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[konrado5]

I have strange situation. My ISP have changed settings of DSLAM port on the moment. They raised snr margin to 9 dB and highered interleave delay (despire I have fast - not interleave). Accurately at that moment my router was beginning to show highered attenuation: Download 26.0 dB, Upload 15.6 dB. Earlier: Download 25.5 dB, Upload 15.2 dB. My ISP says that default setting are restored however attenuation is still raised. What is cause? This problem is from three months.
On this link there are my router's parameters. Please verify:
http://img571.imageshack.us/img571/7831/iy2i.png

My ISP says that DSLAM reports lower attenuation: 23.5 dB on Download and about 11 dB on upstream, however earlier DSLAM reported attenuation 23 dB. I readed that attenuation for download is measured by router. How is it possible that DSLAM report different value?

[kitz]

>> Download 26.0 dB
>> Download 25.5 dB

ummm  are you querying the difference between those?
Seriously I wouldnt worry about it...  I know we say attenuation shouldnt change, but we are talking of larger amounts than that, such a small amount wont have much impact at all on your line.

0.5 db can easily be caused by many things:-  rounding, weather (hot or rain), change of router, change of product, increased bit loading (depending on how your router measures atten)

[konrado5]

I worry about it because attenuation raised when my ISP raised snr margin to 9 dB and highered interleave delay. My ISP says that default setting are restored however attenuation is still raised.

[roseway]

You really can't draw any conclusions from such a small change. Attenuation as reported by the router isn't a simple measurement, it's some sort of weighted average of the attenuations of the different frequency tones which make up the ADSL signal. All sorts of changes in the connection can cause small changes in the attenuation.

[konrado5]

Is it possible that my ISP in fact restored default settings however attenuation measurement is continuously raised as on "snr margin 9 dB and interleave delay raised"?

My ISP says that DSLAM reports lower attenuation: 23.5 dB on Download and about 11 dB on upstream, I readed that attenuation for download is measured by router. How is it possible that DSLAM report different value than my router at the same time?

[roseway]

I don't know the answer, but it's possible that the downstream figure which the DSLAM gets from the router is the value at a single frequency, whereas the figure which the router reports to you is the normal average figure.

[konrado5]

Is it possible that my ISP in fact restored default settings however attenuation measurement is continuously raised as on "snr margin 9 dB and interleave delay raised"?

[roseway]

I don't understand the question.

[konrado5]

I'm worry that my ISP didn't restore default settings of DSLAM port and thus I have continously 0.5 dB raised attenuation.

[roseway]

The attenuation is only a reported value. The fact that the reported value is slightly higher than it was doesn't mean that the line is 'worse' than it was, it just means that some aspect of the connection has changed a bit. I've said it before and I'll say it again: you can't read anything into such a small change.

[konrado5]

However that aspect of connection has changed a bit since my ISP changed settings of DSLAM. My ISP assures me that all changes are backed. How is it possible that that aspect of connection is still actual? I'd like to have previous settings. At that time stability was higher, connection was stable even on average SNR margin 3 dB.

[kitz]

As mentioned 0.5dB of attenuation shouldnt make any difference to your line.  Both Eric and I have given a few examples of when these can occur naturally yet wont make any difference to the stability.

Sometimes it just happens and theres nothing you can do about it.   
I had an Engineer here on Sat because I have a line fault whereby I lose up to 18dB of SNR which can cause my line to drop out completely.   The engineer went to the cab and tested from there..  he didnt do anything physical...  yet by just performing his tests its cost me 2dB.    Theres nothing I can do about that and I just have to accept its one of those things that sometimes happens with adsl.

[neilius]

When our line was switched over to a different provider at the exchange we lost 3dB in line attenuation. When I changed routers at my previous house, there was a 5db difference in what was being reported. 0.5dB isn't much (in fact the amount of change within the actual unit being measured which I assume is volts will vary depending where along the scale this 0.5dB is because dBs are a way of expressing ratios between a measured unit vs a reference value, logarithmically  ).

I really wouldn't worry about it.

[konrado5]

I worry about DSLAM's settings not about attenuation. 0.5 dB raised attenuation mesurement is for me indicator of changed settings. However my ISP assure me that previous settings (on those I had 25.5 dB) are restored.

EDIT: I've seen that today DSLAM doesn't allow connect with other modulation than ADSL2+? Four months ago I could connect with G.DMT, ADSL2 modulation. Is it possible that other attenuation measurement on ADSL2+ is effect of disabling other modulations on DSLAM?

[konrado5]

I have about 50 errored secons if I have 17900 kbps and SNR margin 6.1 dB. As I have 18607 kbps and SNR margin 4.2-.5.0 dB I have 300-400 errored seconds and 0 total SES.