Sky to perform a spot of ADSL line management on some 300,000 lines

[dholdi]

Originally Posted by Saturday

The cynical might say it also has the helpful side effect of reducing Sky's bandwidth requirements.

Lol - I almost put this in one of my replies yesterday, but changed my mind for fear of being labeled cynical.

[Netgeezer]

I'm not trying to argue Sky's position but to try and introduce a level of objectivity into the discussion that is somewhat missing so far. So in the interests of being objective, and devil's advocate I offer the following thoughts and observations. Make of this what you will

Originally Posted by Saturday

So? I'm not sure I understand how that's any justification for a misapplied DLM restriction which is what most of the complaining has been about.

There is no evidence that the DLM has been misapplied, but the fact is that errors have occurred. In an imperfect world I suppose we must anticipate some error.

If a member can't perceive the errors (i.e. they have no perceived impact on the connection, content delivery, stability or speed) then why do they need to be reduced?

Perception is one of those strange things - today's perception is not necessarily tomorrows.

Today, a user who does not access streaming video or voip will not necessarily notice or observe the ADSL error correction going on in the background. They will be quite content at their sync speed, oblivious otherwise.

Tomorrow, the same user becomes aware of BBC iPlayer or takes up a voip service and all hell breaks loose. The previously unperceived errors now show up with a level of service delivery that is wholly inadequate. Now the user is very fed up, that Sky cannot deliver a simple ADSL service without errors. The user then storms off into the sunset with their spotted handkerchief slung over their shoulder, Sky lose a customer.

Every ADSL connection will experience errors and this expectation is built into the firmwares controlling the exchange equipment and router. At "low" levels the error correction processes will handle them. At "high" levels error correction processes will have to work harder and some errors will be uncorrectable. Will you notice? Probably not. At "very high" levels the router firmware just can't cope: with poor firmware the connection will suddenly and catastrophically give up which is what we experienced with the first V1 firmware. With good firmware the connection will hold and the only perceived impact to the user may be a slightly lower throughput than anticipated, as the router will have already reduced the sync to allow for the line noise (i.e. it will have kept the default noise margin by lowering sync).

I was with you 100% until you suggested that the throughput "may be slightly lower". Let us be completely honest here, any ADSL errors will [of course] be corrected by the underlying transport protocol between router and DSLAM. That is a basic modern network protocol at work. However, the reality is that the error correction is at the cost of throughput. There is no "may be" about it. The amount of error correction is completely proportional to the rate of error that occurs. For browsing and file transfer this error correction is largely unseen. For real-time services such as voice and video such error correction manifests itself very clearly, no "may be" about it.

If a member had a poor connection then, in the past, a solution was to manually cap the connection. All DLM is, is an automatic (dynamic) capping process, designed presumably for two purposes: to cut the pressure on Sky support; to optimise the line for "future purposes". The cynical might say it also has the helpful side effect of reducing Sky's bandwidth requirements.

Again, you are partially correct, but also not quite on the money. DLM is not simply about capping. In ADSL there are a number of parameters that may be set to stabilise a line, and not all of these are related to speed. But they have to be set carefully if they are not to cause problems for other ADSL users - not only from Sky - sharing the same cable bundle. And that is why we have seen, on this forum and this thread, users who have experienced DLM with higher speeds and throughput than previously - human configuration errors are corrected by the DLM process. So Sky's version of DLM must be somewhat right (and somewhat wrong).

But for some, possibly many, the result has been a lowering of speed but an improvement of throughput such that they are able to use video and/or voice over IP.

Yet others are facing ridiculously low set speeds and Sky, as evidenced by enough posters on here, are willing to take corrective action.

So, objectively, while the overall DLM is not seen as an outstanding success, it is also not an abject failure. In fact, for an unknown number of some it is a blazing success!

So, to get back to my original point: if a member was happy with the connection, couldn't perceive a problem, or maybe just preferred the problem to the consequence of a fix (i.e. lower speeds), why should they be happy to have their apparently good 16meg connection hacked down to a fraction of that only,eventually, to be told leave it 20 days and we'll put it back how it was? They bought and experienced a product/service that has now dramatically changed with no warning, no justification, and no perceived benefit - and they should be happy because Sky knows best and they should be grateful for what they've (now) got?

It strikes me that the objective is being met to at least some degree. It is not about a member being happy with a flaky connection. As a business Sky, for all the same reasons as BT and other DLM users, seems to have made a decision to work on the quality and reliability of their ADSL service. Speculation suggests it is to prepare to launch video and voice services across this. If that is true, and no Sky staffer has confirmed this on here, then the rationale behind DLM is abundantly clear.

I would be the first to agree with you, and others, that Sky have completely botched the PR on this project of theirs. Unlike Virgin and BT's Phorm projects Sky really had nothing to hide, but chose to do this in the background naively hoping no one would notice. They got that bit very wrong. Yes it has, very obviously from here, generated some ill will, so much so that people have actually left the service.

But, also reported on here, it has made not a few people very happy with their new DLM'd service. We mustn't lose sight of that very positive aspect in the noise of protest.

Like I said at the beginning of this epic I am only appealing for some reasoned calm. We all know, by now, what to do if the DLM has been unsatisfactory. What this thread really needs now is some feedback on the experience of those who have come out of DLM, with a bad low speed, who have consulted with Sky's call centres, and to learn how effective Sky were [or were not] at resolving the users issues.

[NewsreadeR]

Speculation suggests it is to prepare to launch video and voice services across this. If that is true, and no Sky staffer has confirmed this on here, then the rationale behind DLM is abundantly clear.

I think we can rule out speculation, its clearly printed in the document sent to CST staff

DLM is a strategic project that will improve the quality of service that Sky delivers to its broadband customers. With increased stability throughout the Sky network we will be well placed for the development and launch of future products such as ‘progressive downloads’ (PDL).

Obviously I am not going to publish the document, but at the same time, the document does not state 'Confidential'

[Guesswot]

To interject. I am appalled to see my synchronisation and connection speed collapse and my noise level deteriorate. I was so proud of my speed and reliability, so often top of DSL ZoneUk speed test. I was so proud of SKY and indeed of my speed and reliability. So I now wait to see what transpires.

[Saturday]

Originally Posted by Netgeezer

I was with you 100% until you suggested that the throughput "may be slightly lower". Let us be completely honest here,

It would appear that you may be a little hazy on what exactly is going on here. In simple terms, errors are a count of events where the router reports a "problem" with data/transmission. Again in simple terms errors are a result of noise e.g. in the case of CRC errors the router has not been able to differentiate between signal and noise. There are a number of mechanisms to deal with this, the first line of defence being error correction mechanisms. If all else fails then the data is retransmitted or a message sent to retransmit. However, sitting over all of this is an imperative for the router to maintain an adequate noise margin to allow the required differentiation between noise and signal. It does this quite simply by negotiating a sync speed. More noise = lower sync. This means that the router is only then having to handle transient noise i.e noise bursts or, as SRA is not implemented, having to handle large cyclical noise swings. The upshot of this is that a noisy line will be trained down (sync) on initial exchange negotiation to avoid the majority of errors. A user is not likely to notice lower throughput during these noise burts/cycles as they will be overlaid by general network/server congestion issues.

So yes, except in extreme cases (who would undoubtedly benefit from DLM), throughput only may be slightly lower and that will be transient and go largely unnoticed.

Originally Posted by Netgeezer

Again, you are partially correct, but also not quite on the money. DLM is not simply about capping. In ADSL there are a number of parameters that may be set to stabilise a line, and not all of these are related to speed. But they have to be set carefully if they are not to cause problems for other ADSL users - not only from Sky - sharing the same cable bundle.

What? Do you think it is some sort of magic? Up/downstream sync/noise margin and interleave depth/delay - that's about it. The ADSL protocols have a huge amount of "intelligence" built in. DLM is just an automated "kludge" to constrain the router. Sometimes that's necessary, but not as a rule.

I have no idea what you can be thinking of when you talk of "other ADSL users - not only from Sky - sharing the same cable bundle". What are you trying to suggest- that Sky sets out to and does influence crosstalk?

And thank you for your condescending view of my knowledge of ADSL.

Originally Posted by Netgeezer

But for some, possibly many, the result has been a lowering of speed but an improvement of throughput such that they are able to use video and/or voice over IP.

Yet others are facing ridiculously low set speeds and Sky, as evidenced by enough posters on here, are willing to take corrective action.

I haven't seen a post where members are complaining that they can now stream/use VOIP. They are complaining that, for the purposes they wish to use their connection for, their speed has been cut to practically dial up speeds.

Sky are "willing" to take corrective action! Good grief - that's good of them.

[Netgeezer]

I don't want to overburden this thread but just to offer a final rebuttal to the points raised.

Originally Posted by Saturday

It would appear that you may be a little hazy on what exactly is going on here.

No not really. Transmission protocols are easy enough to understand.

In simple terms, errors are a count of events where the router reports a "problem" with data/transmission. Again in simple terms errors are a result of noise e.g. in the case of CRC errors the router has not been able to differentiate between signal and noise. There are a number of mechanisms to deal with this, the first line of defence being error correction mechanisms. If all else fails then the data is retransmitted or a message sent to retransmit.

Which has an impact upon throughput, which is what I said in the first place.

However, sitting over all of this is an imperative for the router to maintain an adequate noise margin to allow the required differentiation between noise and signal. It does this quite simply by negotiating a sync speed. More noise = lower sync. This means that the router is only then having to handle transient noise i.e noise bursts or, as SRA is not implemented, having to handle large cyclical noise swings. The upshot of this is that a noisy line will be trained down (sync) on initial exchange negotiation to avoid the majority of errors. A user is not likely to notice lower throughput during these noise burts/cycles as they will be overlaid by general network/server congestion issues.

Try watching streaming video or hold a voip call over such an affected circuit. It would be in vain. The user certainly would notice the impact to the transmissions.

So yes, except in extreme cases (who would undoubtedly benefit from DLM), throughput only may be slightly lower and that will be transient and go largely unnoticed.

Some definition of "extreme" may be called for. Just a few errors and retransmits will be sufficient to disrupt voip, video may be slightly more resilient, but not much.

What? Do you think it is some sort of magic? Up/downstream sync/noise margin and interleave depth/delay - that's about it. The ADSL protocols have a huge amount of "intelligence" built in. DLM is just an automated "kludge" to constrain the router. Sometimes that's necessary, but not as a rule.

No magic needed, none implied. There are several parameters that can be set on a DSLAM to condition the service delivered. DLM will work on all of them in an attempt to deliver a desirable result - stable, low-error service.

I have no idea what you can be thinking of when you talk of "other ADSL users - not only from Sky - sharing the same cable bundle". What are you trying to suggest- that Sky sets out to and does influence crosstalk?

Gosh! How do you make that leap? What I am saying is that an ISP has to be careful of what settings it applies to an ADSL service so as not to introduce crosstalk. I did say that in the first place.......

And thank you for your condescending view of my knowledge of ADSL.

Another leap........ If you are going to make public comments then you, as do I, must expect them to be tested and challenged at times. You and I may have a differing view on how ADSL is provisioned and configured and that can come out in this [or any other] discussion.

I haven't seen a post where members are complaining that they can now stream/use VOIP.

I didn't say that at all, nor did I imply that. Very clearly, in defence of DLM, I said "But for some, possibly many, the result has been a lowering of speed but an improvement of throughput such that they are able to use video and/or voice over IP." I feel that was a reasonably unambiguous comment.

They are complaining that, for the purposes they wish to use their connection for, their speed has been cut to practically dial up speeds.

I think we all agree that some have been affected in such a way - but there is absolutely no statistic offered [yet] to support that as the normal experience.

Sky are "willing" to take corrective action! Good grief - that's good of them.

I can do sarcasm. But what is it you are inferring in that style of comment? Are you really suggesting that there was an expectation that Sky would not make good? That does not come across in other areas of the forum, nor this particular thread.

There are very many citations here that Sky does indeed make good. Indeed NewsreadeR has made mention of "the 6" that Sky have collaborated through this forum to get a handle on what the issues are. Is that the signature of a company that does not give a monkeys? Their DLM work was not a 100% success! So what? Try and name one IT project that has worked 100% first time. In anything new there is always going to be some fallout.

Again, I am not trying to defend Sky - I did say that I would play devil's advocate. But I also try to take a reasoned view of what is happening here. Perhaps that does put me in the firing line of the more emotionally charged. Meh, what's a guy gonna do?

But in the cold light of day it is clear [to me at least] that as this DLM programme has progressed Sky has, albeit belatedly, started to get its 'arris into gear to put right the faults it has put on some people's lines.

I, for one, am not prepared to give them a kicking for that.

[dholdi]

Just a little question from me, when I stream video from iplayer etc the progress bar is streets ahead of the point that I am viewing, so I guess any errors that do occur are sorted well before I get to that point in the video. As voice must use a fraction of the data that video does this must be less of a problem. Does this mean that sky are looking to improve the quality of their video feeds which, if judging by the iplayer offerings are pretty poor, and if so why - people use the internet for browsing, gaming etc, if you want to watch a film / tv program at tv quality then surely you would turn on the tv and sky box.

[Brian69]

I quite agree Dholdi. There is an old joke, when asked if they would like I player, some wit sent the following reply. "I have a toilet and a washing machine, why would I want to pee in the washing machine?".
I suppose the success of the I-player indicates that a lot of people do.

[woffle99]

I've just noticed that my speed has dropped from reasonably consistent 3 - 3.5 mb (depending on time of day I synced) to a static 2mb. Called sky and sure enough I've been dlm'd and moved to ADSL 2+, hence the change in speed.

I asked if they could change me back to the way it was before and got the spiel about the line being more stable, that my max rate was showing at just under 3mb and so 2mb was the best it could be set to.

When I mentioned that I'd never had problems with speeds, streaming or anything else for the last two years, I was asked if the router was connected to the master socket. I said it wasn't, but that seeing as it had been getting 3mb on the extension and that the master socket is nowhere near my computer I didn't see why that should matter. I was told that they won't even consider looking at manually configuring my line until the router is connected to the master socket.

My questions therefore are these:

Is this right or just a line to get me off the phone?
If it is, should I just lie and tell them it is connected to the master socket - connecting it to the master socket would be a right pain in the rear.
Should I connect it to the master socket, get them to reconfigure and then move it back?

Basically I just want things back the way they were before - what is the easiest way for me to achieve this?

Thanks for listening.

[Netgeezer]

Originally Posted by Brian69

I quite agree Dholdi. There is an old joke, when asked if they would like I player, some wit sent the following reply. "I have a toilet and a washing machine, why would I want to pee in the washing machine?".
I suppose the success of the I-player indicates that a lot of people do.

I missed tonight's last week's episode of Dr Who - so I watched it on iPlayer. Today I watched BBC World's Click technology program. These would have been lost in time had I not been able to use iPlayer. Yes, I could have made better arrangements to stay in, but then I would become a slave to BBCs programming or would have to cut myself off from programs that I enjoy. But iPlayer does what it says on the tin and has liberated me from the programming schedules of the Beeb.

I wouldn't exactly call that tiddling in the washing machine