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Synch rate has dropped overnight

kreynolds
Grafter
Posts: 433
Registered: 05-04-2007

Synch rate has dropped overnight

After several disconnections and last nights Tiscali maintainance, although not on any of the exchanges that were listed, I have found that my synch rate has dropped by half and SNR increaded to 30dB.

ADSL Link Downstream Upstream
Connection Speed 4092 kbps 256 kbps
Line Attenuation 30 db 6.5 db
Noise Margin 30 db 27 db

Yesterday I was seeing 8157 up and 639 down with a noise margin of 17 dB down.

The +Net/Tiscali/LLU disconnections issue is rapidly becoming beyond a joke, Even at the lower synch rate and higher noise margin I am still having disconnections. I am presuming that someone at +Net has altered my profile AGAIN, even after the last time they tried this and subsequent resetting of the profile.
15 REPLIES
Community Veteran
Posts: 3,364
Thanks: 15
Registered: 06-04-2007

Synch rate has dropped overnight

If you disconnect the ADSL line for 20s and reconnect, what does you router sync at now? Still low or back to normal?

At least on LLU you do not have BRAS which means you'd be stuck for 3 days at the low speed.

SW.
--
3Mb FTTC
https://portal.plus.net/my.html?action=data_transfer_speed
kreynolds
Grafter
Posts: 433
Registered: 05-04-2007

Synch rate has dropped overnight

Quote
If you disconnect the ADSL line for 20s and reconnect, what does you router sync at now? Still low or back to normal?

At least on LLU you do not have BRAS which means you'd be stuck for 3 days at the low speed.

SW.


Still the same
N/A

Re: Synch rate has dropped overnight

Quote
After several disconnections and last nights Tiscali maintainance, although not on any of the exchanges that were listed, I have found that my synch rate has dropped by half and SNR increaded to 30dB.

ADSL Link Downstream Upstream
Connection Speed 4092 kbps 256 kbps
Line Attenuation 30 db 6.5 db
Noise Margin 30 db 27 db

Yesterday I was seeing 8157 up and 639 down with a noise margin of 17 dB down.

The +Net/Tiscali/LLU disconnections issue is rapidly becoming beyond a joke, Even at the lower synch rate and higher noise margin I am still having disconnections. I am presuming that someone at +Net has altered my profile AGAIN, even after the last time they tried this and subsequent resetting of the profile.


This is the same as what has happened to me, for the third time now and i'm sick of having to raise tickets to get it fixed. It seemed to happen when i get a particularly bad day of disconnects (like yesterday) and maybe something/someone thinks that changing the noise will help....
kjaerligkatt
Grafter
Posts: 411
Registered: 02-09-2007

Re: Synch rate has dropped overnight

Quote
After several disconnections and last nights Tiscali maintainance, although not on any of the exchanges that were listed, I have found that my synch rate has dropped by half and SNR increaded to 30dB.

ADSL Link Downstream Upstream
Connection Speed 4092 kbps 256 kbps
Line Attenuation 30 db 6.5 db
Noise Margin 30 db 27 db

Yesterday I was seeing 8157 up and 639 down with a noise margin of 17 dB down.


This is incredibly strange - going from an SNR of 17dB to 30dB is an exceptional improvement. 17dB is very good anyway, but 30dB is excellent - the 13dB increase in signal margin equates to a signal over 10 times stronger!!!

That SNR does seem high for the line attenuation you are seeing - maybe the modem is now returning incorrect figures.

I don't think the change in SNR explains the change in sync rate itself - it doesn't add up, but may be indicative of something else. My first thought is a fault on the modem - do you have another you could try?

Neil
kreynolds
Grafter
Posts: 433
Registered: 05-04-2007

Synch rate has dropped overnight

Don't think it's the router. The following stats were taken on 25/08/06 when they'd changed the profile on my connection to 187 up

ADSL Link Downstream Upstream
Connection Speed 187 kbps 286 kbps
Line Attenuation 30 db 6.5 db
Noise Margin 31 db 25 db
carrot63
Grafter
Posts: 599
Registered: 12-07-2007

Synch rate has dropped overnight

Given the current approach to curing LLU woes I would be highly surprised if it wasnt the profile that has caused the change.
kreynolds
Grafter
Posts: 433
Registered: 05-04-2007

Synch rate has dropped overnight

Why bother changing it as it didn't do anything last time, it's going back to the "throw enough stones and the glass might break" method as I mentioned in another thread. Also if Tiscali try to claim that my line won't support higher speeds, I would strongly disagree based on the fact that before LLU on BT it was synching at 8 meg with NO lost connections.
kreynolds
Grafter
Posts: 433
Registered: 05-04-2007

Synch rate has dropped overnight

Why bother changing it as it didn't do anything last time, it's going back to the "throw enough stones and the glass might break" method as I mentioned in another thread. Also if Tiscali try to claim that my line won't support higher speeds, I would strongly disagree based on the fact that before LLU on BT it was synching at 8 meg with NO lost connections.
carrot63
Grafter
Posts: 599
Registered: 12-07-2007

Synch rate has dropped overnight

Sheer blind desperation, coupled with a desire to be visibly doing something? As you pointed out, I've never seen anything suggesting it made a jot of difference on anyones line so far. During my brief 3 month acquaintance with MaxDSL my line sustained stable connections at a lower SNR than Tiscali's default, and nothing has changed since.
N/A

Synch rate has dropped overnight

Its annoying getting the profile reset also because when you ask to be moved to the standard noise profile you get the standard answer (after several days) "but you are already on the lowest profile"

So it then takes another several days to get it changed!! :roll:
chymorva
Grafter
Posts: 275
Registered: 29-08-2007

Re: Synch rate has dropped overnight

Quote
Quote
After several disconnections and last nights Tiscali maintainance, although not on any of the exchanges that were listed, I have found that my synch rate has dropped by half and SNR increaded to 30dB.

ADSL Link Downstream Upstream
Connection Speed 4092 kbps 256 kbps
Line Attenuation 30 db 6.5 db
Noise Margin 30 db 27 db

Yesterday I was seeing 8157 up and 639 down with a noise margin of 17 dB down.


This is incredibly strange - going from an SNR of 17dB to 30dB is an exceptional improvement. 17dB is very good anyway, but 30dB is excellent - the 13dB increase in signal margin equates to a signal over 10 times stronger!!!

That SNR does seem high for the line attenuation you are seeing - maybe the modem is now returning incorrect figures.

I don't think the change in SNR explains the change in sync rate itself - it doesn't add up, but may be indicative of something else. My first thought is a fault on the modem - do you have another you could try?

Neil

Hi,

Actually it is the change in sync rate that gave the increase in SNR. The SNR will increase with lower sync speeds for a given line. It is rather like talking to someone - if you talk more slowly then there can be more noise around, with them still able to understand you.

The reason for the drop in sync speed is the repeated disconnections. The system tries to give as high a sync rate as possible, but if it keeps getting disconnected then it assumes that it is trying to "talk too fast for the current conditions" (to keep with the speaking analogy) and so tries reconnecting at a lower sync speed.

Hope this helps.
kjaerligkatt
Grafter
Posts: 411
Registered: 02-09-2007

Synch rate has dropped overnight

Hi,

Yes, I realise that the SNR decreases proportionally as an inverse of the line rate, but a halving of the line rate should only equate to a doubling of the SNR, or 3dB, surely? This would equate to a SNR increase from 17dB to 20dB, not 30dB.

Neil
N/A

Synch rate has dropped overnight

My sync rate has dropped twice but i haven't had any disconnects and my modem says i've had 3 LOS errors,is that loss of sync?
N/A

Synch rate has dropped overnight

Quote
My sync rate has dropped twice but i haven't had any disconnects and my modem says i've had 3 LOS errors,is that loss of sync?


i'd guess so...