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[camallison]

Over the past 10 months, I have had stats that are up and down like a yo-yo, once as low as 0.8Meg.  BT Mumbaishire have tried to help all they can bless their cotton socks, but it seems to take around 6 weeks before anyone in BT here in the UK takes us seriously and then mysteriously we go back to a good level, without anyone admitting to knowing what the problem was. We have one of the Sam Knows line analysers installed and the same is seen historically since May when that was installed.  At one point we could get a stable 3.4 Meg but are now down to around 1.8 Meg (even though the router stats show a theoertical 2.7 Meg).  It seems to do this up & down in the space of a month or two.  Current stats from the router are:

Uptime:   27 days, 2:41:57
Modulation:   G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]:   448 / 2,720
Data Transferred (Sent/Received) [GB/GB]:   0.98 / 3.74
Output Power (Up/Down) [dBm]:   11.5 / 19.0
Line Attenuation (Up/Down) [dB]:   28.0 / 47.0
SN Margin (Up/Down) [dB]:   19.0 / 14.0
Vendor ID (Local/Remote):   TMMB / ALCB
Loss of Framing (Local/Remote):   0 / 0
Loss of Signal (Local/Remote):   1 / 0
Loss of Power (Local/Remote):   0 / 0
Loss of Link (Remote):   0
Error Seconds (Local/Remote):   1 / 0
FEC Errors (Up/Down):   0 / 101,031
CRC Errors (Up/Down):   0 / 1,049
HEC Errors (Up/Down):   0 / 917
Line Profile:   Interleaved

We have no LLU option on our exchange yet to go with anyone other than BT.  Any ideas to help please?

PS - oh, and Fujitsu have been doing underground line work in the area all summer.

[jid]

With that attenuation you should see a sync of 5536kbps according to the Max Speed Calc:-
http://kitz.co.uk/adsl/max_speed_calc.php

Your errors are very good for your uptime though.

SNR might be set to 15dB target which may be limiting your speeds a bit, what is the SNR usually straight after a resync?

[roseway]

The 'up and down' nature of the connection suggests that there might be an intermittent line fault or some serious source of occasional interference. It's quite likely that this will have resulted in the target noise margin being increased to stabilise the connection. I'm afraid that this sort of problem is the very devil to diagnose, and difficult for BT as well.

Two things which you can do are:-

- Make sure that your own internal wiring and setup isn't contributing to the problem. These pages may help to do this.

- Monitor your connection using Routerstats to see if there is any pattern to the interference.

[camallison]

Thank you both for such speedy help.   

I have a Sam Knows box attached to the line which is giving me excellent info, but will also do as you suggest and try routerstats.  The adsl router is connected directly at the master socket through an adsl NTE5 faceplate.  Only a dect phone is connected to the "phone" side and no other wiring.

Just worked out that we are 2.9km from the exchange by road, where our underground cabling runs.  Does that explain anything.

When I spoke to local linesmen, they did say that the underground cabling had displayed faults and that is why Fujitsu were replacing most of the local cabling - maybe that has/had something to do with it.

[camallison]

These are my immediate router stats using the site you suggested:



[attachment deleted by admin]

[roseway]

Those stats indicate a near-perfect result for your level of attenuation, so it's pretty clear that there is an intermittent problem which isn't showing up at present. You've already got the best internal setup with a filtered faceplate, so I can only suggest that you leave routerstats running and see what happens to the noise margin graph when the problem reoccurs (as it presumably will).

[camallison]

Thanks guys - it's great to have a solid reply rather than BT's ..... "Not my department guv".  As you suggest, I will keep routerstats running for a couple of months on my main machine.

Once again - thanks!   

[jid]

Keep us updated on how it goes 

[camallison]

The "noise" in the attached won't be enough to disturb things will it?

One other thought that came to mind is that we are on an "agricultural" power circuit even though the village is quite large (10,000 souls) and we do suffer occasional power cuts.  My ADSL router is powered from my UPS and so stays up for the short cuts, but does go down for hours sometimes.  Would the ADSl line retrain after such an outage?

[attachment deleted by admin]

[jid]

ADSL will always retrain if the router is turned off then on again, although if it happens in the evening the likelyhood would be that you would loose some sync.

As for the noise on the graph, well, could you post your stats again for us to take a look at.

[camallison]

Stats direct from the router do you mean?  Here they are:

Uptime:   27 days, 10:32:17
Modulation:   G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]:   448 / 2,720
Data Transferred (Sent/Received) [GB/GB]:   1.00 / 3.79
Output Power (Up/Down) [dBm]:   11.5 / 19.0
Line Attenuation (Up/Down) [dB]:   28.0 / 47.0
SN Margin (Up/Down) [dB]:   19.0 / 13.0
Vendor ID (Local/Remote):   TMMB / ALCB
Loss of Framing (Local/Remote):   0 / 0
Loss of Signal (Local/Remote):   1 / 0
Loss of Power (Local/Remote):   0 / 0
Loss of Link (Remote):   0
Error Seconds (Local/Remote):   1 / 0
FEC Errors (Up/Down):   0 / 102,588
CRC Errors (Up/Down):   0 / 1,067
HEC Errors (Up/Down):   0 / 935
Line Profile:   Interleaved

[jid]

Those are the ones yeh:)

For the uptime the amount of errors is fantastic so the spite of noise hasn't done any damage.

Keep on monitoring with RouterStats, a bit of snr fluctuation is normal, especially in the evenings.

[roseway]

I'm getting a bit confused now. In your previous routerstats graph the connection speed was shown as 5248 kbps, which is why I described the result as near-perfect. But now you're showing a connection speed of only 2720 kbps with an uptime of 27 days, so where did the previous routerstats graph come from?

A connection speed of 2720 is quite low for your attenuation, but as it seems to be associated with a fairly high noise margin it suggests that your target noise margin has been increased as mentioned before.

[jid]

I'm getting a bit confused now. In your previous routerstats graph the connection speed was shown as 5248 kbps, which is why I described the result as near-perfect. But now you're showing a connection speed of only 2720 kbps with an uptime of 27 days, so where did the previous routerstats graph come from?

A connection speed of 2720 is quite low for your attenuation, but as it seems to be associated with a fairly high noise margin it suggests that your target noise margin has been increased as mentioned before.

Thanks for pointing that out Roseway, I have only just realised myself

[camallison]

The first graph was using the "live" router stats link on the site you pointed me to.  The later ones were using the programme resident on my machine - see where the confusion arises from.  Now I am confused!