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The 10-day training period -- how important is it to use the "same" modem? (etc)

The 10-day training period -- how important is it to use the "same" modem? (etc)

Hello,

I have just moved to a flat in W2 4PU; the phone line was installed a few days ago; and I am waiting for ICUK to turn up their "Cable & Wireless unmetered unlimited ADSL 2+ " offering. I think I'm going to sprlurge for one of these Fritzi Boxes to connect to my end, but haven't yet clicked the "buy" button. In any case, it's possible/likely that the ADSL will be live before my modem arrives, so I casually asked at work if anyone had a spare ADSL 2+ modem they could lend me for a few days, to cover my needs until my own modem arrives.

Then it occurred to me that I have heard of this 10-day training period at the beginning of an ADSL connection, where various parameters are fine-tuned to optimize the connection.

So I worried that for the duration of the training period, perhaps it is a mistake to terminate the connection with anything other than the actual modem that I intend to use for the life of the connection.

I seem to be fairly close to the DSLAM and I'm hoping to get the best connection possible. I would hate to think that I lost the opportunity for a better connection because there was a random stand-in attached to the line for the first 5 days of training. But I don't want to be ridiculous, either.

Should I wait for the "real" modem to arrive before even tickling the modem on the other side, or should I just relax and stop acting like this is some fine French wine that needs to breathe just the right amount of time or I might as well just use a tin can and some aluminium wire?

And if it makes any difference, as I write this post, the only offer I have received from someone in the office is to use their ADSL 2 (and not even ADLS 2+) modem.

Thank you, and apologies in advance if it is a stupid question.
 
I suspect that it won't make much of a difference, although some routers have better chipsets that seem able to pull more speed from a line than others. But so long as they both support ADSL2+ (check in the routers spec sheet for G.992.5 support), have the correct settings and a reasonable reputation then I think you should be fine.

The most important thing is to keep whatever router you use connected and plugged in for that 10 day period. Disconnecting once to swap routers isn't likely to have a huge impact but try not to disconnect too many times as that could make it harder to train into a higher speed.
 
Follow up questions to your remarks

I suspect that it won't make much of a difference, although some routers have better chipsets that seem able to pull more speed from a line than others. But so long as they both support ADSL2+ (check in the routers spec sheet for G.992.5 support), have the correct settings and a reasonable reputation then I think you should be fine.

The most important thing is to keep whatever router you use connected and plugged in for that 10 day period. Disconnecting once to swap routers isn't likely to have a huge impact but try not to disconnect too many times as that could make it harder to train into a higher speed.

Thanks for this. Your comments surprised me a bit; although I have no knowledge that would justify my being surprised:). So a few follow-up questions please:

1. Your comments seem to imply that as training progresses, the subscriber-side modem invokes no memory of any earlier part of the training. Is that how it works? The training is entirely directed by the service provider side, and there is nothing that my side probes and remembers by itself? I can see why the base-line standard would do this -- but perhaps there are there "better" subscriber-side implementations that do some kind of self-directed learning?

2. After the 10-day training period, when the line is running and stable, can I switch my modem without any need for retraining? That would be a nice consequence of the "subscriber-side is pure slave" architecture, I suppose. (More generally, is there any downside at all to switching modems on a stable, trained ADSL connection).

3. If putting a different modem on the connection is no reason to retrain, are there other things the subscriber might do which are? Plugging a new phone into an unused jack, for example? And while on this subject, should I put some sort of terminator on unused phone jacks during training, or just leave them empty?

4. Does training begin when a service-provider side first comes online, or when a subscriber-side first connects to an untrained service-provider side, or only when an operator presses some button somewhere? (I'd like to know if I should try to have my side all in place ready to connect when the service-provider side comes up).

5. How difficult/onerous is it to re-train or restart training? Can the subscriber-side modem send a signal to force the service provider side to restart training? Or is it necessary for the subscriber to make a phone call to ask support on the ISP side to ask a BT pair of hands to go to the central office and press a button.

6. If I attach an ADSL 2 modem that has no ADSL 2+ support, will any training happen? If I later connect an ADSL 2+ modem, will the 10-day ADSL 2+ training period begin automatically/if I say 'please?'/if I pay money/not-at-all??

This last scenario is a real possibility for me, in that someone just lent me his ADSL 2 modem. I'd like to know if I can attach it now to get service quickly, and then a week later swap it for an ADSL 2+ modem, or if it would be better for me to wait for the real thing to arrive in the post before connecting.

I apologize for the barrage of questions. I allowed myself to bother you only because it seemed to me that the questions are quite generic. Perhaps others can benefit from learning the right way to get service going quickly, whilst still enabling their ADSL 2+ modems to have the best possible relationship with their service providers.

Scott
 
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I think the misconception might be about the way in which "training" works.

In effect, it's continuous. The DSLAM can adjust the parameters of the connection up and down at any point. For instance, switching on christmas lights, or certain other sources of possible noise interference, can result in the speed changing because the "noise margin" can change.

All that the "first 10 days" is supposed to establish are what you might call "baseline" parameters for the circuit. This in turn sets something called a FTR (Fault Threshold rate). So if on day 11 you have, say, a 4Meg connection and a year later it's only 1Meg, you can point to the fact that the circuit used to be capable of 4Meg and the ISP should get BT Openreach to investigate (e.g. degrading circuit). I say should, because I've read plenty of instances where the ISP simply washes their hands of it and just points to the current speed check result which says it's 1Meg capable and it's "just tough".

BT's profiling implementation is slow to respond to changes and can take days to increase speeds back up again following an "event", like the christmas tree lights example, because it places stability above everything else and only increments the speed back up in small slow increments after the "event" is over. On your point 5 this is typically where the subscriber can ask the ISP to "give it a nudge" and retrain, speeding up the process, though it is done remotely, and does not involve a physical visit.

Because it's all "ongoing", not just "in the first 10 days, and then it's set in stone", then you can change modems, you can keep the same modem and vary from ADSL2 to ADSL2+ and back, and it should "adapt" in realtime. From your perspective, for monitoring purposes, the same modem in the same place with all things being equal means you can notice variations from baseline more easily than if you swap kit around. Though variations in performance may be expected sometimes anyway owing to the vagaries of trying to trasmit data down phone lines.

On your point 3 - it may be advantageous to achieve the best rate in the initial training period, just setting the modem up according to instructions e.g. with microfilter in place is adequate. If you don't use your phone line for calls, you can just plug the modem directly into the test socket, assuming you have one (a modern NTE socket) and disconnect everything else. From the perspective of establishing the "FTR" - it's best not to touch anything in the first 10 days e.g. don't change modems or parameters or repeatedly turn it off and on again, which may fool the DSLAM into thinking that the current rate is unstable and dropping it.

All of the above applies to BT's DSLAM and setup. But, someone can correct me if I'm wrong here, I don't think it works quite the same on an LLU C&W setup which is what you have, in that the DLM (Dynamic Line Profiling, which is what this is - the "ongoing training", if you like) isn't quite the same.
 
You have all missed the obvious. Well right up until the very last paragraph of Mark2's answer.

In the opening post he says he is waiting for ICUK C&W service. That product AFAIK is a Shared LLU product and is NOT SUBJECT to any line training. It is not a BT wholesale'd product.

The speed you get from the modem on day one (barring the phone line having future issues) is the speed you are going to get all the time you have that service.

Using different modems will give slight speed variations, though it shouldnt be drastic, its basically down to what chipset the modem has and what chipset the LLU C&W gear at the exchange has. The better the match NORMALLY the better the connection. Other than that swapping modem/routers around if the line is NOT subject to DLM or any form of line training should not affect the connection.

Buying a top end Fritzbox for ADSL or ADSL2+ IMO is complete and utter overkill unless you are planning on doing loads of VOIP or similar. A £30-50 ADSL2+ modem router with a Broadcom chipset, is normally more than enough for most people.
 
In the opening post he says he is waiting for ICUK C&W service. That product AFAIK is a Shared LLU product and is NOT SUBJECT to any line training. It is not a BT wholesale'd product.

As far as I know, for all C&WW services, there is now line training similar for the first few days and they also quote it can take up to 10 days.

This appears to have started for all new provisions since August.

Can be disabled upon request and looks like they will also apply to all lines over time but no date as of yet.

Dynamic Line Management is provided on all new lines as of 1st August,2012 to automatically optimise the balance of speed and stability on new connections. Please read the following document for details or contact us for further information if required.

Dynamic Line Management

Matt
 
As far as I know, for all C&WW services, there is now line training similar for the first few days and they also quote it can take up to 10 days.

This appears to have started for all new provisions since August.

Can be disabled upon request and looks like they will also apply to all lines over time but no date as of yet.



Matt

I stand corrected then :) Nice of you to clear things up Matt.

I wonder why they suddenly introduced it and how many people have noticed? I also wonder how often the DLM kicks in after those first 10 days? Any indications thus far on how it has impacted users speeds? (IE before and after the DLM)?

At least for now it can be disabled upon request though.
 
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