Question Re: ADSL Max training period

Hi chaps,

Firstly, I've searched around a bit for the answer to this question and haven't sound a suitable answer, so apologies if I've missed something.

Recently I have taken up an ADSL Max service with TitanADSL. The line has been active for about 4 days now and as the crow flies, I am 1.5km from the exchange. For the first two days the router (Draytek 2700G) reported a sync speed of around 4200 with an SNR of ~8 and 'Loop Att.' of 40.

This has since dropped to remain between 2500-3200 with an SNR of 12-15, Att. 39. Despite rebooting of the router I cannot achieve a higher sync speed, FYI prior to taking up the service initial reports indicated I could be capable of 5Mbps.

(I've also disconnected any phones and wired the router directly to the master socket to see what effect this has - resulting in a SNR increase of a few db but no speed difference.)

Whilst I understand the training period is probably exactly that, surely my line should be tested to its limits during this period?! Is this normal for the first 10 days or is this unusual behaviour?

Any info anyone can offer would be very appreciated! Cheers.

The default target SNR margin is 6dB. If your line is noisy it is raised in 3dB steps to a maximum of 15dB. Each 3dB raise loses you about 700kbps in sync rate. Your line must have been diagnosed as noisy by the automatic monitoring software.

See http://www.dslzoneuk.net/adslmax_explained.php

4200bkps is a pretty poor line rate for a 40dB line with 8dB margin
You say you have tried at the master socket but have you tried the test socket if you have one? http://www.kitz.co.uk/adsl/troubleshooting.htm

Yes, unfortunately I have tried the test socket! The ring wire is also not connected so I can't blame that.

I've just carried out the BTw speedtester and have the following results:
"Your DSL connection rate: 2752kbps (DS), 448kbps (US)
IP profile for your line is - 2000kbps
Actual IP throughput achieved during the test was - 1763kbps"

I'm still learning all the terminology so do not fully understand that outcome, but it may help someone here

At what point did you resolve all the wiring stuff?

The SNR or 12 to 15 suggests the Max systems have seen instability and raised the margin to make things more stable at the expense of line speed.

The 10 day period is an urban myth since what you've seen happen continues for the whole time you have the line, and there is no magic lets try running the line flat out today, a bit slower one day and faster another. ADSL modems negotiate the best connection they can every time they connect, and at limited by a figure called the target noise margin which appears to have been raised in your case due to instability

In reply to:

---

The 10 day period is an urban myth..........

---

Up to a point...... the MSR (Maximum Stable Rate) of the line is established in the first 10 days, and BT won't do anything about ADSL line performance until the line has dropped by at least 20% from the original MSR, then optimum line performance from the start is desirable.

In reply to:

---

The 10 day period is an urban myth since what you've seen happen continues for the whole time you have the line, and there is no magic lets try running the line flat out today, a bit slower one day and faster another. ADSL modems negotiate the best connection they can every time they connect, and at limited by a figure called the target noise margin which appears to have been raised in your case due to instability

---

The above statement is not true the 10 day training period does exist.
Basically what happens in the 10 day training period is there are two systems that go on your line one called max and the other called rambo(Rate Adaptive Management Box) these are put on to the line to calculate the MSR(maximum stable rate) and the FTR(Fault threshold rate) these 2 figures are set to 2272 by default and need to be calculated in order for your provider to diagnose if there is ever a problem with the connection.
For instance if you called your provider as you had a slow connection they would be able to look at the ftr and if your speed is below this then they can log a fault to bt for a fault threshold breach and that is just one of the many reasons that this process is important.

The best thing to do during the 10 day training period is to plug the router into the test socket and leave it turned on throughout the 10 days as if you reboot the router then this will register with max as a dcn(drop in connection)and as a result will then put the noise margin up and decrease the sync rate in order to stabalise the connection.

FTR=approx 70% of your MSR.

Edited by jonny1310 (Sat 26-Jul-08 05:15:41)

In reply to:

---

The above statement is not true the 10 day training period does exist.

---

Except that it's not a training period - it's a period in which certain baselines are recorded, which is exactly what I said several days ago

In reply to:

---

The best thing to do during the 10 day training period is to plug the router into the test socket and leave it turned on throughout the 10 days as if you reboot the router then this will register with max as a dcn(drop in connection)and as a result will then put the noise margin up and decrease the sync rate in order to stabalise the connection.

---

Except when I forget I switch my router off every night, as I did during the 10 day "training period". I have always sync'd at 8128/448 on my line (apart from a short time when I used a router which couldn't sync at 8128 while interleaved).

A figure of more than 10 switch offs an hour is the figure quoted in BT documents for the action you describe.

I think a lot depends on how it is "switched off". Many routers have "last gasp" technology which means that the power supply has just enough stored charge for the router to tell the exchange that it is being powered down, and it's not a forced re-sync.