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Lower speeds after BT Line Fault - DLM?

tb257
Newbie
Posts: 6
Registered: 28-05-2013

Lower speeds after BT Line Fault - DLM?

Hi!
After having enjoyed more than 2 years of PN’s FTTC broadband without any problems, I had a BT line fault last week. BT has never admitted to there having been a fault or even fixing a fault. When finally a BT engineer attended, the fault had cleared and he didn’t do anything.  Whilst my broadband connection has been stable since then, my download is now 10 Mbps lower.  PN and Openreach investigated. Openreach found no issues and did nothing. PN’s GEA test showed no faults (Bridge Tap: Not Detected; Radio Frequency Ingress: Not Detected; Repetitive Electrical Impulse Noise: Not Detected; Cross Talk: Not Detected).  PN also told me that my speeds are not being restricted by the DLM (how would they know?) and they cannot do anything about the drop in SYNC speeds because what I get is still within the estimated range.

I’m very annoyed by the fact that due to a fault on BT’s equipment (which is beyond my control) and possibly subsequent shoddy repairs, I am now stuck with a worse service, and most importantly, nothing can apparently been done about it!  Has somebody had a similar experience? Is there anything that could be done to get this rectified?
According to PN, DLM is not the issue in my case.  However, I thought DLM sits in the FTTC cabinet (DSLAM) and cannot be remotely controlled - a DLM Reset would need to be done at the cabinet by an Openreach engineer (https://community.plus.net/library/browsing/fttc-dlm-what-it-is-how-it-works/).  So, is there any hope for the SYNC speeds to improve again with time, depending on the the current values of ‘barrier/caution counter’? How long does it usually take? Apparently, a DLM Reset "isn’t something that can be requested nor can we [PN] send engineers out solely to complete a DLM Reset".  However, because it was a BT/Openreach fault that caused this situation, I think that PN should be able to request Openreach to perform a DLM Reset!
5 REPLIES
Plusnet Help Team
Plusnet Help Team
Posts: 5,445
Thanks: 505
Fixes: 190
Registered: 01-01-2012

Re: Lower speeds after BT Line Fault - DLM?

Your current sync speed is 63mbps and your DLM profile is "0.128M-74M Downstream, Interleaving Low - 0.128M-17M Upstream, Error Protection Off" so DLM isn't causing a issue.
Unfortunately there isn't much we can do as your speeds are still within the estimates.
If this post resolved your issue please click the 'This fixed my problem' button
 Matthew Wheeler
 Plusnet Help Team
tb257
Newbie
Posts: 6
Registered: 28-05-2013

Re: Lower speeds after BT Line Fault - DLM?

Could PN please confirm whether they have access/control over the DLM now,  because the ISP didn't use to in case of NGA products (Fibre).  How does PN now know whether DLM is active or not? - Can PN now perform a DLM reset remotely, or can this still only be done by a BT Openreach engineer after clearance of a line fault?
IF (BIG IF) the drop in SYNC speed is not due to the DLM, then clearly it must have a result of a shoody repair job by BT following the fault on their equipment. In other words, BT caused the fault and then carried out a poor repair, but still they are not accountable!
Plusnet Help Team
Plusnet Help Team
Posts: 5,445
Thanks: 505
Fixes: 190
Registered: 01-01-2012

Re: Lower speeds after BT Line Fault - DLM?

We don't have any control over DLM I'm afraid.
In terms of it being active it will always be active on any line.
Wherever it takes action or not is another matter.
If this post resolved your issue please click the 'This fixed my problem' button
 Matthew Wheeler
 Plusnet Help Team
Terranova667
Pro
Posts: 1,277
Thanks: 70
Fixes: 3
Registered: 19-02-2014

Re: Lower speeds after BT Line Fault - DLM?

No ISP has control over DLM it is an automated system all they can do is look at profiles that have been set on your line and see whether DLM has intervened in some way.
in your case DLM has intervened you have low interleaving which means DLM feels the line isn't stable enough and such it lowers some speed to compensate, Sadly nothing can be done about this it's up to DLM to remove the interleaving if and when it feels the line can handle it, This can take days sometimes weeks to happen in some cases not at all you may have to accept the fact your speed might not return.
unless your speeds drop below estimates for your line nothing further will be done I have been down this road myself.  
tb257
Newbie
Posts: 6
Registered: 28-05-2013

Re: Lower speeds after BT Line Fault - DLM?

Thanks for the replies.
So, the only action the DLM has taken is low interleaving on the downstream (affecting ping times), but no capping of SYNC speeds, right? This however would mean that the drop in SYNC speeds must be due to the quality of the repair following the line fault (for example at the PCP) resulting in a poorer overall quality of the copper line from the PCP, right?