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Standard User mlmclaren
(fountain of knowledge) Wed 16-Sep-15 10:48:33
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Struggling To Achieve Estimate


[link to this post]
 
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?

Standard User MHC
(sensei) Wed 16-Sep-15 11:09:12
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Re: Struggling To Achieve Estimate


[re: mlmclaren] [link to this post]
 
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.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User mlmclaren
(fountain of knowledge) Wed 16-Sep-15 11:36:41
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Re: Struggling To Achieve Estimate


[re: MHC] [link to this post]
 
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!


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Standard User WWWombat
(knowledge is power) Wed 16-Sep-15 11:52:29
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Re: Struggling To Achieve Estimate


[re: mlmclaren] [link to this post]
 
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.
Standard User mlmclaren
(fountain of knowledge) Wed 16-Sep-15 12:19:01
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Re: Struggling To Achieve Estimate


[re: WWWombat] [link to this post]
 
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.

Standard User simon194
(experienced) Wed 16-Sep-15 19:41:32
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Re: Struggling To Achieve Estimate


[re: mlmclaren] [link to this post]
 
I have almost identical stats to you on a 350m line which has 120m of Aluminium in it.
Standard User kasg
(knowledge is power) Wed 16-Sep-15 20:46:59
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Re: Struggling To Achieve Estimate


[re: mlmclaren] [link to this post]
 
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.

Kevin

plusnet Unlimited Fibre - sync approx 65000/20000 at 450m - BQM
Using OpenDNS
Domains and web hosting with TSOHOST
Standard User RobertoS
(elder) Wed 16-Sep-15 22:27:21
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Re: Struggling To Achieve Estimate


[re: mlmclaren] [link to this post]
 
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 indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. Sync 59999/14372kbps @ 600m. - BQM
Standard User mlmclaren
(fountain of knowledge) Wed 16-Sep-15 22:42:06
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Re: Struggling To Achieve Estimate


[re: RobertoS] [link to this post]
 
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.

Standard User mlmclaren
(fountain of knowledge) Wed 16-Sep-15 22:45:28
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Re: Struggling To Achieve Estimate


[re: simon194] [link to this post]
 
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???

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