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    Router reports G.DMT

    This is a discussion on Router reports G.DMT within the Technical discussion forums, part of the Broadband Technical Help category; Originally Posted by Saturday OK - I'll bow to your knowledge. However, that doesn't seem to tally with various papers ...

    1. #51
      jb51053's Avatar
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      Re: Router reports G.DMT

      Quote Originally Posted by Saturday View Post
      OK - I'll bow to your knowledge. However, that doesn't seem to tally with various papers I've read. Can you point me towards a reference or two?
      Done


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    3. #52
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      Re: Router reports G.DMT

      Quote Originally Posted by jb51053 View Post
      Perhaps i should have stated that if a sky router is reporting GDMT its ALWAYS using ADSL1.

      8Mb is a typical limit when using fast path, but ADSL1 will do up to 12Mb when using interleaved as apposed to fast path, the additional error correction allowed by interleaving allows for ADSL1 to sync at >8Mb (upto a max of 12Mb) when used instead of fastpath
      Marvellous stuff! So (as I might have said - he he he), when the router says g.dmt it really does mean adsl1. And adsl1 can indeed go faster than 8Mb/s. I've lamented elsewhere, part of the problem is the fact that terminology gets crossed wires and that if I had my own way, we'd all be keeping to the "ITU G.993.ABC. Annex XYZ" terminology to avoid confusion!

      Anyway getting back to the point, I take it that means that the 8Mb/s limits are actually "artificial" (meaning practical) ones imposed by the technology rather than by the standards?
      IQ album "Dark Matter" artwork reproduced with permission. See www.gep.co.uk/iq for more information.

    4. #53
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      Re: Router reports G.DMT

      Quote Originally Posted by mossywell View Post
      Marvellous stuff! So (as I might have said - he he he), when the router says g.dmt it really does mean adsl1. And adsl1 can indeed go faster than 8Mb/s. I've lamented elsewhere, part of the problem is the fact that terminology gets crossed wires and that if I had my own way, we'd all be keeping to the "ITU G.993.ABC. Annex XYZ" terminology to avoid confusion!

      Anyway getting back to the point, I take it that means that the 8Mb/s limits are actually "artificial" (meaning practical) ones imposed by the technology rather than by the standards?
      It's more dependant on the line, to get more than 8Mb using ADSL the line still has to be very short and very good, not many lines over 1.5KM will actually do more than 8Mb using ADSL1

      It seems in the UK ADSL simply out performs ADSL2 and ADSL2+ on lines over about 3KM (sync and stability wise) so the bottom line is, would you prefer to have a line that might just about manage 10Mb and drop out frequently, or a line that does 8Mb and doesnt drop?

      I'd take the stability every time!

    5. #54
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      Re: Router reports G.DMT

      I love this forum

      So, it seems that Sky cap customers with an "unusual" later annex to ITU G.992.1 which shares many characteristics with ADSL2/2+ (I'm still reading up on it but it looks like it's using the same sort of packet aggregation and frame bursting?).

      I agree with Mossywell though. It all gets very confusing when G.DMT can mean so many things.

      Thanks for the education.

    6. #55
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      Re: Router reports G.DMT

      Quote Originally Posted by jb51053 View Post
      It's more dependant on the line, to get more than 8Mb using ADSL the line still has to be very short and very good, not many lines over 1.5KM will actually do more than 8Mb using ADSL1

      It seems in the UK ADSL simply out performs ADSL2 and ADSL2+ on lines over about 3KM (sync and stability wise) so the bottom line is, would you prefer to have a line that might just about manage 10Mb and drop out frequently, or a line that does 8Mb and doesnt drop?

      I'd take the stability every time!
      What I was really asking (badly) is, why is it that G.DMT maximum speeds so often seem to be bang on 8 megs? I.e. where is this speed being set (given that the standard itself doesn't force this to be the maximum speed)?
      IQ album "Dark Matter" artwork reproduced with permission. See www.gep.co.uk/iq for more information.

     

     
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