How DSL works, and what the eircom upgrade means

csd

Folks,

There have been some rather strange assumptions and confused postings made regarding yesterday's announcement of eircom's up-to-8Mb/s NGB service, so hopefully by recapping how DSL networks operate and applying this to what's been made publically available by eircom, it might clear things up for people.

So first the recap bit.

The ultimate bandwidth achievable to any given user depends on network performance at a number of different bottlenecks on the network. I'll summarise these in turn.

Bottleneck 1: The link between the customer's modem and the exchange equipment (called a DSLAM).
The speed achievable here is based on the DSL technology used and the amount the signal deteriorates between you and the exchange, which is mostly dependent on distance (though poor cable and dodgy internal wiring can play a part too). The higher the deterioration (called attenuation), the lower the speed you'll ultimately be able to achieve. The original flavour of ADSL can sync at up to 8Mb/s download speed, while ADSL2+ can sync at up to 24Mb/s (if you live in the exchange!). This appears to be an upgrade for customers using the vanilla ADSL service. Perhaps in the future there'll be something similar (up to 24Mb/s) for those currently connected using the ADSL2+ services.

Bottleneck 2: The link between the local exchange equipment (DSLAM) and the B-RAS (Broadband Remote Access Server).
Once it gets to the exchange, your traffic is mixed in with all the other users on similar products and is forwarded on to the B-RAS. This is done at layer 2 of the OSI stack (so it won't appear in traceroutes), traditionally using ATM but more recently taking advantage of Ethernet. Since you're sharing this infrastructure with others, and the link to the B-RAS is usually less than the sum of the customer bandwidths, it's possible to get congestion in this part of the network due to contention.

Bottleneck 3: The link between the B-RAS and the Internet/wholesale operator.
The B-RAS aggregates many links from DSLAMs around its serving region and either performs IP termination (for eircom's own customers) or forwards the traffic on to the wholesaler. For eircom traffic, this will be the first hop on the traceroute. Congestion here is usually less apparent, as the uplinks from the B-RAS to the Internet/ISP core network are usually at least an order or two of magnitude greater than the links used in Bottleneck 2 above.

Bottleneck 4: Congestion out on the Internet on other networks
Not much eircom or anyone else in Ireland can do about this, short of directly connecting to as many upstream providers as possible.

Many of the problems people have been experiencing with poor download speeds are down to Bottleneck 2 above, so eircom have a programme to move the DSLAMs over to faster connectivity to the B-RAS using their new NGN. This, coupled with a parallel programme to move Bottleneck 3 also onto NGN, in theory gives the ability to provide congestion-free Internet access, even if everyone gets upgraded to 'up to 8Mb/s'.

Talk of 'consistent speeds' should be taken to mean that whatever your line syncs up to, you'll be able to achieve, even during the evening peak. However, if you've so much attenuation on your link already that you can only achieve 1 Mb/s, then the new network isn't going to do much for you. It may be some small comfort to know that it should never achieve less than 1Mb/s throughput (or slightly less to allow for overheads), and be free of packet loss.

So far, so good, but what about the bandwidth caps? I can see two very good reasons for them to do this.

Firstly, if you're going to upgrade everyone on slower speeds to 8Mb/s, how do you protect the revenue streams? You can't just charge everyone the cheapest (former 1Mb/s) price, and you can't unilaterally up everyone's charges to the former 7Mb/s price. So the simple answer is to differentiate using data transferred rather than bandwidth. Basic price discrimination at work.

Secondly, it is commonly known that an 80/20 rule applies when it comes to bandwidth usage on public networks, ie 80 per cent of the bandwith is used up by 20 per cent (or less) of users. While the network upgrades are supposed to help out, I'm sure the impact of suddenly opening up the taps on all those lines currently at 1Mb/s and 3Mb/s has the potential to be quite significant, so it would appear to make perfect sense to at least try and capture some of the costs due to the heavy users. It's possible to argue endlessly about whether this is 'fair', but there's an equally strong counter-argument around light users cross-subsidising the torrent freaks. At least the usage charges are capped so that no one should end up paying more than the top package anyway.

So on balance, is this good news or not? Well I guess the answer depends on who you are.

• If attenuation on your line is such that it struggles to reach 1 or 2 Mb/s, then 'NGB' is not going to improve things much. This is an issue with Bottleneck 1.
• If you're an 'average' user currently struggling with contention-related congestion, then things will get better. How much better depends on how much congestion was there in the first place and what speed your line is ultimately capable of syncing at. However, you may ultimately end up paying more if the new-found speed leads to a HD streaming video/torrent addiction. I guess each customer will have to make a judgement call as to whether it's worth paying more for.
• If you're currently on the 1Mb/s or 3Mb/s packages, not experiencing much in the way of congestion, and downloading over the allowance each month, then it's probably not good news as you'll end up paying more (up to a maximum of €50/month plus line rental).
• If you're a high-end user already paying for the 7Mb/s package, then things should get better. While your line sync rate won't increase much (if at all), at least you should be able to get full speed downloads all of the time. At least for the moment anyway!

Hope this clears things up.

oisin

Thanks for the explanation csd, answers a few questions I had.

bk

Thanks for the info csd.

However I don't see how updating some backhaul to the exchanges can be called Next Generation Broadband, that bit is definitely marketing BS.

Also I see this as nothing but a cynical attempt by Eircom to milk more money out of unsuspecting customers. Put people on a 10GB cap and then charge them €24 per month extra then they currently pay when they go over the cap.

That is a lot of money for a lot of people and a pretty massive price increase. To put it into perspective, in France you can get 100mb/s BB, free calls and digital TV for just €30 per month! :eek:

Owwmykneecap

If you're a high-end user already paying for the 7Mb/s package, then things should get better. While your line sync rate won't increase much (if at all), at least you should be able to get full speed downloads all of the time. At least for the moment anyway!

Looked at their map august they say.

No where near good enough. If only we could take a class action.

FINGAL FAN

Thanks csd . Well put and well argued . Agree with all your points . Well informed .

csd

bk wrote: »

Thanks for the info csd.

However I don't see how updating some backhaul to the exchanges can be called Next Generation Broadband, that bit is definitely marketing BS.

Well I guess that's why we don't work in marketing Besides, Next Generation Backhaul doesn't sound as catchy, and might get lost on the non-technical person!

Also I see this as nothing but a cynical attempt by Eircom to milk more money out of unsuspecting customers. Put people on a 10GB cap and then charge them €24 per month extra then they currently pay when they go over the cap.

Perhaps, but I also wonder exactly how much those on the lowest package are downloading in a month anyway. I would venture that the highest downloaders are perhaps over-represented here on Boards, but for the bulk of eircom's low-end customers 10GB/month is probably fine. My parents would certainly fall into this category.

That is a lot of money for a lot of people and a pretty massive price increase. To put it into perspective, in France you can get 100mb/s BB, free calls and digital TV for just €30 per month! :eek:

True, but in the context of benchmarking broadband in Ireland, this comparison isn't necessarily helpful. France's population density is double Ireland's, and density in the major cities is 3 - 4 times higher if you compare Dublin and Cork with Paris and Lyon.

The slide "CAPEX vs. total households/density" in this PDF illustrates the effect reducing density has on cost per subscriber, even in the French case. Here we see that in Paris it costs just €2,000 in capital expenditure to connect a customer, whereas in the 'average town' it costs €5,000. Applied to Ireland with its lower densities, the costs are going to be higher still.

Viewed for what it is (as opposed to the marketing speak), the elimination of congestion and a speed bump for most customers should be welcome. Sure, it's not startling or revolutionary, but to get that we'll have to see how deep the pockets of eircom's new owner are, as it'll require fibre to a street cabinet full of electronics and/or fibre to the home. Neither of these options is cheap to implement, and are still only going to be viable in urban areas!

bk

csd wrote: »

Well I guess that's why we don't work in marketing Besides, Next Generation Backhaul doesn't sound as catchy, and might get lost on the non-technical person!

That is for sure, but some times I wonder if most marketing people even know how to do marketing.

I also wonder if this might back fire on them, the boy who cried wolf syndrome. People already don't really trust Eircom, now people are going to be sold NGB, but most won't see much difference, this could be bad news when Eircom eventually do FTTC/VDSL2+ or FTTH, what will Eircom call this Really Next Next Generation BB!

csd wrote: »

Perhaps, but I also wonder exactly how much those on the lowest package are downloading in a month anyway. I would venture that the highest downloaders are perhaps over-represented here on Boards, but for the bulk of eircom's low-end customers 10GB/month is probably fine. My parents would certainly fall into this category.

True, same with my parents, but I worry what happens to all these people when one month they go over the cap (perhaps their grandson spends a few days with them or someone breaks into their unsecure Eircom wireless) and suddenly they end up with an unexpected extra €25 on their bill. This could be very hard on many families in the current economy.

Also that would beg the question, if most people stay under 10GB, why have a cap at all? The only conclusion is that Eircom want to push at least a significant percentage of their customers on to more expensive products so they can milk them for more money.

csd wrote: »

True, but in the context of benchmarking broadband in Ireland, this comparison isn't necessarily helpful. France's population density is double Ireland's, and density in the major cities is 3 - 4 times higher if you compare Dublin and Cork with Paris and Lyon.

Ah csd don't roll out that old rubbish excuse. The density of Dublin is about the same as most other European cities, in fact it is very close to Amsterdam that has FTTH.

How is it that UPC can afford to rollout DOCSIS 3 and massively upgrade their network at the moment?

Lets be honest here, Eircom can't rollout true NGB because of their 3.5 Billion debt that they have been saddled with by their owners over the years. You could run FTTH to every home in Ireland twice over for that sort of money.

Eircom do everything possible to keep their capex costs as high as possible so that they can justify the highest line rental in the world to comreg, which they are really using to pay off their debt.

csd wrote: »

Viewed for what it is (as opposed to the marketing speak), the elimination of congestion and a speed bump for most customers should be welcome.

Sure, if it didn't include a big price increase via caps. Of course others might well argue that we should have always been getting that considering the very high prices we pay.

csd wrote: »

Sure, it's not startling or revolutionary, but to get that we'll have to see how deep the pockets of eircom's new owner are, as it'll require fibre to a street cabinet full of electronics and/or fibre to the home. Neither of these options is cheap to implement, and are still only going to be viable in urban areas!

Agreed, no doubt about that. It is do or die time for Eircom, if they don't get their act together, they will lose the most valuable urban areas to UPC and LTE (LTE in the long term).

BTW nice chatting with you csd, nice to chat with someone who knows what they are talking about.

Xennon

Thank you for the posting on DSL systems, very informative.

Firstly, population density or no, Eircom are selling a product at an exorbitant price which doesn't work, end of. It only constitutes the term 'broadband' during daytime hours, at evening time it reverts to narrowband, even dialup performance in some cases.

Regarding the assumption that 10G a month is a reasonable limit for a low usage subscriber, I would question this based on the proliferation of video/multimedia content driven web content on the internet, not to mention that this is a growing media. The parents in-law are avid you-tubers.

The upgrade Eircom is at present carrying out seems to be just an upgrade of the Dslam line cards enabling ADSL2+ to the Dslam, a relatively inexpensive 'upgrade' as this option is available on most of the newer units, however unless the uplinks and/or Bras contention bottlenecks are addressed then all this means is that theres an increase in traffic at the bottleneck. Perhaps there is investment in this new range of upgrades, however my last conversation with an Eircom employee lead me to believe that there will be no substantial investments in the near future.

I hope hes wrong.

csd

bk wrote: »

True, same with my parents, but I worry what happens to all these people when one month they go over the cap (perhaps their grandson spends a few days with them or someone breaks into their unsecure Eircom wireless) and suddenly they end up with an unexpected extra €25 on their bill. This could be very hard on many families in the current economy.

This is an understandable fear, but at least something is being done about it. I understand everyone will get a letter in advance of the upgrade, and there's this download usage monitor doofer that's available from the website (if you're running Windows anyway). If people ignore all of this advice (and the previous advice re securing your router) then what else can be done? Do you really believe that people would be happier staying on a slower product just in case someone broke into their wireless?

Also that would beg the question, if most people stay under 10GB, why have a cap at all? The only conclusion is that Eircom want to push at least a significant percentage of their customers on to more expensive products so they can milk them for more money.

One man's 'milking for money' is another man's 'price discrimination to protect revenue flows'. Of course they could just not upgrade people and keep them on the same old product, but as I said, how many people would honestly prefer to pay the same amount for something quantifiably slower?

Ah csd don't roll out that old rubbish excuse. The density of Dublin is about the same as most other European cities, in fact it is very close to Amsterdam that has FTTH.

Hey, I'm not making this up! That PDF is from an EU website. It's an undeniable fact that the more dispersed a population is, the more expensive it is to provide infrastructure. And come on, Amsterdam? Really? The Netherlands has nearly four times our population in just over half the area -- it's massively more dense! Ireland as a whole is the third-least densely populated country in the EU15.

New Zealand is perhaps a better comparison. A quick examination of the Telecom NZ website reveals the closest equivalent (10GB allowance, rate adaptive to max line sync rate possible) converts to €26.29. According to eircom's website, their basic product is €24.99. TNZ's monthly line rental is €24.37, eircom's is €25.36. Add the line rental and the broadband together and there's only 31 cent/month in the difference. Spooky!

How is it that UPC can afford to rollout DOCSIS 3 and massively upgrade their network at the moment?

A number of reasons, one of which is the answer you gave below, and another is the fact that UPC have a smaller network to upgrade (and it's concentrated in urban areas with higher densities). Add to that, UPC have a large TV-related revenue stream, which I suspect may be able to cross-subsidise the broadband to a greater extent than eircom's declining voice revenues. I've no figures on this though, so just speculating.

Lets be honest here, Eircom can't rollout true NGB because of their 3.5 Billion debt that they have been saddled with by their owners over the years. You could run FTTH to every home in Ireland twice over for that sort of money.

Indeed, though I'm not sure you'd get every home twice! So who takes the blame for this? The government who sold eircom off for a tidy sum? The previous shareholders for, ah, 'extracting value'? The current management and staff?

Eircom do everything possible to keep their capex costs as high as possible so that they can justify the highest line rental in the world to comreg, which they are really using to pay off their debt.

Even if this statement were true (and I'm not sure capex on broadband has anything to do with line rental charges), then is this not the action of a rational company? If you were in charge, would you not do the same thing?

It seems to me that Eircom is in the position it is because of the action of an untrammelled free market. It is a private company, whose board of directors is legally obliged to look after the interests of its shareholders and no one else. This is why I'm always slightly bemused when I see where much of the criticism about the state of broadband in this country is directed. Looking after the interests of the wider public, or the execution of policy to achieve a public good (such as pervasive, cheap broadband), is the government's job. If the government sells off the most effective instrument it has to achieve this public good without retaining a strategic stake with which it might have been able to effect policy, then is that eircom's fault?

Agreed, no doubt about that. It is do or die time for Eircom, if they don't get their act together, they will lose the most valuable urban areas to UPC and LTE (LTE in the long term).

Well the new management certainly appears to be making itself felt, what with the departure of senior execs in recent weeks. Also, I don't think I've ever seen anything quite like this used by eircom to promote a new product before, so who knows, there may be life in the old dog yet!

LTE is a whole other discussion, and I'm not so sure it has the bandwidth needed to cover requirements into the future. I believe that fibre, either to the home or very close nearby, is the answer here.

BTW nice chatting with you csd, nice to chat with someone who knows what they are talking about.

You're too kind!

csd

Xennon wrote: »

Thank you for the posting on DSL systems, very informative.

Firstly, population density or no, Eircom are selling a product at an exorbitant price which doesn't work, end of. It only constitutes the term 'broadband' during daytime hours, at evening time it reverts to narrowband, even dialup performance in some cases.

Exorbitant? Depends on what you're comparing it to (see my post above re New Zealand).

Poor performance? Well yes, many people have been complaining about that, but this upgrade is meant to address exactly this. Is that not a good thing?

Regarding the assumption that 10G a month is a reasonable limit for a low usage subscriber, I would question this based on the proliferation of video/multimedia content driven web content on the internet, not to mention that this is a growing media. The parents in-law are avid you-tubers.

Indeed. I guess the hope would be that the allowance increases in line with these demands as the network upgrades progress. A 1Mb/s video stream would fill 10GB in 21 hours. Enough for most? I know 30GB a month is fine for me anyway. Others' mileage may vary, as the phrase goes!

The upgrade Eircom is at present carrying out seems to be just an upgrade of the Dslam line cards enabling ADSL2+ to the Dslam, a relatively inexpensive 'upgrade' as this option is available on most of the newer units, however unless the uplinks and/or Bras contention bottlenecks are addressed then all this means is that theres an increase in traffic at the bottleneck.

This statement is not true. As was confirmed by an Eircom employee elsewhere, the details of my original post are correct. These are upgrades to the backhaul portion of the network.

Sponge Bob

A DSL network is divided into

Access Network.

This is copper in ireland and in some countries copper into fibre DSLAM at no more than 1km and then back to the exchange in all cases where the key DSLAM is. DSLAMS can be slaved off each other, a process called subtending so a DSLAM can 'pass thru' another DSLAM behind it to a BRAS.

Aggregation Network.

This is largely fibre although there may be a few copper backhauls about. The aggregation in Ireland is the network from the exchange to the BRAS where the 'login' takes place and the IP port is opened. eircom have maybe 20 of these, I have not checked. Galway has one, Cork 2 Limerick 1 or 2 , Sligo has one , Mullingar etc. the erroneously named NGB is an upgrade to the Aggregation network in the main. In every other country NGN is an upgrade to the Access network ( VDSL and 25-50mbit speeds) and to the aggregation network behind it.

Smart let all their lines freely negotiate the maximum line speed nearly 2 years ago and then enforced the package on the BRAS instead. Even though some lines synched at 20mbits you only got the 4mbit you paid for once the BRAS did its thing. Eircom used to provision the DSLAM profile at your package speed ( or less if that ws unstable) even though the IP port is set further back by the BRAS.

Backbone and Core Network.

These are the large pipes that carry traffic from the 20 odd BRAS locations and into the heavy Routers and peering routers to the rest of the h-interInterwoogies. This should be an Ethernet 10gbit class wavelength nowadays although I suspect some of them are only 1gbit or 1gbit bonded to make 2gbits. DNS is in there too.

In Ireland

NGB is an eircom plan to upgrade elements of the aggregation and core networks to 1gbit minimum and sometimes 10gbit. They plan on installing about 150 1gbit and 100 10gbit nodes between aggregation and backbone and generally only in exchanges with at least 1500 working lines or more

However this plan is over 3 years old, it was announced by Pierre Danon when he was eircom chair in around Autumn 2006. He also announced VDSL on the access network in teh main cities, this has been completely dropped.

Xennon

This statement is not true. As was confirmed by an Eircom employee elsewhere, the details of my original post are correct. These are upgrades to the backhaul portion of the network.

I did state that its what it seems to be what they are doing, I hope you are right CSD, as at the moment I am paying stupid money for what ammounts to a good dialup service.

New Zealand is perhaps a better comparison. A quick examination of the Telecom NZ website reveals the closest equivalent (10GB allowance, rate adaptive to max line sync rate possible) converts to €26.29. According to eircom's website, their basic product is €24.99. TNZ's monthly line rental is €24.37, eircom's is €25.36. Add the line rental and the broadband together and there's only 31 cent/month in the difference. Spooky!

Where have i heard that racket before?

20goto10

This all sounds like what Magnet are providing, am I right?