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Where does "Estimated Line Speed" come from?

Community Veteran
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Registered: 26-09-2015

Where does "Estimated Line Speed" come from?

Hi,
I refer to the "Estimated Line Speed" shown on the Plusnet member page  https://portal.plus.net/my.html?action=data_transfer_speed and was wondering what that's based on.  I understand that it comes from BT Wholesale, but it presumably is based on something factual (or semi-factual!).  Comparing notes at work, two of us have lines which run approximately four times faster than that estimated figure.  It's a concern because during fault discussions Plusnet are inclined to throw that figure back in our faces, sort of implying that we shouldn't really be getting anything more than the estimate.
In battle with Plusnet I need to be fully armed with the facts.
Thanks,  Tony S
32 REPLIES
Superuser
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Re: Where does "Estimated Line Speed" come from?

The BT ranges are given by entering your phone number at https://www.dslchecker.bt.com/. The estimate provided by Plusnet (for fibre) is usually the low value from Range A.
David
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Re: Where does "Estimated Line Speed" come from?

Thanks.  I understand that it comes from BT, the question is where or how does BT derive that figure.  Especially as it others, and not just me, find it bears no resemblance to the actual stable speeds that are achieved.    Maybe nobody know where it comes from, and if that's the case then it helps strengthen my argument that Plusnet should pay no heed to it.  The worst case scenario is that Plusnet cite that figure and refuse to address any issue with a line that currently runs faster than it, and I have already seen that implied if not said outright.
Community Veteran
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Re: Where does "Estimated Line Speed" come from?

As usual, there doesn't appear to be any official documentation publicly available detailing how the estimates are worked out.
A long time ago, my estimated speed was strongly linked to my line's current performance, but that was way back when the estimate was just one figure for ADSL and one figure for ADSL2+. Before I disconnected the bell wire, the estimate used to say I couldn't get broadband, or I might get 256k (while actual speed was in the range 1 - 1.8 Mb). Then the estimate almost seemed to change between 2Mb and 2.5Mb with the IP profile. Currently my ADSL2+ estimate is "Up to 5.5" with a range of 4 - 6.5, my line might just manage an ADSL2 line rate of 3.8, if my line attenuation of 58dB is what it ought to be, then the estimates seem unrealistically high. The address checker gives me an ADSL2+ estimate of "Up to 4" with a range of 3 - 7, I don't know why the phone number gets a higher estimate despite the fact that the line's actual speed is lower than the estimate.
I think the estimate is based on data on your line's current performance, the performance of neighbouring lines (if of similar length), and expected speeds for estimated line length or tested loop loss. Some of the data available from Openreach that could be used to pick an estimate is described in the eMLC user guide (available from here), but it doesn't cover how the BTWholesale ADSL estimates are derived.
Community Veteran
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Re: Where does "Estimated Line Speed" come from?

Thanks.  Interesting to hear that it at least sometimes gets updated based on actual speeds in service.    Ours is still sitting at 1.0meg even though the line hasn't been below 3.5 even under fault conditions ever since we moved here four years ago.
Community Veteran
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Re: Where does "Estimated Line Speed" come from?

The download range given for ADSL should give the upper limit as your normal speed if it's higher than the estimated. If it is higher than yours, it could be one of your neighbours on your DP is achieving that speed.
VileReynard
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Re: Where does "Estimated Line Speed" come from?

My download speed has taken a big hit over the last week or two - by about 10 Mbps.
I'd send a pretty graph showing the trend over the last 6 months, but plusnet won't let me.
Quote
The upload folder is full. Please try a smaller file and/or contact an administrator.

That's for a 400KB file.

Community Veteran
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Re: Where does "Estimated Line Speed" come from?

You aren't reading enough Jeremy.
hadden
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Re: Where does "Estimated Line Speed" come from?

Further to Anotherone's post above, I've observed the influence of other connections nearby first hand.
Back when there were very few ADSL connections, I noticed that the BT estimate followed exactly any changes in my actual connection speed, after a short delay.
Over the years that estimate gradually got further away from my actual speed as that estimate takes into account other poorer nearby connections. My current BT estimate is "up to 2.5" Mbps and that is reflected on the Plusnet page as "Estimated line speed: 2.0Mb (This may vary between 1Mb and 3.5Mb) - Checked on 2015-10-28 09:18:08".
However my actual speed has been just over 6Mbps for a few years.
Community Veteran
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Re: Where does "Estimated Line Speed" come from?

Hi John, out of curiosity if you put your phone number into the DSL Checker, what is it currently giving you as the Upper Limit on the Downstream Range (RH column)?
hadden
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Re: Where does "Estimated Line Speed" come from?


Hi Anotherone
Here are the stats.
FTTC Range A (Clean) 80 71.3 20 20 -- Available
FTTC Range B (Impacted) 80 66.8 20 19 -- Available
WBC ADSL 2+ Up to 2.5 -- 1 to 4 Available
ADSL Max Up to 2 -- 1 to 3.5 Available
WBC Fixed Rate 1 -- -- Available
Fixed Rate 1 -- -- Available
Other Offerings
Fibre Multicast -- -- -- Available
Copper Multicast -- -- -- Available
I hadn't looked close at this for a while, as it wasn't very meaningful for my connection. However I now note that the Plusnet page is reporting the ADLSMax figures. My current connection mode is ADSL2.
(I would have attached a screen capture if 10kB hadn't been too much for the current status of the forum  Roll eyes ).
Community Veteran
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Re: Where does "Estimated Line Speed" come from?

It was that RH column called Downstream Range that I was particularly interested in  Wink
(Yes there is a very annoying issue with Uploading at present).
jem16
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Re: Where does "Estimated Line Speed" come from?

Quote from: Anotherone
It was that RH column called Downstream Range that I was particularly interested in  Wink

That's the column of numbers immediately before the Available that he's give you - ie 1 to 4 for adsl 2+ and 1 to 3.5 for adsl max.  Wink
Community Veteran
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Re: Where does "Estimated Line Speed" come from?

Yep I know, Ta  Wink  The reason for the subsequent remark was that it isn't saying what I anticipated, whether that's because John has got his connection configured to ADSL2, I wouldn't know. There is still a lot of mystery about how they derive some of these figures, despite efforts to provide more meaningful values. The impression I've been getting of late is that they are now deliberate under-estimated in many cases, due to the flack they have received because of people finding their connection speed dropping below the original estimates.
jem16
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Re: Where does "Estimated Line Speed" come from?

Quote from: Anotherone
Yep I know, Ta 

Sorry - misread your comment to mean you hadn't seen it.
Quote
The impression I've been getting of late is that they are now deliberate under-estimated in many cases, due to the flack they have received because of people finding their connection speed dropping below the original estimates.

That wouldn't surprise me although mine says 3 to 7 on that checker - currently connected at 7043kbps.