

Sorry - till BT pull there finger out your stuck with whatever the system *thinks* is best for your line...

So that's why sky won't request a DLM reset because they would have to pay Bt for the engineer to come out

Ahh but if I had read your post correctly then I would have seen you have come off the back of a fault which had work done to correct it.

In general engineers can request a DLM reset after working on a fault, but I'm led to understand that in most situations most are told not to bother as it should recover the line its self within the 8 (or whatever) day period. I've seen resets done where a fault has dragged someone down from 80 to 8mbit.

I'm not sure why a DLM reset *requires* an engineer - all they do is go to the cab and call there service desk who do the reset anyway. Thus they attach a price to it. (I have no idea how much it is, and you could try and tell them you would pay, but TBH its not worth it)

I'm not sure if the FTTx DLM is better or worse than the traditional ADSL(2+) DLM as I have no 1st hand experience of it as yet, and given the things I'm reading I might stay on my shonky ADSL2= service at 7mbit rather than a flapping 80mbit service with an enforced modem which does some curious thinks with both VPN and UDP traffic... (Why a bridged device should hold a UDP state I'll never know - unless the NSA/Chinese have found another way to snoop.)

A full reset will put the line back to how it was when installed - it will aim for max sync then look at errors etc and decide what to do. Also keep in mind as more people go on the cab X-Talk will go up, that will knock your speed anyway over time (Have a search here) the other problem is the BT estimate - if your within that tough luck. I used to have a 14mbit estimate (lol) now it's a 6.5-9mbit.

Welcome to the land of BT - you as the end user are generally powerless, and agreeing to use there service means you agree to let them 'manage' your line and internet experience as they see fit.

Give it 10 days and see what happens. Don't reboot the modem or anything like that trying to force sync up - it will just assume you have a LOS event and drop your speed further. See what happens and it its still bad then give Sky a call back and ask them to check. And FYI 'errors' can be a lot of things.... Most telecoms people will be interested in eroded seconds, or errored minuets most CPE only reports CRC or FEC errors.

In reply to a post by IamQ:

A full reset will put the line back to how it was when installed - it will aim for max sync then look at errors etc and decide what to do. Also keep in mind as more people go on the cab X-Talk will go up, that will knock your speed anyway over time (Have a search here) the other problem is the BT estimate - if your within that tough luck. I used to have a 14mbit estimate (lol) now it's a 6.5-9mbit.

I knew that was the case but the bloke from sky was adamant that a reset had been done and my line would stay as it was with the slow speed and bad ping for 8 days then the DLM would set the speed after monitoring 8 days later.

I had my DLM reset 2 weeks a go by TalkTalk Business.

I had a new install that was constantly disconnecting then finally went down completely. Diagnosed as copper break. This happened over the space of 4 days from first problem to complete break. Engineer replaced some cable and got me up and running (perfect though this time).

A few hours after the fix, the DLM came down on me like a ton of bricks. It had monitored the connection issues for this time and finally applied a huge amount of interleave. THis was caused by the fault. Obviously DLM wasn't reset and assumed unstable line. Engineer had not reset the DLM.

So, called TalkTalk Business who agreed and got Openreach to reset the DLM within 12 hours. Since then been rock steady with 0 interleave with full sync and a max attainable download of 106.

But, the DLM reset was instant. I didn't have to wait. My connection dropped the day after I called TalkTalk and reconnected as new. If you have to wait another 8 days for improvement then it just wans't reset. Clearly the bloke from SKY was just fobbing you off.

Post deleted by RobertoS