Line Speed Throttled

[#1]

Ticket Ref:- 27886238
My problem is that BT and F9 have a line profile for me of 2500 kbps but I can only download at a maximun of 1700kbps, i.e. the line is profiled somewhere at 1750 kpbs either on F9 or BT's system.
Here are the facts:-
from F9
High-speed Broadband
--------------------------------------------------------------------------------
Estimated line speed:
Not recorded (service activated before we introduced estimates).
Current line speed:
2500
From BT:-
Test1 comprises of Best Effort Test: -provides background information.
Your DSL connection rate: 2848 kbps(DOWN-STREAM), 448 kbps(UP-STREAM)
IP profile for your line is - 2500 kbps
Actual IP throughput achieved during the test was - 1500 kbps
From "My Broadband Speed"
Today 10:47 1666 kbps (208kB/s) 378 kbps (47.3kB/s)
and from my router:-
DSL Line (Wire Pair): Line 1 (inner pair)
Protocol: G.DMT Annex A
Downstream Rate: 2848 kbps
Upstream Rate: 448 kbps
Channel: Fast
Current Noise Margin: 12.0 dB (Downstream) 21.0 dB (Upstream)
Current Attenuation: 56.4 dB (Downstream) 31.5 dB (Upstream)
Current Output Power: 18.2 dBm (Downstream) 11.9 dBm (Upstream)
I think you can agree from the above data that I should be recieving a line rate of close to 2500 kbps, but somewhere along the way I am being throttled at 1750 kbps whether this is at plus.net or BT, I'm not sure but I hope you will be able to advise on the issue or what to do to get the line un-throttled.
Dave

[#2]

Hi Dave,
Because you're using a contended service, you will not always get the "profiled" speed because of contention and line overheads.
The speeds you're getting are actually perfectly reasonable given your line conditions.

[#3]

I understand what you are saying, but when my line profile was set at 2000 kbps, I could download at approx 2000 kbps, but since my line profile has increased to 2500 kbps, I can now only download at approx 1700 kbps at any time of the day/night, its as though the BRAS profile is stuck at 1750 kbps.

[#4]

That's a fair comment.
Have you tried rebooting your router recently?

[#5]

Yes I have, makes no difference, still capped at around 1700 kbps.

[#6]

Check your exchange VP status http://usertools.plus.net/exchanges/

[#7]

Virtual paths: Green. No capacity issues, even in the historical data.

[#8]

Update:
After numerous restarts of the router, SNR set at the exchange increased to 15dB, therefore reducing sync to around 1800kps, and ip profile to 1500kbps, which reflected in only being able to download at this rate.
However a week later my sync speed is back to around 2400 kbps with an ip profile of 2000 kbps, but again, max download is still capped at around 1700 kbps, I really can't work this out, is there any one out there that can shed some light on this.
PS for your info, I know I can download at higher speeds on this line as I have in the past.
Dave

[#9]

I don't think there is any evidence of a cap, a real throughput speed of 1700kbps with an IP Profile (idealised throughput) speed of 2000kbps is good. I know you said you achieved 2000kbps previously with a 2000kbps profile but to achieve that some of the overheads have to be counted as data. Are your old figures and new ones from exactly the same source?

[#10]

I use several sources, and they are always the same results. I know about the overheads of adsl and I have factored these in, what I can''t understand is when my line has a profile of either 1750, 2000 or 2500 kbps, as stated in both BT Speedtester and plus.net line profile, the maximum download from these multiple sources is always the same - approx 1600-1700 kbps.
I have asked plus.net/BT to reset my SNR to aid further testing, however there seemed to be an issue with this, and it looks like it is being investigated by their suppliers, so maybe they have found some fault after all.
Dave

[#11]

You need to make sure that it's noted on your ticket that you believe now that you are better informed that the number of router restarts you did caused the target to get raised to 15dB, otherwise you are likely to get the response that the target was raised in an attempt to stabilise your line.
What's the best speeds you've had? Do you know what the target SNRM was then?
Can you / have you heard any crackling or other intermittent noises on your line?