In reply to a post by filbert42:

The line tester was predicting speeds of 12-19Mbs. I couldn't wait...

With bated breath, I logged in a did a speed test. Result before, (with ADSL) ~5Mbs, after (VDSL) ~ 6.2Mbs - wow!!!!

Just checking ... You do realise that the BT estimations are usually of sync speed? Not the throughput of a speed tester?

Running speed tests is absolutely fine for checking that performance stacks up against the sync speed being achieved, and for checking that all the hardware is working together. However, the speedtest results aren't meant for comparison against the line speeds specified by the BT estimator.

The BTW estimation tool comes with the proviso: "Throughput/download speeds will be less than line rates and can be affected by a number of factors within and external to BT's network, Communication Providers' networks and within customer premises."

With a speed of 6.2Mbps, and an exchange distance of around 1.6km, I guess you are on 20CN ADSL. If you had access to ADSL2+ (21CN), you'd probably be getting speedtest results closer to 15Mbps.

In reply to a post by filbert42:

The ISP says that they can't log a fault with BT as it is within the "tolerance band" or some such excuse.

The estimated range represents the 20th and 80th percentiles of speeds of similar lines. BT will accept a fault from the ISP only if you fall into the bottom 10%, unless the line testing equipment also reports a physical fault.

I guess the gap between the 20th percentile - bottom of the estimated range (12Mbps line speed, or sync speed) - and the 10th percentile is this "tolerence band".

If things continue badly, or get worse, it might be worth regular reports into the ISP. They'll keep running the line tests and, who knows, one might fail one day.

In reply to a post by filbert42:

I'm about 1500m (by road) from the cabinet (which, ironically is a about 100m the *other* side of the exchange).

So, is there any point to FTTC, is it all a just a big sham???

Telecoms is all about the statistics. Like everything, FTTC is useful to some people, not so useful to others.

The statistics say that, when you consider your total loop length measured to the exchange (1500m + 100m = 1600m), it is comparatively short: you are in the top 15% of the country.
http://postimg.org/image/dm5cc5tx5/

On the other hand, the same statistics say that the loop length to the cabinet, the D-side only at 1500m, is comparatively long: you are in the bottom 4% of the country.
http://postimg.org/image/bp372fcnn/

The combination together doesn't happen often - so you are comparatively rare. I would guess at less than 0.5% of the country.

But more than 90% of the people in the same position would likely have had a choice of 21CN ADSL2+ (like @edwincluck), and stuck with the 15Mbps+ offered by that. That puts you into a group of around 0.05% of the country ... or around 14,000 premises out of 28 million.

Thanks for the very full reply, WWWombat.

I have to admit that, although I have a reasonable technical background, I don't understand all the technology here.

As far as I can see, my exchange (Suckley - WMSUC) has ADSL Max but not 21CN.

I also didn't expect the sync speed to be radically different from the download speed (and, indeed, my router says it's 6733 and I get download speeds that are near that). What I don't understand is why the BT wholesale speed test is so variable and often so far from reality.

If I look at the BT broadband availability screen, I get results that say that "FTTC Range A (Clean)" speeds are from 12.8 to 19.6 Mbps and "Range B (Impacted)" speeds are from 5.3 to 14.4 Mbps.

I am at the bottom end of "Impacted" and the screen explains what it means by "Impacted" but doesn't tell me how I can find out whether my line is in that category or not. Or whether things can be "fixed".

I have done a quiet line test and it sounds nice and quiet to me.

As for being in the 0.05% there are times when one would prefer to be among the masses! I think I might have to wait for Fibre To The Pole (which is just across the road from me) - which is what I think G.Fast means.

The current position is that my ISP has asked BT to look into it and will absord the charge (I won't post the name before the whole process is finished, I don't think it would be fair to them)

In reply to a post by filbert42:

I also didn't expect the sync speed to be radically different from the download speed (and, indeed, my router says it's 6733 and I get download speeds that are near that).

Which router are you using and can we see all of the stats please?

It's one of those Tecnicolor boxes (TG598v3). Here is a screen-shot of the main page, which I think, gives what you are asking for:

Router Stats

Here's a copy and paste of the text:

Broadband Connection

2.1 Type VDSL
2.2 Status Up
2.3 Uptime 1 days 21 hours 42 mins 7 secs
2.4 Line Rate (Down / Up) 6733 kbps / 1285 kbps
2.5 Noise Margin (Down / Up) 6.3 dB / 6.9 dB
2.6 Attenuation (Down / Up) 35.6 dB / 17.3 dB
2.7 Power (Down / Up) 9.6 dBm / 10.5 dBm

Is there anything more that is useful that I can get from it?

Thanks

Thanks for that. It confirms your line is performing badly.

So in your opinion what is the speed someone should expect with VDSL2 attenuation of 35dB?

I'd suggest in the 4 to 10 Mbps region, but with the caveat that at those distances VDSL2 performance is far from totally predictable

I just had a quick look on MyDslWebStats to see sync speeds others are getting for around the same attenuation and these speeds appear to represent the lower end.

I think 10Mbps should be possible given an ideal connection but I don't know how bad the wiring is between the modem and the cabinet.

I didn't know about that site - useful, I've now put my data up and also the TBB ping monitor. All under 'filbert'

Wow, impressive

I see G.INP is active on your connection

Impressive? In what way?

I'm not convinced about G.INP as the stats page on dslstats shows lots of nothing:

Text

1 23 45 67 89 1011 1213 1415 1617 1819 2021 2223

Downstream              Upstream General        rtx_tx                  0                       0                       rtx_c                   0                       0                       rtx_uc                  0                       0                       LEFTRS                  0                       0                       minEFTR                 0                       0                       errFreeBits             0                       0               Bearer 0         RxQueue                 0                       0                       TxQueue                 0                       0                       G.INP Framing           0                       0                       G.INP Lookback          0                       0                       RRC Bits                0                       0                       Interleave depth        1                       0.00                     INP                     0.00                    0.00                    INPRein                 Not available         Delay                   0.00                    0.00            Bearer 1         Interleave depth        Not available        INP                     Not available         INPRein                 Not available        Delay                   Not available