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    ADSL and ADSL2 - Advice pls

    This is a discussion on ADSL and ADSL2 - Advice pls within the Sky Broadband help forums, part of the Sky Broadband help and support category; Sorry for the long post but can someone please explain the differences between ADSL and ADSL2 please? Is one more ...

    1. #1
      deskmonkey's Avatar
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      ADSL and ADSL2 - Advice pls

      Sorry for the long post but can someone please explain the differences between ADSL and ADSL2 please? Is one more stable than the other, Can ADSL 2 be activated on a line and choked to reduce the conflicts?

      The reason Iím asking is that it appears that I have been placed on ADSL instead of ADSL2.

      For info Ė For several years I wasnít able to receive any broadband due to line length apparently. ADSL max came along and Bt checker stated I could get it at around 512. BT came out and activated the line etc.. and for about 2 days I had BB. Sadly I kept losing sync with the exchange so BT cancelled my BB. Sky unbundled the Bishop Auckland exchange and its checker reported that I could receive ADSL2. I was up and running with no problems for a couple of days running at a speed of around 700 kbps. Gradually though I was beginning to lose connections and drops in speeds. This led to a call to Sky CS. It took ages to get through to them that it wasnít a wireless issue, as I could talk to the router no problem Ė it was the router not talking to the exchange that was the problem.

      Anyway looking at my stats it seems that I am now on G.DMT mode (ADSL?) as opposed to ADSL2 a couple of weeks ago. Does this mean that my line has been capped?

      If I have I canít get my head around how I can now get ordinary ADSL when previously I couldnít Ė whatís changed? Iíd of thought that ADSL2 would provide a more stable signal. Is that right

      Iíve replaced filters, used the test socket and BT state that thereís no faults on the line.

      The other thing is that judging by my stats I think I should be getting twice the speed (attenuations always 63.5db) If placed on ADSL2 would that be the case?

      Hereís some stats for those savvy enough to understand them.

      THIS MORNING
      /usr/sbin/adslctl: ADSL driver and PHY status
      Status: Showtime Channel: INTR, Upstream rate = 512 Kbps, Downstream rate = 416 Kbps
      Link Power State: L0
      Mode: G.DMT
      Channel: Interleave
      Trellis: ON
      Line Status: No Defect
      Training Status: Showtime
      Down Up
      SNR (dB): 4.6 7.0
      Attn(dB): 63.5 31.5
      Pwr(dBm): 14.8 12.5
      Max(Kbps): 512 608
      Rate (Kbps): 416 512
      G.dmt framing
      K: 14(0) 17
      R: 16 16
      S: 16 8
      D: 8 8
      ADSL2 framing
      MSGc: 1 1
      B: 14 17
      M: 16 8
      T: 1 1
      R: 16 16
      S: 17.0666 8.8888
      L: 120 144
      D: 8 8
      Counters
      SF: 765135 765133
      SFErr: 2434 208
      RS: 3251830 6503630
      RSCorr: 2192811 1770
      RSUnCorr: 2231 0

      HEC: 1571 144
      OCD: 0 0
      LCD: 0 0
      Total Cells: 12760008 0
      Data Cells: 532862 0
      Drop Cells: 0
      Bit Errors: 0 0

      ES: 5461 0
      SES: 5440 0
      UAS: 42 0
      Total time = 3 hours 37 min 44 sec
      SF = 765135
      CRC = 2434
      LOS = 31439
      LOF = 0
      ES = 5461
      Latest 1 day time = 3 hours 37 min 44 sec
      SF = 765135
      CRC = 2434
      LOS = 31439
      LOF = 0
      ES = 5461
      Latest 15 minutes time = 7 min 44 sec
      SF = 27347
      CRC = 322
      LOS = 2238
      LOF = 0
      ES = 195
      Previous 15 minutes time = 15 min 0 sec
      SF = 52930
      CRC = 428
      LOS = 3998
      LOF = 0
      ES = 387
      Previous 1 day time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
      SF = 52931
      CRC = 260
      LOS = 3360
      LOF = 0
      ES = 444
      15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
      SF = 52930
      CRC = 167
      LOS = 2925
      LOF = 0
      ES = 574
      15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
      SF = 52990
      CRC = 294
      LOS = 3308
      LOF = 0
      ES = 675

      THIS MORNING AGAIN, I didnít remote reboot the router btw

      /usr/sbin/adslctl: ADSL driver and PHY status
      Status: Showtime Channel: INTR, Upstream rate = 512 Kbps, Downstream rate = 704 Kbps
      Link Power State: L0
      Mode: G.DMT
      Channel: Interleave
      Trellis: ON
      Line Status: No Defect
      Training Status: Showtime
      Down Up
      SNR (dB): 6.8 7.0
      Attn(dB): 63.5 31.5
      Pwr(dBm): 15.0 12.5
      Max(Kbps): 800 608
      Rate (Kbps): 704 512
      G.dmt framing
      K: 23(0) 17
      R: 16 16
      S: 8 8
      D: 16 8
      ADSL2 framing
      MSGc: 1 1
      B: 23 17
      M: 8 8
      T: 1 1
      R: 16 16
      S: 8.6666 8.8888
      L: 192 144
      D: 16 8
      Counters
      SF: 2820 2818
      SFErr: 0 0
      RS: 23978 23953
      RSCorr: 17 0
      RSUnCorr: 0 0

      HEC: 0 0
      OCD: 0 0
      LCD: 0 0
      Total Cells: 79057 0
      Data Cells: 0 0
      Drop Cells: 0
      Bit Errors: 0 0

      ES: 1 0
      SES: 1 0
      UAS: 20 0
      Total time = 1 min 15 sec
      SF = 2820
      CRC = 0
      LOS = 1
      LOF = 0
      ES = 1
      Latest 1 day time = 1 min 15 sec
      SF = 2820
      CRC = 0
      LOS = 1
      LOF = 0
      ES = 1
      Latest 15 minutes time = 1 min 15 sec
      SF = 2820
      CRC = 0
      LOS = 1
      LOF = 0
      ES = 1
      Previous 15 minutes time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Previous 1 day time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0


      Thanks Guys n Gals


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    3. #2
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      Re: ADSL and ADSL2 - Advice pls

      Don't get hung up on whether you are on ADSL (G.DMT) or ADSL2+. This will only really be of any importance if your line had an attenuation of ~42db or less.

      Your attenuation is 63.5db and that is well into the point where getting a reliable, stable connection can't be guaranteed with any ADSL technology.

      The stats you posted show that your line is generating a very high level of errors. Your noise margin dropped so low that you lost connection hence the change in the second set of stats. A very low noise margin will also exacerbate the error level.

      You say Sky moved you from ADSL2+? I'm not at all surprised. For your current line condition G.DMT is the right mode for your connection.

      You really need to do some reading and this forum is an excellent source. Start with the first sticky in my signature at the bottom of this post to understand the relationship between connection speed and attenuation and the importance of an adequate noise margin. Then move on to the cabling and faceplate help forum to understand what might be possible to remove some of that line noise.

    4. #3
      deskmonkey's Avatar
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      Re: ADSL and ADSL2 - Advice pls

      Saturday,

      I'm not sure what Sky has done - unless its a fluke, but I've been up and running now for 13hrs since I posted the stats above (taken this morning).

      I emailed Sky CS a couple of days ago and it seems to have done the trick. I've been placed on G.DMT and its made loads of difference.

      The only curious thing though is that from the stats below you'll notice that my line attenuation is now only 15.5db!!!!! How can that happen?

      Thanks for your advice earlier, the sticky's in your sig made interesting reading too.

      dm

      /usr/sbin/adslctl: ADSL driver and PHY status
      Status: Showtime Channel: INTR, Upstream rate = 512 Kbps, Downstream rate = 416 Kbps
      Link Power State: L0
      Mode: G.DMT
      Channel: Interleave
      Trellis: ON
      Line Status: No Defect
      Training Status: Showtime
      Down Up
      SNR (dB): 10.1 7.0
      Attn(dB): 15.5 31.5
      Pwr(dBm): 14.5 12.5
      Max(Kbps): 512 608
      Rate (Kbps): 416 512
      G.dmt framing
      K: 14(0) 17
      R: 16 16
      S: 16 8
      D: 8 8
      ADSL2 framing
      MSGc: 1 1
      B: 23 17
      M: 8 8
      T: 1 1
      R: 16 16
      S: 8.6666 8.8888
      L: 192 144
      D: 16 8
      Counters
      SF: 531830 531828
      SFErr: 0 102
      RS: 2260282 4520538
      RSCorr: 6097 1384
      RSUnCorr: 0 0

      HEC: 0 60
      OCD: 0 0
      LCD: 0 0
      Total Cells: 8870547 0
      Data Cells: 224231 0
      Drop Cells: 0
      Bit Errors: 0 0

      ES: 6084 0
      SES: 5247 0
      UAS: 312 0
      Total time = 13 hours 6 min 50 sec
      SF = 2751010
      CRC = 300441
      LOS = 17497
      LOF = 0
      ES = 6084
      Latest 1 day time = 13 hours 6 min 50 sec
      SF = 2751010
      CRC = 300441
      LOS = 17497
      LOF = 0
      ES = 6084
      Latest 15 minutes time = 6 min 50 sec
      SF = 24113
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Previous 15 minutes time = 15 min 0 sec
      SF = 52989
      CRC = 0
      LOS = 1
      LOF = 0
      ES = 1
      Previous 1 day time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
      SF = 52930
      CRC = 0
      LOS = 2
      LOF = 0
      ES = 2
      15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
      SF = 52931
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
      SF = 52931
      CRC = 0
      LOS = 1
      LOF = 0
      ES = 1

    5. #4
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      Re: ADSL and ADSL2 - Advice pls

      Ignore the 15.5db, that's a known router "bug". Rebooting the router (sometimes it needs a reset) will get it reporting correctly again. Though if you have a good connection, leave it alone

      Good to hear your connection is stable. This is almost certainly down to your noise margin. If you've read my sticky you'll know that disconnections will happen if it drops much below 6db. In your first set of stats it was 4.6dbat the time they were taken. The latest shows it at 10.1db which should easily be enough to keep it above the danger zone.

      I can't think of anything Sky CS could do to improve your noise margin other than set your connection speed which they've already done and is unchanged from your earlier stats. I think it more likely that something on your line has changed. How are you connected? Have you changed anything?

    6. #5
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      Re: ADSL and ADSL2 - Advice pls

      I've changed absolutely nothing!
      I'm currently connected wireless through the netgear dongle with no probs.
      The netgear router is situated around 0.5m away from the master socket. This only has our landline in and the router, both connected by an ADSL faceplate fitted by a BT engineer a couple of years ago when I'd tried to get BB previously.
      There is no power sockets nor cables (that I can see) anywhere near the router either. I've even tried elimination by removing the landline, using the test socket etc but doesn't really make any tangible difference.


      ?4U - would purchasing a smaller telecom cable to connect the router and socket make a slight difference d'you think? It came with a 1.5m length which is just curled up at the mo.

    7. #6
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      Re: ADSL and ADSL2 - Advice pls

      Quote Originally Posted by deskmonkey View Post
      Iusing the test socket etc but doesn't really make any tangible difference.
      If you're sure? The differences will/may be in connection speed and/or noise margin. Attenuation should be the same - maybe a 1db shift downwards.

      Best not to coil the cable. No need to buy a shorter one unless it is too untidy.

     

     

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