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FTTC Fibre using backwards technology in the UK

ezplanet
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FTTC Fibre using backwards technology in the UK

I am a business user with 2 sites, my main site is in the UK and the secondary site is in Italy.

In both cases the sites are at the outskirts of a small town, both are at the furthest possible distance from the telephone exchange.

Until recently both sites had ADSL, the speeds at both sites were quite comparable, both within 10% of 8.8 Mbit/s download and 900 Kbit/s upload.

Back in August 2019 I decided to upgrade from ADSL to Fibre in the Italy site. In the area they just upgraded the local cabinet to FTTC availability, so I went for it. My ISP in Italy is Vodafone. The upgrade on my end involved removing the microfilter, which was no longer necessary, the whole bandwith is thus taken by the FIBRE line. The telephone is now provided via an IP phone. Vodafone provides their Vodafone Station Revolution with an RJ11 socket to plug your phone into, however, since I prefer to use my equipment I plugged in instead a BT Home Hub 5 modified and flashed with OpenWRT. For the phone I purchased separately an IP Phone device.

The speeds obtained are as follows:

ATU-C Vendor ID:                         Broadcom 192.20
ATU-C System Vendor ID:                  Broadcom
Chipset:                                 Lantiq-VRX200
Firmware Version:                        5.7.9.9.0.6
API Version:                             4.17.18.6
XTSE Capabilities:                       0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2
Annex:                                   B
Line Mode:                               G.993.2 (VDSL2)
Profile:                                 17a
Line State:                              UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS): Near: 0 / Far: 2
Errored seconds (ES):                    Near: 0 / Far: 1
Severely Errored Seconds (SES):          Near: 0 / Far: 0
Loss of Signal Seconds (LOSS):           Near: 0 / Far: 0
Unavailable Seconds (UAS):               Near: 88 / Far: 88
Header Error Code Errors (HEC):          Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P):       Near: 0 / Far: 0
Pre-emtive CRC errors (CRCP_P):          Near: 0 / Far: 0
Power Management Mode:                   L0 - Synchronized
Latency [Interleave Delay]:              0.14 ms [Fast] 0.0 ms [Fast]
Data Rate:                               Down: 100.484 Mb/s / Up: 18.911 Mb/s
Line Attenuation (LATN):                 Down: 7.4 dB / Up: 7.3 dB
Signal Attenuation (SATN):               Down: 7.4 dB / Up: 7.5 dB
Noise Margin (SNR):                      Down: 7.0 dB / Up: 9.2 dB
Aggregate Transmit Power (ACTATP):       Down: -22.4 dB / Up: 12.5 dB
Max. Attainable Data Rate (ATTNDR):      Down: 115.063 Mb/s / Up: 29.989 Mb/s
Line Uptime Seconds:                     152224
Line Uptime:                             1d 18h 17m 4s

 

As you can see from the above the line can do a lot more, but Vodafone Italy caps it to 100/18.

The advantage of this technical configuration (practiced by all providers in Italy) is that the telephone line is no longer shared with a telefone and thus the whole bandwith is used for the FTTC fibre.

 

Encouraged by the success in Italy, in January 2020 I requested PlusNet to upgrade my UK site from ADSL to fibre (FTTC).

The first surprise was that the phone and microfilters had to be left in place, as phone and fibre had to continue to share the same copper pair. Nedless to say that this is an awful waste of bandwidth especially because, in general, we rarely use the landline, but also because this is our secondary phone line and we never use the phone at all. In Italy too, we make most use of mobile phones that have cheaper calling plans.

And here is the result of the performance for the UK based PlusNet FTTC:

ATU-C Vendor ID:                         Infineon 178.6
ATU-C System Vendor ID:                  45,43,49,20,74,65,6C,65
Chipset:                                 Lantiq-VRX200
Firmware Version:                        5.7.9.9.0.6
API Version:                             4.17.18.6
XTSE Capabilities:                       0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2
Annex:                                   B
Line Mode:                               G.993.2 (VDSL2)
Profile:                                 17a
Line State:                              UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS): Near: 97878 / Far: 1361
Errored seconds (ES):                    Near: 8 / Far: 162
Severely Errored Seconds (SES):          Near: 0 / Far: 0
Loss of Signal Seconds (LOSS):           Near: 0 / Far: 202
Unavailable Seconds (UAS):               Near: 56 / Far: 56
Header Error Code Errors (HEC):          Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P):       Near: 7 / Far: 0
Pre-emtive CRC errors (CRCP_P):          Near: 0 / Far: 0
Power Management Mode:                   L0 - Synchronized
Latency [Interleave Delay]:              8.0 ms [Interleave] 0.0 ms [Fast]
Data Rate: Down:                         33.639 Mb/s / Up: 7.518 Mb/s
Line Attenuation (LATN):                 Down: 23.7 dB / Up: 33.5 dB
Signal Attenuation (SATN):               Down: 21.1 dB / Up: 33.0 dB
Noise Margin (SNR): Down:                6.0 dB / Up: 6.2 dB
Aggregate Transmit Power (ACTATP):       Down: 5.0 dB / Up: 5.1 dB
Max. Attainable Data Rate (ATTNDR):      Down: 38.780 Mb/s / Up: 7.738 Mb/s
Line Uptime Seconds:                     9323
Line Uptime:                             2h 35m 23s

 

On the UK line there is only one phone plugged in and the microfilter is brand new.

 

The result for the UK fibre is appalling. I am not sure why they even call it 'fibre' when the performance is comparable to a good ADSL.

Why are we so backwards in the UK? Why do we have to share the same copper for FIBRE and Phone and we cannot have the whole bandwidth used for the Fibre with the telephone service provided via IP as they do in Italy?

32 REPLIES 32
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Re: FTTC Fibre using backwards technology in the UK


Moderators Note


This topic has been released from the Spam filter and moved to Business from Fibre.

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dws1900
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Re: FTTC Fibre using backwards technology in the UK

@ezplanet 

 

If you search  for

peter cochrane thatcher techradar

You will see why. Sad

 

As for why its called 'fibre' when its really hybrid fibre (in the case of FTTC), the reason is marketing, making something sound better than it really is.

 

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Re: FTTC Fibre using backwards technology in the UK

The amount of bandwidth used by the voice telephone signal on the line is negligible and will have virtually nothing to do with why one is faster than the other. The main difference, based on the different attenuation values, will be due to the distance from the cabinet.

ezplanet
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Re: FTTC Fibre using backwards technology in the UK

@ejs, what you are saying is not true. Since the voice telephone frequencies are right in the middle of the broadband spectrum, this limits the available VDSL bandwidth proportionally more than what it would otherwise. The evidence is right in my first post. Those two lines had surprisingly comparable performance when they were both ADSL and BOTH shared the telephone line with the broadband service. Now the Italy line no longer shares its bandwidth with a telephone and look at the bandwidth we get!

Plusnet Help Team
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Re: FTTC Fibre using backwards technology in the UK

I can confirm that the distance to the cabinet matters most on FTTC. It's not uncommon to get good ADSL speeds (similar to what you had in Italy) but an FTTC service to perform relatively slowly. You'd likely just simply be close to the exchange but far away from the cabinet. Smiley

[edit]

To add there are countless people getting full 80mbps FTTC which indicates that the phone line has no effect other than the quality/distance.

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 Anoush Mortazavi
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dws1900
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Re: FTTC Fibre using backwards technology in the UK

@ezplanet 

 

POTS/ADSL/VDSL Spectrum, see attached

Superuser
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Re: FTTC Fibre using backwards technology in the UK

Well that disproves the ‘phone spectrum is in the middle of VDSL’ statement.

ADSL performance is predicated on the overall length of e-side plus d-side circuit. VDSL is predicated only one the d-side length. VDSL performance falls off sharply on d-side length as well.

It is not enough to compare ADSL to VDSL performances based on overall circuit length - you need to also know where the ‘local’ cabinet is located.
dws1900
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Re: FTTC Fibre using backwards technology in the UK

@Gandalf 

I can confirm that if you are too far away from the dslam, for example 1500m, you will not even get the often quoted UK superbroadband speed of 24Mbs, let alone the EU definition of 30Mbs.

ADSL connection speed was 17Mbs, VDSL connection speed currently 22.5Mbs.

Guess I will have to move to the city, or into a field(to get the new rural coverage), being an In-betweenie really sucks!!

Real value for money Sad

RealAleMadrid
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Re: FTTC Fibre using backwards technology in the UK

@ezplanet 

The VDSL technology in the two countries is more or less the same, your diagnosis that removing the phone component from the VDSL line causes a massive speed increase is totally wrong. As other posters have said you cannot directly compare ADSL and VDSL lines based on only distance to the exchange. As EJS states the reason for the lower speed in the UK is purely due to the greater distance to the FTTC cabinet.

 

ezplanet
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Re: FTTC Fibre using backwards technology in the UK

OK, let me ask one question: what is the maximum speed that can be achived with FTTC in the UK. Let's say I am in sight of the cabinet and the copper is about 6/10 metres just the cable length to go from my indoor's socket, through the bends around the walls, under the drive to the cabinet right by the side of the entrance to my drive...if that were the case, what is the maximum download/upload speed?

 

Plusnet Help Team
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Re: FTTC Fibre using backwards technology in the UK

Download speed of 80mbps and upload speed of 20mbps as the highest FTTC product is 80/20 but I believe the maximum achievable is something like 100/40 however with G.Fast technology that still uses the copper line it's about 200/50.

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 Anoush Mortazavi
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dws1900
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Re: FTTC Fibre using backwards technology in the UK

@ezplanet 

 

Theoretically see diagram

Practically using GFast if available > 100Mbs

FTTC upper Band 80Mbs

Check speed availability http://www.dslchecker.bt.com/adsl/ADSLChecker.welcome

Request GEA from Plusnet test to determine the length of the line.

You may be surprised as it may not be as direct as you expect.

 

ezplanet
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Re: FTTC Fibre using backwards technology in the UK

If I understand correctly the latest reply, the maximum download speed available with FTTC (VDSL2 Profile 17a) sharing the copper pair with a telephone line is 80 Mbit/s.

I think that in this case we can ignore all the comments around telephone bandwidth and the negligibility of the impact of sharing a telephone with FTTC on the same copper pair using microfilters because the impact of having the telephone line is easily calculated:

 

100 Mbit/s   (maximum FTTC VDSL2 17a profile)

less

 80 Mbit/s  (maximum achievable sharing FTTC with phone as declared above)

equals:

20 Mbit/s which is the speed/bandwidth we indeed loose by sharing the copper wire with a telephone line (see my first post and the comparison with how the FTTC is supplied in Italy)

 

Given that those 20 Mbit/s are a constant that cannot be changed (the microfilters take a constant frequency bandwidth), in case of a clean line without losses, 20 Mbit/s represent only 20% of the copper pair capacity, however the further we get from the cabinet the greater the impact over the FTTC bandwith (remember, the telephone bandwidth is a constant and therefore it does not reduce proportionally with distance).

 

From the above I can deduce that if my UK line (now achieving only a little over 30 Mbit/s, see first post) was not sharing the copper pair with a telephone I could expect a download speed of around 50 Mbit/s, thus the telephone line impacts by 40% on my available bandwitdth.

 

Why is nothing being done to improve this situation by moving the telephone line to IP Phones as they do in Italy?

Plusnet Help Team
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Re: FTTC Fibre using backwards technology in the UK

@ezplanet As per my previous post, the maximum achievable speed on FTTC could be in excess of 100mbps and on G.Fast over 200mbps. Both of these services use the copper phone line back to the cabinet. Smiley

[edit]

Openreach are working towards supplying properties with FTTP (fibre straight from the exchange to the property) but it's not an endeavour that will happen overnight, there's a considerable amount of work to replace the copper infrastructure across the country. Generally from what I've seen, the areas which can't get FTTC look to be getting FTTP first.

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