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BT & PlusNet Speed test results Explanation please?

shutter
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BT & PlusNet Speed test results Explanation please?

Have recently experienced a 50% drop in download speed, which raised a ticket, and was "solved "on wednesday (7 May2008) evening.  My speed has been constant around 950 kbps download since I went on broadband about December 2007. the speed dropped to average about 460 when I raised the fault.  On completion, Wed evening , at 18:06 , I did the Plusnet speed test and found it back to normal 966 download, and 374 upload (374 has been constant throughout the faulty period)  Just to check it out, I did another test at 18:17 and got 1038 download, and 374 upload.  Fine I thought, and closed the ticket as satisfactory.
Thursday evening, 20:19,  did the PN speed test to see if it was still good, and it has dropped to 723 down and 373 upload..... again at 21:40  721 download and 299 upload.
Friday 9 may 14:38  721 download    373 upload  (plusnet speedtester)
Decided to go for the full monty, and did the BT speedtester,  here are the results

Test1 comprises of Best Effort Test: -provides background information.
    IP profile for your line is - 750 kbps
    DSL connection rate: 448 kbps(UP-STREAM)  992 kbps(DOWN-STREAM)
    Actual IP throughput achieved during the test was - 647 kbps
If you wish to discuss these results please contact your ISP.
If you are experiencing problems with specific applications, servers or websites please contact your ISP for assistance.
Your test has completed please close this window to exit the performance tester.

Can someone explain why my line profile is 750 kbps when I have checked several broadband suppliers (capability speed checks) on my post code, and address, who say it is capable of at least 1mb..... and what/when/how does the 992 figure come into the equation.
When I had such good results immediatly PN csc said my profile had been amended and it should be ok..... and was....
For all the "change the router, filters, equipment, people." ... I have changed nothing before, during or after the testing period. I have still got everything in place exactly as it was when I started broadband....
57 REPLIES 57
chillypenguin
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Re: BT & PlusNet Speed test results Explanation please?

Quote from: shutter
I have checked several broadband suppliers (capability speed checks) on my post code, and address, who say it is capable of at least 1mb.....

They can only guess what connection speed you may get, and as for accuracy +/- 1M is not unrealistic.
Chilly
godsell4
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Re: BT & PlusNet Speed test results Explanation please?

Quote from: shutter

    DSL connection rate: 448 kbps(UP-STREAM)  992 kbps(DOWN-STREAM)

... and what/when/how does the 992 figure come into the equation.

Log into your router, and you will see these two numbers will match the ADSL sync speed at the time you ran the BT speedtester.
--
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https://portal.plus.net/my.html?action=data_transfer_speed
shutter
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Re: BT & PlusNet Speed test results Explanation please?

Which means?
And does not answer my query.....  (a summary)
From inception/connection of broadband  average speed (any time of day or evening)  950 kbps download
Fault appears    average speed drops to less than 50%
Fault checked//serviced//repaired      speed returns to 966 and 1038 kbps download
24 hours later speed reduced again to 752 kbps
24 hours later (still) speed 752 kbps
with all due respect, chilly, your response was not helpful.
HPsauce
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Re: BT & PlusNet Speed test results Explanation please?

Are you able to obtain the downstream attenuation and noise margin (SNRM) from your router? Please post them here.
SNRM can vary (mine does a LOT) and on a long line (as yours probably is) this can easily change your sync speed or introduce errors. It can only need a small sync speed change to move you into the next IP profile "band". Moves up take 3 days to be "established" in the IP profile while moves down can be very quick indeed.
HPsauce
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Re: BT & PlusNet Speed test results Explanation please?

For reference this is the relationship between sync speed and IP profile for slower connections:
Line sync speed - IP Profile

from 288Kbps  - 0.25Mbps
from 416Kbps  - 0.35Mbps 
from 576Kbps  - 0.5Mbps 
from 864Kbps   - 0.75Mbps 
from 1152Kbps  - 1Mbps 
from 1440Kbps  - 1.25Mbps 
from 1728Kbps  - 1.5Mbps 
So if your line was capable of "around" 1mbps a "good" sync of 1200 would give a 1Mbps profile, but a sync of 1150 gives 750Kbps.
But drop just 15% below 1 Meg (to 850kbps) and you only get 500kbps.
Note that a stable 992kbps sync gives 750kbps IP profile as your test confirmed. BUT it only needs just over a 10% drop in sync speed to push you down to 500!
Anyway, post your attenuation and SNRM which will indicate what could be "thoretically" possible.
shutter
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Re: BT & PlusNet Speed test results Explanation please?

O.K. have managed to get into the voyager.home pages, and found this bit of information

What does Latency Type  Interleave  mean?  I have read that having Interleaving on, is not recommended????Huh


Line Mode G.DMT   Line State Show Time
Latency Type Interleave   Line Up Time 00:20:11:16
Line Coding Trellis On   Line Up Count 3

Statistics Downstream Upstream
Line Rate 992 Kbps 448 Kbps
Noise Margin 14.2 dB 19.0 dB
Line Attenuation 63.0 dB 25.5 dB
Output Power 17.5 dBm 12.1 dBm
HPsauce
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Re: BT & PlusNet Speed test results Explanation please?

Well with 63dB attenuation you "could" theoretically get close to a 2mbps sync speed. BUT it's been knocked back by a high SNRM of 14.2db. 6dB is more normal and my line runs happily at 3db but that's another matter. Roll_eyes
The question is why is your SNRM high? It could be due to errors/noise on the line which are ongoing or it could be a legacy of the problems you've had.
The first place to look is usually your own wiring. What sockets, extensions etc. does your home phone system have and where is the router (or is it a modem) connected?
Interleaving is an error correction mechanism. It can be turned off (to give a little extra speed) if your line is stable, but only when everything else is sorted out.  Cheesy
godsell4
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Re: BT & PlusNet Speed test results Explanation please?

Have you read these two pages ?

http://community.plus.net...-dynamic-line-management/
http://community.plus.net...d-faults-how-to-diagnose/
Please do so.
What is the history of your line ... have you had a fixed speed 512kb/s or 1Mb line for a few years and just been moved onto MaxDSL?
SW.
--
3Mb FTTC
https://portal.plus.net/my.html?action=data_transfer_speed
shutter
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Re: BT & PlusNet Speed test results Explanation please?

Quote

The first place to look is usually your own wiring. What sockets, extensions etc. does your home phone system have and where is the router (or is it a modem) connected?

I refer to my original post, where I state, that  since transferring to wireless broadband with Plusnet, I have not changed any wiring, or equipment, It has not been moved, replaced, or reconfigured.

Edit....just noticed I put 2009 instead of 2009 ! line below....

The speed from inception until 30 april 2008 was in excess of 950 kbps and constantly above that figure no matter what time of day or evening I checked, (usually three times a day)  On a couple of occasions I managed 1.2 mb  and I vaguely remember a 1430 kbps once....
No equipment, wiring, was changed or moved, during the Faulty period.
At the end of the fault, the speed was checked, as mentioned in the orignal post.
24 hours later..... still no changes to wiring or equipment, and the speed is down again to below 750kbps 48 hours after fault "fixed" still less than 750
If I have not done anything..... and the fault has been fixed..... the line speed reported is 992 why am I only getting less than 750 .....

Undecided

Godsell4..... the history of the line  is in my orignal post, and again in this post. 

HPsauce
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Re: BT & PlusNet Speed test results Explanation please?

Who knows what's changed where or why, it's not always visible or obvious or how things interact, so rather than just say it's unchanged please describe:
Quote from: HPsauce
What sockets, extensions etc. does your home phone system have and where is the router (or is it a modem) connected?

zubel
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Re: BT & PlusNet Speed test results Explanation please?

The fact that nothing has changed at your end is often brought up and to be honest, it's possible that something has changed without your knowledge.
For example, a filter may have started to break down (they do frequently - I think the best lifespan I have received from a filter is circa 2 years)
It is definately worthwhile following troubleshooting steps - the first being to plug into the master test socket and record your router stats then.  If there is a wild variance between the test socket and your current location then the fault is almost certainly internal to your premises.
If the sync is nearly identical, then it points to external interference.
You are at the end of a very long line and as such it is to be expected that your sync will vary more than usual.  Lets see if we can't get it working as best as possible.
B.
nadger
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Re: BT & PlusNet Speed test results Explanation please?

As has been pointed out the snr margin is high and target is normally 6dB - you can ask PlusNet to reduce this margin and see what happens to your download speed and stability.
Unfortunately you don't know the margin prior to having the fault.
Do you have the ability to plug into the master socket?
pierre_pierre
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Re: BT & PlusNet Speed test results Explanation please?

We must be unlucky, of is it Just the Scots?  just back from the Western Highland, most places of habitation have a "wooden" garage with a microwave dish, at my second place of abode, had a free courtesy connection, at 3500  in the wilds of nowhere Smiley Shocked Cool Huh Roll_eyes
shutter
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Re: BT & PlusNet Speed test results Explanation please?

Which does not explain the reason for my original post, pierre. Undecided