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    Reminder about the reality of DLM on Openreach FTTC

    This is a discussion on Reminder about the reality of DLM on Openreach FTTC within the Sky Broadband (Fibre) Help forums, part of the Sky Broadband help and support category; thinkbroadband :: Reminder about the reality of DLM on Openreach FTTC With BT Wholesale ADSL and ADSL2+ services having ran ...

    1. #1
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      Reminder about the reality of DLM on Openreach FTTC

      thinkbroadband :: Reminder about the reality of DLM on Openreach FTTC
      With BT Wholesale ADSL and ADSL2+ services having ran for some years most people have grown to understand how the system manages their connection, but with the FTTC services there has been a lot less information made public, in addition to a lack of control for the broadband provider.

      The Openreach Fibre to the Cabinet products use a DLM system that has three main modes, the only control a retail provider has is to pick which of these three profiles your new FTTC connection will run on, or swap you between the various modes.

      • Standard best overall balance between speed and stability for general internet users.
      • Stable prioritise stability over speed for IPTV videoconferencing, home workers and businesses transferring data and IPTV.
      • Speed prioritise speed over stability for online gamers.


      In all three modes the system will tune the connection, setting fast or interleaved mode for error correction and once in interleave mode vary the depth of interleaving, the deeper the interleave the more tolerant the line is to errors at the expense of increasing latency and some throughput speed.

      Where the most myths occur is the speed with which the DLM system will react to issues and the pattern is something like the following:

      1. New connections are left wide open so should run at the upper limit that the modem and DSLAM can negotiate.
      2. On the first day if severe instability (levels governed by which of the three modes the line is running in) then DLM will intervene.
      3. Normally the DLM waits for a day after provisioning before making any DLM choices, and then only if the modem was trained for at least 15 minutes the previous day so that some data is actually available.
      4. Aside from adjusting interleaving depths, the DLM can set a maximum and minimum sync rate (where the minimum is usually half the maximum). This is often referred to as banding and the purpose of the minimum is that to stop a line syncing at a stupidly low speed due to a noise burst e.g. thunderstorm i.e. the modem will keep negotiating until the minimum sync can be obtained.
      5. The upshot is that usually within 48 hours most lines have had their DLM conditions set.
      6. VERY IMPORTANT: While the DLM is set at an early stage, changes in line conditions will continue to affect the line and potentially cause DLM changes in the future for as long as the FTTC service is active.

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      Re: Reminder about the reality of DLM on Openreach FTTC

      So Sky have the ability to move me to speed if I were to ask them to ?

      Although reading the comments posted dlm may do that if I wait 3 weeks.


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      Re: Reminder about the reality of DLM on Openreach FTTC

      I am not sure how it works and which option/s Sky use/s.

      Sky Fibre Unlimited Pro: Connected at 80,000 kbps / 20,000 kbps
      Previous ADSL2+ Speed 19999 kbps 1153 kbps, Line Attenuation 17.5 db 6.9 db, Noise Margin 7.5 dB 8.7 dB
      Speedtest: 17.15MB/s 0.97Mb/s Ping 31 ms

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      Re: Reminder about the reality of DLM on Openreach FTTC

      Sky have no control over FTTC DLM whatsoever.

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      Quote Originally Posted by Scubbie View Post
      I am not sure how it works and which option/s Sky use/s.
      We await an answer to the question though!
      ++ speedyrite ... powered by NOW Broadband from June 2018 ++
      (previously powered by Sky Broadband from July 2007)

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      Re: Reminder about the reality of DLM on Openreach FTTC

      It would be nice to know what they do use.

      I suspect that someone will think that we do not have w right to know.

      Sky Fibre Unlimited Pro: Connected at 80,000 kbps / 20,000 kbps
      Previous ADSL2+ Speed 19999 kbps 1153 kbps, Line Attenuation 17.5 db 6.9 db, Noise Margin 7.5 dB 8.7 dB
      Speedtest: 17.15MB/s 0.97Mb/s Ping 31 ms

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      Re: Reminder about the reality of DLM on Openreach FTTC

      I suspect Sky will have no more control over Fibre than they do for the Connect ADSL package.

      TomD


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      Re: Reminder about the reality of DLM on Openreach FTTC

      Is this the cause of all the "half speed" threads on the official sky fibre forums?

      Any way to view/ change the profile on an unlocked modem?

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      Re: Reminder about the reality of DLM on Openreach FTTC

      Quote Originally Posted by Isitme View Post
      I suspect Sky will have no more control over Fibre than they do for the Connect ADSL package.
      Sky actually have significantly more control with Connect than with fibre, but that isn't saying much. It's apples & oranges really, BT wholesale have no involvement in Sky fibre.

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      Re: Reminder about the reality of DLM on Openreach FTTC

      Then who does have control of the fftc - Willy Wonka?

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