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[Black Sheep]

Hi Colin,

Apart from the reset, did he do anything else this time?

Colin

Other than a Pair Quality Test that returned a result of 61, no.

@ Black Sheep - Does that look about "right"?

I tried my hardest to get him to run a "reassurance" TDR test, but he wouldn't do so as my new sync speed already exceeded the newish 30 Mb estimate (It was only 14.6Mb a few months ago).

This was his update to Plusnet on completion of this morning's visit:-

"SFI notes: cse called for co-op on ongoing speed issue , circuit in sync at 27.4meg down. rrt shows geren since 28/02/2012. I have recalculation dlm as suspect may have failed to increment automatically.

now in sync at Downstream Line Rate (Mbit/s) 35.3 Upstream Line Rate (Mbit/s) 6.4 these speeds are well
above that expected for area given distance from pcp and local lineplant." 

As long as the connection stays in sync over the next few days & error counts don't cause DLM to take "negative" action, I will remain reasonably pleased with the eventual outcome, ignoring the thought that the switch to the 17a profile could/should have brought my connection a little closer to a stable 40Mb sync speed.


Paul.

EDIT:

IP Profiles graph following this morning's visit is attached.

<Talks in hushed tones icon> Nice one BE. We've always said that your line would be capable of these speeds, but crikey, it aint half taken some time to arrive here !! 

The figure of 61 you mention. That is the AC Balance figure that really dictates the quality of your line, in relation to resisting 'noise' ingress. After all, if 'we' could eliminate noise completely, we could probably supply 300Mb down Cu/Ali without the need for FTTC/FTTP.
So, to answer your question ............ yes, 61dB is a great value BE.

What I can't get my head around, is why Andy has decided against performing a TDR scan ?? This is the easiest test in the whole, wide world to accomplish. With multiple 'repeat reports' akin to your job, I would have set the TDR trace going and whilst the trace is running, ring your landline number in order to 'load up' the circuit to its max. In it's 'normal state', the TDR trace would be looking back towards the Exchange against the nominal 50Vdc. If there is a 'HR' developing, but is only small, the TDR will probably miss this. By ringing the circuit with the meter connected, the circuit's conditions change to between 90-120Vac, thus giving the TDR trace a far better chance of 'seeing' the HR.

I digress, Andy was the man-on-site, not me. He must have had his reasons, so I can't really comment further on this.

Either way, fingers crossed, you're back to where you want to be. Big up to you for persevering, and Alex for not giving up. 

[burakkucat]

Although I got a little grumpy over PlusNet's inaction in the early days of your troubles, I would now like to publicly congratulate them for "staying with you". By following that path, they have allowed you, us and themselves to learn more about the "unknowns" of a VDSL2 circuit. 

 

[Bald_Eagle1]

Update 10/03/2012:

From my logs I noticed the modem had resynced "on the fly" at just after 5:00 this morning.

Sync speed is down to 33.14Mb, IP Profile at 32.07Mb & throughput at 30.14Mb:-




It was a little higher until I disconnected/reconnected the router only to force a new PPP session to update BT's IP Profile. It had stuck at yesterday's 34.19Mb:-



Maybe I was just unlucky to connect to a slower Plusnet gateway this morning.

I can’t see what might have caused the re-sync other than DLM trying different settings until it finds a suitable balance between speed & stability over the first 48 hours.
The 10 day training period does not exist for VDSL2/FTTC connections (despite what ISPs & BT agents might tell us).

I noticed that Interleaving had been turned off for both DS & US, hence the ping time of only 5ms.

I thought that a little strange though as I still see quite a lot of various errors & error seconds.

Interleaving had always been on at varying depths (up to 1700) for my DS & off for US until yesterday.

Following yesterday’s DLM reset & until this morning’s re-sync, DS interleaving was at a depth of 16 & US at a depth of 8.
Now they are both at a depth of 1 & 1 (off).

Impulse Noise Protection is also currently at 0.00 for US & DS, as is delay.
I don’t ever recall seeing that previously for my connection.


I think during the next 24 hours will be when the connection stabilises (according to BT’s SIN 498 document):-

“2.2.5 Dynamic Line Management

Dynamic Line Management (DLM) is employed in GEA-FTTC. DLM constantly manages lines to maintain a target stability. It does this for as long as the product exists.

At provision, the line is put on wide open profiles, allowing downstream line speeds of up to 40Mbit/s, and upstream line speeds of up to 2Mbit/s or 10Mbit/s depending on the upstream product option selected.

On the first day of operation, DLM will intervene if severe instability is detected.

Otherwise, DLM will wait until the day after provision before intervening, provided that the line has been trained up for at least 15 minutes during the preceding day.

If DLM intervenes it will set a capped profile with a maximum rate and a minimum rate, where the minimum rate is set at approximately half of the maximum rate.

The purpose of the minimum rate is to ensure that the line does not train at a rate which is significantly below the level the line should be able to achieve. If this happened, then the line is likely to remain at a very low rate till a re-train is forced by the user powering off the Active NTE.”



The time frame mentioned is rather vague (in days rather than hours), so maybe BT’s day starts at 5:00am?

My modem re-synced in the early hours (around 20 hours after the DLM reset), when SNRM is at its lowest.
Maybe it would have achieved a higher speed if it had re-synced at around 2:00pm, when SNRM is usually at its highest.

I’ll resist the urge to FORCE any re-syncs for the next few days as I really don’t want DLM to think my connection has become unstable again.

[Bald_Eagle1]

Update 11/03/2012:

Well, since the tentative joy following Friday's DLM reset when my connection synced at over 35Mb, there have been a number of connection "on the fly" re-syncs.

The connection has just re-synced at 23887k, resulting in an IP Profile of 23120k & throughput speeds are :-




Not looking quite so good after all then 

[attachment deleted by admin]

[waltergmw]

@ Bald_Eagle,

I remember you said you were initially quite pleased, as the fibre service remains significantly faster than your old exchange based ADSL solution.
However I'm sorry to say these types of problems are inevitable on some, hopefully a very few, twisted pair lines which are demonstrating their lack of VDSL capabilities for a reliable future-proof solution.
Matters are exacerbated by the lack of a Universal Service Obligation.

In this respect the Virgin Media co-axial solution seems more reliable, although again it must be approaching the network capacity.
Note that it is in effect a "water-pipe type solution" with everyone being fed by a single sealed fat coaxial cable. Their failures will become much more obvious much faster.

Perhaps we all need to become Lunies up in the Vale of Bowland !!!!

Kind regards,
Walter

[Bald_Eagle1]

Update 19/03/2012:

My connection now appears "quite" stable, sync speed 29822 k, with 36Mb+ attainable over the last few days (connected for almost 183 hours now - a record???)

Being switched to the 80Mb/20Mb trial some time tomorrow (as an experiment on a sub-40Mb connection).

I don't expect any miracles, but watch this space............


Paul.

[Bald_Eagle1]

Update 20/03/2012:

It seems that I was switched to the 80/20 Trial just after midnight last night.

It WAS just an experiment & miracles weren't expected, neither were they delivered.

This is the confirmation from Plusnet from this afternoon:-

Code: [Select]

Test Outcome Pass
Test Outcome Code GTC_FTTC_SERVICE_0000
Description GEA service test completed and no fault found .
Main Fault Location OK
Sync Status In Sync
Downstream Speed 32.2 Mbps
Upstream Speed 5.7 Mbps
Appointment Required N
Fault Report Advised N
Profile Name 0.128M-80M Downstream, Interleaving Off - 0.128M-20M Upstream, Interleaving Off
Time Stamp 2012-03-20T00:00:00

PTTR: 27681 (31196 profile on 20/03/12)

RADIUS: 14:24:43 (on going)

Summary:  Line now on the 80M profile with INP Off but will likely change profile shortly
as the line is only achieving 32.2Mbps due to loop loss limitations.



[JoshShep]

How has your connection been Paul?

I was put on 80/20 myself as you know, at provision my speeds went to 38/5 up and have settled at 33/5, I noticed it's 2 days before DLM makes changes.

Good luck with your connection mate!

All the best,

Josh

[Bald_Eagle1]

Hi Josh,

How has your connection been Paul?

Not brilliant. See the attached IP Profiles graph.

The 80/20 trial was just an experiment, to see if perhaps power would be increased to try to give me "something" from the highest frequency band.

Unfortunately, it was a non-starter.

The only thing that got my speeds up a little was the DLM reset while I was still on the 40/10 service.

It gave me a 35Mb sync speed & 33 Mb throughput, but it only lasted a few hours before the connection re-synced at a lower speed.

There have been a few re-syncs since then, 4 in quick succession this morning that left me with a sync speed of only 24.9Mb until I rebooted the modem & achieved a sync speed of 29.11Mb. 

I was put on 80/20 myself as you know, at provision my speeds went to 38/5 up and have settled at 33/5, I noticed it's 2 days before DLM makes changes.

My connection obviously couldn't wait for 2 days 

From the other forum, I notice you sometimes have much higher Attainable Rates than that.

Have you tried out the Windows "Ongoing" graphing scripts that MIGHT just show where things look "problematic"?

Good luck with your connection mate!

I don't think it's luck that I need, rather an engineer to find the "fault" & fix it once & for all.


Paul.


EDIT:
Would you Adam & Eve it?

The connection re-synced again at 8pm.
Sync speed down to only 23.16Mb.

It MAY have coincided with an incoming phone call, but SNRM had gradually dropped to 2.2dB from 6.1dB one hour earlier.

A few minutes following this latest re-sync, SNRM peaked at 10.3dB, but it seems to be fluctuating quite a bit.

The connection also re-synced around 40 minutes later, at 27.1Mb.

It may be coincidence that the weather has been quite warm today?
The modem has remained quite cool though.

The attached graphs show fluctuating SNRM & Sync speeds today.

Testing a telephone with a dangly filter in the test socket (everything else disconnected - apart from the VDSL2 connection in it's usual socket) causes big SNRM drops.


@ Black Sheep

Any suggestions for what to say when I contact Plusnet yet again on Monday?

P.S. The whole master socket & faceplate was completely replaced in November when my drop wire was also replaced.

[waltergmw]

@ paul,

I know of one case only, where a brand new SSFP of BT origin failed within 6 weeks.
I know this is clutching at straws but you might just try getting it changed.

Kind regards,
Walter

[Bald_Eagle1]

Well,


The connection re-synnced again at 05:46 this morning at 28.3Mb.

The internal wiring is still disconnected by removal of the faceplate & a telephone is still plugged into the test socket via a dangly filter.

Strangely, use of the telephone was then only showing a drop in SNRM of 0.5dB (from 6.6dB to 6.1dB).

Obviously the outside temperature was a lot cooler at 05:46 this morning.

By 08:30 (sunny & warm again) use of the telephone causes a drop in SNRM of 2.5dB.

I wonder if warmer, drier weather is having some effect, either upon the cabinet's equipment and/or the D-Side cabling/joints, thus highlighting an intermittent HR fault???

[burakkucat]

That could be a possible cause. 

I'd like to see what Black Sheep is able to suggest . . .

[Black Sheep]

TBH ..... I've not got a damned clue.

As FTTC/P is 'not my bag baby' (well, just not yet), then I really don't have much to go on ? Our old mucker BE has more idea than I, regarding all things Fibre.

Having read on this forum with interest about cross-talk being more prevalent on FTTC, and as such, down-grading the circuits, I can't help wondering if it's this that is the cause of all BE's woes ??

As I say, I genuinely don't know.

[Bald_Eagle1]

Well, just for the hell of it, I swapped the modem & power supply at around 10:40 this morning.

Whether it was the modem swap, or just a new connection, apart from one connection re-sync at 16:00 this afternoon (following another drop in DS SNRM level), the connection has seemd O.K. at a sync speed of only 28.5Mb though.

The phone can now be used again without large SNRM drops.

I did phone home a few times from work today (whilst watching the modem's GUI remotely via LogMeIn), so I suppose the ringing pulses might have also caused a "fix" (maybe of a temporary nature as I have read about in various places).

In a way, I was hoping the connection would fail completely so that an engineer would have to deal with what may or may not have been an intermittent line fault.
Time will no doubt tell...................

[Bald_Eagle1]

I plugged the faceplate back into the master socket, reconnecting the internal wiring.

The connection has stayed up since swapping the modem, but DS SNRM dropped in the early hours to a low of 2.1dB.

Strangely, picking up the telephone this time immediately increased DS SNRM to 5.3dB.
Picking up the phone again dropped it to 4.6dB.

Hanging up the phone increased DS SNRM to 5.6dB & it is currently 5.8dB.

An incoming call reduced DS SNRM to 5.1dB & it returned to 5.8dB when the call was terminated.

Does any of that suggest anything problem-wise?