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[drewk]

I recently installed DSLstats v5.2, but it is not working quite right. I have a D-Link DSL-2750b modem/router with the AU_3.06 firmware. Attached is a typical SNR-per-Tone graph.

The modem is operating okay, except for some line noise problems (a "high open"), but for the most part it stays connected, albeit at lower than maximum speed. I am only a short distance from the CO and subscribed to low speed 1 MBPS service. (This is an ISP in the USA, not UK.)

The first problem is there are no upstream SNRs. The "adsl info --SNR" command yields all zeros for these tones. Any idea how I can configure this modem to provide the upstream data? Doesn't the US SNR information need to come from the CO?

The second question is the rather symmetric appearance of the downstream graph. Is than an indication of some particular line noise problem?

Drew

[konrado5]

On some routers or DSLAMs (I thing it is rather second), it is possible to gather correct upstream datas only in diagnostic mode (no active connection).
1. Telnet 192.168.1.1 (or other IP address of your router)
2. adsl connection --diagmode
3. wait a few minutes
4. adsl info --linediag
5. You can plot datas with script (on Linux):
http://forum.kitz.co.uk/index.php?topic=13882.0

Best regards
konrado5

[drewk]

Ok, thanks. I'll try that tomorrow. I assume that I need to enter "adsl connection --normal" to get out of diag mode?

Another strange thing with this modem: on the Bitloading graph several of the low DS tones have absurdly  high bit numbers (attached).

I'm wondering if I may need to re-flash the firmware... Is anyone else here using the DLink 2750B modem ( hardware version T1)?


Drew

[roseway]

That bitloading is clearly wrong. What do you get if you send the command adsl info --Bits ?

[drewk]

Here is the bitloading for those tones:

30           0
   31           0
   32           31
   33           4294967269
   34           32
   35           80
   36           0
   37           0
   38           0
   39           0
   40           31
   41           4294967269
   42           63
   43           4294967292
   44           0

DSLStats graphs the last three digits of those big numbers, not that it matters-- they are clearly crazy numbers. I have seen this from time to time before; sometimes they are normal.

Modem has since retrained at a higher speed (but the crazy bitloading is still there). Graph is attached. I'll try re-flashing the modem firmware and see if it goes away.

I have a line problem with a "high open" causing lots of noise. I have since installed 7.5K resistance across the line which has improved the SNR graphs greatly (before and after graphs attached). The resistors maintain 5 ma of "sealing current" on the line which has eliminated the noise. Of course, the line condition may still degrade further. Have had no luck getting the telco to fix it as the noise has only been intermittent up tilll now and they claim the speed is "acceptable".

Drew

[roseway]

I've never seen that problem before. I could trap out those obviously wrong values and display them as zero perhaps, although that might be hiding a possible issue of course.

[konrado5]

Ok, thanks. I'll try that tomorrow. I assume that I need to enter "adsl connection --normal" to get out of diag mode?

No, "adsl connection" simply.

[drewk]

I've never seen that problem before. I could trap out those obviously wrong values and display them as zero perhaps, although that might be hiding a possible issue of course.

Yes, there is no need to do that. The graph is readable with these large numbers as long as "include with bitloading" is selected for SNR (otherwise the graph is scaled to the large bit numbers and the normal bit tones are squished to the bottom).

[burakkucat]

Here is the bitloading for those tones:

   30           0
   31           0
   32           31
   33           4294967269
   34           32
   35           80
   36           0
   37           0
   38           0
   39           0
   40           31
   41           4294967269
   42           63
   43           4294967292
   44           0

   Hmm . . .

Those numbers are just 2³². The puzzle is why such a value is output.

[drewk]

   Hmm . . .

Those numbers are just 2³². The puzzle is why such a value is output.

I haven't done anything more as far as investigating those numbers or reloading the firmware. I am just letting the modem cook after solving my line noise problem. The speed got bumped up again last night to 1184/448 (from the original noisy line speed of 864/160). Now the bitloading graph appears more normal (except for the 32-43 tones).