Are disconnections and re-syncs a 'feature' of Max DSL?

[CurlyWhirly]

I am no longer within my 10 day training period and I know my line is around 5 km in length but even so does anyone else on Max DSL find that at peak times (mainly in the evenings from 6 PM onwards), eventually your connection drops due to a falling SN/R margin?

I don't expect this happens with short lines where I would guess that even with a full 8128 Kb sync there would still be enough spare SN/R margin to absorb any interference or crosstalk

What happens with me is that I sync at (say) 4.736 Mb in the morning and my connection is fine until the evening where the SN/R margin gradually drops until it reaches 3 dB and then I lose the connection.

When the router re-syncs it re-syncs at a slightly lower speed (4.512 Mb) and the same thing happens around 24 hours later.
It's a never ending cycle and has happened every day since I was on Max DSL.

It wouldn't be so bad if the sync speed came down over time and then was fixed at a speed that would allow enough SN/R margin to 'absorb' fluctuations in line noise level but this doesn't appear to be happening despite a BRAS line profile being used

I did try a SpeedTouch tool which initially worked as I set my SN/R to 9 dB but even with this tool when I came online this morning, the connection had dropped last night so I will either have to set the SN/R margin at an even higher level of 12 dB or just accept that my line will disconnect in around 24 hours time.

Anyone else experience this?

 

[Corasik]

5KM is quite a long line for a 4 meg connection, suprised your getting that much. Didnt know you have any option to chance your SNR margin, I thought that was set automatically by BT.

Personally though, I would have thought that with a 5km line, your attenuation would be up to a point that a 3 meg connection would be about the limit on max. Perhaps if it keeps dropping gradually, you'll eventually hit a stable speed. (Or does it reconnect faster again later on?)

 

[CurlyWhirly]

5KM is quite a long line for a 4 meg connection, suprised your getting that much. Didnt know you have any option to chance your SNR margin, I thought that was set automatically by BT.

Here's the tool I was on about http://dmt.mhilfe.de/down/st7/dmt.zip and here is a screenshot http://i52.photobucket.com/albums/g18/gavinp_2006/gavin516v6_c.jpg

It seemed to work at first but doesn't make any difference.

5KM is quite a long line for a 4 meg connection, suprised your getting that much.

Me too.
I can only assume that my line is around 5 km in length from a 54 dB attenuation figure as AFAIK it's roughly 10 dB for every kilometre of line length.

Personally though, I would have thought that with a 5km line, your attenuation would be up to a point that a 3 meg connection would be about the limit on max.

Same here but apparently it isn't 'learning' about my line quality, etc, and after making notes for the last 2 weeks, my sync rate has varied from 3.840 to 4.736 and has been within this range practically from the start of me going on to Max apart from the first day when I had a sync of over 5 Mb but the connection didn't last long obviously

Perhaps if it keeps dropping gradually, you'll eventually hit a stable speed. (Or does it reconnect faster again later on?)

When a re-sync happens, it syncs at the higher end of my range and then when I lose the connection, it resyncs at the lower end but it keeps doing this in a never ending cycle.
I even queried this with Zen and they said it's normal behaviour for a rate adaptive line unless you are close to the exchange and have sufficient SN/R to insulate the line from 'noisy' periods at peak time.

 

[Phemo]

I have the same problem. Line syncs at 3800 ish then in the evening it drops and loses sync and comes back at 3400 ish. Then for some reason it keeps trying higher, almost every day. The target SNR hasn't been changed either so it doesn't seem like it's getting anywhere ... until now, where I've just noticed that it's actually been at 3200 ish for 3 days with no problems.

 

[tolien]

In theory, the DLM should kick in and turn up your target SNR, but it's pretty patently screwed for a good number of lines.
Other than poking your ISP with a stick till they poke BT to fix it, there ain't a lot you can do.

 

[CurlyWhirly]

I have the same problem. Line syncs at 3800 ish then in the evening it drops and loses sync and comes back at 3400 ish. Then for some reason it keeps trying higher, almost every day. The target SNR hasn't been changed either so it doesn't seem like it's getting anywhere

Yes that is exactly what happens with me and isn't a big deal if I'm offline but if my line drops while I'm online I find it annoying.

According to BT, the actual line rate supportable will be determined during the first 10 days of use, after which time the highest stable rate possible will be set.

The above doesn't seem to be happening in my case

 

[tolien]

The sync rate isn't, and never will be, fixed. The MSR is more or less your BRAS limit and nothing else.

 

[CurlyWhirly]

In theory, the DLM should kick in and turn up your target SNR, but it's pretty patently screwed for a good number of lines.
Other than poking your ISP with a stick till they poke BT to fix it, there ain't a lot you can do.

Ok, cheers Tolien.
I'll contact Zen again and ask them to poke BT on my behalf

By the way, it has nothing to do with me turning my router on and off all the time as I keep it on 24/7.

 

[CurlyWhirly]

I've just contacted Zen and they have promised to send a request to BT to have my 10 day training period reset as I think that 2 days of thunderstorms (and subsequent line disconnections while in my 10 day training period) may have messed up my BRAS profile.

I can only wait now.