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Standard User Hothead17
(newbie) Sun 17-Jan-21 19:36:32
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Does sky have DLM?


[link to this post]
 
Hi all,

Since I got sky in September I've always had a sync speed close to 80meg I don't remember the exact sync figures. Over night the sync speed dropped to 67999 and has been like this for a few days now. So I am curious if this is temporary and will recover?

I was thinking it's crosstalk

Thanks
Standard User j0hn83
(fountain of knowledge) Mon 18-Jan-21 10:41:23
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Re: Does sky have DLM?


[re: Hothead17] [link to this post]
 
Yes it does.
All OpenReach VDSL2 connections use the OpenReach DLM.

The DLM has capped/banded your line at 68Mb.
It can be temporary but can last months.

Providers can request OpenReach to reset the DLM but some don't seem to use this option.
Standard User Hothead17
(newbie) Mon 18-Jan-21 11:20:27
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Re: Does sky have DLM?


[re: j0hn83] [link to this post]
 
Thanks for the reply

I'll wait it out for a coupe of weeks and see how it goes before I contact sky
Thanks


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Standard User dect
(fountain of knowledge) Mon 18-Jan-21 11:42:47
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Re: Does sky have DLM?


[re: Hothead17] [link to this post]
 
The SNR margin on the router stats may give you an indication if your line has any headroom to improve from 68Mb if the banding is removed.
Standard User Hothead17
(newbie) Mon 18-Jan-21 12:21:25
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Re: Does sky have DLM?


[re: dect] [link to this post]
 
Thanks.

I'm not sure if these are the correct stats but all I can see is

Noise margin - 11.2db

Line attenuation D1(4.9db), D2(10.6db), D3(16.4db)
Administrator MrSaffron
(staff) Tue 19-Jan-21 10:30:47
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Re: Does sky have DLM?


[re: Hothead17] [link to this post]
 
Might not be banded, a chunk of noise may have caused it to resync and as noise was still present sync was lower.

Now noise has gone away a single resync might be worthwhile to see if speed comes back. 11.2dB noise margin suggests there may be some spare for a higher sync.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User j0hn83
(fountain of knowledge) Tue 19-Jan-21 12:46:43
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Re: Does sky have DLM?


[re: MrSaffron] [link to this post]
 
11.2dB noise margin and an exact 67,999 sync (1 of OpenReach's banding levels) is a banded line.

It's about a 1 in 1500-2000 chance your sync will land on an exact banded figure.
Add the drop in expected sync and increase in SNRM and I would be utterly amazed if it wasn't banded.

Definitely banded. Quite a harsh banding at that so likely dropped to that in stages.

Edited by j0hn83 (Tue 19-Jan-21 12:47:35)

Standard User Hothead17
(newbie) Tue 19-Jan-21 13:47:40
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Re: Does sky have DLM?


[re: j0hn83] [link to this post]
 
Thanks for the replies.

According to the my sky page (does a speed test everyday incase you weren't aware) it was at 79, next day 73 the day after 66. So that does go with your theory.
Standard User j0hn83
(fountain of knowledge) Tue 19-Jan-21 13:52:07
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Re: Does sky have DLM?


[re: Hothead17] [link to this post]
 
Yep.

73,399 more than likely (another banding level used by the DLM)

It would be rare for banding to drop straight to 67,999.

OpenReach used to have quite a few banding levels and they added even more fairly recently so I don't know what they all are any more.
The 2 I mentioned are definitely banding levels used.
Standard User Hothead17
(newbie) Tue 19-Jan-21 14:16:21
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Re: Does sky have DLM?


[re: j0hn83] [link to this post]
 
Will it try to recover over time or do I need to contact sky to try to get them to get openreach to reset it?
Thanks
Standard User j0hn83
(fountain of knowledge) Tue 19-Jan-21 14:26:05
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Re: Does sky have DLM?


[re: Hothead17] [link to this post]
 
In reply to a post by Hothead17:
Will it try to recover over time or do I need to contact sky to try to get them to get openreach to reset it?
Thanks


It can vary between lines depending on stability.

Some banding removes in days or weeks. It can last longer though.

Banding used to get stuck but the DLM is much better at removing it now.

It used to require an on site OpenReach engineer to remove banding but ISP's now have the ability to request OpenReach do this remotely.

There isn't much point having the banding removed if the issue that caused it still exists. It would just be added back by DLM again.
Banding is usually applied when a line resyncs too many times in a set time period.

Constantly rebooting the Hub can cause this or power to the property being turned on/off a lot.
Line faults that cause the line to resync a lot will cause banding.

If there's a line fault it should be fixed. If the resyncs were due to you rebooting the Hub or power going on/off then you know the cause of the banding.

Edited by j0hn83 (Tue 19-Jan-21 14:26:35)

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