Page 1 of 1

No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 12:24 am
by gregando

We have an issue with our Internet that started on Thursday night - we lost sync all of a sudden on our router. I submitted a ticket with Exetel, and finally got an SMS on Sunday saying that Exetels supplier had restored service, but we still did not get sync.

We are using a Billion 7404VGPO.

Since then, I have tried a different modem (A Netcomm NB6Plus4) which did get sync, however I noticed that the sync speed was about 30% slower than what I used to get.

So I put my Billion back on the line and again, no sync. At least not until I manually forced it to sync under ADSL rather than ADSL2(+) - then it got a similar sync speed to the Netcomm - again around 30% slower than it used to be.

As soon as I tried ADSL2(+) on the Billion again, there was no sync. Force ADSL - sync comes back up.

I don't think this issue is resolved yet, I still thing there is something wrong with the line that is preventing ADSL2 connections, and it seems my modem doesn't like failing back to ADSL.

The thing is, I have been using ADS2(+) fine for over 2 years now.

My ticket was auto closed, but the Ref No is 3717627.

Thanks for your help,

- Greg.

Re: No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 7:34 am
by Dazzled
Greg, could you post the DSL line status from the working modem? It is possible that a stability profile was put on the line after your support request. This increases the noise margins allowed, but at the expense of line speed. It's a way of dealing with noise induced dropouts. Are you aware of the line attenuation before the trouble occurred?

With luck, this may come down to a flaky modem, although the technician did "restore service". Should you need to write for support again, reply to the last email with the numbered header, and the ticket will automatically reopen.

Re: No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 10:09 pm
by gregando
Okay, I don't know if I confused you, but both modems are working, except the one I own I have to force to ADSL instead of ADSL2+ to get line sync.

Unfortunately I am not sure what the line attenuation was before the trouble, but I will provide both modem's link speeds and attenuation for comparison:

My Billion Modem (Forced to ADSL):
Downstream Sync: 7040000
Upstream Sync: 768000
Downstream Attenuation: 31.5 dB
Upstream Attenuation: 17.5dB

Netcomm NB6Plus4 Modem:
Downstream Sync: 7712000
Upstream Sync: 800000
Downstream Attenuation: 33.0 dB
Upstream Attenuation: 17.5 dB

Should I respond to the email and reopen the ticket?


Re: No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 10:31 pm
by Dazzled
I was hoping to see the noise margins. The rates are a bit slow for the attenuations. I was expecting upstream to be the Optus capped speed of 812 kbps.

I don't know why the Billion won't work with ADSL2+, but they can be cranky things with their not well explained coding gain setting, which appears to affect noise margins. Perhaps vary it, starting at 5, there are some threads here. The Netcomm is a more typical unit. With those attenuations, would you be about 1.7 km (crow distance) from the exchange?

Re: No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 10:46 pm
by gregando
Ah sorry - Hopefully more useful info here eh...should have done this to begin with. Thanks for the help so far.


Connect Mode
Profile Type
Activate Line
Coding Gain
Tx Attenuation
DSP Firmware Version E.67.2.37
Connected true
Operational Mode t1.413
Annex Type AnnexA
Upstream 800000
Downstream 7136000
CO Vendor
Elapsed Time 0 day 0 hr 0 min 28 sec

Downstream Upstream
SNR Margin 13.5 dB 15 dB
Line Attenuation 31.5 dB 17.5 dB
CRC Errors 3 0
Latency Interleave Interleave


Line Mode T1.413 Line State Show Time
Latency Type Interleave Line Up Time 00:00:00:45
Line Coding Trellis On Line Up Count 1
Statistics Downstream Upstream
Line Rate 7488 Kbps 800 Kbps
Attainable Line Rate 7904 Kbps 1104 Kbps
Noise Margin 12.4 dB 18.0 dB
Line Attenuation 33.0 dB 17.5 dB
Output Power 19.8 dBm 12.7 dBm
K (number of bytes in DMT frame) 235 26
R (number of check bytes in RS code word) 10 4
S (RS code word size in DMT frame) 1 4
D (interleave depth) 32 8
Super Frames 2595 2535
Super Frame Errors 0 0
RS Words 176490 43095
RS Correctable Errors 0 0
RS Uncorrectable Errors 0 0
HEC Errors 0 0
OCD Errors 0 0
LCD Errors 0 0
Total Cells 779689 0
Data Cells 236 0
Bit Errors 0 0
Total ES 0 0
Total SES 0 0
Total UAS 12 0

Re: No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 10:54 pm
by gregando
And I think your "As The Crow Flies" estimate would be very accurate, probably about 1.5ks - Nice estimation!

Re: No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 11:05 pm
by Dazzled
Margins of 12/18 dB are normal, and the attenuation approximately matches the line length. It looks right to me, but It still seems a little slow. Have you tested either modem in isolation (everything else unplugged from the wall phone points), in case there is an unsuspected noise source at home? Keep unshielded phone cables short and as far from appliances and monitors as you can manage.

Re: No Longer Connecting On ADSL2

Posted: Tue Mar 01, 2011 11:18 pm
by gregando
Yeah, I am on what used to be called naked, so nothing is plugged in except the modem. No other sources of interference as far as I can tell...

Is it possible I am on ADSL1 for some reason? Should I reply to the email and re-open the ticket?

Re: No Longer Connecting On ADSL2

Posted: Wed Mar 02, 2011 12:14 pm
by Dazzled
You won't get 800 kbps up on ADSL1, so that question is easy. By all means reopen the ticket, cross fingers, but I suspect the external line will prove to be within standard, although your comment "Exetels supplier had restored service" indicates something was done externally. Is it possible that the Billion previously was getting away with a very low noise margin, particularly if you used coding gain?