Kitz Forum
Broadband Related => ADSL Issues => Topic started by: Weaver on November 10, 2015, 01:38:33 PM
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Article at ThinkBroadband:
http://www.thinkbroadband.com/news/7234-highlands-and-islands-announce-next-areas-to-benefit-from-faster-broadband.html
- about arrival of FTTC in Western Isles plus the odd place on the West Coast of the mainland of Scotland.
(I presume he's talking about FTTC, even though he keeps saying "fibre-based", seeing as he mentions VDSL2. FTTC is of course copper, not fibre at all, that would be FTTP/FTTH. But this could confuse newcomers.
Should know better than to get drawn into the slipshod marketing-speak that the government and various salesmen have got drawn into, where fibre has started to be misused to means "anything at all fast" so the likes of cable internet, and copper in FTTC and FTTDP/ FTTRN have been described as "fibre".)
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Article at ThinkBroadband:
http://www.thinkbroadband.com/news/7234-highlands-and-islands-announce-next-areas-to-benefit-from-faster-broadband.html
- about arrival of FTTC in Western Isles plus the odd place on the West Coast of the mainland of Scotland.
(I presume he's talking about FTTC, even though he keeps saying "fibre-based", seeing as he mentions VDSL2. FTTC is of course copper, not fibre at all, that would be FTTP/FTTH. But this could confuse newcomers.
Should know better to get drawn into the slipshod marketing-speak that the government and various salesmen have got drawn into, where fibre has started to be misused to means "anything at all fast" so the likes of cable internet, and copper in FTTC and FTTDP/ FTTRN have been described as "fibre".)
In the interests of balance and fact ........ FTTC is a hybrid of Fibre and MPF (Copper/Ali cable). It is Fibre to the Cabinet, which means if it's located outside your house, that 99.9% of the circuits make-up is Fibre.
Of course, the location of the Cabinet will vary dramatically between different EU's, so it is totally impossible to market the product in any other way other than FTTC, or super-fast broadband.
They can't factor in each and every EU's premises and distance from their serving Cab, for each and every single location in the UK ...... that would be madness.
The way you've described it could confuse newcomers
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@BlackSheep -could confuse users, agreed. Mea culpa. (Autocorrected by iPad to "mea cuppa" repeatedly, which I quite liked, then I had to wrestle and defeat the thing, for I am mighty.)
My "it's copper" is perhaps a bit tooo short.
What a naive user perhaps wants to know is IMHO
* FTTC - performance is length-related, don't get max perf necessarily
* Is subject to interference, weather and so on
* crosstalk spoils perf, droops over time (barring g.vector)
* Lightning risk, hence the "it's copper" huge oversimplification (apol)
* FTTP - performance is (practically speaking) not length-related, just works
* highly reliable not subject to interference, nor weather etc
* no crosstalk
* no lightning risk, as no long metallic path
So the difference as we know really matters to the user. The govt and the marketing men don't seem to care or know the difference.
Much respect for BlackSheep's contribution, as always.
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@BlackSheep - the 99% point is indeed a good one.
I wonder what the length ratios are typically, and what the lightning risk is like then
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New developments: I got this tweet from some government[?] bod:-
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@HIEdigital: Hi @CecilWard Work is due to start in Broadford in the early half of 2016. Please DM us your details so we can look into it for you. Thanks.
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Wow. Didn't say what "work" might mean.
Upgrade to 21CN might be a start. Would save me quite a bit of money as it would halve my per-MB charges for office hours / peak time, which are doubled currently because it's 20CN. (No diff between 20CN-21CN for off-peak.
Presume that 21CN would give me ADSL2+ ? (and ADSL2) That would speed things up a bit.
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If they're talking about FTTC, then who knows what use that would be to me, an EO line currently, 4.6 miles long (est. by-road). Who knows where they would put some cabinet(s)? On that depends everything. Where do they put them if they have distant users?
Or what about a tin box "node" on a pole if they are doing FTTDP/FTTRN. ( Is that just a trial, or real yet? ) Would that be close?
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Could they start offering FTTP? What does that depend on?
If that's a possibility then that's what I should be going for, AA charges are a bargain given the high reliability you would get.
Sooo many questions and nothing to go on, no "availability checker".
I hope they will somehow let A & A know. If I can find out something, perhaps I can put A & A in touch with the relevant human who knows what and when. Perhaps I need to _do_ something.
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Am definitely getting ahead of myself. Hope drives you crazy.
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@BlackSheep -could confuse users, agreed. Mea culpa. (Autocorrected by iPad to "mea cuppa" repeatedly, which I quite liked, then I had to wrestle and defeat the thing, for I am mighty.)
My "it's copper" is perhaps a bit tooo short.
What a naive user perhaps wants to know is IMHO
* FTTC - performance is length-related, don't get max perf necessarily
* Is subject to interference, weather and so on
* crosstalk spoils perf, droops over time (barring g.vector)
* Lightning risk, hence the "it's copper" huge oversimplification (apol)
* FTTP - performance is (practically speaking) not length-related, just works
* highly reliable not subject to interference, nor weather etc
* no crosstalk
* no lightning risk, as no long metallic path
So the difference as we know really matters to the user. The govt and the marketing men don't seem to care or know the difference.
Much respect for BlackSheep's contribution, as always.
As I yours, Weaver.
I think one has to always bear in mind, that the majority of End Users really aren't that bothered with the circuits statistics and characteristics. I promise you hand on heart, most EU's won't even realise their circuits performance has dropped through cross-talk, or that a lightning strike may see the DLM over-act (non-G.INP Cabs).
They are of course expecting an 'Always on' service and that it does what is says on the tin, which is what happens with FTTC.
It's whether the information given at the point of sale is fully understood by the EU, and/or that it is given over in a concise manner by the sales advisor.
However, all that information can not ever be covered in a short marketing advert, poster campaign hence the onus being put upon the EU to ask questions if necessary.
Yes, there's always going to be someone coming on here telling a tale of san elderly relative being miss-sold a product, but these are in the low percentages thanks to programmes like 'Watchdog' etc.
In short, it's impossible to market exactly what FTTC Broadband is all about to the average layman, without a certain amount of dialogue taking place. :)
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@BlackSheep - apol, by "lightning risk" I meant _kit destroyed_, or worse, not DLM. A big thing to appreciate if you are thinking of long metallic path vs FTTP.
I have lost ~£3k worth of hardware over the years. A £2.5k server, a £700 router recently I forget how much else. When the weather is bad sometimes I used to leap out of bed and run to pull out the DSL lines from the NTE5s. I didn't always get there on time though.
An end to lightning risk is one of the big selling points for FTTP for me.
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A valid point indeed, especially for rural EU's like yourself. But, playing Dick Advocaat for a minute, BT as a company or the EU as a whole, probably won't make decisions based on 'Acts of God'. :)
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Btw, the reason I put crosstalk in my list of things a growing boy should know is not a techie one. Users need to be warned that the performance they are quite will drop over time, unless the cab is full, and many inexperienced users here have come round moaning about their sync rate sliding southwards, they have been mis-sold on perf. and so on. So it is worth knowing, and can be explained in a concise, very non-geeky way.
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@BlackSheep lots of locals lose kit around here every winter. The weather is ridiculously bad here, force 10 gales are regular events, lines are very long, and people are only saved by the accidental fashion for home users using WLANs all the time, thus protecting their kit.
Last winter an outdoor wooden building that my wife had put up was destroyed by the Bernoulli effect I believe. It was literally pulled in half, the top half was wrenched upwards leaving the bottom half still securely bolted into the ground, but the low pressure pulled the planks apart, the top half then took off went flying horizontally and landed upright some ten metres away, with the other half still in situ.
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I hope she was all right ;) (sorry couldn't resist) Actually I now have an image of somebody in a shed on a loo, and the top half being ripped off, a bit like in the films.....
I'll get my coat.....
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@Ronski :-)
Janet had a barbecue and a kitchen set up in the (posh) shed
Lost umpteen ££ as all the contents were scattered and generally knackered, she gave up on it and didn't put up a replacement.
The weather is just ridiculous here sometimes, with rain flowing uphill up the road and spraying off upwards at you when you come to a crest after which there is a long downhill slope. I can't remember the wind speeds in Jan last winter, but I remember it was 130mph in Jan 2005. Several locals were killed, a man in a caravan was blown off a cliff, and an entire family, of three generations, was washed away by the sea in the Western Isles ill-advisedly trying to drive over a causeway between South Uist and Benbencula. Horrible.
I'm trying to think up some optical isolation setup for my router, and I'd like to get some proper specific insurance for networking equipment, servers and so-on, but haven't a clue where to start.
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I wonder if there is an availability checker or whatever that actually works, the ones I have tried just seem completely broken. I'd like something that shows me what the planned developments are. I can't see any point in secrecy, it buys the powers that be some goodwill by relieving long-suffering would-be users' frustration, if they show what is planned well in advance and there's no hiding it as the gossip machine and crowdsourced BTOr surveillance is pervasive and very effective, and aside from that BT guys are quite happy to tell you what is happening according to their internal rumour mill.
Some of the BT guys I have talked to don't understand much about DSL, the Internet and networking, they find it all v confusing, a blur of TLAs and jargon. One guy I talked to a while back, a really nice guy, was definitely in this category. I think he was trying to tell me about planned FTTRN but didn't have all the vocabulary, so I had to use a bit of reading between the lines / guesswork to make it out. They've all just been incredibly helpful, one guy even gave me a free Pressac NTE2000 just to be nice as he just had one in his van.
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I think the problem with BT releasing their plans is that they can change at any moment, remember the fuss and problems when the availability checker used to show an estimated date and people complained because the dates kept slipping.
With reference to the storms I guess it must be like the bad storms we had many years ago in the South East of England, fortunately we don't get them very often, but it sounds like you get them every year.
Regarding insurance, try someone like Hiscox, they are expensive but apparently very good. I recently changed over to them, cost me another £15 a month but it's worth it for the peace of mind.
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Does FTTP become available on some / all / no exchange upgrades nowadays ?
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I think all updates about the progress of any current FTTC deployment are published by the local council / authority responsible for it.
I think FTTP might get made available in a few places, if that worked out the cheapest solution for a few properties somewhere. I doubt they would do FTTP for a whole exchange, it would only be for a few specific areas.
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Weaver, if you are worried about the BT line suffering a lightning strike, why don't you only terminate the modem/router to the line and use a Wi Fi extender ( like a Netgear WN 2000RPT ) to isolate the rest of your equipment from the line. Provided that you use mains surge protector on your equipment, only the modem router should be vulnerable. Using WiFi to isolate your modem from the outside world is hardly likely to affect your speed considering your few neighbours around where you live ???
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@benji09 I've recently lost one £700 router so I need to protect everything (bar the three modems they are cheap). I'm thinking about putting the modems onto a VLAN switch, aggregating them into one VLAN-tagged pipe and putting that through an RF link into the PPPoE Input of the router, which understands VLAN tags with PPPoE.
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I'm also thinking about Ronski's tip concerning insurance and get a few grand's worth of cover for all the hardware.
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*** BAD NEWS ***
The powers that be emailed my wife and told her flat out that they are not offering any solution for rural users. No FTTC for the likes of me and presumably no FTTP either.
I assume this is because they are going to put up one single cab near the exchange? I don't know, but the plan is to let all the haves have much higher speeds than ever, given that they are the ones most in need, obvious eh?
Anyway I completely lost it at this point, and sent back a furious and utterly pointless response to the couldn't give a stuff officer at HIE or whoever it is. I will post said rant up if anyone is st all interested in a bit of fun.
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I'm also thinking about Ronski's tip concerning insurance and get a few grand's worth of cover for all the hardware.
When working at Hot-sites, we have to protect the EU's equipment using Line Isolating Units. For PSTN and DSL we would use a 3C and a 12C. Although it only electrically separates (via a transformer) up to 20Kv ...... if I remember rightly ???
I may be way off the mark there, as although we fit these units, it might be one every 5yrs !!
PS ...... again if memory serves, you're looking at approx. £500-600 for the two units !! :-X :)
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Two words for Weaver to consider: Optical isolators. You will, of course, need as many as the number of lines you are currently using. ;)
I am referring to the devices that Openreach will use when a circuit needs to enter (exit) a "hot" area. ("Hot" as in hazardous high voltages.)
[Edit: I see Mr Sheep's hoofs are faster than my paws.]
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Sorry Weaver, I forgot about your duplicated internet connection. Since I have had not used that facility, I can't comment about it. The fact you mentioned MODEMS instead of MODEM/ROUTERS means that even if it were technically possible to set up duplicate WIFI paths, then combining the data stream would not possible anyway ?
Reading the latest replies about you lack of an increase in line speed at this, BT must come with something in the future to include you and others in the same position as yourself. Maybe they may come up it a pole mounted regenerative repeater ( two complementy modems connected back to back ) in the future, as cheap non F/O fix.......
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So it seems I am out-of-luck.
No high speeds until [?]2020 (haha), but possibly some other goodies!
Could someone help me with a few answers to easy questions?
* 21CN: Do I get a 21CN exchange then? Could anyone tell me if that's a definite yes in an FTTC deployment.
(21CN is good as it halves my data costs in the daytime peak hours. )
* Does it then also mean that I could definitely get ADSL2? A bit more speed then compared with ADSL1, if so.
* Any chance of SRA some day? (Q: don't know if I have a modem that can support it? DLink DSL-320B currently)
Note to self: I will get 1500+8 byte MRU/MTU working now with my DLink modems. Excellent
* ADSL2, or ADSL2+, or both?
* Which do I choose? (Ultra-long line 4.6 mi from the exchange.)
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@burakkucat - I have looked at optoisolators and found a suitable device qty 6. All a bit of a nightmare.
But seeing as I might be getting a fourth line, just possibly, I will need to go with the cleaner VLAN tagging switch plan as I run out of free ports on the Firebrick to use as modem links, and in its favour the VLAN switch plan has been written up in detail by an AA staff member, or user I forget which.
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BTW - If anyone feels up to putting me straight on those few questions I would be extremely grateful.
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Feeling pretty miserable and deflated after having had dealings with Goebbels department at the HIE where everything is shiny and wonderful, unless you are a rural user, and what are the chances of one of those in Skye or in the Highlands.
* Aside from possible 21CN-ness and possible ADSL2, then I'm stuck until we see what 2020 may bring - if the year of the USO turns out not to be just another bad-taste joke.
Maybe wait another decade again then, powerless, to see if those in control of our lives decide to throw us a few scraps, or see if technology gives us a break, or if there is a big shift in local politics.
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Apart from answers very gratefully recvd, and any welcome exchange upgrade bonuses, this is unfortunately the end of this story for another four years or ten years or whatever.
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@BlackSheep, @Burakkucat - the optoisolators I was looking at possibly spoke Ethernet were rated as good for 100 Mbps anyway. Can't remember the mfr, would need to dig out my notes, but they were ~£50 (× 2 × 3)
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* ADSL2, or ADSL2+, or both?
* Which do I choose? (Ultra-long line 4.6 mi from the exchange.)
ADSL2 and not ADSL2+.
At a length of 4.6 miles, you will not be able to use all the tones of ADSL2+ so ADSL2 will be the correct choice. Although ADSL2 uses the same number of tones as G.Dmt (a.k.a. ADSL1), they are used more efficiently.
For the circuit from EABSE to The Cattery, Beattie Bellman states "Recorded Line Length: 2481m, Estimated Attenuation: 34dB". The Huawei MSAN at the exchange end is configured for ADSL2+ mode by default but will drop back to ADSL2 or G.Dmt if the CPE requests it. Due to the length and quality of the circuit none of the higher tones (of ADSL2+) are used. Hence I have configured the modem to use ADSL2 mode.
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@Burakkucat -many thanks for confirming my suspicion, as I seem to remember this from long ago.
I will presumably have to somehow get into all the DLink modems and lock them to ADSL2-only mode, not "auto". God knows how. I'll maybe have to get AA on the case.
Just so I understand, why is ADSL2+ actually a _bad thing_ rather than just being of no advantage?
What would happen if I simply left things on auto?
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I remember ADSL2 allows a single bit in a bin, not requiring two bits min as G.Dmt does. So a bit of extra performance there.
Any chance of SRA ever?
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My other questions was, do I definitely go 21CN?
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Just so I understand, why is ADSL2+ actually a _bad thing_ rather than just being of no advantage?
What would happen if I simply left things on auto?
In my own case, I noticed better performance with ADSL2 rather than with either G.Dmt and ADSL2+.
The number of bits per tone (bin) comes into the consideration . . . and I know that Kitz has a write up, in the main site, which explains all.
As for the "badness" of ADSL2+ in your case? :hmm: Consider that you have a wide band receiver (modem(s)) listening to what the wide band transmitter (DSLAM) is sending. Now due to the length of the circuit, the top 50% of the frequency range cannot be used due to excessive attenuation. Your receiver, being configured to use those higher frequencies, turns up its gain in an attempt to "hear" something. But fails. It persists. Now Hamish, in his hire car, is taking old Mother McDonald to see the doctor. Hamish's car, due to its age, tends to act as a wide band spark transmitter similar to that of Marconi's best from the beginning of the 20th century. You wide receiver happily picks up the signal transmitted by Hamish's car and, as a result, you have a burst of CRCs. As no useful signal will ever be received in that top of the frequency range, it makes sense to turn off the receiver . . . i.e. configure the modem not to use them. :)
SRA. I always configure that as on, on the off-chance that one day it may be implemented! :D
20CN & 21CN. That question can be sub-divided into Broadband access and telephony.
The latter first. My understanding is that Beattie Bellman had big plans to move to VoIP for 21CN telephony. After a number of reviews, technical, financial, etc, the idea was dropped for the foreseeable future. So all classical telephony is very much 20CN.
Broadband access. I believe (but will be happy to be corrected, if wrong) that the equipment for ADSL2+ and upwards (i.e. VDSL2) is all termed 21CN. :-\
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@burakkucat - re ADSL2+ got it. The wider the bandwidth of the rx system the more crap flies in. I didn't think about hardware being reconfigured much, I just imagined that and ADSL2+ system had wider-band capable hardware and the differences are down to software only. Obviously your design is far superior, with variable bandwidth hardware.
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@burakkucat -just for me being super dim;
Q1: if you are going to offer FTTC, then is it true that your exchange, at least the xDSL side of it, ignoring PSTN, is fit to be called 21CN? This is the crux of things. I get 50% off daytime peak dats from AA if the exchange "is 21CN".
Q2: if you are offering FTTC, do non-FTTC users on the exchange always get offered an option of ADSL2 ? (or only g.dmt)
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Not necessarily.
Smaller exchanges may take the fibre incoming supply instead from another nearby 'head end' larger exchange.
So the FTTC cabs will be supplied from a different exchange to the one the user's phone and ADSL comes from.
In this case the local exchange will remain on ADSLmax, and the users will have the options only of ADSLmax or FTTC.
So no, in this case the exchange remains on 20CN.
Indeed very long term I see this as the modus operandi for BT once the entire UK has FTTC.
Large regional exchanges supplying maybe 1000+ cabinets in the entire surrounding area.
Eventually these FTTC units will be able to supply the voice service as well leading to all these smaller local exchanges being closed.
All users will be by then have been swapped to FTTC compulsorily so the local exchange building becomes redundant and can be sold off for housing plus the E sides cabling in ducts recovered and sold.
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b*cat bows, in gratitude, to c6em for answering Weaver's most recent queries. :)
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Mother McDonald and Hamish
It would have been better if you had used Father Ted and Mrs Brown in this example can already here Mrs Brown say to father will you feckin speak up can't here you with all that p00 :D
https://www.youtube.com/watch?v=Jreqe8rTy3Y (https://www.youtube.com/watch?v=Jreqe8rTy3Y)
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Not necessarily.
Smaller exchanges may take the fibre incoming supply instead from another nearby 'head end' larger exchange.
So the FTTC cabs will be supplied from a different exchange to the one the user's phone and ADSL comes from.
In this case the local exchange will remain on ADSLmax, and the users will have the options only of ADSLmax or FTTC.
So no, in this case the exchange remains on 20CN.
Indeed very long term I see this as the modus operandi for BT once the entire UK has FTTC.
Large regional exchanges supplying maybe 1000+ cabinets in the entire surrounding area.
Eventually these FTTC units will be able to supply the voice service as well leading to all these smaller local exchanges being closed.
All users will be by then have been swapped to FTTC compulsorily so the local exchange building becomes redundant and can be sold off for housing plus the E sides cabling in ducts recovered and sold.
Some places did get 21CN ADSL2+ after most of the area served by the exchange has either got FTTC or FTTP, like mine - and since IPstream has been retired here it's ADSL2+ or FTTC/FTTP only. I have no idea what drives BT's decision making on that, just as it's unclear why they cherry picked certain streets here for the full FTTP treatment but decided others (with people on much longer lines) can make do with FTTC. I am reasonably sure that the FTT* comes from a more distant exchange, so that would not be why.
TalkTalk also came in afterward and LLU'ed my exchange too so they're on the same wavelength (or doing it to avoid paying to use BT's voice network).
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On 21CN:
At a previous address, the exchange (Brookwood) was slow (for a large exchange) to get 21CN. FTTC went live around 6 months before 21CN.
Ordinarily, I'd think the cabinets could have been wired to a different head-end (Woking), but that exchange was even later to get FTTC.
On optical isolation:
Would it be enough to just use some media converters for the ethernet connection (on the PPPoE leg)? Something that did 100base-tx to 100base-fx, leaving a short fibre leg?
http://www.cclonline.com/product/85222/INSIXTMC100SC/Wired-Accessories/Dynamode-Insixt-INSIXTMC100SC-100TX-100FX-SC-Multimode-Media-Converter/NET0664/
On the future prospects:
If the superfast coverage stays 4 miles away, it is at least only 4 miles away. Any prospect of setting yourself up with a wireless backhaul to a friendly bod near the cab?
On 21CN:
I think b*cat got the history (with voice and data) correct. For me, the distinguishing feature *now* is that 20CN was based on an ATM core, while 21CN is based on an IP core.
As BT have said they expect most subscribers to be using IP-based voice by 2025, the question is ... how? Do they intend to re-invoke the original 21CN picture, with voice converted at the MSAN (or, presumably, now including the DSLAM MSAN in the FTTC cabinet)? Or do they introduce voice gateways in the house, and convert it to IP before it ever leaves the home!
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@WWombat on the friendly bod idea, I have one in mind, but it would be a really cheeky big request I feel, putting her in a very awkward place when she wants to say no. The other thing is that the 3 mile link to her is very difficult, there's no line of sight, so there would have to be a two pairs of dish antennae high on the moor or something, and god only knows how I would get power to the units, plus the fact that the 130mph winds would rip them to pieces.
We are due for >85 mph winds this afternoon, my brother-in-law has been going round the place looking for potential missions and anything loose. I'm going to get someone to do a dress rehearsal with the generator. Am also hoping the new fat UPS will prove its worth. Have two UPSs now, one for a PC and its display, and another huge one for all the networking equipment.
Need to refuel the generator and make sure it starts ok. Really need a more expensive push-button-start one as this pull-cord thing is too difficult for my wife to start.
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Weaver, Slightly off topic, but reference your lightning strike problem, do you leave a long wave radio on during the day - possibily tuned to Radio 4 ?
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@benj09 - should I Benj?
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The lightning isolation preferred solution now is to use a single pair of 100 Mbps fibre media converters back-to-back, on one side is a port for PPPoE on the router (a Firebrick) and on the other side is a VLAN switch (prob HP) to which all the modems are connected. This allows me to have more than three modems if I can get yet another line out of BT, solving the limitation of the number of free ports on the Firebrick (currently zero).
I can't remember where I found a good-looking fibre media converter. Damn, keep losing urls, will now have to do the research again. Will also have to find s pair of v short fibre links. The fibre media converters were £50 × 2, rather better than × 2 × 3 for the original solution without the switch.
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Weaver, If I hear on the weather forecast that a storm may be coming - even where I live, outside London - I put the radio on to listen to the clicks and bangs to warn me of problems to come. does give false positives, but allows me to play safe. In the case of bad storms coming it alows me to disconnect my Sky FTTC modem/router, and change wirelessly to my son's Virgin line, taking all my VOIP lines as well ! So in answer to your question I would definately, if I were you, listen to your long wave radio. Bear in mind that the Met Office does the same thing, but on much lower frequencies...........
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Nice bit of info ^^^^ Cheers. :)
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I watch the website lightningmaps.org when things are looking bad, which draws a map of lightning strikes every so many secs, and I have an iOS app called NetWeather or something like that which does pretty much the same thing, with updates every 15 mins or so for lightning strikes all over Europe.
Perhaps I need to buy a traditional style radio, and then I need a small child or a slave to monitor it, as I am asleep most of the day (suffering from CFS and little sleep at night some times because of pain). An app that could do push notifications would be very good, as the two services mentioned earlier don't alert you, you just have to keep peering at them.
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On 21CN:
I think b*cat got the history (with voice and data) correct. For me, the distinguishing feature *now* is that 20CN was based on an ATM core, while 21CN is based on an IP core.
As BT have said they expect most subscribers to be using IP-based voice by 2025, the question is ... how? Do they intend to re-invoke the original 21CN picture, with voice converted at the MSAN (or, presumably, now including the DSLAM MSAN in the FTTC cabinet)? Or do they introduce voice gateways in the house, and convert it to IP before it ever leaves the home!
Those of us (vaguely) familiar with the telecommunications history of this nation will recall how ISDN was going to be the next big thing. One circuit to each end user, into which could be plugged a variety of devices. The circuit was to have been digital and existing analogue telephones would need to be connected via an adaptor (ADC & DAC, dependent upon the direction being considered). ISDN was to have been a small subset of a totally IDN . . . But then ATM and Broadband (using FDM) appeared. So now we have (essentially) analogue local loops -- i.e. all that is maintained by Openreach -- with the rest of the infrastructure completely digital. (Give or take an odd exception.)
My limited understanding of what was proposed for 21CN telephony was that the conversion to/from IP would have been performed at the end-users premises. I.e. there would have been some form of active NTE/NTU into which the classical analogue telephone could be connected.
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On optical isolation:
Would it be enough to just use some media converters for the ethernet connection (on the PPPoE leg)? Something that did 100base-tx to 100base-fx, leaving a short fibre leg?
http://www.cclonline.com/product/85222/INSIXTMC100SC/Wired-Accessories/Dynamode-Insixt-INSIXTMC100SC-100TX-100FX-SC-Multimode-Media-Converter/NET0664/
At £7-66 (inc VAT) each it's almost worthwhile buying a pair, with which to play! :)
Obviously a length of glass (or plastic) fibre, with appropriate connectors, would also need to be sourced. :-\
I have a vision of Ian setting up such a link between his shed and the house. ;)
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Perhaps a pair of ex-BT NTE2D's (http://www.ebay.co.uk/itm/BT-NTE-2D-Digital-Wideband-Adaptor-PSU-NTE2D-/391312615249) could be used, back to back?
Having one in my grotto, I have previously given it an examination. Two fibre links (glass or plastic) would be required as there are separate "Go" and "Return" paths. The "Go" of Unit 1 connected to the "Return" of Unit 2, etc.
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Incidentally, if a line that is disconnected at both ends, or tv aerial that has been unplugged, can pick up a charge during stormy conditions that can wreck your equipment when plugged back in afterwards. One of my work mates years ago was working on an an aerial distibution system in the sub basement of our building, realised the the coax cable from the roof had not been grounded. He found this fact out only when tried to weld his pliers to the rack and the cable braid of the coax. He was so surprised that he fell of his elephant box onto the floor.....................