DLM question

Discussion in 'Broadband' started by Graham J, Jan 28, 2015.

  1. Graham J

    Graham J Guest

    I have an ADSL service provided by Demon (now owned by Vodafone).

    The router normally reports:

    Up speed 736k
    Down speed 2272k
    SNR margin 6db
    Loop loss 60db

    Over the past few weeks I have been testing some unreliable routers on
    this line. These routers sometimes re-sync every few minutes, but never
    stay in sync for longer than about 2 hours. The issue is now understood
    and discussed elsewhere.

    Not surprisingly the DLM has altered the line performance and the
    original router now reports:

    Up speed 672k
    Down speed 1152k
    SNR margin 15db
    Loop loss 61db

    This is to be expected.

    I have completed the testing of the faulty routers, and for 4 days have
    had the original reliable router connected, and this has maintained sync
    for the whole time without a break.

    But it still reports the same slow speed and SNR margin.

    How long is it likely to take for the DLM to recognise that the line is
    reliable, and to increase its speed?

    Is there anything I can do to encourage it?

    If I have to ring Vodafone, is there anybody there who will understand
    the request to reset the BRAS profile so that the DLM starts to retrain
    from scratch?
    Graham J, Jan 28, 2015
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  2. Graham J

    Martin Brown Guest

    If you disconnect and allow it to resync in the mid afternoon when
    available SNR is at its best then you might get out of the mad house.

    I am a bit surprised how high your uplink speed is on that 60dB lossy
    line - I can only get 448k even though my downlink will sync at ~5M.
    It may just need a resync of your modem to get it back to normal now.
    Three days without any line drops should be enough to take the SNR
    margin down by 3dB @ faster sync rate. Mine sits at an annoying 12dB on
    a much less lossy line due to local line noise. There is a rule of thumb
    on Kitz as to how long you need to wait for DLM to adjust.
    Martin Brown, Jan 28, 2015
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  3. Graham J

    Graham J Guest

    Martin Brown wrote:

    Tried a resync - no effect.

    One of the things Kitz suggests is a complete disconnection for at least
    30 minutes, provided the line has been up for a few hours. I might
    disconnect it overnight when I'm not using it ...
    Graham J, Jan 28, 2015
  4. Graham J

    Mark Guest

    IME target SNR margin can take ages to lower. I would ask your ISP to
    reset it.
    Mark, Jan 28, 2015
  5. Graham J

    Andy Furniss Guest

    448 is the old home user capped rate.

    If your exchange doesn't have adsl2 then that's why (in theory you could
    pay more and get 882 IIRC).

    If it does have adsl2 then some ISPs don't uncap unless you ask.
    Andy Furniss, Jan 28, 2015
  6. Graham J

    fred Guest

    It took 30 days here for it to sort itself out after a few changes, I
    was just about to brave the unhelpful desk when the rate came back in
    huge leaps every night, logged by the router as momentary disconnections
    between 2 & 3am.
    fred, Jan 29, 2015
  7. It my experience with BT it could take months to change and it could
    take months to get to speak to someone who even understands what BRAS is
    so that they can refuse to reset it for you.
    Brian Gregory, Jan 31, 2015
  8. Graham J

    Graham J Guest

    Brian Gregory wrote:
    I've heard that the only way is to ask for a Migration Code - you then
    get put through to somebody who asks what the problem is, and can
    resolve it.
    Graham J, Jan 31, 2015
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