adsl2+ sync, BT profile, and disconnections

After having a solid adslmax connection, I was upgraded to "upto20mbps". I was told that there would be disconnections etc for about ten days.

However, I'm now getting disconnections which reconnect immediately maybe about once a day. This is on a fully filtered Netgear DGN2200 upgraded to the latest firmware with an iPlate which has also started syncing higher for over a week, at 15143 down, and 1256 up, while my BT profile is 11000

http://i177.photobucket.com/albums/w235/2pods/Router...

Any ideas ?

Your margin is very low (2.8dB) that would be why.

If you can graph the router (MRTG, Routerstats etc) then watch it when you get a disconnection and see what it reports. It's also worth checking all your internal wireing etc etc.

You will end up on a 9dB profile which should stop you dropping the line, however it will start to eat into your sync speed.

Either leave it to it's own devices and down to the BT DLM system, or call Zen and ask for a 9dB (Or higher) target margin. (Though this *WILL* impact your sync)

I've phoned Zen, and am in the process of doing the usual stuff (router plugged into the test socket, trying to scounge another router), and will change the filter tonight.

When you say it will affect my sync, does that mean what I'm actually synced at (if so, I won't miss much, as I'm synced at 15000 something, while my speed and profile is about 10600) ?

"Each 3dB increase of SNR is worth anywhere between 400 to 1200kbps of Sync speed drop."

Your Profile is so low because you have been disconnecting.

How did you end up with such a low, 2.8 dB, NM?

I've no idea.

This was just before 21N upgrade
http://i177.photobucket.com/albums/w235/2pods/Router...

This was just after the upto20mbps upgrade
http://i177.photobucket.com/albums/w235/2pods/Router...

and you've seen the current one.

I meant to ask. What is NM ?

On 21CN the BT systems can adjust your target Noise Margin down to 3db under certain circumstances (I was told if BT systems see the line as ultra stable at 6 it will reduce it). If your noise margin is 3db after a re-synch I would ask Zen to increase it to 6 if you want more stability.

I manage a line with these stats which is ultra stable and has an SNR of 3 for months
Mode State Up Speed Down Speed SNR Margin Loop Att.
ADSL2+(G.992.5) SHOWTIME 1239000 22073000 3 8

NM = Noise Margin.

I think you've got to a low NM = 2.8 dB cuz 10 days ago you re-synced with a standard NM of 6 dB and since then noise on line has increased so that its margin has been cut.

After changing a filter last night, there was a bit of an improvement (though later on it was showing a margin of 1.8 !).

No doubt I'll jinx it, but according to the log, so far there have been no disconnects since about 11.00pm last night and the current NM is 4.5db.

The longer cable etc should come tomorrow, so I'll try it in the test socket then.

Longer cable still not arrived, but it seems to have been stable (touches fibreboard) since the filter change.

I have a steady downstream sync of 14834 kbps, upstream 1252 kbps, NM 4.1 db on a 28.5 db line.

Assuming it stays like this, will the IP profile rise or stay at 11000Kbps ?

Tried a TP-Link router. Immediately synced @ 16001kbps, but with a NM of 0.5gb !
It turned out just the same. So it's been constant drops and reconnections. All in the space of a minute or two between losing and regaining sync. I only have the test socket left to try, but surely as the extension was fitted bt BT themselves (I originally had the Home Highway socket in the room where the router was, and they had to change that back to a "normal" BT socket.) it should have been OK ?

Have a look at this lot from my logs............

Netgear N300 DGN2200 Latest Firmware V1.0.0.36_7.0.36
Connected via BT fitted extension wired directly into the master socket, which is fitted with an IPlate. Main cable enters house via very thin cable into a what looks like a lozenge shaped connection box, and from there to the master socket.

NEW FILTERS
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Stayed up from Wednesday 6th July 23:39 Until Saturday, Jul 09,2011 13:45:41. Reconnected immediately at a higher sync 15325kbps from 14834 kbps.
Rebooted to enable syslog broadcast and connected higher again at 15329kbps.
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Dropped again (once was me rebooting router)
Saturday, Jul 09,2011 17:30:26 connected again Saturday, Jul 09,2011 17:30:37
Disconnected Saturday, Jul 09,2011 17:42:28
reconnected Saturday, Jul 09,2011 17:43:14 at a lower 15180 kbps
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Stayed up from Saturday until Monday. NM slipped to 2.9
Disconnected Monday, Jul 11,2011 11:49:25 immediate Reconnect Monday, Jul 11,2011 11:50:11
Disconnected Monday, Jul 11,2011 11:53:08 Reconnected Monday, Jul 11,2011 11:53:52
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New Modem Cable
Reconnected 15083

Disconnected Monday, Jul 11,2011 21:53:08. Reconnected
Monday, Jul 11,2011 21:53:20 at lower sync 14853 kbps
Stayed up until Tuesday 12 July 03.17. Reconnected at a higher rate Tuesday 12 July 03.59 15030 kbps
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Disconnected Wednesday, Jul 13,2011 15:55:36. Reconnected Wednesday, Jul 13,2011 15:56:21.
Disconnected Wednesday, Jul 13,2011 16:15:31. Reconnected Wednesday, Jul 13,2011 16:16:16
Disconnected Wednesday, Jul 13,2011 16:16:31. Reconnected Wednesday, Jul 13,2011 16:17:34
Disconnected Wednesday, Jul 13,2011 16:33:58. Reconnected Wednesday, Jul 13,2011 16:34:48
Disconnected Wednesday, Jul 13,2011 16:37:47. Reconneceted Wednesday, Jul 13,2011 16:37:59
Currently connected 15158kbps 2.1db NM
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Thursday connected for 18 hours 14 minutes @ 15158 kbps with 2.9db NM
and then until:

Disconnected Thursday, Jul 14,2011 18:44:04. Reconnected Thursday, Jul 14,2011 18:44:47
Disconnected Thursday, Jul 14,2011 18:47:47. Reconnected Thursday, Jul 14,2011 18:47:59 @ 15034 kbps with 3.1 db
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Friday so far still connected for 16.50 hours @ 15034 with 3.4db NM

Disconnected Friday, Jul 15,2011 13:01:03. Reconnected Friday, Jul 15,2011 13:01:15
Disconnected Friday, Jul 15,2011 13:02:45. Reconnected Friday, Jul 15,2011 13:03:34 @ higher sync 15285 kbps with 3.1 db NM
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Friday Jul 15, 2011 16.38 tried new TP-Link router. Now getting 16001kbps, but with a NM of 0.5gb !
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Replugged Netgear back in Friday July 15 17.58.62
Disconnected Friday, Jul 15,2011 19:48:53. Reconnected Friday, Jul 15,2011 19:49:49. so far connected until july 15 23.07 @ 14951 kbps with NM of 2.6 db.
Still up on Saturday July 16 11.36 with 3.4 db NM.
Disconnected Saturday, Jul 16,2011 12:13:34. Recconected Saturday, Jul 16,2011 12:48:58.
Disconnected Saturday, Jul 16,2011 12:49:13. Reconnected Saturday, Jul 16,2011 12:50:12
Disconnected Saturday, Jul 16,2011 16:38:42. Reconnected Saturday, Jul 16,2011 16:38:54.
Disconnected Saturday, Jul 16,2011 16:41:33. Reconnected Saturday, Jul 16,2011 16:42:34

Stayed connected so far at Sunday, Jul 17,2011 15026 kbps @ 2.8db NM
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Monday 18 July, 2011 09.38, So far has stayed up for 1 day 16:56:51
Still @ 15026kbps and the NM has gone up to 3.0db on a 29.5db attenuation.
Finally disconnected Monday, Jul 18,2011 17:49:59. Reconnected Jul 18,2011 17:50:57
Disconnected Monday, Jul 18,2011 17:56:01. Reconnected Monday, Jul 18,2011 17:56:46
Disconnected Monday, Jul 18,2011 21:52:26. Reconnected Monday, Jul 18,2011 21:53:18 to 22.57 @ 14653 kbps with a 2.9 db NM
Disconnected Tuesday, Jul 19,2011 05:41:18. Reconnected Tuesday, Jul 19,2011 05:42:06
Disconnected Tuesday, Jul 19,2011 10:17:30. Reconnected Tuesday, Jul 19,2011 10:18:13
Disconnected Tuesday, Jul 19,2011 10:20:13. Reconnected Tuesday, Jul 19,2011 10:20:26
Disconnected Tuesday, Jul 19,2011 12:11:19. Reconnected Tuesday, Jul 19,2011 12:12:20
Disconnected Tuesday, Jul 19,2011 12:17:49. Reconnected Tuesday, Jul 19,2011 12:18:01
Disconnected Tuesday, Jul 19,2011 13:22:54. Reconnected Tuesday, Jul 19,2011 13:23:44
Disconnected Tuesday, Jul 19,2011 13:49:14. Reconnected Tuesday, Jul 19,2011 13:49:26 currently 14.40 @ 15056 kbps with 3.1db NM
Disconnected Tuesday, Jul 19,2011 18:31:27. Reconnected Tuesday, Jul 19,2011 18:31:39 Currently connected Jul 19,2011 22:09:04 14789 kbps with a 2.9 db NM
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Wednesday, Jul 20,2011 11:57:28 still connected @ 14789 kbps with a 3.8 db NM
Rebooted the router Wednesday 20 July 2011 14.49,reconnected @ 15098 kbps with a 3.1 db NM.Still connected 16.29
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