Weird throughput 'problems'

[Webby]

There could be 100 different reasons why down to network routing/those particular servers etc.

[john46]

you need an absolute minimum of 3 db preferable 6db to guarantee stability squeezing the last bit of connection speed out of a line like yours is not needed you will hardly notice any difference

[chris6273]

I understand that fact John.

What I'll do if I have the problem when I get home is reset my SNR slider to 100% (Which should reset the Noise Margin to ~6dB hopefully - The default SNR) and see if the problem still occurs.

[chris6273]

I got home tonight and wanted to get both problems sorted so what I did was replace the cable out of the XF-1e with another (BS6312 to RJ11) and plugged it into the Test Socket.

Now I didn't touch any of my SNR settings at all and I was quite amazed by the results when it synced up:

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Connection Speed: 24276 kbps 1211 kbps
Line Attenuation: 16.5 db 6.4 db
Noise Margin: 1.1 db 6.2 db

Believe it or not while I was writing the part above, my connection must have received a massive spike in interference (At 21:33) and I managed to catch the SNR being reported at -1.0 and about 50 CRC Errors per second (I observed the connection getting around 157 CRC errors an hour after I fiddled around with the Microfilter before the spike).

What on earth could cause a drop of 2dB within 2 seconds!?

Obviously my router has resynced at a lower rate. As it is now:

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Connection Speed: 22874 kbps 1219 kbps
Line Attenuation: 16.5 db 6.4 db
Noise Margin: 1.0 db 5.8 db

The throughput for the ThinkBroadband Files was stable around 1513KB/s before the spike so could it be a peering issue?

Other downloads from Apple and Rapidshare were downloading at 2.4-2.5MB/s (Downloaded Seperately).

[john46]

at that very low noise margin any thing could cause a spike like that If you want to avoid that then you MUST increase the noise margin you are not going to lose out that much speed wise It is a matter of speed or stability only you can choose but i know what i would do

[chris6273]

Thanks for the reply John.

Sometime today, my router resynced with a 4.0dB Noise Margin at 21,392Kbps :).

I left router stats going and noticed some sudden ups and downs throughout today. The SNR was stable until about 09:10 today when it rose to about 2.8dB:

Then at 11:10 the SNR dropped to 0 and the line resynced:

And then at 12:51 the SNR dropped to 0 and then rose to 4dB (Along with a lower sync):

What could possibly be causing the SNR drops/rises? I'm guessing the rise at 09:10 was street lighting being switched off, but what could possibly be causing the others?

When I get home, I'll test the throughput speeds on files from ThinkBroadband and see if they are still a problem because the line has minimal errors with its low sync now.

[john46]

your SNR is to low that is the cause it needs to be at 6db to give you a chance of a stable connection adsl2+ is very noise aggressive

[imjolly]

I would watch again tomorrow and see if the drops occur at about the same time suggesting there is something switching on/off causing the interference and not just random spikes/troughs

[imjolly]

john46 I don't think noise margin need to be set at 6db but if it happens again at same time it's a matter of trying to identify what is causing the drop.  noise margin is ok if you can eliminate the interference

[john46]

true I suggested it because of some earlier very low noise levels with the posters very high connection speed the increase of noise margin would hardly be noticed