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Author Topic: FTTC - Distance from the Cabinet - Realistic speed estimate  (Read 212295 times)

Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #225 on: August 30, 2011, 12:01:02 AM »

No news is good news?

No unforced disconnections since Friday.

The line seems stable & no audible crackling on the phone.

Hopefully, the next step(s) will be instigated on Tuesday (whatever they are).

At least I've managed to get some plastering & plumbing done in the meantime.

Paul.
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alexrolls

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #226 on: August 30, 2011, 12:49:06 PM »

Hi Bald_Eagle1,

Your support ticket has been updated.  As per the ticket we will need to monitor the line over the next 24 hours to allow the DLM reset to complete which the engineer initiated.  I will contact you tomorrow if any further action is required.
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #227 on: August 30, 2011, 01:01:01 PM »


Your support ticket has been updated.  As per the ticket we will need to monitor the line over the next 24 hours to allow the DLM reset to complete which the engineer initiated.  I will contact you tomorrow if any further action is required.


Thanks Alex. Fingers crossed  ;)

Paul.
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #228 on: August 30, 2011, 06:05:20 PM »

Walter, Mr Eagle and B*Cat ......... had half a FTTC job today  ;D. Ended up as a 'No access'.

Anyhows, whilst at the Cab, I thought I'd take the attenuation reading before and after the dial tone had been put through to the DSLAM. Results ?? The attenuation was exactly the same.

Therefore, any attenuation readings taken from the EU's premises back towards the Exchange, only account for the D-side network. HTH in future investigations for the EU's and any ISP's looking on. ;) ;D
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waltergmw

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #229 on: August 30, 2011, 06:48:44 PM »

Hi RP and thanks for using your time so effectively !

That does perhaps make some sense as the attenuation observed is presumably part of the synchronisation process between the DSLAM and the EU's modem. Did you by any chance monitor the SNR as well ?

However I'm unclear what this means for Paul as his attenuation figure seems far too high for a normal twisted pair run of about 800 m (as obtained from the BT O records) between his house and the PCP. If I'm not mistaken RP you've said an 800 m line distance might be expected to have VDSL2 speeds far closer to the maximum than Paul's service provides now.

(I'm also perplexed as to how DLM settlement is expected to increase the sync speed by a significant amount when I believe Paul says his bRAS is 21,166 Kbps now when he had observed far higher figures before?)

“Curiouser and curiouser!” Cried Alice !!!!

Kind regards,
Walter

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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #230 on: August 30, 2011, 06:57:03 PM »

Hi RP and thanks for using your time so effectively !

That does perhaps make some sense as the attenuation observed is presumably part of the synchronisation process between the DSLAM and the EU's modem. Did you by any chance monitor the SNR as well ?

However I'm unclear what this means for Paul as his attenuation figure seems far too high for a normal twisted pair run of about 800 m (as obtained from the BT O records) between his house and the PCP. If I'm not mistaken RP you've said an 800 m line distance might be expected to have VDSL2 speeds far closer to the maximum than Paul's service provides now.

(I'm also perplexed as to how DLM settlement is expected to increase the sync speed by a significant amount when I believe Paul says his bRAS is 21,166 Kbps now when he had observed far higher figures before?)

“Curiouser and curiouser!” Cried Alice !!!!

Kind regards,
Walter

Walter ...... thanks for you comments. You see I do think about you, even when I'm not on here.  ;D

I can't remember the D-side distance I quoted on the FTTC Install I did the other week, but I'm sure it was less than 800mtrs Walter ?? Thought it was around 400-500 mtrs ?? Whatever, the synch speed was exactly 39.9Meg on that particular line and I hoped to give a wee bit of guidance in relation to Baldy's line length.

I too am like you and feel time is being wasted with regard to the DLM. The engineer stated he only got 20-odd meg at the DSLAM, then either a full port/card reset is needed, or a lift and shift carried out. DLM will not get any higher without this.

Glad you said it and not me Walter !! Didn't want to upset Baldy any more than what he is. :lol:
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renluop

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #231 on: August 30, 2011, 07:45:46 PM »


Glad you said it and not me Walter !! Didn't want to upset Baldy any more than what he is. :lol:
He having been balded, I have been wondering where his other feathers were being plucked from :-\ :o ;)
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #232 on: August 30, 2011, 09:10:34 PM »

Evenin' All,

Rather than respond individually, I'll just provide an update.

Plusnet's Alex has confirmed he has discussed this case with BT who advised him that the line had been Port Flexed and the DLM system reset.

He also confirmed the Port Flex is simply a reset of the broadband port I am connected to in the cabinet. The DLM reset is a reset of the DLM system which controls my line.

The BT agent asked Alex to monitor my line for the next 24 hours to allow the DLM reset process to complete and to get back in touch with them if my speed has still not improved. He will re-check this tomorrow and take any further action needed if required.

Well, my IP Profile (bRAS) is now 24244 k.

It was at that level when one of the engineers requested a profile reset some time ago.
However, shortly afterward it dropped back to around 15000 k.

I do hope the improvement from around 22Mb to 24.2 Mb is not classed as a suffient improvement to avert any further action.

A property less than 100m across the road from me has estimated FTTC speeds of 27.9 Mb downstream based upon speeds achieved by consumers in the area.
I believe I was that consumer as my download speeds were stuck at that level for a while shortly after the start of the gradual decline.

Touch wood, my line now appears stable with no unforced disconnections or crackly phone lines.

We now have absolute confirmation that attenuation values for FTTC only take into account the D-side line between the end user & the cabinet (as suspected all along - despite what my latest visiting engineer stated).
The only thing I don't have is a record of my line's attenuation from when it was achieving higher download speeds, to use as a comparison with the recent verbally reported value of 23 dB.

From what have gathered about FTTC, it appears that higher speeds can be expected up to a distance from the cabinet of around 1200m. Thereon, speeds tail off dramatically, no doubt due to the different frequencies used for FTTC, resulting in higher attenuations than for the same line length being used for ADSL.
I have also gathered that FTTC download speeds are usually a lot closer to the bRAS than is the case with ADSL - maybe quite a bit over 90% compared to around ADSL's 85%.

What I don't know is whether or not my current attenuation of 23 dB is about right for my distance from the cabinet of around 820m.
If it is, I very strongly suspect it must also have been around 23 dB when I was achieving higher speeds.
If my attenuation is currently substantially higher than when FTTC was installed, there must still be a problem with the D-side that wasn't present for the first couple of weeks following installation.

Plusnet have previously confirmed that no records exist from the original installation & I only started keeping records following my speeds suddenly dropping from 33 Mb to 27-28 Mb. At that time I thought a 5 Mb drop was a problem!!

razpag recently quoted a line length of 488m when obtaining a JDSU attenuation reading of 13.5 dB & speed of 39.9Mb. The next time he installs FTTC on a line length of 820m. I just know he will be bursting to confirm the attenuation & SNR values in this thread ;D. It will address so many questions in one hit.

So, will my speeds improve significantly over the next 24 hours via DLM?
They have not done so previously, so I suspect not.

Is a bRAS (IP Profile) of 24 Mb now correct for my line?
Not if it has achieved much higher speeds in the earlier days.

What else needs to be physically done to get my connection back to the equivalent of a brand new installation with 40 Mb at the cabinet?
Possibly a simple lift & shift?

Has my speed been capped via DLM due to all the disconnections & crackly phone line over the last 2 months?
Probably, but what is now causing my profile to be "stuck" - faulty electronic equipment in the cabinet or at the exchange?

Why are we continually going over the same ground?
Can it really be a simple lack of knowledge of how FTTC actually operates?
The various engineers who have visited my home all appear to have a slightly differing take on matters, so maybe it is.
Plusnet also previously admit they are not too sure either.

What's with all the "Baldy" references already :lol:?

I'm not saying where the other feathers were being plucked from other than to say I don't need all 3 from the back, crack, & sack wax treatment ;) :lol:

More news tomorrow folks.
I already have it typed out - "Success - 35 Mb bRAS, 32-33 Mb downloads back again" :no:

Paul.
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #233 on: August 30, 2011, 09:32:29 PM »

Quote from a page or two ago, "Quite a while later he phoned me to say he had found that the speed was only 22 Mb at the cabinet".

A 'port flex' should have reset this back to 40Meg. If it hasn't, the port is more than likely faulty. Your speeds are still very similar to when you were 'double jumpered' at the Cabinet, therefore it would suggest that the port hasn't reset back to default 40Meg ??

The only variable we don't know, is the length of the stray 'double-jumper' ?. If it was connected to your D-side as mentioned by the engineer, but the other end was hanging loose (not chill-axeing  ;D) only a few feet away within the Cabinet, then the 'extra attenuation' would be negligible. If the other end was connected direct to another E-side or D-side, then the attenuation would quite substantial.

The only definitive way of knowing what your line is capable of, is to have an engineer 'see' if your port is giving out 40Meg at the FTTC.

Regarding 'records'. I'm sure BTw would have a record on RRT of your 35Meg connection rate from their 'Baseline' data stats. I wouldn't know how you could retrieve these though ?? I would think only your ISP, or an engineer working on a 'live' fault would be able to glean that info from them.
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #234 on: August 30, 2011, 10:01:52 PM »

Quote from a page or two ago, "Quite a while later he phoned me to say he had found that the speed was only 22 Mb at the cabinet".

A 'port flex' should have reset this back to 40Meg. If it hasn't, the port is more than likely faulty. Your speeds are still very similar to when you were 'double jumpered' at the Cabinet, therefore it would suggest that the port hasn't reset back to default 40Meg ??

The only variable we don't know, is the length of the stray 'double-jumper' ?. If it was connected to your D-side as mentioned by the engineer, but the other end was hanging loose (not chill-axeing  ;D) only a few feet away within the Cabinet, then the 'extra attenuation' would be negligible. If the other end was connected direct to another E-side or D-side, then the attenuation would quite substantial.

The only definitive way of knowing what your line is capable of, is to have an engineer 'see' if your port is giving out 40Meg at the FTTC.

Regarding 'records'. I'm sure BTw would have a record on RRT of your 35Meg connection rate from their 'Baseline' data stats. I wouldn't know how you could retrieve these though ?? I would think only your ISP, or an engineer working on a 'live' fault would be able to glean that info from them.

I suspect a visit to the cabinet to check speeds there will have to be the next step, possibly requiring another home visit to check speeds at the master socket.

To help me understand clearly, when speed is checked for 40 Mb at the FTTC cabinet, is it done before (E-side) or after the DLM equipment (D-side), or both?

Somewhere in the equation is the capping of upload speeds (2 Mb for my package & I currently have no problem with upload speeds, although I did have for a while - down to 0.67 Mb). Do you know whereabouts this capping is implemented?

If a lift & shift is carried out, I presume that would be in the FTTC cabinet. Would I still end up using the current DLM hardware (potentially faulty) for my connection?
Is there ever a need to do some physical work at the exchange?

 Questions, questions, questions  :D

Paul.
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #235 on: August 30, 2011, 10:16:36 PM »

Quote from a page or two ago, "Quite a while later he phoned me to say he had found that the speed was only 22 Mb at the cabinet".

A 'port flex' should have reset this back to 40Meg. If it hasn't, the port is more than likely faulty. Your speeds are still very similar to when you were 'double jumpered' at the Cabinet, therefore it would suggest that the port hasn't reset back to default 40Meg ??

The only variable we don't know, is the length of the stray 'double-jumper' ?. If it was connected to your D-side as mentioned by the engineer, but the other end was hanging loose (not chill-axeing  ;D) only a few feet away within the Cabinet, then the 'extra attenuation' would be negligible. If the other end was connected direct to another E-side or D-side, then the attenuation would quite substantial.

The only definitive way of knowing what your line is capable of, is to have an engineer 'see' if your port is giving out 40Meg at the FTTC.

Regarding 'records'. I'm sure BTw would have a record on RRT of your 35Meg connection rate from their 'Baseline' data stats. I wouldn't know how you could retrieve these though ?? I would think only your ISP, or an engineer working on a 'live' fault would be able to glean that info from them.

The speed at the FTTC is checked directly onto the DSLAM port (via a link cable from the Fibre Cab to the existing cab). As mooted above, when the E-side dial tone is put 'in circuit', there is no change to the 40Meg speed as the attenuation is (at this point in the proceedings), only from the DSLAM located in the Fibre Cab down the link cable to the existing Cab.

Capping is applied remotely by the ISP's. Currently, FTTC products offer up 2 or 10 meg Upstream connections. Capping is there for a variety of reasons ..... non-payment of bills, downloads over and beyond FUP, to maintain a stable circuit.

If a 'L&S' is performed, it will only require the engineer to re-jumper within the Cab to the new port, (or in laymans terms), to reconnect to a new pair in the link cable.

HTH.   
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #236 on: August 31, 2011, 12:20:36 AM »


If a 'L&S' is performed, it will only require the engineer to re-jumper within the Cab to the new port, (or in laymans terms), to reconnect to a new pair in the link cable.
 

So, if I now understand matters a bit more clearly, all the pairs in the link cable are already connected to their own DSLAM port inside the fibre cabinet?
Inside the old cabinet, some/most of these pairs are not connected to anything. They may just be hanging loose?

When FTTC is installed for each customer who orders it, the engineer never actually goes inside the fibre cabinet.
He just connects one of the loose pairs in the link cable to the customers D-side inside the old cabinet.
Something stops (or should stop) some of the broadband going back down the E-side toward the exchange

If only 22 Mb was seen by my engineer at the cabinet, he really meant that only 22 Mb was showing inside the old cabinet at the end of the link cable.

Let's just say I am currently connected to DSLAM port No.1 inside the fibre cabinet via the link cable from the old cabinet.
A 'L & S' would disconnect me from DSLAM port No.1 & connect me to DSLAM port No.2.
Assuming DSLAM port No. 2 has never been used, DLM cannot have affected it & 40 Mb should be seen at the old cabinet end of the link cable.

If 40 Mb is not seen at the end of the link cable the unused DSLAM port No.2 could be faulty & DSLAM No. 3 will be tried & so on until 40 Mb is found.

In other words, it should end up just like a brand new installation giving me 40 Mb, less a few Mb for my D-side's attenuation.
The DLM should restart the training period until my now bang tidy D-side line makes it settle at let's say 35 Mb just for argument's sake.

If it really is as simple as that, the question has to be asked, why was this not tried before now e.g. when BT reset my profile a few visits ago to only 24 Mb, stating that was all my line could ever achieve?
It doesn't sound like a major and/or costly operation.

Are all the DSLAMS ports inside the fibre cabinet already "live", or do they need to be switched on at the exchange only whenever a customer orders FTTC or when initiating a 'L & S'?
In other words, is it just possible that only 22 Mb was/is being delivered down the fibre to the fibre cabinet?

If all my wittering above is a load of nonsense, I'm sure you will put me straight again (please)  :)

Paul.
« Last Edit: August 31, 2011, 07:08:26 AM by Bald_Eagle1 »
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #237 on: August 31, 2011, 07:36:59 AM »

Nail on head Paul.

Yes indeed, the ports are all pre-connected to the Fibre cab via a link cable. We (Openreach CSE Engineers) do not have access rights to the FTTC, nor do we need it.

The ports are dead until made 'live' via an order. Having said that, there may be situations where the port has been 'stopped', so voltage may be present (ie-synch can be attained) but there will be no virtual path to obtain an IP address. This might happen if an EU has had VDSL but is moving house.

As I say, I too am learning on the odd chances I get to go on these jobs. Shame this hadn't reared it's head 6 months ago, I was doing roughly 3/4 FTTC Installations a day. The problem is, as an engineer you aren't overly consumed with in-depth investigations into speed, attenuation etc ........ your main concern is the actual installation. If that makes sense ?
 
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silversurfer44

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #238 on: August 31, 2011, 08:25:06 AM »

Quote
e.g. when BT reset my profile a few visits ago to only 24 Mb, stating that was all my line could ever achieve
Unless Plusnet can do some arm twisting I feel the above statement could be correct.
Regardless of the connection achieved when the FTTC was first installed for what ever reason BT are now saying your line can only achieve 24Mb.
Depending on the wording of your contract you will be receiving a satisfactory (to BT) connection rate.
I hope you and the Plusnet guys are successful in your quest, but remember who you are ultimately dealing with.
My post is not a reflection on OR or anyone other than the provider of the system/line, and I don't mean Plusnet.
Good Luck.
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #239 on: August 31, 2011, 08:49:13 AM »

Nail on head Paul.

As I say, I too am learning on the odd chances I get to go on these jobs. Shame this hadn't reared it's head 6 months ago, I was doing roughly 3/4 FTTC Installations a day. The problem is, as an engineer you aren't overly consumed with in-depth investigations into speed, attenuation etc ........ your main concern is the actual installation. If that makes sense ?


@razpag,

Thanks for confirming my understanding. I now see the whole thing in a much clearer light.

I realise that as an engineer, your priority is to install FTTC & make sure it works O.K.

However, as there is currently so little real-life situation data available (connection stats etc.) that would help end users understand & manage their expectations in a realistic manner, it would be really helpful if you could find the time in your busy real work schedule to make a quick note of the JDSU stats & ACTUAL LINE LENGTH for us for your next few installation/repair jobs (whenever they may be).

I wonder if any of your colleagues would be interested in forwarding such data too.

I don't mind compiling a record that would assist me personally in reporting problems etc. & probably any others who experience similar problems, and/or avoid end users wasting everyone's time by falsely reporting "problems" that are not really a problem in that their expectations may be too high.
e.g. I would not be pursuing this matter if I had never achieved higher speeds, or if I discovered that my D-side line actually went all over the place before it reached my house & ended up as say 2000m from the cabinet.

I knew what to expect via ADSL for my D-side line from the exchange & I knew when & when not to report a problem, with some confidence that I was genuinely not wasting anyone's time.

I believe we have now finally managed to get to the crux of my particular issues.
It has been quite a slog, with many (far too many) words written in various places.

Historical, real-life data to work with could/should have made this a very simple matter, with clear indications of where the problem(s) were located at a very early stage in the investigation.

On a commercial basis, just imagine how much money BT could have saved by tracking down the "real" issues & fixing them at the outset.
ISPs would also benefit by not having to keep updating fault tickets & chasing BT for the "right" sort of engineer to fix the "right" fault.

Paul.
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