Training Period

Just been upgrade from my old 1mb line to a 8mb max service, now I am aware of the \10 day BT training period, however my speed has dropped from 3mb this afternoon to little better than a 56k connection now is this a normal part of the training period?

Connection down 4000/up 448
Line Attenuation down 55db / up 15.5db
Noise Margin down 6db / up 22db

can anyone see whats wrong that might be causing this crappy speed. I did ring Freeola and the impression that I got was that this was not a normal part of the training period and that I should wait until monday to see if it settles which to be honest sounded like a fob off.

http://www.thinkbroadband.com/faq/sections/radsl.html#225
"visit www.speedtester.bt.com and this will test the download speed and also give you your current IP profile value. A warning about the tester site, it does not always work if lots of other people are using it."

Done that, my line synchs at 3.5mb

what about the IP profile?

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my speed has dropped from 3mb this afternoon to little better than a 56k connection

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Speed doing what? This sounds like ISP throttling to me. Some ISPs throttle P2P traffic to this sort of speed.

Test1 comprises of Best Effort Test: -provides background information.
IP profile for your line is - 152 kbps
DSL connection rate: 448 kbps(UP-STREAM) 4000 kbps(DOWN-STREAM)
Actual IP throughput achieved during the test was - 117 kbps

im not doing any p2p this is normal surfing and speed tests

IP profile for your line is - 152 kbps
BT wholesale have limited your connection speed, usually because of disconnects/low sync events. If your line rate remains stable it should rise after 3 days or so.

does that 3 days include weekends?

That looks like somewhere you had a really bad sync. If will take 3 days synced at 4000 which it now is before it resets the profile to 3.5Mb. Switching off and on if necessary should not upset things, as long as you don't sync below 3424. However, the BT end could cause re-syncs both up and down while it searches for your highest stable sync.

See the profile setting table here

Its an automatic system so runs 365 days a year.

And not just in the first ten days of your account, either. This is part of normal operations, not training. If something, however temporary, knocks your speed down, BT's system waits for three days to establish a new rate and raises you to it. This may seem harsh, but if you are subject to frequent disconnections because of poor conditions, you would probably prefer to have a connection all the time rather than one that is sometimes good and usually not there at all.

But the settings established during training, SNR etc., effectively restrict the top sync speed available, although there are occasional automatic adjustments made later, normally to lower the speed, and very occasionally to increase it - thought that normally requires the customer making big waves.

This only happens if your line is so noisy that the target SNR has to be continuously raised in 3db steps until a stable line is arrived at. Then if whatever caused the problem later disappears MAX rarely reduces the target SNR back down on its own, at least not in any decent time frame. However, that is the only possible long term limiting effect on your actual line speed during training. The other main reason for training is to basically set up what is considered your fault level speeds under which BT will respond. Otherwise, if you happen to sync stably at a relatively low speed during training but your target SNR is not raised above the target of 6db and you later get a better noise figure, that better SNR will be traded for more speed when you next sync. Not forgetting the three days to recover form a low sync even of course, but that is active all the time not only during training.

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MAX rarely reduces the target SNR back down on its own, at least not in any decent time frame

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BT stated some time ago that DLM has been improved to detect if a line is more stable over a period of a few days, and then to lower the target SNR margin accordingly. However anybody who leaves their modem on continuously would need to force a resync to take advantage of this.

The '10 day period' has no significance other than that empirically BT have found that in the majority of cases the settings chosen by DLM have stablised by then (usually long before). The system makes a note of the speed at this time, but only as a basis for the service team to evaluate whether a line has significantly deteriorated later on.

Your noise margin down is right on the limit at 6dB, this is causing your IP Profile possibly to be lowered due to noise errors.

Where your phone line comes into the house should be a BT socket with a split front plate. If you have a socket like this undo the two screws of the lower plate and pull the plate gently forward. This front plate is plugged into a hidden socket on the left behind it. Plug your router, with as short a lead as possible into this socket without a filter. If your noise margin is better, say 12dB or more you have faulty internal extension wiring.
(Removing this front plate disconnects all internal extension wiring).

Brian

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The system makes a note of the speed at this time, but only as a basis for the service team to evaluate whether a line has significantly deteriorated later on.

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That is the point I was trying to make. The only thing that is set by the training period is the threshold level above which a speed is deemed to be acceptable. The Maximum Stable Rate (MSR) is the highest sync rate detected in the period. The only real significance of this is that the Fault Threshold Rate (FTR) is 30% less than it. If your system synchronises at anything above this, it is deemed to be performing within acceptable bounds. I may have some of the detail wrong here and I have no idea if there is any possibility of changing this.

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Your noise margin down is right on the limit at 6dB, this is causing your IP Profile possibly to be lowered due to noise errors
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It's supposed to be 6dB. It's a MAX dsl line.

It only goes over 6dB, if the line is in sync at 8meg & has margin to spare or BT has forced a higher margin due to problems.

Sorry, very much disagree with you, 6dB is very marginal.

Extract from: http://www.farina1.com/bookmark/000004/2005/02/27/00020260.HTM

What would be the ideal attenuation and SNR values?
Quote:
Ideally you want low attenuation, and a high SNR, some examples are:

If you have a line of 2km long, and the downstream attenuation is 20dB with a SNR of 30dB that is very good.
A 2km line with the same attenuation of 20dB and SNR of 8dB is not very good. The SNR is now low.
A 6km line with an attenuation of 57dB, and SNR of 18dB is very good also. You do expect the attenuation to rise as the line gets longer.
A similar 6km line with 57dB attenuation, but a SNR of 5dB is really on the edge of working, or not working, and thus very bad.
Normally you would expect a lower attenuation line to have a high SNR. If you do not have a high SNR, and the line is unstable then it is worth looking at the wiring in the property. We would suggest a visit to bbs.adslguide.org.uk to discuss the issue on our forums, where people will ask about the wiring in the house and hopefully suggest some course of action.

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Brian

I don't pretend to be knowledgable on the subject - but I am about 3 KM away from my exchange and have a max DSL with 6dB. My neighbours either side of me are the same. A friend just a few hundred metres from the exchange is also 6dB on a max connection, whilst my Sister who lives ina different town and is five KM from her exchamge is also on 6dB.

Surely that suggests that max is 6dB doesn't it?.

Incidentally I always get around 6mb with a 37 attenuation.

6db is the target for MAX products - trying to get the most out of your line. Higher than 6db means you have a higher margin - maybe you are close enough to easily get 8Mbps, maybe your line has a higher target due to instability issues, maybe you are not on MAX.

I'm definitely on max and I have 6db. I think that was my point - that 6db is the target. The poster that I responded to was suggesting that is was not??

The 6db is the default target, but quite commonly the target noise margin may be higher, e.g. 9db, 12db, 15db for noisier lines.

Disagree all you want. ADSL is my job.

6dB is the standard margin target on a MAX line. MAX will aim at the best speed for a margin of 6dB. If it gets 8meg, then there will most likely be some spare margin & the router/modem will show this.

If the line has problems, noise, dropouts, etc, then BT will set the margin target higher, 9dB, 12dB, or 15dB & hence the downstream speed will be slower than a 6dB margin.

Thanks all of you. I guess i have learnt something the hard way :-)

I will bend to more knowlegable people. Thanks for putting me right, I'd better not believe everything I read on the internet or maybe I interpreted it incorrectly. At my age that is very easy to do!

Hope my post has not mislead anyone.

Brian

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It only goes over 6dB, if the line is in sync at 8meg & has margin to spare or BT has forced a higher margin due to problems.

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What happens if your router has an uptime of over 14 days on the standard 6 dB default setting?

My uptime is just over 11 days.

I hope that my SNR isn't reduced to 3 dB as, with my attenuation (53 dB), my router couldn't cope!

I reckon it will stay at around 6db, as that is the default and generally lowest target noise margin. I wouldn't worry

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I reckon it will stay at around 6db, as that is the default and generally lowest target noise margin. I wouldn't worry

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Thanks for that mate as I was a little concerned as last time when I asked to have my SNR raised to 9 dB (I wasn't using the SpeedTouch 585 back then which seems to manage my long line a lot better than my old Billion router ever did), after around 18 days I woke one morning to find that my SNR was back on the default 6 dB setting.

I know that even my 585 wouldn't be able to cope with a 3 dB setting as my SNR usually drops to 4 dB in the evenings on 6 dB (default setting)!

If it's stable at 6dB then it should be ok. Mine runs for weeks at 6dB without dropping sync & has been know to drop to 4dB for days without problems.

Its a lack of bandwidth at entanet, this weekends been pretty bad at times. I've seen it dip below 100kb/s and i'm sync'd at 7776kbps.

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If it's stable at 6dB then it should be ok.

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It is now with the SpeedTouch 585 but not with my old Billion hence the reason why I asked to have my SNR raised to 9 dB a while ago!

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Mine runs for weeks at 6dB without dropping sync & has been know to drop to 4dB for days without problems.

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My SNR drops to around 4 dB every evening but always recovers to 6 dB through the day.

If my SNR was lowered automatically to 3 dB by BT's DLM then I know my line would get unstable as the SNR would probably drop to 1 dB or lower in the evenings leading to a dropped connection!

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Disagree all you want. ADSL is my job.

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You also, not surprisingly, appear to know the difference between SNR and SNR Margin which your antagonist failed to do - he showed this by quoting a passage about SNR when he was talking about SNR margin.

An SNR Margin of 0 would be marginal. It is the boundary between a negative value which won't work (by definition) and a positive which will. Having a positive value of 6dB gives a margin or error which is liekly to be enough in most circumstances - it means that the measured SNR is four times the minimum acceptable SNR for the channel.

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It is now with the SpeedTouch 585 but not with my old Billion hence the reason why I asked to have my SNR raised to 9 dB a while ago!

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Since the SNR is a measure of the strength of signal compared with the noise on the channel, you can't change that by a setting, only by increasing the signal or reducing the noise.

I suspect that you are talking about the SNR Margin which is not the same and confusing the two is not a trivial matter, causing most of this thread to be meaningless.

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I suspect that you are talking about the SNR Margin which is not the same and confusing the two is not a trivial matter

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Yes you are right, I was talking about SNR margin. Sorry.

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causing most of this thread to be meaningless.

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However I don't agree with the above.

speed increased but became unstable and has been dropping back to 1mb ever since, my router lost synch several times my noise margin keeps changing from negative to as high as 9db. During the 10 day training period when the MSR is found does that mean that at the end of the training period the MSR is the maximum speed I will get, or is this the minimum.

Whatever your line is syncing at (exchange contention and ISP contention permitting) you "should" get. So if you sync at +6000kbps you'll get around 600kb/s for example.

The problem I've found moving to MAX over fixed (I'm on my 10 days now too) is when it loses sync just once, it automatically drastically lowers your sync rate and it takes absolutely ages for it to go back to the higher rate (if at all).

The reason this is happening for me is that whilst I have a superb line during the day, it gets noiser at night and regardless of speed (it happened when I was on 2mb too) it loses sync occasionally when the router can no longer keep sync.

I initially synced at 7776kbps and was getting 770kb/s, but 4 days and just 3 loss of sync's (which my router did recover from without disconnecting anyway!) later I'm at 6528kbps and getting 650kbps.

I've also discovered my line is interleaved, which means pings to jolt.co.uk are around 40ms instead of the 20ms they were when my line was fixed.

Ideally i'd like my line to just sync permanently at 7776kbps and be on fast mode, regardless of how often the router loses sync, but this being MAX that aint gonna happen.

So am I right in thinking that after the training period speeds become dynamic for instance one day I could get 1.5mb the next could be 3mbs? So long as it does not fall below the fault threshold

It'll fluctuate the sync speed training to maintain the maximum, after 10 days it locks at that sync. That's your maximum speed you'll see. Best time to check it is around 12pm for speed.

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after 10 days it locks at that sync

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Sorry, but that's not true. BT are quite clear on this - the only thing that happens after 10 days is that the system makes a note of the sync speed as a reference for customer service to compare against if speed issues are reported in the future. That's it. The modem continues to sync at the highest speed it can whilst achieving the target SNR margin. Max continues to monitor the line and adjusts the target marging and interleave settings if appropriate. The BRAS IP profile continues to be adjusted in line with the sync speed.

Agree with most of your post, but the target SNR margin is set during training, thus limiting your re-connection maximum sync speed. And:-

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Max continues to monitor the line and adjusts the target marging and interleave settings if appropriate.

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That doesn't seem to be true in practice, even if it is supposed to be. Otherwise, why would we need the DMT, and why do ISPs have to be kicked and dragged to get BT to reset the SNR Margin, and remove Interleave?

Edited by RobertoS (Tue 13-Mar-07 22:20:09)

Nope. Only MSR & FTR are set in the 1st 10 days.

The SNR margin & BRAS are ongoing throughout the life of the ADSL service.

The margin should & normally does adjust as required 6 - 15dB according to any line problems & hence your sync speed. It's not set in stone in the 1st 10 days.

Well I've still got a crappy speed, I must be drawing to the end of my training period, for the most part I have to admit my speed has increased. However I have had resynchs, my noise margin has fallen into the negative and has raised as high as 9db, (this seems worse at night), this morning my router lost the connection altogether and my speed is now no better than an old dial up connection. Am I right in thinking that it will take three days at least to recover? I know that this period is about searching for the best connection for my line so again am I right in thinking that all these problems are part of that process. I am beginning to wish that I had stayed on the 1mb service, at least it was reliable for the most part.