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[sorcerer]

Hi guys,

Very new here and don't want to pee anyone off but I'm trying to help a friend find out why he's getting slow broadband. He's on BT Infinity 2 (80/20) and is only getting about 35/5. He's using a Huawei HG612 and we've been running the logging software for three days now. I know that's not much info for you to go on but I go on my holidays on Tuesday and was just wondering if anyone could give us a rough indication of what may be wrong, with the info that we do have (he's going to continue logging while I'm away, so you'll probably have too much when I come back   )

Anyway, we have three days-worth of 'Ongoing stats' that I've zipped and the file size is 2.46Mb, and the associated zipped 'Current stats' file is 6.35Mb. I'm not sure if that's too big to post here into the forum or even if you want the files in zipped format, so to be on the safe side I've uploaded them to Dropbox and you can get them here https://www.dropbox.com/s/q0h3aouyq8j5zvy/current_stats.zip for the current stats and here https://www.dropbox.com/s/zlw1xta8ba7omu4/ongoing_stats.zip for the ongoing stats.

Thanks for the help and sorry to be a numpty   

EDIT: In case it's relevant, he was getting about 35 Mbps down and 1.5 Mbps up on original Infinity. When he upgraded to Infinity 2, download speed stayed about the same but upload speed increased to about 5 or 6 Mbps.

[roseway]

I've moved this to a more appropriate place. I know nothing about VDSL2, but I expect someone will be along shortly.

(Welcome, by the way )

[sorcerer]

I've moved this to a more appropriate place. I know nothing about VDSL2, but I expect someone will be along shortly.

(Welcome, by the way )

Ok, thanks very much 

[ColinS]

Hi, and welcome. 

I'm attaching two of your images so that people can see them.

[ColinS]

Hello again,

From the first image it looks like your friend's line has been banded by DLM at 48/8, and is actually achieving ~40/8. These are line sync rates and not throughput, which may be where the 35/5 figure comes from? But still less than 80/20, obviously.

However, he has a moderate interleaving depth (629) which requires about a 20% overhead, which may explain why he is achieving less than he is currently banded at.

Why he has been banded may be the result of something that happened in the past.  Is he aware of anything that 'happened'?

However, he also has an INP (Impulse Noise Protection) level of 3, which suggests that there may have been noise on the line at some point.  Is any audible on the phone?

How far is he from the FTTC cabinet?  The attached graph suggests he is on a somewhat longer line.

Hope this helps, and that others will chip in too.

[sorcerer]

Thanks for your replies Colin, it's much appreciated.

Why he has been banded may be the result of something that happened in the past.  Is he aware of anything that 'happened'?

However, he also has an INP (Impulse Noise Protection) level of 3, which suggests that there may have been noise on the line at some point.  Is any audible on the phone?

No, nothing has happened out of the ordinary and there is no noise on the line at all. To be honest, I was a telephone engineer (cable jointer) on BT for 20 years before a back injury led to medical retirement, and I recently asked an old colleague of mine to do a line test for me - all came back clean and clear, with no battery contacts, no earths etc., etc., just a perfect (for telephony at least) line.

I'm not sure of actual line length from the fibre cab but again, my mate is going to look at the cabling records to get line length for me, and as soon as I know I'll let you know too - unfortunately, time is the problem as I go away on Tuesday so it may be a while before I can get that info to you.

What puzzles my (very) untrained eye is the bitloading graph, as there is nothing over Tone 1950 - does that not indicate that half of the bandwidth is not being used and therefore he never will get more than half speed? Or have I got it completely and utterly wrong?

Thanks again for your help.
EDIT: Doh! I think I've just realised about the bitloading graph - that's what you mean by banding isn't it? They've capped him at that rate so he never will achieve any higher speed until the cap comes off or they move him into a higher band. I just want to point out that I'm not thick, I just had to finish before broadband came along   

[ColinS]

Not so untrained as you may think.

No, the banding is not exactly as you fear, it is a reduction in the line speed imposed by DLM in the light of line conditions.  Can I ask if your friend actually ever received an 80/20 service at installation time, or is this just what he expected because this is what the product's called?

If you look at the attached graph you will see that the attenuation in the D2 band is 51.6dB and the D3 band is not in use at all as you noticed, probably because the attenuation is > 65dB.  This is borne out by the Hlog graph above, where tones at and above 1950 are ~-80dB or more.  This is typical of a longer line, but could also be an aluminium line, and is the main reason why he will never get 80/20, unless he moves closer to the cabinet 
[Edit] Our good friend Bald_Eagle_1 on here has VDSL on a very long ~1Km D-side, and although he once could get as much as 30Mb/s DS (less than your friend), he can now get only 20Mb/s. 

We're all learning here, so don't worry if something is not immediately obvious.  There are quite a few people around who could use the services of a good cable jointer!   

[burakkucat]

I may just be caterwauling from the top of the telephone pole but until such time as our Baldy Bird provides his assessment, this is what I think . . .

Due to the physical state of the D-side pair (its length or metal), the attenuation is too high for the D3 band to be used. As a consequence the DS maximum attainable rate (theoretical sync rate) is somewhere between 40 - 50 Mbps. (Edit: attainable rate graph is attached, below.) If the currently applied banded profile is removed, I do not expect the DS throughput to be much more than 44 - 45 Mbps. Is it worth having the 80/20 service? 

If that were my line, I would check the cost of the 40/10 service and compare it with the price of the 80/20 service.

  (Attempting to 'whistle up' an Eagle . . . )

[ColinS]

Unsurprisingly, we are in agreement B*Cat. A very good suggestion.

[sorcerer]

Ha ha, cheers Colin 

Can I ask if your friend actually ever received an 80/20 service at installation time, or is this just what he expected because this is what the product's called?

No, he never did get anything like those higher speeds. I remember that on the original flavour of Infinity his IP Profile was something like 39 down, 1.9 up, and he was actually achieving a throughput of about 35 down, 1.6 up. When he upgraded to Infinity 2, download speeds remained about the same and upload increased to about 5 or 6 Mbps.

If you look at the attached graph you will see that the attenuation in the D2 band is 51.6dB and the D3 band is not in use at all, probably because the attenuation is > 65dB.  This is borne out by the Hlog graph above, where tones at and above 1950 are ~-80dB or more.  This is typical of a longer line, but could also be an aluminium line.

[Edit] Our good friend Bald_Eagle_1 on here has VDSL on a very long ~1Km D-side, and although he once could get as much as 30Mb/s DS (less than your friend), he can now get only 20Mb/s. 

Oh dear, that must be SO frustrating!!   

We're all learning here, so don't worry if something is not immediately obvious.  There are quite a few people around who could use the services of a good cable jointer!   

Once again sir, thank you   

[burakkucat]

I remember that on the original flavour of Infinity his IP Profile was something like 39 down, 1.9 up, and he was actually achieving a throughput of about 35 down, 1.6 up.

I wonder if that was the original 40/2 service? 

[sorcerer]

Sorry, I missed the intervening posts. He's only just upgraded to the 80/20 service but it's actually free of charge for existing BT Infinity customers - just that they tie you into a new 18-month contract, but no actual monetary increase.

So, the concensus is that he's getting the best he can and that there's no actual 'problem' with equipment as such, except for possible aliminium cable in the run somewhere - is that correct chaps?

Cheers

[sorcerer]

I remember that on the original flavour of Infinity his IP Profile was something like 39 down, 1.9 up, and he was actually achieving a throughput of about 35 down, 1.6 up.

I wonder if that was the original 40/2 service? 

I would hazard a guess that it was.

[burakkucat]

So, the concensus is that he's getting the best he can and that there's no actual 'problem' with equipment as such, except for possible aliminium cable in the run somewhere

Perhaps aluminium cabling in the D-side or perhaps 650 - 700 metres of copper. If you can get sight of the relevant network records, that may disclose all. 

[sorcerer]

So, the concensus is that he's getting the best he can and that there's no actual 'problem' with equipment as such, except for possible aliminium cable in the run somewhere

Perhaps aluminium cabling in the D-side or perhaps 650 - 700 metres of copper. If you can get sight of the relevant network records, that may disclose all. 

Right, hopefully I'll get the network records tomorrow and let you know.

Thanks for all your help folks, very much appreciated