Openreach to rollout 3dB target SNRm for FTTC next year

1.2.2
VDSL2 noise margins
Currently the default target downstream noise margin is set to 6dB.
From March 2017 the target downstream noise margin shall be set to either 3, 4, 5 or 6dB
the actual value shall be determined by the Dynamic Line Management (DLM) algorithm based on line stability.

http://www.btplc.com/sinet/SINs/pdf/498v7p2a.pdf

Great news for those on stable, but longer lines.

Based on our observations speed increases are roughly in line with the following figures.

~ For existing Sync speeds of around 20Mbps - each 3dB is worth 3Mbps
~ For existing Sync speeds of around 40Mbps - each 3dB is worth 6Mbps
~ For existing Sync speeds of 60Mbps or more - each 3dB is worth 11Mbps.

BT wholesale ADSL (copper) lines already have a 3dB profile available to them. Obviously this increase wont make any difference if you are already syncing at the maximum speed ie 80Mbps or 40Mbps if you are on a 40/10 or 40/2 product.

Good find Max. Thanks .

Actually it was kitz who spotted this.

Thanks for clarifying as well . She's a star. Probably knew before the SIN was updated .

Yep. But sadly Target 3dB SNRm won't benefit me at all. Stayed with 80/20 (wish openreach uncapped 80/20 for the line to go faster as it support to the maximum Attainable Rate)

Edited by adslmax (Mon 14-Nov-16 23:16:55)

Unlikely to happen with G.fast around the corner. If people close to the cab could get say 120meg with VDSL2 unrestricted then they're not going to pay the premium for 160meg. However, a doubling of the speed from 80 to 160 by upgrading to G.fast will be more appealing and appear as "better value for money".

This has been testing for a while in certain areas. I've yet to see it on a line though presumably wasn't in my area.

On my service, on a stable line with the connection speeds you see in my sync, I'll be quite pleased to see this.

Relatively few people are close enough to get 80/20, and many in 40/n can't even get that. I'll be quite surprised in G.Fast comes in free.

I didn't mean G.fast would be free.

If someone is on 80/20 and want more speed, then I imagine they'd be more likely to pay the premium for G.Fast than if they were already getting say 110mbps from an unrestricted VDSL connection.

Would be nice if they gave use a free speed increase, change profile from 80/20 to 120/20, then you pay extra for 160/20 & upwards.
And also tweak lower profile say to 60/20 to help those on the lower speeds, I kmow a few who can't get 80/20, but could get around 57/15.

There is a potential scenario where a VDSL2 cab runs out of ports but G.fast ports are available, and they might move people across to free up VDSL2 capacity. Whether that would happen no idea but the wholesale and EOI requirements make that sort of thing harder

Not a very good business model.

I guess this could benefit me. My SNRM hovers around 5dB and my sync is over 4Mbps higher than my attainable, which is presumably based on 6dB.

In reply to a post by lee111s:

I didn't mean G.fast would be free.

If someone is on 80/20 and want more speed, then I imagine they'd be more likely to pay the premium for G.Fast than if they were already getting say 110mbps from an unrestricted VDSL connection.

Well that's pretty much the way it's been on Virgin for a long time when they did free boosts but also offered higher tiers, If BT went that way I think it would be a very good business model to adopt

BT Consumer offer 55/10. Not as well as, but instead of, 40/10.

Virgin operate their own network AND bill end users.

Openreach is completely different.

Openreach builds where its customers, the Communications Providers, want it to. Those Communications Providers being BT Wholesale, Sky, TalkTalk and Vodafone. Plus a few small fry who do not use any of those.

BT is the largest fixed broadband provider in the UK, with a market share of 31 per cent. Sky and Virgin Media both have a market share of about 20 per cent, while TalkTalk has a 15 per cent share and EE has 3 per cent.

That's for mid-2015, according to the Financial Times.

BT Wholesale and Openreach are part of BT Group, and it is unrealistic to think pricing structures are not discussed at Group level, even if BT Wholesale is excluded from the discussion.

I stand by my point that it's very unlikely that VDSL2 on the Openreach network will go above 80/20.

In reply to a post by MrSaffron:

There is a potential scenario where a VDSL2 cab runs out of ports but G.fast ports are available, and they might move people across to free up VDSL2 capacity. Whether that would happen no idea but the wholesale and EOI requirements make that sort of thing harder

That doesn't sound like something Openreach would do, unlikely I think.

I can't even begin to describe how excited I am by this.

BT are really pushing the envelope here. State of the art a decade ago.

I am happy but also find it comical for the reasons you said.

Its took them about 4 years to rollout g.inp on hauwei from first vdsl cabinet deployment.
Its still not rolled out on ECI even tho g.inp has been around for almost a decade.

5 years into FTTC they decide they can do 3db profiles, and if ECI doesnt get a working g.inp this upcoming spring these profiles are likely to further widen the gap between ECI and hauwei on performance as its way easier to achieve a stable 3db with g.inp.



Really fast decision making at BT towers

My line currently on 4.6db snrm has comparable error rates to 6.4db tho, so I wonder if I can hold out the sync till next march with further crosstalk dropping it to around 3db and BT drop my target snrm I can then keep my sync speed. Fun times

Edited by Chrysalis (Tue 15-Nov-16 22:44:57)

Chatting to a Kellys engineer he told me the strategy for the 3db profile is so BT can offer a speed boost for infinity 2 customers following the upgrade to infinity 1. Scuttlebutt is it will be up to 100mb, which also means offering a speed directly comparable to Virgins package.

I wouldn't treat a Kelly's 'Engineer' words as gospel because they're usually full of <insert expletive here>

I wouldn't treat a Kelly's 'Engineer' words as gospel because they're usually full of <insert expletive here

Superb

In reply to a post by Nightglow:

Would be nice if they gave use a free speed increase, change profile from 80/20 to 120/20, then you pay extra for 160/20 & upwards.
And also tweak lower profile say to 60/20 to help those on the lower speeds, I kmow a few who can't get 80/20, but could get around 57/15.

Free upgrades are very difficult for Openreach. Would harm the business case for G.fast too. They are going to have a hard enough time trying to prise open the vice-like wallet of the average UK consumer to get then to part with more cash without reducing the difference between the products more.

Sky and TalkTalk would probably go to Ofcom with complaints that Openreach were overcharging for 80/20 if they were to offer more for free.

A non-starter I suspect.

I liked the quotation marks. Subtle.

John

I'm still on my seemingly "stuck" 35M profile, it's been that way for around 9 months now, after a failed attempt to use a HH5a as VDSL modem, as well as trying a new router (which was better) got DLMs attention.

My link is solid now for 50 days -- it's only gone down through powercut or me moving kit (which I leave off for 30 mins+ now)

34999 7.7dB / 6995 7.4dB

I wonder if the shift to potential 3/4/5 dB will release me from 34999. So far I've not put the effort into raising a fault report/visit, and indeed whether I will or not may depend on how long the new virgin cable infrastructure being deployed here (cabs/cables all in in my road in mid Dec, no service yet) takes before it's offered and I go 200 or 300 Mbps.

In theory, the philosophy that Openreach ought to employ would be:
- reduce target SNRM
- monitor resulting error rates
- reduce further if error rate is green; stop reducing if error rate is amber; increase back if error rate is red.

Lines that have been banded from high error rates are unlikely to be able to stomach any reduction in target SNRM, as it would cause extra errors. In fact banding can be considered as an alternative method to increasing the target SNRM (in your case to 7.5dB).

IMHO, DLM has been particularly aggressive in use of banding in the last 6-8 months, and particularly lax about removal of banding. Openreach will need to rethink the impact of DLM and banding if dynamic SNRMs are to be useful to those lines.

DLM has decided to reduced SNR to 6.6 from 12.1 after 392 days connected as it went downtime this morning for a few minute - here is full stats:

Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 6.0 6.1
Attenuation (dB) 11.3 0.0
Output Power (dBm) 12.5 -1.2
Attainable Rate (Kbps) 83367 21278
Rate (Kbps) 79999 19999

Edited by adslmax (Wed 11-Jan-17 17:44:51)

Or maybe my cabinet is reduced SNR cos of more taken in or due to crosstalk?

Openreach will be extending their 'trial' of the variable dB and new DLM algorithm from Monday 16 January to select cabinets on the following exchanges (below).

A few points here though:

- ECI cabinets are excluded (I assume the new DLM is not fully tested/supported yet).
- Any line that has had the existing DLM intervene, due to poor performance, will be excluded from being moved over.
- Around 10% of lines are expected to move to the new XdB and DLM algo.

Ashburton
Ashcott
Ashreigney
Ashwater
Axbridge
Axminster
Baltonsborough
Bampton, Devon
Banwell
Barnstaple
Bath Kingsmead
Batheaston
Beaford
Beaworthy
Beckington
Bere Alston
Bickington
Bickleigh
Bideford
Bigbury-On-Sea
Bishops Lydeard
Bishops Nympton
Black Torrington
Blackawton
Blagdon
Blagdon Hill
Bleadon
Bovey Tracey
Bow
Box
Bradford -On-Avon
Bradford- On-Tone
Bradworthy
Branscombe
Bratton Clovelly
Braunton
Brayford
Brean Down
Brent Knoll
Bridestowe
Bridgerule
Bridgwater
Bristol West
Brixham
Broadhembury
Bruton
Buckfastleigh
Buckland St.Mary
Budleigh Salterton
Burnham-On-Sea
Burrowbridge
Castle Cary
Chagford
Chapmanslade
Chard
Charlton Mackrell
Cheddar
Chelston
Cheriton Bishop
Cheriton Fitzpaine
Chew Magna
Chewton Mendip
Chillaton
Chilton Polden
Chiselborough
Chittlehamholt
Chudleigh
Chulmleigh
Churchill
Churston
Clevedon
Clovelly
Colaton Raleigh
Colyton
Combe Down
Combe Martin
Combwich
Compton Dando
Copplestone
Cornwood
Corscombe
Corton Denham
Craddock
Cranmore
Crediton
Crewkerne
Crowcombe
Crownhill
Croyde
Cullompton
Dartmouth
Dawlish
Devonport
Ditcheat
Dittisham
Dolton
Drewsteignton
Dulverton
Dunster
East Allington
Edingworth
Evercreech
Exbourne
Exeter
Exeter Exminster
Exford
Exmouth
Faulkland
Feniton
Flax Bourton
Frogmore
Frome
Gara Bridge
Glastonbury
Harbertonford
Hartland
Hatch Beauchamp
Hatherleigh
Hawkchurch
Haytor
Hele
Hemyock
Henlade
High Bickington
Holbeton
Holford
Holsworthy
Honiton
Horns Cross
Ilchester
Ilfracombe
Ilminster
Instow
Ipplepen
Isle Brewers
Ivybridge
Kennford
Kentisbeare
Kingsbridge
Kingskerswell
Kingston St Mary
Kingswear
Langport
Langtree
Lapford
Launceston
Lewdown
Lifton
Limpley Stoke
Loddiswell
Long Ashton
Long Sutton, Somerset
Longdown
Lulsgate
Luppitt
Lustleigh
Lydeard St.Lawrence
Lydford
Lyme Regis
Lynton
Maiden Bradley
Manaton
Mark Moor
Marston Magna
Martock
Meare Heath
Mells
Midsomer Norton
Milborne Port
Milverton
Minehead
Modbury
Morchard Bishop
Moretonhampstead
Nailsea
Nether Stowey
Newton Abbot
Newton Ferrers
Newton St.Cyres
Newton Tracey
North Cadbury
North Curry
North Molton
North Petherton
North Tawton
Nunney
Oakford
Oakhill
Okehampton
Ottery St.Mary
Paignton
Pill
Pilton
Pinhoe
Plymouth
Plymstock
Porlock
Portishead
Priddy
Princetown
Puriton
Radstock
Roborough
Salcombe
Saltford
Sampford Peverell
Seaton
Shaldon
Shaugh Prior
Shebbear
Shepton Mallet
Shiphay Collaton
Shirwell
Sidbury
Sidmouth
Silverton
Somerton
South Brent
South Chard
South Molton
South Petherton
Sowton
Spaxton
St. Budeaux
St. Marychurch
Stalbridge
Starcross
Staverton
Stockland
Stogumber
Stoke Canon
Stoke Fleming
Stoke Gabriel
Stratton On The Fosse
Street
Stroud
Sutton Cross
Swimbridge
Taunton
Tavistock
Tedburn St.Mary
Teignmouth
Temple Cloud
Templecombe
Timberscombe
Timsbury
Tiverton
Topsham
Torcross
Torquay
Torrington
Totnes
Trowbridge
Washford
Wedmore
Wellington
Wells
Wembury
West Coker
West Harptree
Weston Super Mare
Weston Zoyland
Whiddon Down
Whimple
Widecombe -In-The-Moor
Williton
Wincanton
Winkleigh
Winscombe
Winsford, Somerset
Witheridge
Wiveliscombe
Woodbury
Woolacombe
Worle
Wrington
Yatton
Yealmpton
Yelverton
Yeovil
Yetminster

Unbelievable (nothing for Cuckoo Oak) ?

I appreciate the information but its a case of "no surprise" with the ECI cabinets as rolling out 3db without g.inp is risky.

why do you want 3db? you have a max sync anyway.

I suppose so! But I start to worrying now because my Sync Rate might reduced pretty soon or later because of Attainable Rate have dropping slighty since 2014. Before used to be 113675k but now at 83367k. The SNR also drop too since 2014. Before use to be at 13.7dB now at 6.0dB.

Edited by adslmax (Wed 11-Jan-17 20:24:18)

You're syncing max rate anyway right? So makes no difference to you...

I guess you show that SNR of 7.7dB is equivalent to about 33Mbps.

If you get a target of 3dB, your attainable is likely to increase by 12Mbps - ish.

I wonder why the remote system would lower the SNR if the line in question already achieves max sync ?
Surely it would be better to have a little built in stability ?

Crosstalk is the only reason can think of, in which case the max attainable wouldn't really increase by 12meg or whatever, it would simply allow it to maintain a higher connection rate?

No Midlands exchanges on that list by the looks.

Looks like crosstalk to me.

Mines gone from 82Mb attainable to 68Mb in 18 months and the cab is pretty much full now.

Hmmm not 1 Welsh exchange on that list as far as I can see. Wonder why that is? Where do you get this list?

Don't get too worried, I see none for around this way (SE of England) either.

I'm not that bothered - just thought it was a bit strange that there aren't any Welsh exchanges mentioned at all. I'm happy with my 64Mbps-ish sync @ 6.2db for now.

I wonder what sort of increase I'd get when it does kick in nation-wide??

No North East ones either, I wouldn't worry.

Probably somewhere in the region of 6-12meg extra.

That would be a nice gain. Even at 64Mbps, with BT TV, 2 Laptops and 2 kids on their tablets, my connection is showing hints of starting to struggle

Unless you're constatly streaming UHD or downloading large files all of the time, then it really shouldn't be.

64mbps would get you 10 simultaneous HD Iplayer streams.

It looks like the only exchanges to get this update are all down south. is this the north south divide again. None as I can see in the north west

It not that bad really. I do watch some of the UHD content on BT. I think the times it struggles is when BT TV is showing 1 channel and recording 2 more porgrams at same time, coupled with the girls watching youtube on their tablets and the wife doing what she does on her laptop!

Still can't complain - a mate who lives about 500m from me still only gets 0.5Mbps!!

I'll comment here rather than on several other posts that are complaining about North/South diviude, no exchanges in Wales, nothing in NE, none is SE ...

All of the exchanges appear to be those located in just one region - South West England, Somerset, Devon, Cornwall and may be Wiltshire. That seems to be a sensible choice rather than dotted around all over the UK.

I believe it's all in Devon and Somerset.

Trowbridge is Wiltshire, Bristol West is ??? I thought I had seen one or two in Cornwall but without getting an atlas. The pint is still valid that they are in just one defined geographic area

Actually you're right. Main concentration does seem to be Devon and Somerset with some bordering areas in other counties included.

And Chapmanslade is also in Wiltshire, yet they miss Warminster & Westbury both are only 3 miles from the village.

Edited by Nightglow (Thu 12-Jan-17 11:15:22)

There will be good reason and a boundary needs to be drawn ...

Maybe it is based on where the main fibre connections and hubs are ... Perhaps Chapmansbury goes to Frome in Somerset whereas the others could be linked to somewhere like Salisbury.

My FTTC connection at my mother's is on one of the affected exchanges. It was one of the first to be enabled on the cabinet in May. Between mid June and October I lost 12 Mbps. I wonder what will happen after 16/01.

TBB speed tests

Wed 11/01/17 21:15	55.13 Mbps	57.67 Mbps	18.60 Mbps
Wed 11/01/17 04:55	58.23 Mbps	58.12 Mbps	18.61 Mbps
Thu 22/12/16 23:23	58.18 Mbps	57.77 Mbps	18.62 Mbps
Fri 04/11/16 06:25	57.83 Mbps	57.69 Mbps	18.59 Mbps
Sun 30/10/16 14:22	57.85 Mbps	57.59 Mbps	18.57 Mbps
Fri 17/06/16 04:44	69.93 Mbps	69.95 Mbps	18.43 Mbps
Sun 12/06/16 23:29	69.92 Mbps	69.63 Mbps	18.59 Mbps
Sun 12/06/16 03:12	69.81 Mbps	69.87 Mbps	18.60 Mbps
Tue 31/05/16 17:17	67.04 Mbps	66.65 Mbps	18.59 Mbps
Sun 29/05/16 23:03	49.36 Mbps	73.47 Mbps	18.64 Mbps
Thu 26/05/16 02:50	74.04 Mbps	73.85 Mbps	18.61 Mbps
Mon 23/05/16 17:11	74.10 Mbps	44.76 Mbps	17.73 Mbps

BT HH5 Troubleshooting extract

1.	Product Name:	HomeHub5
3.	Firmware version:	v0.07.06.09028-BT (Type B) Last updated 3/11/2016
4.	Board version:	01
5.	VDSL uptime:	4 days, 16:11:10
6.	Data Rate:	19999 / 62582
7.	Maximum Data Rate:	22937 / 62491
8.	Noise Margin:	7.6 / 6.0
9.	Line Attenuation:	22.5 / 18.1

No one, apart from those in BT, knows what the parameters are to switch from a 6dB to 3dB profile or back. It could look at up time, error rates, total errors, SNR variation over 24/48 hours, how close you are to your service speed (80/55/40/15), have you have 3dB before and DLM reverted you to 6dB and probably a combination of factors.

It will be a case of wait and see.

I live in Frome, we are on the list but 99% of Frome is on ECI which according to the post over on kitz is excluded

In reply to a post by wolvesmad:

No Midlands exchanges on that list by the looks.

There is one! Wellington, Telford, West Midlands

In reply to a post by adslmax:

In reply to a post by wolvesmad:

No Midlands exchanges on that list by the looks.

There is one! Wellington, Telford, West Midlands

WRONG

That is most likely to be Wellington in Somerset

Well I hope g.inp gets resolved in the spring on my eci cab then I might see the lower snr at some point here in Frome..

Edited by choppersrock (Thu 12-Jan-17 17:41:28)

In reply to a post by Zarjaz:

I wonder why the remote system would lower the SNR if the line in question already achieves max sync ?
Surely it would be better to have a little built in stability ?

The O&M system might reduce the target SNRM, but if the actual sync is already at the maximum then it wouldn't / couldn't reduce the actual SNRM to be less than the current 6dB.

Of course, if takeup slowly increases the crosstalk, that max attainable is going to come down anyway...

In reply to a post by MHC:

There will be good reason and a boundary needs to be drawn ...

I just saw that BT are behind on getting to their phase 1 target in CDS - by around 10,000 premises.

Perhaps this just helps them bring a few more subscribers into SFBB range.

As it is a BDUK thing, then the intervention area has likely been done by Huawei cabinets anyway.

In reply to a post by smallal:

Chatting to a Kellys engineer he told me the strategy for the 3db profile is so BT can offer a speed boost for infinity 2 customers following the upgrade to infinity 1. Scuttlebutt is it will be up to 100mb, which also means offering a speed directly comparable to Virgins package.

Now how the hell would a Kelly's employee know anything about BT strategy? Ignore him.

In reply to a post by Icaras:

In reply to a post by smallal:

Chatting to a Kellys engineer he told me the strategy for the 3db profile is so BT can offer a speed boost for infinity 2 customers following the upgrade to infinity 1. Scuttlebutt is it will be up to 100mb, which also means offering a speed directly comparable to Virgins package.

Now how the hell would a Kelly's employee know anything about BT strategy? Ignore him.

Wait & see

Edited by Nightglow (Fri 13-Jan-17 10:01:48)

Given a few more hours in a day will be able to create a special group for the postcodes believed to be involved, and can then do comparisons for FTTC speeds compared to say 12 months ago

On the CDS scenario, don't know the exact number of premises in contract paperwork as was signed, but in terms of delivery the fighting is going to be about the drop from VDSL2 coverage, to 24 Mbps or 30 Mbps thresholds. In what has been delivered 84% can get over 24 Mbps and a lower 81.8% on our figures. That said there is some FTTP still in build, and there has been some infill work. Will do an overall CDS report at weekend, as the commercial areas have an impact on the 90% target too.

What I will say is I am expecting CDS to fight tooth and nail over even a slight delay even if this just down to extra time needed for FTTP work. The journey so far has not been a friendly one.

Interesting to see my Exchange listed in this.

I was the first to get FTTC when my cabinet was done:.
- Speedtest: 55Mb/s download and 17Mb/s upload
- IP Profile: 57.1Mb/s download and 20Mb/s upload.

After a few weeks
- Speedtest: 52Mb/s download
- IP Profile: 53.89Mb/s download
When ordering the speed estimate given by BT was 51.5Mb/s so still pretty much spot on.

Then on 3/10/2013 my neighbour got FTTC and gave me a big hit. In one day:
- IP Profile: 36.7Mb/s

Got a friendly OpenReach engineer to do me a DLM reset on 5/10/2013
- Speedtest: 39.3Mb/s
- IP Profile: 40.7Mb/s

ISP sent an OpenReach engineer round, but they weren�t much help. Basically all they kept saying was �tester says the line is running at 100%�, had no answer when I pointed out that it was 13Mb/s faster before, and didn�t have a clue what crosstalk was when I mentioned it.


Wind on 3 years to today, and the rollout of G.INP and so on have given me a slight gain. Now:
- Speedtest: 45.6Mb/s download and 11.5Mb/s upload

Also over the duration BT revised down the Wholesale checker results. It now lists
- Clean: 62.8-46.4Mb/s download and 18.5-12.54Mb/s upload
- Impacted: 47.4-25.5Mb/s download and 15.2-6.94Mb/s upload.

Will be intrigued to see what the lower target SNRm will do. Doesn�t seem that long ago we were able to set it ourselves with BeThere and the tweaking on the modem/routers!

I don't think there's any training on crosstalk. I don't remember any.

So as you'll appreciate some engineers will know about it but many won't. Maybe there's no training because there's nothing an engineer can do about it?

an engineer can do something about, its called a pair swap
they could also replace bundles with less densily populated bundles to reduce likelyhood and extremity of crosstalk.

Of course these things take up time and money so they like people to think nothing can be done about it.

Of course these things take up time and money

And there's the rub. Money for improvement is in short supply given that the vast majority of users seem hellbent on paying as little as they possibly can for broadband access with large numbers gravitating towards the cheapest supplier that they can find.

BT OR & perhaps also VM might be able to improve their respective systems if they charged more however this would be considered unacceptable by many especially so those ISPs who seem to feel that BT OR should be supplying first class connectivity, preferably FTTP, for next to nothing regardless of the cost to BT which like the ISPs is essentially a private company rather than a charity.

A pair swap would be a trial and error thing, and no way of knowing if in another week another user goes live in the bundle and gives you even worse cross talk.

true, but its still not the same as stating they powerless.

a guy on kitz after the openreach exec team got involved had a speed issue resolved, when management approve it suddenly they can get things done.

They redug a trench, fed some new cable through and swapped his port at the cabinet all in a single day.

Normal support channels got him nowhere.

His experience has shown what can happen when the CP is taken out of the equation and we deal with openreach direct.

Without CPs been in the middle openreach also can take a larger revenue as the CP middle man mark up is removed from the relationship as well.

I see CPs been involved in the line retal arrangement as akin to a letting agent renting out properties, they are a useless leech.

Edited by Chrysalis (Fri 13-Jan-17 19:43:25)

I see CPs been involved in the line rental arrangement as akin to a letting agent renting out properties, they are a useless leech.

I and suspect many others wholeheartedly agree with your statement.

Completely agree Mr.S.

Hear hear.

How much do you think this issue cost to resolve?

the wages of 2 men 6 hours work.

I dont know what equipment was used to do the digging.

How is that relevant to if something is possible or not?

If something isnt done due to it been deemed too expensive that is not the same as something been not possible.

of course you only referring to CPs not end users, as CPs are openreach customers.

CPs can quite easily misjudge what is what.

Just because CPs agree silly arrangements like only accepting a minimum sin test been carried out on a line to see if its voice capable, it doesnt mean end users would agree to such nonsense.

e.g. in my own case I have paid circa £960 in line rental that has been passed onto openreach at this address, all the callouts that have occured since then have probably not reached that figure in costs to openreach.

Not to mention the number of properties where line rental is paid and there is no callouts whatsoever, line rental is like the insurance business, some customers will not be profitable but the majority will be and that subsidises those who are not.

I am surprised some are trying to defend this openreach and middleman CP arrangement and the current service levels in place. Even openreach themselves have said its not satisfactory.

Edited by Chrysalis (Fri 13-Jan-17 21:54:41)

not everyone judging by the replies

It's possibly to replace every piece of copper cable in the country, it's neither practical nor is it cost effective to do so.

It looks to me that OR did a special favour to resolve that line issue, which wasn't part of their normal protocol.

In reply to a post by adslmax:

Or maybe my cabinet is reduced SNR cos of more taken in or due to crosstalk?

This.

I never said it was cost effective, I just said its possible. I also never suggested they should be replacing all of the copper nationwide,

Of course tho without CPs been in the way leeching of revenue and with openreach able to increase prices to compensate for lack of CP profit margin, openreach would also have more headroom to do better fixes on their network.

Generally tho replacing copper is dumb anyway as its not future proof. But thats the path openreach have chosen.

Edited by Chrysalis (Sat 14-Jan-17 01:01:39)

In reply to a post by Chrysalis:

Generally tho replacing copper is dumb anyway as its not future proof. But thats the path openreach have chosen.

The only thing that is truly future-proof is a reliable crystal ball and a bottomless pit of money... companies do what they can with what's available.




edit- typo

Edited by billford (Sat 14-Jan-17 01:12:02)

In reply to a post by MrSaffron:

What I will say is I am expecting CDS to fight tooth and nail ... The journey so far has not been a friendly one.

That's *really* obvious.

In the recent meeting, one Devon councillor was ripping into BT for having not installed many of the vouchers from the recent voucher scheme. Once it was pointed out that BT wasn't involved, the vitriol went, and he listened to the (reasonable) explanation.

In reply to a post by MrSaffron:

... over even a slight delay even if this just down to extra time needed for FTTP work.

The last meeting suggested the delays were mostly related to wayleaves, and are likely to be sorted in the first 3 months of the year.

If I have the numbers right, the delays affect around 4% of the total premises due to get SF speeds. That makes the delay/numbers very similar to those encountered by North Yorkshire. That delay didn't cause any particular fractiousness, but did allow the council to apply a little leverage to encourage completion of 3 "at risk" commercial cabinets.

In terms of outcome, it seems that CDS is getting a similar result to the rest of the country. A project complete almost on time, and certainly within budget. But the experience on the journey ...

In reply to a post by MrSaffron:

Given a few more hours in a day

Funny how Santa never brings *that* present...

In reply to a post by MrSaffron:

On the CDS scenario, don't know the exact number of premises in contract paperwork as was signed, but in terms of delivery the fighting is going to be about the drop from VDSL2 coverage, to 24 Mbps or 30 Mbps thresholds. In what has been delivered 84% can get over 24 Mbps and a lower 81.8% on our figures.

I agree where the fight will happen.

From previous work, I figure that 3dB can be worth as much as 11Mbps for people capable of getting 60-80Mbps (because they have all tones available). For lines with speeds around 20-30Mbps, 3dB is likely to give them something in the region of 3 or 6Mbps. The gain at the lower end when they only get the D1 band, the higher gain if they get D1 and a good chunk of D2.

Using your coverage figures (in the fibre guide) around distances of 900-1200m, it seems those speed increases could equate to extra range of 150-300 metres, and extra coverage of 3-5%.

Those numbers could be critical.

In reply to a post by MrSaffron:

That said there is some FTTP still in build, and there has been some infill work. Will do an overall CDS report at weekend, as the commercial areas have an impact on the 90% target too.

That was another aspect noted: that there was outstanding commercial work that means they won't hit 90% even when phase 1 completes.

In reply to a post by Nightglow:

In reply to a post by Icaras:

Now how the hell would a Kelly's employee know anything about BT strategy? Ignore him.

Wait & see

It was notable that, even when BT were planning to deploy vectoring, they still weren't planning on increasing the top speed to 100Mbps.

And vectoring would likely have get a bigger gain than a 3dB profile.

An increase in VDSL2 top speed /now/ will reduce the market for G.Fast upgrades (to the 160Mbps level).

In reply to a post by Chrysalis:

true, but its still not the same as stating they powerless.

a guy on kitz after the openreach exec team got involved had a speed issue resolved, when management approve it suddenly they can get things done.

They redug a trench, fed some new cable through and swapped his port at the cabinet all in a single day.

Normal support channels got him nowhere.

His experience has shown what can happen when the CP is taken out of the equation and we deal with openreach direct.

Without CPs been in the middle openreach also can take a larger revenue as the CP middle man mark up is removed from the relationship as well.

I see CPs been involved in the line retal arrangement as akin to a letting agent renting out properties, they are a useless leech.

Well my local MP and myself was getting no where for the last 2 to 5 years with BT's Exec team via emails or over the phone.

We only got our fibre installed when I wrote a polite email to the CEO of BT Group and the Chairman's Office of BT also including a copy of the email that I had just sent my local MP along with evidence etc.

And then a few days later they did some more work down my road then re-booked the engineers and our fibre was installed.

So in my eyes you have to get the people at the top aware of the issues before anything will get done and I think it shouldn't be that way.

Paul

In reply to a post by PaulKirby:

In reply to a post by Chrysalis:

true, but its still not the same as stating they powerless.

a guy on kitz after the openreach exec team got involved had a speed issue resolved, when management approve it suddenly they can get things done.

They redug a trench, fed some new cable through and swapped his port at the cabinet all in a single day.

Normal support channels got him nowhere.

His experience has shown what can happen when the CP is taken out of the equation and we deal with openreach direct.

Without CPs been in the middle openreach also can take a larger revenue as the CP middle man mark up is removed from the relationship as well.

I see CPs been involved in the line retal arrangement as akin to a letting agent renting out properties, they are a useless leech.

Well my local MP and myself was getting no where for the last 2 to 5 years with BT's Exec team via emails or over the phone.

We only got our fibre installed when I wrote a polite email to the CEO of BT Group and the Chairman's Office of BT also including a copy of the email that I had just sent my local MP along with evidence etc.

And then a few days later they did some more work down my road then re-booked the engineers and our fibre was installed.

So in my eyes you have to get the people at the top aware of the issues before anything will get done and I think it shouldn't be that way.

Paul

Exactly the same situation, getting 9-14Mb here, despite checker say 70Mb minimum,& contining drop connection, nearly 18 months of getting nowhere with BT/OR at normal levels.
Made myself unpopular by writing to CEO's of BT & OR, with a fortnight, 2 engineers turned up & moved me to the rear pole ran new cable from house & down back lane, had a other few problems,so whole job took them two & half days to sort.

What is so annoying is the number of engineers, think it was eight sent previously to sort problem at various times, one wanted to do something, yet some bean counter wouldn't authorise it, so the problem continue,it shouldn't be like this,the OR engineer on the ground should be allow more freedom to sort the the problem.

Edited by Nightglow (Sat 14-Jan-17 10:26:41)

Have found the phase I target figure 277,000 at over 24 Mbps, in terms of 'fibre' based well past that point, so distance performance is key here, and the pessimism of our model means we are likely to under shoot BT Group figures. Got one more process running to collate intervention area data.

We have looked at our model versus reality from speed tests and they line up, but scope for a small improvement around the 1km mark, but want to do a deeper split to look at difference per cabinet manufacturer etc. Hope is that in time might be able to see difference vectoring makes, and run multiple models depending on the cabinet type. Too few premises involved in LR-VDSL trials to get anything useful from that trial.

Another factor meaning 90% is hard, is while new build numbers are small, it has a bit of an effect especially if not all of them get VDSL2/FTTP

The tracking of Airband coverage is a challenge, and need to see speed data to see what we call it speed wise. We do see some really great fixed wireless services, but also see some mediocre ones that tick a superfast box but rare to see someone on that product. Can't imagine the outcry if the most popular BT Infinity product was an up to 15 Mbps service.

At end of the day this is looking like a case of very close to targets, and will be able to add my if you want to ensure 100% coverage, best to plan to deliver 110%. The reality of the project target NOT being 90% in each community/constituency/district council area is something I think lots of councillors/MPs are starting to only just understand.

In reply to a post by Ignitionnet:

In reply to a post by adslmax:

Or maybe my cabinet is reduced SNR cos of more taken in or due to crosstalk?

This.

What is the precent take up in my cabinet now? How to find out? Maybe Ribble or Andy HCZ will know.

Edited by adslmax (Sat 14-Jan-17 11:30:13)

In reply to a post by adslmax:

What is the precent take up in my cabinet now?

Why? It doesn't matter anywhere near as much as knowing how many of the 10-12 pairs that are neighbours to your pair through the full length of the D-side.

In reply to a post by MrSaffron:

Have found the phase I target figure 277,000 at over 24 Mbps,

I agree.

Looking forward to the data coming out...

In reply to a post by MrSaffron:

but scope for a small improvement around the 1km mark,

Dang. Just at the important point...

In reply to a post by MrSaffron:

Can't imagine the outcry if the most popular BT Infinity product was an up to 15 Mbps service.

Like Australia? For a year, the 12/1 product was the most popular to FTTP subscribers.

Even now, the 12/1 and 25/5 products combine to take 80% of the market on FTTP and 90% of FTTN (which is an "up to 100" vectored variety).

NBN Package Mix - FTTP
NBN Package Mix - FTTN

In reply to a post by MrSaffron:

if you want to ensure 100% coverage, best to plan to deliver 110%.

I agree 110%

In reply to a post by MrSaffron:

The reality of the project target NOT being 90% in each community/constituency/district council area is something I think lots of councillors/MPs are starting to only just understand.

I wonder what we'll see going forward. Will Gigaclear stick to a 95% target, so only hit half of the remainder? How much rein will they be given by councillors?

Gigaclear contract is 35,000 premises so a long way from getting to 100%, and short of 95% too, but Airband and the outstanding lot likely to take it to 95%, if BT get to 90%.

http://www.thinkbroadband.com/news/7611-connecting-d...

The analysis, believe BT is 20,000 short based on our understanding of what has been delivered, so will be interesting to see how much closer it gets by March. Even if BT stopped now would just a 7% miss on original target, so while a miss compared to many procurement exercises not massive, but can see FTTP areas with postcodes not live where checkers say they are building to, while others are giving us speed test results in live postcodes.

If my cabinet is 100% take up full, does it mean my sync rate 79999k will drop below for the first time since Feb 2014 and how far will it drop to? I hope it won't drop below 79999k when the cab is full?

Edited by adslmax (Sat 14-Jan-17 13:25:48)

No one can tell you until someone does the mathematics and knows all the detail on where in the cable bundles your line is with relation to the other people who have ordered the service.

It doesn't matter how full the cab is.

It matters more about whether the 10-12 copper pairs surrounding yours have taken VDSL2 service or not.

That means you can get close to the worst-case crosstalk from just 10-12 other subscribers.

Or, if the other 287 FTTC subscribers are on other D-side cables you can end up with nearly (*) no crosstalk at all.

Even when the disturbers are in the worst possible placement, it still depends on the manufacturing quality of the cable: just how uniform is the thickness of copper, the thickness of insulation, the twist rate of a pair and the twist rate of the individual binders.

It is, to all intents and purposes, random. It is likely that you will experience more crosstalk on a full cab ... but there is no guarantee as to whether you experience nearer the minimum or maximum.

(*) - The tie pairs guarantee that you have crosstalk from some VDSL2 subscribers for a short length. The extent of the impact will depend on takeup (**) and the distance between the two cabinets.

(**) - Once the binder in the tie pair (group of 25 pairs) is full, you'll likely have gotten most of the crosstalk from this short portion of your line; once the tie-pair cable is full (100 pairs), that likelihood will reach 100%.

Why can't BT Wholesale Broadband Diagnostic Test or Availability Checker to show how many % of the lines take up of the cabinet?

It's not relevant to anyone.

Also, Wholesale are not the owner of the cabinets, Openreach are.

In reply to a post by adslmax:

Why can't BT Wholesale Broadband Diagnostic Test or Availability Checker to show how many % of the lines take up of the cabinet?

Several years ago Openreach or BTW used to publish to ISPs the DSLAM and MSAN numbers, card occupancy in them and ports used at all exchanges for ADSL. It was available to the public through Prodigynet - or at least to their customers.

As were the complete order history and current orders for your line.

They got stopped from letting us see that data.

In reply to a post by adslmax:

Why can't BT Wholesale Broadband Diagnostic Test or Availability Checker to show how many % of the lines take up of the cabinet?

As the others said, it's useless to you.

But also because, quite frankly, it would be extraordinarily useful market intelligence data for all of their competitors.

In reply to a post by Zarjaz:

I wonder why the remote system would lower the SNR if the line in question already achieves max sync ?
Surely it would be better to have a little built in stability ?

Not sure how fibre works but if we look at sky ADSL, there is a power management module used to reduce output power which lowers the noise margin, reduces DSLAM energy and thereby lower costs.

Here's the one sky uses as far as I know:

http://www.assia-inc.com/products-services/pdf/Brief...

Savings equate to around 3KWh per line which is 30 to 50p a year per customer, multiplied by several million customers, you have your answer.

Edited by ukhardy07 (Sat 14-Jan-17 23:53:32)

BT uses their own home-brew DLM equivalent to Assia's.

Lowering the power will reduce the received signal strength, so reduce the SNR. That will tend to reduce the sync speed.

If you want to maintain speed, then you can only reduce the transmit power on those lines already syncing at full speed. That might be 20% of lines at 80Mbps, or 30% of lines at 40-55Mbps.

However, crosstalk can cut in at any point, as new subscribers join. If you are on a reduced power, and they reduce your working SNRM you will need to increase power to get back your error-free margins. And other neighbouring lines will do the same.

As each of you increase your power, you'll start interfering with all your neighbouring lines a little more ... so they all have to react.

It can be a vicious circle...

I have always wondered if DLM cuts power on lines with excessive snrm, user thinks its crosstalk, then if the sync falls below max power is never increased again.

You could be right, but that would make DLM rather dumb. Unfortunately, as time goes by, DLM seems to elevate its dumbness.

One problem I have with "power" is that it is a tricky concept to deal with, and one that many people (including me) cannot handle properly.

For example, we are very used to seeing the idea that profile 17a is listed with a maximum power of 14.5dBm, and seeing modems report power - anywhere from -10dBm to 13+dBm.

But those numbers are aggregate power, accumulated from the individual power on each tone. And there is another limitation that affects the individual power on tones: the PSD (power spectral density), measured in dBm per Hertz.

So, when we see a modem report a lower-than-expected (aggregate) power value, it might be because
- there are fewer tones than expected
- the PSD mask has limited power of many tones
- "something" has reduced the power of individual tones (eg UPBO or DPBO). (*)

There's also the gotcha that we're counting in log scales. Doubling power is +3dBm. Or, when calculating aggregate power, doubling the number of tones at the same power is also +3dBm.

LR-VDSL has a change that allows aggregate power to be +20.5dBm instead of 14.5dBm. A 6dBm difference means quadruple power ... but aggregated over (roughly) only half as many tones ... so could mean octuple power per tone. Wow.

Except it has to fit inside the broad parameters of the existing PSD mask (power per hertz), but benefitting from removal of the DPBO shaping that would otherwise allow coexistence with ADSL.

Who can tell, off the top of their heads, whether +6dBm in aggregate amounts to more or less than the change in shape of the PSD mask?

---

(*) - The UPBO article is interesting. It shows that the settings can be tuned to a "preferred distance", above which the upstream speeds fall away considerably.

In reply to a post by WWWombat:

You could be right, but that would make DLM rather dumb. Unfortunately, as time goes by, DLM seems to elevate its dumbness.

I believe there is also a form of "conflict of interest" on the specification of requirements from Openreach DLM.

The idea of a lower default margin, or simply its availability as happened with the ADSLx BT Wholesale one, is a great idea for most customers at little cost to Openreach. Also conferring on "BT" the bonus of higher average rates to put against Virgin Media.

The conflict comes in that it has been clear from the early days that the BT Wholesale estimate table for any given line, which has to be culled from the Openreach one for VDSL2, has aggressively revised downwards as soon as actuals fall. Again we know the BTW ADSLx ones always tracked actual over time, but the underlying emphasis seems to have changed for VDSL2.

The BT Wholesale and probably the Openreach attitude now seems to be strongly on holding that lines can degrade for a number of reasons, so they aren't going to spend money sorting out even significant degradation.

It's a "Shrug the shoulders - that's what happens" sort of approach. "The user still has a service so what the heck?"

Edited by RobertoS (Mon 16-Jan-17 14:51:16)

In reply to a post by RobertoS:

The BT Wholesale and probably the Openreach attitude now seems to be strongly on holding that lines can degrade for a number of reasons, so they aren't going to spend money sorting out even significant degradation.

It's a "Shrug the shoulders - that's what happens" sort of approach. "The user still has a service so what the heck?"

Agreed, though I have no proof, other than various ISPs telling me that if they report a fault BT will do nothing as it is still above the acceptable level.

BT will have to be a little careful in the future though I suspect. Many countries are switching to their mobile phone networks and I am very impressed with what 4G can do ( though admittedly not where I currently live). I know a lot of people in the UK have already given up their land lines and as 4G becomes more widely available I suspect this will accelerate. Unfortunately thanks to Plusnet switching it off I can not see my recent usage, but if I was to take all the money I pay for phone and broadband, that would buy me a fair whack from a mobile network.

There has to be some threshold for fault investigation though.

I've seen some people (with low cost ISPs) requesting an engineer just because their sync rate has dropped from 80Mbps to 75Mbps.

In reply to a post by AndyHCZ:

There has to be some threshold for fault investigation though.

I've seen some people (with low cost ISPs) requesting an engineer just because their sync rate has dropped from 80Mbps to 75Mbps.

I probably do the same if my sync rate has dropped to below 74999k from 79999k to ask my isp to get engineer out to reset DLM.

And that is one of the reasons why we have a fault threshold.

What do you get them to do if it wasn't caused by DLM?

In reply to a post by RobertoS:

It's a "Shrug the shoulders - that's what happens" sort of approach. "The user still has a service so what the heck?"

To use an Americanism, its all about stopping the truck rolls. Whatever approach is used in the field, the aim is to be able to shrug the shoulders apart from a limited, manageable, number of lines. We just need BT to pick an approach that works for us as well as them.

Vectoring, for example, would have been an approach that lets them shrug shoulders, but would probably have happier subs.

nice timing from rev, its as if he read my post O_o

https://www.youtube.com/watch?v=YFdZcEx8oog

Obviously there needs to be some kind of triage or procedure to put in place to keep things in check, but the current system of only checking for voice compliance is clearly not fit for purpose.

In reply to a post by Chrysalis:

nice timing from rev, its as if he read my post O_o

https://www.youtube.com/watch?v=YFdZcEx8oog

Obviously there needs to be some kind of triage or procedure to put in place to keep things in check, but the current system of only checking for voice compliance is clearly not fit for purpose.

Yes but when an engineer goes out on an SFI job one of the tests they are required to do is an ADSL test on their handheld tester. This checks for errors and has a threshold, over which the test will be classed as a fail. So this notion that the engineer just goes out and only runs a Pair Quality Test (to check for SIN349) is incorrect.

They rarely do more then a SIN test when visiting me. In and out in about 10 mins.

The only time's I have had more done is if there is a really big obvious problem with the line that they cannot pretend is not an issue or when I was a customer of aaisp and shaun typically ripped into BTw to ensure stuff got done.

What do you mean by an ADSL test please? There's a huge difference between the ADSL capability of a line and ADSL2/2+/VDSL2 requirements. I'm assuming the 28kbps requirement is dead, or is it?

We also used to get reports of an ADSL test fail simply meant the line was declared unfit for ADSL, permanently, after being used satisfactorily for years.

Has the 3dB rollout taken place, my exchange Kingsmead was listed, but no improvement/increase here with speed.

This was a SFI visit and if so, which modules did the ISP book?

It's just a test on the handheld tester. It connects to the ADSL for 4 minutes and checks for PPP session, sync speed and CRC, FEC issues etc. This then gets submitted when the job is closed down. It's mandatory and is one of the tests that the engineers are marked and graded on for SFI jobs.

There's also a completely different type of job where the engineer goes to the house, checks line meets SIN349, upgrades the socket if required and then listens for noise on the line. That's a different job type and isn't an SFI task. The CP can order whichever is appropriate, I assume.

Edited by deleted (Tue 17-Jan-17 11:55:48)

Is the qualitative part of the test restricted to error rates?

Is there nothing that checks other signs of a dodgy line, or dodgy connection?
For example
- non standard patterns on hlog
- high noise from neighbours on QLN
- nasty variations to SNRM
- jumps in attenuation
- bad speed mismatch with attenuation
- throughput matching the sync speed
- packet loss
- latency

In reply to a post by Icaras:

It's mandatory and is one of the tests that the engineers are marked and graded on for SFI jobs.

@revk definitely thinks it isn't mandatory. His further implication is that it isn't even optional!

"SFI2 is a broadband support product that tests to voice standards."

Certainly the BTWholesale Knowledge Based Diagnostics test will check most of what you've listed there. I believe they pick up something like 90% of faults for ADSL and over 95% for FTTC (this is probably higher now as tests have improved).

Most ISPs book a SFI visit when the KBD tests come back showing no fault detected. It's therefore, in most cases, a performance issue rather than a specifically clear fault.

I don't think the issue is as such Openreach and SFI, but more BT Wholesale and they way they handle performance issues or faults that they've been unable to identify with their KBD.

Edit: I should add here that you some very experienced and knowledgable support staff working at niche ISPs (like AAISP) who quite frankly, know a lot more than their support contacts within BT Wholesale. I suspect quite a lot of the BT Wholesale front line support staff have limited ISP and carrier level network training and understanding. This clearly creates an issue when an ISP has definitive evidence of a network fault (and its location) and at the same time the BT Wholesale Support staff member is unable to understand or input that fault into the system.

If you look at RevK's latest post http://www.revk.uk/2017/01/teaching-us-to-suck-eggs-... this shows a classic example of this. There will be some very experienced and knowledgeable within Openreach that AAISP could work with to resolve this, but the problem is the system and protocol from BT Wholesale does not allow this.

Edited by deleted (Tue 17-Jan-17 12:29:02)

In reply to a post by WWWombat:

In reply to a post by Icaras:

It's mandatory and is one of the tests that the engineers are marked and graded on for SFI jobs.

@revk definitely thinks it isn't mandatory. His further implication is that it isn't even optional!

But that would mean if an engineer got to a job and couldn't get sync on his tester he'd walk off as long as the line is up to SIN349 standards! That's not what happens though.

The base module (for end users) of a SFI visit solely checks that the line is compliant with SIN349. This is a voice line test.

It's possible that the PSTN complies to SIN349, but the broadband service isn't in sync. The engineer would find out why the broadband service isn't in sync and that would determine who is responsible for the SFI charge.

Yep, have had an engineer do that. Despite an HG612 getting a connection sometimes at 6Mb on VDSL2 for 30s and then timing out, a JDSU on the same line could not get any kind of VDSL2 connection.

PPP session? And you did mean xDSL, not ADSL which worried me.

Edited by RobertoS (Tue 17-Jan-17 13:22:55)

In reply to a post by RobertoS:

PPP session? And you did mean xDSL, not ADSL which worried me.

Yes, ADSL or ADSL2+, VDSL2 faults wouldn't come out as an SFI job. PPP session-it just tries to connect to the BT Wholesale test server.

Edited by deleted (Tue 17-Jan-17 13:36:23)

But PPP? With where?

Edited by RobertoS (Tue 17-Jan-17 13:37:06)

I don't really understand your question! Maybe there's a different term for it but that's what we call it anyway. The tester basically checks that it can communicate with BT Wholesale's test domain. So it's checking that there's throughput basically.

In reply to a post by godsell4:

Yep, have had an engineer do that. Despite an HG612 getting a connection sometimes at 6Mb on VDSL2 for 30s and then timing out, a JDSU on the same line could not get any kind of VDSL2 connection.

Your visit wouldn't have been an SFI, they don't exist for FTTC jobs.

We're way off topic though here! This thread is about SNR for VDSL2 and somehow we're having a conversation about the merits of SFI!

Edited by deleted (Tue 17-Jan-17 14:01:23)

Yes but when an engineer goes out on an SFI job one of the tests they are required to do is an ADSL test on their handheld tester. This checks for errors and has a threshold, over which the test will be classed as a fail.

Except of course that the thresholds on the scripted tests are set very leniently indeed .......... It can even drop sync a few times and still deem it a pass ....... chocolate and teapot spring to mind.

You mention that these scripted tests check for a PPP session, nope, only the manual sync test (well on a JDSU at least) tests PPP, and then only to Btw test log in (this works on some LLU connections too)

Your visit wouldn't have been an SFI, they don't exist for FTTC jobs.

Yep, it would have been a "Super Fast Visit Assured'

In reply to a post by Nightglow:

Has the 3dB rollout taken place, my exchange Kingsmead was listed, but no improvement/increase here with speed.

No change for me on the Chilton Polden exchange either. I seem to recall that the news about the roll-out starting said "from" rather than "on". I had hopes of it happening fast, but on reflection BT are probably right to not roll the change out at once to all the exchanges mentioned.

Edited by awontroba (Tue 17-Jan-17 18:26:58)

In reply to a post by Zarjaz:

Yes but when an engineer goes out on an SFI job one of the tests they are required to do is an ADSL test on their handheld tester. This checks for errors and has a threshold, over which the test will be classed as a fail.

Except of course that the thresholds on the scripted tests are set very leniently indeed .......... It can even drop sync a few times and still deem it a pass ....... chocolate and teapot spring to mind.

You mention that these scripted tests check for a PPP session, nope, only the manual sync test (well on a JDSU at least) tests PPP, and then only to Btw test log in (this works on some LLU connections too)

Oh right, Exfo does on the timed test but as you say it only works on BT Wholesale connections anyway. I've never used a JDSU.

Edited by deleted (Tue 17-Jan-17 18:26:06)

And to be fair, who actually looks at these close out tests ...... I bet if I didn't store and upload any for a month I'd not be pulled up for it........

In reply to a post by awontroba:

No change for me on the Chilton Polden exchange either. I seem to recall that the news about the roll-out starting said "from" rather than "on". I had hopes of it happening fast, but on reflection BT are probably right to not roll the change out at once to all the exchanges mentioned.

The post with the list says:-

from Monday 16 January to select cabinets on the following exchanges (below).

A few points here though:

- ECI cabinets are excluded (I assume the new DLM is not fully tested/supported yet).
- Any line that has had the existing DLM intervene, due to poor performance, will be excluded from being moved over.
- Around 10% of lines are expected to move to the new XdB and DLM algo.

Today is Tuesday only 17 January!

Plus of course the full roll-out is:-

Currently the default target downstream noise margin is set to 6dB. From March 2017 the target downstream noise margin shall be set to either 3, 4, 5 or 6dB � the actual value shall be determined by the Dynamic Line Management (DLM) algorithm based on line stability.

That doesn't seem to mention only for Huawei cabinets but following Andy's post is seems quite possibly the case.

Yes, we get our hopes for something happening up, then wait, and wait, and often end up disappointed.
I had missed both "select cabinets" and "10% of lines".
Probably the selection will be to aid BT/CDS in reaching targets, not to pander to speed freaks like me.

And indeed AF wrote:

We believe that some tactical deployment of vectoring and changes to the Openreach DLM (namely allowing a lower target noise margin of 3dB) may be deployed in parts of Devon and Somerset to improve the reach and speed of VDSL2.

Edited by awontroba (Tue 17-Jan-17 21:00:13)

In reply to a post by Nightglow:

Has the 3dB rollout taken place, my exchange Kingsmead was listed, but no improvement/increase here with speed.

Don't know if was a coincident or not, but we had a power cut today from around 2pm- 2:30pm.

My SNR before was 6.1dB with a Sync of around 65000kbps

After the power was returned my stats are

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 28402 Kbps, Downstream rate = 97804 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 74000 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 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): 3.8 8.7
Attn(dB): 16.0 0.0
Pwr(dBm): 13.4 6.7
VDSL2 framing
Bearer 0
MSGc: -6 26
B: 174 237
M: 1 1
T: 0 42
R: 8 16
S: 0.0752 0.3781
L: 19456 5374
D: 16 1
I: 183 127
N: 183 254
Q: 16 0
V: 3 0
RxQueue: 42 0
TxQueue: 14 0
G.INP Framing: 18 0
G.INP lookback: 14 0
RRC bits: 0 24
Bearer 1
MSGc: 154 -6
B: 0 0
M: 2 0
T: 2 0
R: 16 0
S: 6.4000 0.0000
L: 40 0
D: 3 0
I: 32 0
N: 32 0
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0
Counters
Bearer 0
OHF: 0 190699
OHFErr: 0 133
RS: 1816823296 2167361
RSCorr: 13275 289
RSUnCorr: 0 0
Bearer 1
OHF: 2136155 0
OHFErr: 0 0
RS: 21360934 0
RSCorr: 36 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 50513 0
rtx_c: 467 0
rtx_uc: 0 0

G.INP Counters
LEFTRS: 6 0
minEFTR: 74006 0
errFreeBits: 38720151 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 587822838 0
Data Cells: 23749650 0
Drop Cells: 0
Bit Errors: 0 0

Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0

ES: 0 124
SES: 0 0
UAS: 22 22
AS: 34312

Bearer 0
INP: 49.00 0.00
INPRein: 0.00 0.00
delay: 0 0
PER: 0.00 3.98
OR: 0.01 64.22
AgR: 74132.27 20063.54

Bearer 1
INP: 4.50 0.00
INPRein: 4.50 0.00
delay: 3 0
PER: 16.06 0.01
OR: 79.68 0.01
AgR: 79.68 0.01

Bitswap: 24663/24663 98/98

Total time = 9 hours 32 min 14 sec
FEC: 13275 289
CRC: 0 133
ES: 0 124
SES: 0 0
UAS: 22 22
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 2 min 14 sec
FEC: 81 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 580 2
CRC: 0 1
ES: 0 1
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 9 hours 32 min 14 sec
FEC: 13275 289
CRC: 0 133
ES: 0 124
SES: 0 0
UAS: 22 22
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 9 hours 31 min 51 sec
FEC: 13275 289
CRC: 0 133
ES: 0 124
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0

Almost back to the speed I was getting when I first got FTTC.

no idea as with the current system there is a game of chinese whispers, and the end user isnt told.

Interesting that you seem either to have a sync-time noise margin of 9dB, or you connected at a noisy time. Downstream SNRM 8.7dB.

Even more interesting is that along with that you have downstream interleaving on Bearer 1! This is highly unusual. (Bearer 1 is to do with G.INP having been implemented on lines previously on pure deep interleaving). I don't recall ever seeing that before.

I think you've got the SNRM values the wrong way round, I read it as 3.8 down 8.7 up which would appear to agree with the previous sync speed of 65Mbps at 6.1dB. This is a common result of a power outage when the FTTC modems sync up at different times so I believe the Op is still on a 6dB target and the SNRM has fallen as other modems have come online. I am not sure about your G.INP comments, not sure what's going on there!

In reply to a post by Realalemadrid:

I think you've got the SNRM values the wrong way round, I read it as 3.8 down 8.7 up which would appear to agree with the previous sync speed of 65Mbps at 6.1dB.

Yes, you're right .

Still, it is strange to see a sub-6dB SNRM alongside a Max speed that is higher than the actual.

Nonetheless, a power cut across the cabinet's coverage area is the hardest time to figure whether BT just turned on variable SNRMs.

Yes, I'd think it's a new downstream SNR margin as the downstream attainable rate would not be higher than the rate if the line was connected at a downstream SNR margin of 6 dB but then dropped due to crosstalk.

Edited by deleted (Sun 22-Jan-17 16:31:20)

I might have been pandered to. My line is on the Chilton Polden exchange.

My BT HH5B resynced a while ago. On connection SNR down to the lowest I have ever seen for it - 3.2

12:28:07, 28 Jan.	DSL Link Up: Down Rate=71988Kbps, Up Rate=19999Kbps; SNR Margin Down=3.2dB, Up=7.3dB

Higher upstream rates

5.	VDSL uptime:	0 days, 01:28:22
6.	Data Rate:	19999 / 71988 (was 20000 / 61660)
7.	Maximum Data Rate:	22698 / 73333 (was 25320 / 62407)
8.	Noise Margin:	7.5 / 3.3  (was 9.2 / 6.4)
9.	Line Attenuation:	22.4 / 18.1 (was 22.5 / 18.1)

And better TBB speed test results

Sat 28/01/17 13:50	63.66 Mbps	63.20 Mbps	18.58 Mbps
Sun 22/01/17 01:29	58.24 Mbps	58.15 Mbps	18.60 Mbps

I hope this is permanent and not a blip. Time will tell.

Over the weekend (28-29th) I also noticed lower SNR marging and about 10Mb increase in sync speed

Modem Stats

Modem Stats 2

It stayed there until the morning of 31/01. Now it is back to where it was before i.e. 6db with sync speed of 47994 (1Mb up or down)

Does Ronski's recording give the raw xdslcmd stats please? If so, did those with the high sync and low margin show Bearer 1? If it does I expect the values for sync on it to be zero but that's fine.

I ask because that would suggest G.INP is active, and I'm fairly sure there was a post saying the low margin trial would not be used on lines with G.INP.

I don't like your 47994 current sync. That smells of banding, but the only way to know would be a re-sync which I advise against at the moment. Again the raw stats would be nice, which you can get yourself if on a Windows, without the Ronski if it doesn't give them.

I don't have the raw stats at the moment. But if you see screenshots - it says GINP enabled. INP 48. Interleaving On (8). I had G.INP enabled for a long time. Clearly I had 3db profile enabled for a couple of days with G.INP enabled.

I have a 5dB target margin on a line with G.INP enabled

I'm not sure this is evidence of the 3dB trial.

If you had a target SNRM of 3dB, as opposed to merely running at 3dB, you would expect the attainable and actual speeds to be similar.

Your actual speed is considerably higher than your attainable, suggesting the actual SNRM (3dB) is considerably lower than the target.

Also of note is that the same situation happened on your upstream, whereas @WilliamG's line didn't show any change in upstream behaviour.

It looks more like a DSLAM restart/power-outage.

In reply to a post by WWWombat:

If you had a target SNRM of 3dB, as opposed to merely running at 3dB, you would expect the attainable and actual speeds to be similar.

Unfortunately, my modem has no knowledge of the target SNRM and so my attainable is calculated as being a lot less than my actual

Whether its a proof or not. the point is there were changes to the SNRM which did change my sync. I did speed tests and there was a 6Mb increase.

Speed Tests

Edited by deleted (Wed 01-Feb-17 17:15:02)

Understood.

The point I was making back is that there are other reasons for what you have seen, and have been for a long time before this trial existed.

The first part of analysis now is to figure out which case you are following...

In reply to a post by BatBoy:

Unfortunately, my modem has no knowledge of the target SNRM and so my attainable is calculated as being a lot less than my actual

Interesting. I wonder why some seem to know, and some do not?

I can only comment on mine obviously. What are these other ones that seem to know?

In reply to a post by WWWombat:

Understood.

The point I was making back is that there are other reasons for what you have seen, and have been for a long time before this trial existed.

The first part of analysis now is to figure out which case you are following...

You could be right but I am not aware of any other reason which could have lowered the SNRM. This is the first time I have see it and it was actually below 3db. Should have taken the telnet stats. If it happens next time I'll do that.

Just to mention that I live in Reading (Earley area), and the exchange is not on the list of test exchanges (someone posted a list on these forums). So not sure how we take these results.

I'll try to do a resync tonight or early tomorrow morning (15 min power cycle method).

Luckily the monitoring app I use tells me the SNRM when my modem resyncs, so I know the target is 5dB.

In reply to a post by sohail2k:

I don't have the raw stats at the moment. But if you see screenshots - it says GINP enabled. INP 48. Interleaving On (8). I had G.INP enabled for a long time. Clearly I had 3db profile enabled for a couple of days with G.INP enabled.

Sorry, I'm not particularly familiar with that layout and didn't see the G.INP line above the table. I was looking in the table .

As for telnet stats, that's what I'm looking for in relation to your current sync - I see in a later post you say you will be getting those .

In reply to a post by sohail2k:

but I am not aware of any other reason which could have lowered the SNRM.

When you see the SNRM value in the modem stats, it reflects the current actual situation, not the target. The actual value varies second-by-second, depending on the noise interference encountered. Noise can change, so SNRM can change too.

A low SNRM can be seen with a normal sync speed, for example, after a new subscriber is activated. In this case, the attainable speed will be lower than the current, normal speed. Next time there is a resync, the sync speed will likely be reduced.

A low SNRM can be seen with a high sync speed, for example, after a DSLAM has been restarted, or the area has had a power cut. In this case, modems can start with a 6dB target and a higher-than-normal speed but, as other subscribers start up in parallel, the SNRM value will drop. In this case, the attainable speed will be lower than the current (excessive) speed, but will be around the normal speed for the line. Next time there is a resync, the sync speed will return back down to normal.

In your case, it looks more like the latter has happened. The attainable speed (in the screenshot) was much lower than the actual speed. A resync put everything back to normal.

Easy - you record a copy of the figure at the time of training, either by being passed it, or inference from the first sample after sync negotiation has completed.

Not sure that attainable is going to be reliable, as many will be based on the old relatively standard 6dB margin being fixed into the code for the maths

That's what I think too, mine is apparently using the default of 6 to do the calculation for the attainable.
Which ones are using the actual target margin?

That doesn't make sense. Do you think your modem has synced at 5dB but it's working out it's attainable from a 6dB snrm? Because that isn't possible.

In reply to a post by sohail2k:

Understood.
You could be right but I am not aware of any other reason which could have lowered the SNRM. This is the first time I have see it and it was actually below 3db. Should have taken the telnet stats. If it happens next time I'll do that.

Just to mention that I live in Reading (Earley area), and the exchange is not on the list of test exchanges (someone posted a list on these forums). So not sure how we take these results.

I'll try to do a resync tonight or early tomorrow morning (15 min power cycle method).

If the SNRM drops and the sync rises the attainable will rise in a similar pattern. If the attainable remains what it usually is, and is considerably lower than sync, then it's almost certainly not a lower target snrm.

As I, MrSaffron and others have pointed out, it is entirely possible. In fact almost certainly happening. It merely requires the 6dB to be hard coded in the modem's firmware, and from several examples that appears to be the case.

How else, under the pre-existing regime, does the attainable rate significantly exceed the actual when the sync-time margin is 9dB or higher? On both VDSL2 and ADSLx, different DLMs from different suppliers.

Hard coded in the firmware? that's a load of nonsense. It's an OpenReach setting, absolutely nothing to do with CPE firmware. The attainable is way higher when interleaving + FEC is enabled.
The max attainable rate calculation was rather loosely defined in the original VDSL2 ITU documents and many modems incorrectly calculate it, particularly when interleaving is enabled. The target SNRM is absolutely not "hard coded" in firmware.

And to add, of course it's entirely possibly. On an exchange where the trial isn't active, where only the sync had risen significantly, the attainable had remained static, I'd stick with "almost certainly not".

Edited by j0hn83 (Fri 03-Feb-17 11:41:13)

Openreach do not set the base figure in the modem. End of. How it is obtained is entirely up to the modem manufacturer, as you correctly point out.

The posters concerned know what they are observing and how to interpret it. They also know how their actual/attainable/SNRM behave when the Openreach base setting at the DSLAM is 6dB, and how that behaviour has changed.

You said it is impossible for the modem to be using 6dB as the base figure for calculating attainable. You cannot possibly know that for exactly the reason you state.

Similarly, all the posters (including myself) discussing the matter are fully aware of the effect interleaving has on the calculation and that the result is usually crackers.

As has been stated, the only way to be sure of the sync-time DSLAM setting is to take the stats immediately after connection, or better still from the modem log if it records it.

Re one of your inclusions added while I was writing my previous reply

In reply to a post by j0hn83:

The attainable is way higher when interleaving + FEC is enabled.

Not when G.INP is active.

I think you are misunderstanding what has been suggested and looks to be consistent with observed results, that the modem calculation of attainable rate assumes a fixed 6db SNRM and doesn't use the actual SNRM value. So the target SNRM for the attainable rate calculation is hard coded in the modem firmware.

In reply to a post by RobertoS:

Re one of your inclusions added while I was writing my previous reply

In reply to a post by j0hn83:

The attainable is way higher when interleaving + FEC is enabled.

Not when G.INP is active.

That's why I didn't say G.INP. G.INP is not interleaving or FEC.

With G.INP active both downstream interleaving and FEC are also active. G.INP is not invoked unless interleaving is needed. By adding retransmission it is able hugely to reduce the interleaving depth.

Edited by RobertoS (Fri 03-Feb-17 11:57:24)

In reply to a post by Realalemadrid:

I think you are misunderstanding what has been suggested and looks to be consistent with observed results, that the modem calculation of attainable rate assumes a fixed 6db SNRM and doesn't use the actual SNRM value. So the target SNRM for the attainable rate calculation is hard coded in the modem firmware.

I'd also agree

Modems shouldn't assume any target SNRM. It should actually use the set target. As seen with Williams line. Maybe, maybe the likes of a home hub made specifically for BT could do something like that, but it goes against how it's designed to work. You can't trust stats from most GUI's though, and I wouldn't trust stats from any modern they behaved in that way. Any Broadcom based or any half decent modem that works as it should, doesn't have target snrm hard coded anywhere. Using such stats to work out of you're on this trial is as helpful as peeing into the wind.

You're still not getting it. No one has suggested that the modem sets or assumes a value for the target SNRM. That is defined by DLM and the DSLAM and was normally 6dB until the trial of lower values started. The hard coded value is only used for the attainable rate calculation.

I'm glad someone gets it...

Using a hard coded figure for this calculation is logical too, as it helps you see if your performance is poor due to a bad SNR environment too.

I know that's what you meant. I'm disagreeing with the fact the attainable is hard coded to a 6dB target. Again, as clearly seen on Williams line. His attainable is increasing as the target snrm is lowered. That's exactly as it should be, and how it is on any decent modem working as it should. I regard all Broadcom based chipsets in this category.

If a modem is using a hard coded 6dB to work out attainable, it's not working as it should, or it is designed specifically for the U.K. market on a ridiculous assumption it will always be 6dB.

In my opinion any modem that works in this way (incorrectly) shouldn't be trusted as to wether it's part of this particular trial. Doing so is as useful as peeing into the wind. "My sync has gone up and my downstream snr is 3dB" does not mean they are in the trial, especially on an exchange not on the list published. That was my original point. Using a decent modem (Broadcom for 1) and comparing the attainable is a sure way to work it out. Monitoring the stats at the time of sync would also confirm it. Again, best done with something like a Broadcom modem, that gives proper stats.

We can agree to disagree though. Opinions are like ****holes, everyone has 1, including me ;D
No offence meant, just putting my point across.

OK, let's take you through it. Assuming no faults on the line and SRA is not in operation. A few scenarios.

If you have a sync-time margin of 6db we can safely assume you are not on the trial, as if you were that would simply demonstrate your line is not good enough. How is the max attainable calculated, in particular what figures are used and where do they come from?

If following that sync the SNRM falls to 4dB, what happens to actual and attainable? If the SNRM rises to 8dB, what happens to actual and attainable?

Now say you have a sync-time margin of 3dB. How is the max attainable calculated, in particular what figures are used and where do they come from? Then as above, what happens with a 2dB move in either direction, assuming a drop to 1dB does not break the connection.

Another way

1. Line syncs to a 6dB target margin and attainable sync and actual are very close
2. DLM forces a 9dB target margin, so we now expect the attainable to still be very close to the actual, or still reflect the previous figures when it was 6dB