Declining Sync Speed

[mogden]

Recently my data rate has been fading away. I used to be able to sync at 5000+kbps, now as you can see it's down below 4000 - more importantly my BRAS has slowly gone from 4500 to 3000! 

It would seem that the SNR margin has gone up in a similar proportion - it used to sync around 6 and is now (as you can see) around 10. Also interleaving has been switched on.

No hardware has been changed.

Is there anything I can do? If I contact support will they be able to (ask BT to) move my target SNR to where it was? Any other explanations?

Dump from ADSL status of router:

Downstream Upstream 
SNR Margin 10.4 23.0 dB
Line Attenuation 56.8 27.5 dB
Errored Seconds 15 2 
Loss of Signal 3 3 
Loss of Frame 0 0 
CRC Errors 0 0 
Data Rate 3936 448 kbps
Latency INTERLEAVED INTERLEAVED 

[Rik]

Your stats suggest that the router is losing sync fairly frequently. When the line management software sees that, it acts to stabilise the connection by pushing up the target noise margin, which pushes down the sync speed and profile.

Before contacting support, you need to check your internal wiring and connected equipment for faults, the best way being to move the router to the test socket if you have an NTE5 master socket. That disconnects all your internal wiring and equipment, so if the problem continues, it's likely to be a BT fault.

You can raise the problem with support immediately, but if they get an engineer out and he finds the issue is with your equipment/wiring, you will be facing a bill f £160+.

[mogden]

Thanks for that Rik.

The only time the router resyncs is when I tell it to to try to get the speed back! I am connected to the master socket.

All I really want IDNet to do is ask BT to lower the target SNR (because I have no idea why they increased it in the first place unless it was in response my my continual fiddling) - will they do this?

[Rik]

You have three losses of signal recorded there, plus 15 errored seconds. That suggests, unless you have been unplugging the router for very brief periods, that the line is showing some instability. The BT software will only normally trigger an upward movement in target noise margin if it detects frequent re-syncs - more than 10/hour.

If the margin has been increased for this reason, BT will not normally reduce it manually, however, it will drop by 3db if you maintain a stable connection for a couple of weeks.

You can ask IDNet to try to get the margin changed, but I suspect that they will struggle if there are any signs of instability on the line.

[mogden]

Right- well I can test that one Rik.

I've cleared the router log and will leave well alone for a few days and see if the target SNR goes up.

...I'm almost certain that the three breaks were the three I did this morning trying to sync at a better speed.

[Rik]

Possible, but they were errored seconds - usually if you disconnect, they wouldn't be recorded as single errored seconds (how did you re-connect, re-booting or pulling the plug? The latter is a bad technique as it looks like instability to the monitoring software.)

[mogden]

Possible, but they were errored seconds - usually if you disconnect, they wouldn't be recorded as single errored seconds (how did you re-connect, re-booting or pulling the plug? The latter is a bad technique as it looks like instability to the monitoring software.)

Well one of them was replacing the microfilter in case that was degrading! That may well have taken three seconds! 

[Rik]

Replacing a filter, or unplugging generally, takes a lot longer than three seconds - but it depends whether the modem continues to record errors are the line drops. If you are going to change anything, it's generally better to power the router down first - this sends a dying gasp signal to the exchange to say it's been turned off, and the software doesn't count that as instability.

[mogden]

Well you learn something every day!  8) OK I'll remember to switch the router off and on again.

Will the router re-sync itself when/if BT rethinks the target SNR or should I switch the thing off and on again occasionally to see if they've had a change of heart?

[Rik]

The router won't re-sync unless it is overcome by noise, remorse or emotion.

So, the rule of thumb is to leave it connected until you have achieved at least 14 days with an unbroken connection, then re-boot the router.

[mogden]

Right!

One day and counting (let's hope Powergen realise the importance and don't cut the power...)

[Rik]

I tend to use a UPS to prevent such problems - but then I'm just paranoid.

[mogden]

I think I'd be lynched if I suggested a UPS in the bedroom. She's only just got over the modem being there!

[Rik]

You can get very discrete units these days. You're OK till the power goes off and they start beeping.

[mogden]

AHAAAAAAA!       

I got given a BT Voyager 220V and thought I'd have a tinker this morning:

Brainwashed the device to stop the BT lock, then connected it and my sync speed went from 4000 to 5184!  8)

So finally my poor old Origo 8400 gets put in the spares bin.

I am expecting my BRAS to go from 3500 to 4500 after 3 days - is this correct?

[Rik]

It can take up to 5 days, Matt, with BT's new blip logic. It is, though, a case of sit an wait. You'll only get a profile of 4000 at that speed though.

[mogden]

I thought it was as per Kitz.co.uk

http://www.kitz.co.uk/adsl/IPprofile.htm

5184 is over 5120....!

[Rik]

You're right, sorry, there was a typo in my list. 

[mogden]

You're forgiven 

It'll probably drop below the threshold tonight anyway. Still with a 9.3 SNR things may improve still further....

[Rik]

I hope so.

[mogden]

  Well, the sync speed survived the night - and the BRAS is up to 4500 this morning! 

Ordered a fancy BT ADSL faceplate cover in celebration!

Thanks for your help Rik

[Rik]

My pleasure. If my results are anything to go by, the next thing to order is a 2Wire 2700 router.

[Lance]

the next thing to order is a 2Wire 2700 router.

Good to see you singing our song at last Rik!

[Rik]

 

I'd have probably got one a long time ago if I could have ordered through retail channels, Lance. I just don't 'do' eBay.