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Author Topic: Is my ADSL line really "training" or is it just plain useless?  (Read 6885 times)

vic

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Is my ADSL line really "training" or is it just plain useless?
« on: January 31, 2007, 07:57:01 PM »

I have for the last few years had a 2Mb broadband service from BT. I recently decided to change ISP, the migration to the new provider seemed to go very smoothly with out a problem last Thursday (25th Jan). I noticed that morning that the line had sync'ed to a higher speed, with 5.5Mb down and 488k up. Although disappointed that it had not increased to 8Mb I had already been told to expect about 5.5Mb so this was not a surprise. The noise margin on the line also dropped from around 19db to around 6dB. Again having read lots of the good stuff on this web site I was also expecting this to. The Thinkbroadband speed tester was showing I was getting around 4.5Mb download, and around 370k up.

I recalled reading an item on this web site about improving your noise margin by disconnecting the wire from pin 3 on your master socket as this had been known to cause noise on the line. I did this the following day and re-booted the router (a Voyage 2091 with unlocked ISP code - Dynalink). I checked to see what effect this had and was initially disappointed as it only showed a slight increase in the noise margin, this now been between 6.5 and 7 dB. However, I then noticed the sync speed had increased giving me 8Mb down and 448k. The router was even suggesting a sync speed of 1Mb would be achievable. Great a thought, less see what this does to the down and upload rates I thought.

I have been monitoring the down and up rates over the last few days, still using Thinkbroadband. The download rates have been steadily falling and now they are back to just over 2Mb. the upload rate is also falling but not by the same degree. I can see that there are errors on the line, there were before the upgrade, but there are a lot more now.

I have been advised by my new ISP that the rates will fall (and this is normal?) but should pick up as I progress through the training period. I have read conflicting information as to what this training period actually does, and also if the BRAS profile, which I believe is what controls your down/up load rates, continues to update itself through the life time of your broadband service, or whether it is set in stone after the 10 day period.

Can any body shed some more light on this grey area for me. Is my download rate going to recover at all, or am I going to be stuck with this 2Mb limit?

As I mentioned above I am using a Voyager 2091 router with modified firmware to enable me to continue to use it on a non BT service. the firm is from Dynalink whose routers I believe use the same chipset. I had replaced the Voyager with a new Belkin F5D9630 router, but even with help from Kitz and others, include Belkin (who I must say were pretty useless), I could not find any way of displaying the error stats on the line. So I changed back to using to using the Voyager so I could keep a check on the errors (and took the Belkin back to the shop). Could the router be contributing to the problem, is it worth changing it?

If any one out there has a few minutes and give me some advise I would very much appreciate it.

Thanks

Vic
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havelock

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Re: Is my ADSL line really "training" or is it just plain useless?
« Reply #1 on: January 31, 2007, 10:31:46 PM »

If you Sync rate is around 8Mbit still and only your throughput is dropping then theres a BT line fault. The training period works by sending every sync event over the 10 day training period and after some mathematical trickery decides what the best stable sync rate you should acheive - this is your BRAS profile.

This is not set in stone, and a 3day period of higher sync at any point after the training period SHOULD increase your IP (BRAS) profile, though its fairly common for this not to occur.

Basically, run a PTTR test (http://speedtester.bt.com - it's busy so keep trying using a genuine telephone number and full adsl login username) ; it should eventually provide you with an IP Profile, a Sync Rate (MSR) and a Throughput value. If your throughput is less than 70% of your MSR then you can get your ISP to raise a BT fault for you, though you'll prolly be advised to wait till the end of the training period before they do.

Rgds
Havelock
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kitz

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Re: Is my ADSL line really "training" or is it just plain useless?
« Reply #2 on: February 01, 2007, 12:29:02 AM »

Hi

Havelock has said most of it..  you need to check your IP profile from the speedtester link really so we can see what you IP profile is.

I wanted to comment on this bit though

>>> also if the BRAS profile, which I believe is what controls your down/up load rates, continues to update itself through the life time of your broadband service, or whether it is set in stone after the 10 day period.


Your bRAS profile is ongoing and will change throughout the whole of the time you are on Max.

>> that the rates will fall (and this is normal?)

Depends on your line, the idea is that after a few days things should start to stablise.

Your actual throughput should be more or less in line with your bRAS (IP profile) since it is that which will be limiting your actual speed.

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How to get your router line stats :: ADSL Exchange Checker

vic

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Re: Is my ADSL line really "training" or is it just plain useless?
« Reply #3 on: February 01, 2007, 12:45:04 PM »

I would like to thank you both for your feedback and help. I tested the link this morning with the BTw Speedtester as suggested and got completly different test results - which I must say has left me far happier!

When tested the downstream sync speed was correctly identified as 8032k. The IP Profile value given for the line was 7000k, and the average throughput during the test was 6340k. I am pretty relieved about that.

Does the BT Speedtesting check the throughput between your router and the local exchange? I guess the variance with the Thinkbroadband tester (which I ran straight after and it still give me 3Mb download indication) is due to the fact that to reach it you have to traverse the internet.

One final question if I may. My modified Voyager 2091 router now has a an additional information field in the ADSL line status display. This advises you what the "Attainable Line Rate" is in addition to the rate at which you have actually sync'ed. While this is only slightly higher for the down speed (8544k compared with the current sync speed of 8032k), the attainable up speed is more than double, it is currently sync'ed at 448k while the router suggests that 968k would be attainable, at one point it suggested 1Mb would be attainable. Is the fact that it has only sync'ed at 448k a restriction that BTw or my ISP have set?

Thanks once again for your assistance. I guess my ADSL line is not useless, you have helped prove that to me.

Thanks

Vic
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mr_chris

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Re: Is my ADSL line really "training" or is it just plain useless?
« Reply #4 on: February 01, 2007, 12:59:28 PM »

448k is a maximum set by BT. Office (known as 'Premium') connections are allowed to sync up to 832kbps upstream.

Similarly, 8128kbps is the maximum downstream that has been set (or 8032 as some people seem to be finding - whether that's to do with Interleaving or not I don't know)

Hope that answers your question :)
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Chris

havelock

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Re: Is my ADSL line really "training" or is it just plain useless?
« Reply #5 on: February 01, 2007, 02:50:27 PM »

8032kbps / 8 = (1.004 Mb/s -10% Network overheads) = 903.6Kb/s theoretical maximum throughput

Your Bras Profile is limiting you to 7000kbps though so I doubt you'll ever see above this speed unless you only use your BB connection in the ghost hours (1-5am)

ADSLGuide / Thinkbroadband is known for being on a problematic route for some ISP's - BT's speedtester still runs across the internet afaik, it just has a better route than most.

FYI, interleaving shouldn't really affect your download speed (much), but it will increase ping latency by ~30-50ms, which if you're an online gamer is quite a lot.

Rgds
Havelock
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kitz

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Re: Is my ADSL line really "training" or is it just plain useless?
« Reply #6 on: February 01, 2007, 05:27:58 PM »

Glad that your results are now looking more normal. :)

I have seen a few reports of users not getting what they thought they should on the adslguide speedtester.  In the past Ive noticed myself that they have 2 speedtest servers and one of them seems to give me a higher result than the other.

Because speeds on max are more variable its well worth checking a few different speedtesters.  Theres a list here
http://www.kitz.co.uk/adsl/speeds.htm

My current fav is the BBMax one which I tend to find gives me the most accurate results in line with what I can download on http in real time.
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How to get your router line stats :: ADSL Exchange Checker
 

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