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Standard User tom262
(newbie) Tue 01-Apr-14 22:07:34
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Sky's DLM disabled for better sync speed


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I recently was migrated from BE to Sky broadband, and completed the initial 10 days 'line training' with the DLM monitoring the line.
During this period my connection speed dropped from my old BE speed of between 3 and 4Mbps with 6db noise margin... to 2.7Mbps and a noise margin of 9db...

I got on to Sky support and after trying various things to get my speed back up to pre Sky speeds... they agreed to turn off the DLM for my line, after which my speed went back up to around 3Mbps and noise margin of 7.5
Although the line is very long to the exchange it is a stable connection always has been.
Can someone please explain why Sky use the DLM which seemed to favour stability over speed on my line. I hope Sky leave the DLM off as there is no problem with noise/stability on my line.
Thanks, Tom
Standard User RobertoS
(sensei) Tue 01-Apr-14 22:39:44
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Re: Sky's DLM disabled for better sync speed


[re: tom262] [link to this post]
 
A strange question, I accept, but could you tell us your exchange please? I'm wondering if O2/Be were there but Sky isn't.

Assuming I'm wrong, Sky do aim for stability rather than speed. On shorter lines than yours they start at 4Mbps then ramp up, as opposed to BT Wholesale who start fast and adjust down as needed.

My broadband basic info/help site - www.robertos.me.uk | Domains,site and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 59.4/14.4Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
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Standard User tommy45
(knowledge is power) Tue 01-Apr-14 23:30:20
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Re: Sky's DLM disabled for better sync speed


[re: tom262] [link to this post]
 
In reply to a post by tom262:
Can someone please explain why Sky use the DLM which seemed to favour stability over speed on my line. I hope Sky leave the DLM off as there is no problem with noise/stability on my line.
Thanks, Tom
IMO Sky use DLM to save on support calls, and very little else, It's why BT are so stuck in their ways regarding DLM too, It very rarely acts in the end users favour, in particular if they play online games or use voip as as well as lowering (capping ) the speed to a lower value ,it will also add interleaving delay ,It's an outdated system that should have been replaced long ago,
Fortunately ISP's can now basically manually configure BT retail based 21cn products apart from FTTC openreach as yet won't let ISP's have hardly any control

Edited by tommy45 (Tue 01-Apr-14 23:32:44)


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Standard User tom262
(newbie) Wed 02-Apr-14 02:25:05
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Re: Sky's DLM disabled for better sync speed


[re: RobertoS] [link to this post]
 
Thanks for the replys RobertoS and Tommy45,

My Exchange is Hayes North BT Code LWHAY
Line length is 5.7Km so as you can see it is quite a distance, but a surprisingly stable
line, no noise or drops in connection, stays like that for weeks at a time.

As Sky have disabled the DLM is it worth trying for a re sync during approx mid afternoon to see if I can squeeze any more speed out of the connection, as I mentioned before with BE I could manage a maximum of just short of 4Mbps at 6db Noise Margin.
Currently Router Stats Lite shows 2,912Kbps and 8db Noise Margin (@2.20am)

I found the Sky support helpful and was surprised that they turned off the DLM, saying if the line shows any instability to get back to them and enable the DLM. But I know from previous experience it will be ok.
Standard User IanBB
(member) Wed 02-Apr-14 03:06:22
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Re: Sky's DLM disabled for better sync speed


[re: tom262] [link to this post]
 
In reply to a post by tom262:
As Sky have disabled the DLM is it worth trying for a re sync during approx mid afternoon to see if I can squeeze any more speed out of the connection, as I mentioned before with BE I could manage a maximum of just short of 4Mbps at 6db Noise Margin.


I don't see why not as the worst that could happen is the DLM is triggered again.
Standard User ian72
(knowledge is power) Wed 02-Apr-14 08:17:46
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Re: Sky's DLM disabled for better sync speed


[re: tommy45] [link to this post]
 
In reply to a post by tommy45:
IMO Sky use DLM to save on support calls, and very little else


I think that is a certainty. They use a noise margin that will make the majority of lines stable so that they get fewer support calls and most customers wouldn't even notice the difference except there Internet doesn't often go down.

Big companies generally look to control costs and the best way to do this is be conservative and to standardise. So, everyone gets the same, relatively conservative, noise margin.

If people want to change this then the best way is to change to an ISP that gives the flexibility - I know there are at least a few around. Mass market generally won't give that flexibility - different prioirities.
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