Removing ADSL from the network?

The bank masking on that BT does to allow FTTC & ADSL to coexist is having a really serious penalty on people with long lines from the cabinet.

It's far to say many people would see a gain of at about 20mbit down if the VDSL2 band plan could use the frequencies that ADSL2+ does. Alternatively the cabinet could try both ADSL2+ and VDSL2 and see what is best suited for the line?

Considering the pressure politicans are putting on BT right now to get more of the country up to the 10mbit/sec this seems like a good course.

OR could notify service providers say 6-12 months in advance that ADSL service to lines connected to FTTC cabinets would be seriously disrupted (not terminated perhaps?) if they don't move to FTTC products.

Anyone left on exchange fed ADSL would suddenly be overwhelmed by crosstalk and would have a very serious incentive to move.

Big problems that I can see are regulatory. But I think it would be worth it to get people on long lines from cabinets up from 5meg/sec to 20-30meg, until more ftth or gfast gets deployed. A stopgap measure for sure.

Personally I think that ADSL should be phased out.

They can and should just put all current ADSL lines onto VDSL2 and allow VDSL2 to use those "bands". Then they can limit those who where on ADSL to something like 2mb up and 10mb down and not charge extra for VDSL2.

Makes sense to me for the most part. But maybe not do this at some locations where there are customers on ADSL with very long lines where VDSL would just to reach.

Three years notice required for phasing out of product usually

It's not within OR's power to make decisions like this. The ANFP is controlled by the NICC, which is industry wide and is essentially answerable to Ofcom.

I cannot imagine the LLU operators agreeing to this except, just possible, in those areas where they aren't present. Then there are little issues about capacity in cabinets and so on.There is a lot of sense in the proposal (aren't they doing this in New Zealand?), but it's probably only viable in some rural areas. I can't see it being accepted in urban areas.

A good idea where you can get fibre, but this idea isn't new, was mention back in March.

http://www.dupre.co.uk/2015/03/20/adsl-max-services-...

It would of course mean at keast 2 or 3 FTTC cabinets for each PCP, to cater for all the ADSL users forced over. Considering the issues OR has delivering capacity upgrades and new build at present, this would be a long term delivery at best.

The number of cabinets would depend on the PCP in question. In a lot of rural locations a single cabinet would be plenty as the largest supports up to 288 line and that's plenty for many PCPs. Of course the cabinets that have been installed may not be sufficiently sized, but I've no idea what rules were adopted.

In any event, I only see this as (possibly) a rural area solution, not one for towns.

nb. the rules for the 10mbps USO have yet to be determined of course, but this may be an enabler. Not the removal of ADSL across the network, but possibly the removal from services via certain rural cabinets.

Edited by deleted (Mon 07-Dec-15 09:10:46)

Or they might just plump for the improvements that VDSLplus offers i.e. more bits per bin and better noise floor performance which means more speed for those further out. With luck a software upgrade, with worse luck a line card swap out or worst case a DSLAM replacement.

Of course until the decision is made on the future of Openreach everything is a might, and if independent we can expect the plans of Sky to dominate as they are calling for the total split so heavily i.e. they may want to focus away from xDSL totally and start a 10-15 year FTTH roll-out plan instead and walk away from any CityFibre plans.

Hi, ADSL Shouldn't be Phased out, we cannot get any sort of fibre due to the lines being bad, such as aluminium cable, the VDSL Signal over the lines is rubbish, sub 10Mb speeds and .3Mb upload speeds, whereas on ADSL I get 13-15Mb down and a constant 1Mb up,
I know BT should provide FTTP or replace lines etc...
but what about people who want FTTC (High Speed)
and an ADSL line as a backup,
remember ADSL comes from the exchange with large amounts of backup power, whereas FTTC does have backup power but does not last as long as ADSL would in a power outage,
And what if someone does this Crash/Outage,
Because remember the New cabinets are not always discreetly out of the way!

There would be maximum benefit from combining both. There is no substitute for the low frequencies which have much greater range. I suspect that 10mbps could be pushed out to perhaps 4-5km from the cabinet if they were available at full power.

Most people have either VDSL or ADSL, not both and for many rural cabinets ADSL will really not be an option. Aluminium is an irrelevance. It will affect both VDSL and ADSL anyway.

Given that there are tens of thousands of cabinets, then there are bound to be the very occasional catastrophic losses, but any one failure is a very small effect nationally (really had if you are affected of course). But the number of properties affected will never be in the tens of thousands as we are with the rcurrent floods. Even the phone network isn't fully protected. There are regular incidents of diggers damaging lines, telephone poles being brought down through accidents and so on. This is a matter of cost/benefit.

FTTC cabinets have limited battery backup, but there are processes to swap these out with fully charged ones if the power outage is extensive. Rural exchanges only have limited battery backup too. A mobile generator is required if an outage is prolonged.

In any event, xDSL services from cabinets are quite widely used in the rest of the world, often in the US where exchanges ("central office" in their parlance) are much further apart than in the UK.

Exchange in towns have Generators built in, and the rural exchanges yes, have limited battery backup, but BT has planned a lot more battery backup time in these small exchanges (due to not being able to have a generator), than the FTTC Cabinet, so ADSL from the exchange still has its benefits.

Plus if ADSL was phased out, people who only want broadband for small usage would have to pay more, and BT would have wasted their money on deploying 21CN!

Oh and Two phone lines is how you achieve FTTC and ADSL!

I can't find the stuff about the ADSLx from cabinets trials Andrew. I'm sure you wrote about it.

That could help a lot of slow lines if it comes about.

21CN is/was about a lot more than ADSL2+ provision from BT Wholesale., and Sky/TalkTalk LLU doesn't use it. Often present and sold before 21CN was available.

The broadband part of 21CN is WBC, and it's ride-along WBMC that most BT Wholesale ISPs use.

In reply to a post by TheEulerID:

FTTC cabinets have limited battery backup, but there are processes to swap these out with fully charged ones if the power outage is extensive.

If extensive and prolonged, which is when the limited capacity would run out, there wouldn't be enough standby batteries. I think they only apply to localised power losses.

Edited by RobertoS (Mon 07-Dec-15 11:41:09)

And no SLA that requires consumer broadband to be a available to five 9's or better standard

Of course, but if there's a widespread power failure then surely it's a complete irrelevance as to whether the cabinets in the area have power or not. Almost nobody will have any domestic power either and, presumably, those which are truly mission critical and have auxiliary power supplies (hospitals, major business etc.) will have proper resilient business networks.

Ummm.

There seems to be rather a large amount of truth in that.

This needs to happen, and would give a much better service for everyone.

But it won't because OFCOM are obsessed with fake competition with everyone reselling the same service. Hence, there are LLU providers with kit in the exchanges that would then be pointless. The LLU providers will want to keep their kit so it won't happen.

Of course it would depend on the area but in urban areas most PCPs would require more than one FTTC cabinet.

And who is going to pay?
This ADSL consumer pays under £6 per month for an unlimited adequate stable connection
The FTTC alternative looks to be around £18 per month upwards
Forgive me if I opt out

ADSL might well be cheaper now but there will be a tipping point in future where price of ADSL and VDSL based products are similar as they try to "persuade" customers to "migrate" so they can decommission ADSL hardware. If the operators margins are as tight as they would have you believe they wont continue to support the two systems forever.

In reply to a post by MrSaffron:

Of course until the decision is made on the future of Openreach everything is a might, and if independent we can expect the plans of Sky to dominate as they are calling for the total split so heavily i.e. they may want to focus away from xDSL totally and start a 10-15 year FTTH roll-out plan instead and walk away from any CityFibre plans.

As Sky have dived headlong into making their LLU assets and full-loop copper redundant in the name of enhancing UK broadband you mean?

In reply to a post by mr_mojo:

The [power] masking on that BT does to allow FTTC & ADSL to coexist is having a really serious penalty on people with long lines from the cabinet.

It's [fair] to say many people would see a gain of at about 20mbit down if the VDSL2 band plan could use the frequencies that ADSL2+ does.

This whole thread starts on a premise that I haven't seen challenged yet, and both of the statements above need to be challenged, at least in part.

1) First, power masking is not even across all lines; it depends how far the cabinet is from the exchange.

The ANFP uses a CAL value to denote this electrical distance, and CAL values of 0, 2, 4, ... 50, 52dB. A best estimate is that each CAL step (of 2dB represents a real distance of approx 200m).

For cabinets that are very close to the exchange, there is no masking at all. From the ANFP graphs, a CAL of 0 applies no masking at all - and looks like it is used for cabinets within 100-200m of the exchange.

Even CAL values up to 10 apply limited masking (in the sense that the spectrum is limited, and the power restriction is small).

CAL values of around 20dB (cabinet-exchange distances of 2km) seem to give the maximum amount of masking - being both the widest spectrum and deepest power restriction.

Beyond CAL values of 20dB, the power masks start to shrink again (in this case, the affected spectrum narrows, but the power restriction stays deep).

Looking on MyDslWebStats, you can see examples of these lines.
Here are a couple that have almost no masking; the first looks to be a cabinet close to the exchange, while the second looks to be far away, but both are on 80/20 speeds:
http://postimg.org/image/9fg2c8pk9/
http://postimg.org/image/rlwve8mal/

The conclusion is that power masking *can* have an effect on long lines (as well as short lines), but that it isn't the same on all lines. For some, there will be little effect at all.

Unfortunately, we have little idea how many lines are on near or far cabinets vs those on middle-distance cabinets, so it is hard to work out the total possible impact.

Statistically, you'd expect there to be few cabinets close-in to the exchange, a medium number in the middle (with the worst impact) and more cabinets at further distances.

I'd guess that there's a fairly even spread between the "no gain" locations, and the "full" gain" ones.

2) Would it be fair to say that many people would gain 20Mbps by getting rid of the masks?

2a) How much speed could be gained in the best possible case - a line with maximal masking, but where the D-side is short enough for full 80/20 speeds?

Here is an example of a line with around the maximum masking possible:
http://postimg.org/image/jmyy2o001/

The "missing bits" caused by the power mask can be roughly calculated from three shapes:
- A triangle, tones 104-440, bits 13-3, plus
- A rectange, tones 440-512, bits 12-3, plus
- A triangle, tones 512- 531, bits 11-3

I make that a total of approx. 2,500 missing bits.

Meanwhile, the bits that *are* present (using a similar process) add up to 21,000 bits. So we can gain 2,500 bits to the 21,000 that are already in use: about a 12% gain.

I calculate the *best case* gain available to therefore be 10Mbps. This probably applies to lines up to 400m from their cabinet.

2b) What about lines that are far from the cabinet?

Here is an example of a line with around the maximum masking possible, but this time with speeds of 30/8 (around 900m-1km):
http://postimg.org/image/mw1xmag19/

In this case, the missing bits comes out somewhat lower, as the longer line isn't capable of reaching a full 15 bits ... I calculate around 1500 bits are missing, which would be around 6Mbps.

2c) And longer lines?

Much harder to quantify, as examples are harder to come by on MDWS.

This line runs at 17/1, and has a medium level of masking:
http://postimg.org/image/7qjb5gqn3/

In this case, the missing bits comes out to be around 800, so about 3Mbps.

Conclusion
a) Removal of power masks could improve some lines, but certainly not all.
b) For fast lines, around 80Mbps, the best improvement is around 10Mbps
c) For slow lines, around 30Mbps, the best improvement is around 6Mbps.
d) On average, though, the gain will be around 3Mbps (slow lines) to 5Mbps (fast lines).

When the gains are reduced to realistic figures like this, is it still worth persuing?

Considering the pressure politicans are putting on BT right now to get more of the country up to the 10mbit/sec this seems like a good course.

To do so requires stopping all exchange-based services, and deploying enough cabinets to cope with the extra demand ... which most locations do not already have.

The kind of gains mentioned - 5Mbps for short lines, 3mbps for longer lines - might be better achieved by the deployment of vectoring to cabinets, without bothering to turn off exchange-based services. Vectoring can be deployed tactically - only on cabinets that have lines where a USC benefit can be seen.

Would it be cheaper to deploy vectoring to existing cabinets - and just those cabinets which could gain - than deploying whole new ADSL-replacement cabinets on every exchange?

Clearly - they are racing to invest hundreds of millions to go to FTTH, or are they hoping someone else will if the conditions are right and they can reap the benefits?

The odd few hundred millions pounds aren't going to make much of a dent in the infrastructure at the national level.

In reply to a post by Seansmit17:

Personally I think that ADSL should be phased out.

No thanks, I'm quite happy with not having to rely on my connections all being powered by the local cab and all vulnerable in the same way. It's nice having lines that carry on working when the cab loses power or gets mowed down.There are distinct benefits to a little mini diversity in the real world.

Perhaps some further deployment of FTTP (or in some cases actually finishing the half rollout BT have abandoned - such as in Exeter - there is stackloads of half rolled out FTTP service!)

Edited by therioman (Mon 07-Dec-15 19:37:56)

In reply to a post by TheEulerID:

The odd few hundred millions pounds aren't going to make much of a dent in the infrastructure at the national level.

It'd make more of a dent than either what Sky have stumped up so far or the precisely zero that, for all the bluster about how it'd lead to a new age of outside investment, they've committed to if Openreach are separated from BT Group.

In reply to a post by craski:

ADSL might well be cheaper now but there will be a tipping point in future where price of ADSL and VDSL based products are similar as they try to "persuade" customers to "migrate" so they can decommission ADSL hardware. If the operators margins are as tight as they would have you believe they wont continue to support the two systems forever.

But that will not be for a few years and also some people are happy with the speed they get from ADSL, certainly if they live near the exchange.

I know a few people on ADSL and have been having letters and emails from their supplier, mainly BT to change to Fibre, but they won't as they don't require it.

In reply to a post by TheEulerID:

Most people have either VDSL or ADSL, not both and for many rural cabinets ADSL will really not be an option. Aluminium is an irrelevance. It will affect both VDSL and ADSL anyway.

But aluminium's affect on VDSL is far more significant than ADSL. My connection syncs at 47 Mbps on a 300m line due to a 120m section of aluminium and deteriorating Cu/Al joints on either end of it.

I'm not happy with ADSL - on a 20CN exchange and used to get the full 8Mbit all the time, now lucky to get 2Mbit in the evening and it's certainly been getting worse year on year for the last 3 years or so, fairly close to the exchange and full sync so a bandwidth issue with 20CN I think, I suspect it will be in BT's interest to 'turn a blind eye' to 20CN bandwidth provision issues so ADSL connections will likely get worse over time, unless of course most switch to Fibre and leave the old ADSL bandwidth for the few that remain on it

like you said it will take a few years, but I think ADSL will only really be widely used on the few remaining cabinets that aren't upgraded beyond 2017, BT will make it less and less attractive for the stubborn last few to hang on in areas that have FTTC/P..

Edited by deleted (Tue 08-Dec-15 20:05:03)

In reply to a post by Spetznaz:

I suspect it will be in BT's interest to 'turn a blind eye' to 20CN bandwidth provision issues so ADSL connections will likely get worse over time,

IIRC, the 20CN DSLAMs have got a fixed amount of upstream bandwidth to support the backhaul, and couldn't be upgraded - except, of course, moving subscribers onto a port in a different DSLAM. Now, with all the hardware being end-of-life, it certainly can't be upgraded with new hardware.

There isn't a lot they can do, except continue the path to migrate cabinets to FTTC, and to migrate exchanges to 21CN, both of which are happening.

In reply to a post by simon194:

But aluminium's affect on VDSL is far more significant than ADSL. My connection syncs at 47 Mbps on a 300m line due to a 120m section of aluminium and deteriorating Cu/Al joints on either end of it.

No. Aluminium's affect on high frequencies is far more significant than ADSL. I have the same issue as you, with a 40-45m sync on what should be an 80m line due to Alu. This is because the top half of the spectrum is just completely nuked by aluminium.

The bottom section, where the ADSL frequencies are, is mostly unaffected, or only slightly affected.

Unfortunately, those frequencies are hit by the ADSL power masking.

If there were no more ADSL, we'd regain some speed there at the low end.

Without ADSL, VDSL from the cabinet would, at all times, be at least as good as ADSL. Right now, in areas where you are a long way from the cab, VDSL can actually be worse than ADSL, as it doesn't have the low frequencies to use.

The debate will only get anywhere when TalkTalk and Sky agree to this, what BT Group wants is almost irrelevant, the lobbying power for ADSL2+ lies with the LLU operators.

You're completely correct of course, which only highlights how stupid the whole idea of LLU was, forcing competition for competitions sake, driving up costs and causing a race to the bottom on pricing (and therefore service).

I'm sure I've read previously that BT were prevented from rolling out more fibre decades ago as it would make competition harder.

Spetznaz

ADSL has already been removed on many exchanges with ADSL2+ ( WBC). You can see some dates that this was done on the checkers when it reports the removal of IPstream.

The ADSL equipment is past the end of it's life ( Brought around 2000-2006 ) and must be kept going by caniblisation of recovered equipment elsewhere.

Here they are talking about all varieties of ADSL so including ADSL2+ which is still being provided on some small exchanges by BT and is what all the big LLU operators use.

I would recpmmend moving to Fibre as soon as you can get it as the increased upload makes a significant difference to the user experience.

I'm sure I've read previously that BT were prevented from rolling out more fibre decades ago as it would make competition harder.

I remember the Tomorrow's World episode where they were talking about BT fibre and the ability it would have to bring a wealth of TV and fast connectivity into our homes. My understanding is that BT ended up giving up because the powers that be wouldn't allow them to become a TV broadcaster as well as offering their other services. Without the TV fibre was an expensive white elephant because their just weren't the requirements for high speed data back then - TV was the business case and without it there was little point.

Of course they did roll out fibre in Milton Keynes but that then bit them as they couldn't run ADSL over it...

That would make sense as I would expect over the years more and more people on my exchange have taken up ADSL and with a limited backhaul possibly based on a moderate take up when it was first installed in 2004 it has been pushed to its limit, especially at peak times.

Luckily we should be getting our FTTC cabinet going live next week according to one of the openreach guys who was working on 'finalising things' today, as ADSL appears to be slowly grinding to a halt here!

Okay thanks for clearing that up, I'm a little confused about my exchange though, there are 3 fibre cabinets that are getting FTTC through BDUK funding, 2 live some months ago and mine which is due in the next week or two, I was led to believe that all/some of the cabinets are possibly being fed from a bigger exchange, there is one obvious candiate about 5 miles away in a reasonably big town (i.e. its a 21CN exchange) but my exchange still shows as 20CN, but.. one of the live FTTC cabinets is for EO lines, so right outside the exchange, surely this means the exchange must be 21CN now?, or am I missing something, therefore in theory I should be able to upgrade to ADSL2+?, not that there is much point now.

Edited by deleted (Thu 10-Dec-15 23:41:23)

Not likely. The new cabinet will have its phone lines from the exchange and its fibre supply from the remote exchange, just like the others.

Quite what the routing of that fibre will be I have no idea.

Spetznaz

All the FTTC cabinets are connected to equipment in a 'Headend exchange' or 'Handover point'. This is not always the local exchange. Originally there were planned to be around 1000 of these, ( out of 5500 in total), these are where the responsibility is passed from Openreach to the ISP/Wholesaler for the service. The new cab, oitside the exchange, will just piggyback on existing fibre that exists between exchanges to get back to the Headend site.

21CN infrastructure will exist at these exchanges but may not at the local exchange. There are now several thousand exchanges with FTTC that do not have WBC/ADSL2+ from BT and about 1000 that do not have an LLU operator in that would provide ASDSL2+ services. Yours is one on these.

TalkTalk has ADSL2+ in the most exchanges but BT is rolling out to additional ones slowly, they may be using recovered 21c DSLAMs from places where FTTC and LLU has reduced ADSL2+ workers to the point where some DSLAMs are no longer required.

There is not much point in upgrading to ADSL2+ if you have the option of FTTC. (Unless you are a long way from an FTTC cab where it can give a better service even though the Cab is closer to you)

Roberto

If the exchange has fibre existing to serve the rest of the services ( 90+%) they will either connect to it in the 'Exchange manhole' just outside the building ( enabling the building to be sold off at some theoretical future date) or connect to the existing transmission equipment inside the building.

If it didn't have fibre before, it is likely that the new fibre would have been run in (or alongside) the existing duct to the building before branching out to the seperate Cabs. Only where the cabs are already on a route from another exchange would they be connected direct to the other exchange.

Existing duct ( or overhead route) is always cheaper than providing new.

Quite . We have no idea about the specific exchange, which I was talking about. Not that I had no idea about the alternatives.

Its the best way forward, everyone on BTw would gain, however the obvious issue is LLU ADSL customers.

The estimate of 20mbit seems about right to me, although this depends on the distance between cabinet and exchange, if cabinet is close to the exchange the power cutback is very low and way less than 20mbit is lost, if its at the distance my cabinet is, then power cutback is heavy and circa 15-20mbit is lost. If its really far out tho then less tones will be affected and its not quite as bad although still worse than the cabinets very close to the exchange.

The problem is if BTw only lines moved to the cabinet they would still need power cutback to protect ADSL LLU lines, LLU providers are stuck in the exchange for ADSL services.

Either LLU providers would need to move dslams to cabinet.
LLU ADSL is removed as a product (angry LLU isp's would never happen under ofcom).
Or the D side FTTC lines are all seperated from ADSL lines, so no crosstalk. (openreach wouldnt do it due to expense).