Struggling To Achieve Estimate

So been connected with FTTC since February...

I had a new line installed from a DP in the street to my property in new ducting...

The thing I have noticed since install is that my achievable sync is right at the bottom end of my estimates 'seen here'

Measuring my line's length by road and adding a lot of extra length to allow for service loops I get my line length as around 350 - 420 depending on how much I add on to it, according to graphs such as the one found here I should get around 70Mb/s but currently my HG612 gets the bottom end of the estimate and even below depending on time of sync.

My stats from the HG612 are as follows,

# xdslcmd info --show
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 22345 Kbps, Downstream rate = 59152 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 59609 Kbps

Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.1 7.2
Attn(dB): 16.6 0.0
Pwr(dBm): 13.6 7.3
VDSL2 framing
Bearer 0
MSGc: 18 26
B: 239 237
M: 1 1
T: 64 42
R: 0 16
S: 0.1281 0.3781
L: 14984 5374
D: 1 1
I: 240 127
N: 240 254
Counters
Bearer 0
OHF: 44867945 2131886
OHFErr: 107 59
RS: 0 1889042
RSCorr: 0 41
RSUnCorr: 0 0

Bearer 0
HEC: 839 0
OCD: 52 0
LCD: 52 0
Total Cells: 1990448387 0
Data Cells: 151349083 0
Drop Cells: 0
Bit Errors: 0 0

ES: 95 55
SES: 0 0
UAS: 24 24
AS: 92348

Bearer 0
INP: 0.00 0.00
INPRein: 0.00 0.00
delay: 0 0
PER: 2.05 3.98
OR: 93.28 64.22
AgR: 59702.78 20063.54

Bitswap: 14244/14244 3352/3352

I recently switched from Plusnet to Zen due to a list of issues from Customer Service - Performance, due to these issue with Plusnet I never bothered trying to query this but now I'm with a provider that has so far been very helpful during my switch, wondering wether it might be worth asking them to have a look into it and potentially get something done to improve the connection.

The reason I raise this also is when I had my line connected (as this property never had one originally) the Openreach engineer who did the voice line was very reluctant to do the connections every 30 meters as required and only did it a few DP's down until he found a pair that went all the way back to the PCP...

This adds to my concern hat he might of used a pair with a potential fault to fill in a distance such as the one he mentioned ("I found a pair from end of road all the way up to cab, so that saved about 150m")

Currently G.INP has been disabled on my line due to a DLM reset done when I migrated, with G.INP enabled on the downstream I can gain another 8000Kb/s of sync, I currently get 55Mb/s from speed test's and upon joining Zen said I would get 59.8Mb/s down & 18.7Mb/s up...

So whats my chances or should I just leave it as is?

Cannot really suggest what you should do however for comparison: Your line Attenuation figures suggest that you could achieve a higher sync however the 6dB SNR means a "noisy" line and it is sync'd at max possible. My line has a 16.7dB attenuation and is around 420m long - max achievable is normally over 80Mbps.

Had a quick chat with Zen and they where pretty honest by saying that my speed does match the estimate given and that BT (Openreach) wouldn't accept any issue if they tried to raise it as it was within the boundaries...

So pretty much what I expected really... though it's good to know that its possible to get more from the line than currently and that BT Wholesales checker wasn't just winding me up!

My previous line was also 16.7dB attenuation; after a couple of years, crosstalk was invading enough to drop the speed just below 80Mbps.

That line was probably 370-400m, and seemed like decent 0.5mm copper.

Interestingly, the upstream details were pretty much the same as yours, with a max attainable of 22Mbps even with the same (small) amount of FEC protection (16/254).

You aren't experiencing many errors, so the line seems stable. Just not as fast as it could be.

I currently get 55Mb/s from speed test's and upon joining Zen said I would get 59.8Mb/s down & 18.7Mb/s up...

Those estimates from Zen seem to tie very nicely with the bottom of the A-range from BTW. Note that the BTW speeds are line speeds, so are an indication of what sync speed you could get, not what download speeds (or speedtest results)

BTOR will respond to line faults, and to line test results (from the ISP) that say there is a fault. As expected.

However, if there is no indication of a line fault, and the *only* reason for calling an engineer is because of the speed, then they tend to only accept such lines if they are in the bottom 10% of speeds (of similar lines). Or if there has been a sudden, large, drop in speed.

The bottom of the A-range shows the 20th percentile ... so 20% of lines go slower than this, but only the slowest 10% will attract interest.

Currently G.INP has been disabled on my line due to a DLM reset done when I migrated, with G.INP enabled on the downstream I can gain another 8000Kb/s of sync,

That's a hefty improvement. Not the best, but not far off...
http://www.kitz.co.uk/adsl/images/retransmission_lin...

I'm not sure I've seen BTW's estimates change as a consequence of G.INP, but that extra 8Mbps drives you well away from getting an Openreach engineer to attend.

Well currently I'm just happy to have a stable connection and with a property move imminent, it's not something I'm too worried about...

upstream is my main priority, downstream only becomes an issue when it drops below 40-50Mb/s.

I noticed that nearly all ISP's now estimate the lowest figure from BTw's checker, suppose it so customers don't get [censored] at the ISP when they can't get Openreach out.

Currently though all looks pretty good, alot of locals have come over to FTTC in the last few months after Virgin Media failing on there promises for 5/6th year running ....

Crosstalk seems to have been only a tiny issue for me with me losing around 3000Kbps but then I can gain that back if I sync at the right time and then the SNR just varies between 5.9 & 6.3 that I've seen.

I have almost identical stats to you on a 350m line which has 120m of Aluminium in it.

My FTTC estimates are absolutely identical to yours, down to the decimal points. I reckon my distance to the cabinet is about 450m. My current sync is 64769/19999 but has been over 70000 for short periods.

It's worth noting that you are on Fast Path.

G.INP in general comes in and replaces Interleaving from what we have seen in the shortish time it has been available, so getting rid of the speed loss caused by historical Interleaving on FTTC. As you do not have Interleaving, it's possible G.INP will not come into play.

I suspect something did change in your exchange connections on migration, that did have a direct effect on your sync.

The DLM has been reset on the line and has put it back to what it used to be before G.INP...

Yes, you are correct, G.INP does normally replace Interleaving but based on my line clocking up errors I reckon it will switch soon... I just hope this time it does the upstream too.

In reply to a post by simon194:

I have almost identical stats to you on a 350m line which has 120m of Aluminium in it.

Yes I do suspect there may be Alu at play here... it's not just my connection thats like it to be fair and based on the wide estimates given by BT Wholesale it wouldn't surprise me if they had notes on the system to make the checker aware of it.

I would say it was noise but the landline phone quiet tests are the quietest I've ever heard so???

Ummm. I have my doubts. You may get G.INP, but no significant speed gain.

Edited by RobertoS (Wed 16-Sep-15 22:51:47)

Well I'm not too fussed to be honest... just want the best stability and consistency from the line possible..

I was going to upload about 15-20GB's worth off stuff to One Drive and a few FTP uploads too while at work but PC went into standby so looks like I'll be running them through the night

Attenuation seems high for that length of line.

Max: Upstream rate = 21369 Kbps, Downstream rate = 64028 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 64031 Kbps

Down Up
SNR (dB): 6.2 6.9
Attn(dB): 17.2 0.0
Pwr(dBm): 14.0 7.2

Line length 500m +/- 20m.

All copper, tested to death previously due to very severe issues so very clean; very, very, very heavy crosstalk.

Edited by deleted (Wed 16-Sep-15 23:42:13)

Aye, I thought that too... I reckon Openreach Voice Engineer couldn't be arsed to do a good job and just grabbed a pair down the road that might of been unused due to a fault possibly...

Oh well, take what I can get at the moment, won't be here to much longer anyway.

When G.inp got switched on on my line, I gained about 6Mbps! I was syncing at around 60000Kbps before that. Here's my stats now on a 350m (according to BT but attenuation suggests it could be longer) line:

Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 6.3 6.1
Attenuation (dB) 19.4 0.0
Output Power (dBm) 12.6 7.4
Attainable Rate (Kbps) 66252 16665
Rate (Kbps) 66212 16703
B (# of bytes in Mux Data Frame) 243 237
M (# of Mux Data Frames in an RS codeword) 1 1
T (# of Mux Data Frames in an OH sub-frame) 0 64
R (# of redundancy bytes in the RS codeword) 10 16
S (# of data symbols over which the RS code word spans) 0.1173 0.4534
L (# of bits transmitted in each data symbol) 17327 4482
D (interleaver depth) 8 1
I (interleaver block size in bytes) 254 127
N (RS codeword size) 254 254
Delay (msec) 0 0
INP (DMT symbol) 49.00 0.00

Edited by WelshWArrior (Thu 17-Sep-15 08:17:22)

59.1meg sync on a 59.7 estimate I dont think anyone will treat that as a fault.

is the upper estimate 80th percentile?

No wonder my engineer looked gutted after my pair swap, I was happy to get back above 70mbit but he seemed shocked as if he was expecting the full 80.

I know, it's the reason I've never really bother trying to report it..

In reply to a post by Chrysalis:

is the upper estimate 80th percentile?

Yes.