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[Chrysalis]

I still think most people are substantially underestimating the psychological aspects.

Do you think people would be campaigning for interleaving to be removed if all lines had interleaving? I don't think people would be complaining about ECI cabinets so much if ECI were all that was installed. The problem is that one thing (ECI cabinets, interleaving) is not as good as the other thing (Huawei cabinets, no interleaving), and that's not fair.

Not sure what ECI vs Hauwei has to do with interleaving.

I think the point you trying to make is if someone has e.g. always been interleaved, would they be bothered given they never experienced fast path latency? Probably not no.  Also fast path in somewhere like scotland would perhaps be similar to a high interleaved connection in london.

[Chrysalis]

I was intentionally not counting ping-pong type cases as I was only talking about throughput, and the word doesn't imo really apply if you are not keeping the line 100% in use any way. I mean if you choose to send packets more slowly than you can, then you cannot say you have a slow line. aim talking about the capacity of a link  not the speed of any use case, if you see what I mean.

That is not to say that RTT is not important or that stop-and-wait type scenarios are not important, indeed no, it's just that for my present discussion that would be a different question, one is about links and the other is about use cases.

I think Kitz is actually agreeing with me, sometimes the engaging of interleave is accompanied by extra RS codword bloat? Is that correct. about that is just a choice made by the designers, it does not mean that the reduction in throughput was caused by interleave itself - is that correct?

So if I am understanding Kitz correctly, then I am disagreeing with J0hn and maybe getting an understanding of his opinion?

So could the answer be that you happen to get an additional phenomenon kicking into place when you choose a setting called 'interleave' but the name is misleading because it comes with a free side dish of onion rings that you did not order?

Weaver I will admit I am now confused.  If you are saying your question was only intended for throughput then your first post doesnt suggest that at all.

RTT affects everything even throughput, in the older days of Windows XP, RWIN was a static value and was dependent on the speed of the ethernet port, around 4k for 10mbit, around 16k for 100mbit and around 64k for gigabit.  On the internet they often caused bottlenecking even on adsl speeds because so many downloads were over high RTT (lack of CDN's).
Now days the RTT limitation on throughput is mitigated via a combination of CDN popularity to provide low RTT servers and modern OS's which autotune RWIN to higher values.

The point of my post was that if I e.g. download a game of steam, I dont really care if it takes 2 or 3 or 4 hours to download, I can wait.  But if I am doing something like loading a web page I am sensitive to the response time.  The one activity I do where the capacity of the line has a meaningful effect is probably streaming, higher burst speed allows more buffered content to load quicker so video content starts playing earlier and at higher resolutions.  I have even posted a fair few times I could probably get by on a 40mbit service, but I stick to the higher speed service due to my technical nature and its a just because I can thing.

On a psychological level people seem much more sensitive and more likely to moan with line banding vs interleaving, even tho the former has less of a negative affect on performance.

[Weaver]

I think I rather drifted off topic myself because I got drawn into discussions about actual performance rather than psychology which was my original question.

And I was using a different interpretation of the word 'throughput' - I was meaning dsl link throughput, whereas you were using a more inclusive interpretation 'system performance' including the behaviour of the devices at the two ends, software and the use case, so that you were dealing with real world actual performance. That was just my particular choice of terms/topics.

I think that you and I are fully in agreement on all points, but I may have expressed myself poorly.

My point about 'psychology' was concerned with the question of why do people get steamed up specifically about interleave rather than just saying 'my internet x activity eg web browsing is slow'. If people do not know about the effect of rtt on page opening time for complex webpages that are not cached especially where objects are small, then they will not be able to blame interleave. So the question then is whether or not people are aware of the link and then blame interleave for poor responsiveness in web browsing.

I wonder if people consider that high interleave depth can have large performance benefits, and that it is done for a reason, not to hurt performance. I would argue that if intelligent system tuning is done correctly, which is quite an 'if', the use of high interleave depth allows you to push for higher sync speeds which increase error rates while on the other hand interleave reduces a certain type of errors, so that it can be a trade off that allows you to get a higher link speed without breaking a certain chosen error rate limit. Does that sound reasonable? I think doing this kind of assessment must be pretty hard though, as knowing the pattern of error types is not straightforward.

I myself have always tried as hard as possible to do what ever I can, which is usually not much, to push up interleave depth as far as I can, as I don't care at all about rtt. I am hoping that I have modern software that uses large window sizes. But I desire every ounce of raw link throughput (in my terms, ie sync rate, allowing for bloat) that I can get with links as slow as I have.

[boost]

Presumably because people have learned it's not enough to express they are receiving bad service, they must find as much information as possible to contribute to the solution.

It's almost certainly the reason any of us use this forum

However, not all end user research is as exhaustive as it could be. We are experts at filling in the blanks with the little to no information we possess, I suppose?

[ejs]

Not sure what ECI vs Hauwei has to do with interleaving.

The point was that I think people aren't complaining so much about the technical differences, they are complaining because they consider one worse than the other.

I think the point you trying to make is if someone has e.g. always been interleaved, would they be bothered given they never experienced fast path latency? Probably not no.  Also fast path in somewhere like scotland would perhaps be similar to a high interleaved connection in london.

They'd probably be a few people freely giving their opinion on what idiots Openreach are and how if they were in charge they'd operate the DSL lines so much better.

[ejs]

I wonder if people consider that high interleave depth can have large performance benefits

The interleaving depth number is largely irrelevant, but yes, lots of people probably do think that a larger depth number is "more interleaving", and then people will be watching their stats, and if they see line rate and interleaving depth both go down slightly, they'll erroneously conclude that the reason for this must have been the DLM turning down the interleaving depth a little.

[niemand]

Interleave takes its toll with serial transactions and the extra delay introduced. Nothing to do with throughput as far as browsing goes.

I've used a modem with old firmware and had interleave applied due to behaviour of Openreach DSLAMs and noticed almost immediately. Nothing to do with psychology and I don't obsessively monitor my connection so wasn't aware objectively that it was there.

[ejs]

None of which really answers the original question though.

I take it then that pretty much everyone here is of the opinion that all the people complaining about interleaving will be doing so for perfectly valid reasons largely originating from the additional delay? And it's got nothing to do with people knowing that their line has got worse? You may have noticed the change, but would you be complaining if your line were always like that?

[Chrysalis]

I understand now Weaver, so do people complain simply because they can because they interleaved without understanding the pros and cons of it?

Some probably do yes. But as ignition has said, there is also valid complaints, as interleaving does impact performance in a way that can be noticed.

[Weaver]

Chrys - exactly. I myself think, "ooh good, I have a high interleave depth, that might mean the possibility of a faster sync rate".

[kitz]

Chrys - exactly. I myself think, "ooh good, I have a high interleave depth, that might mean the possibility of a faster sync rate".

   I myself think there goes a good chunk of my sync speed, plus delay

So could the answer be that you happen to get an additional phenomenon kicking into place when you choose a setting called 'interleave' but the name is misleading because it comes with a free side dish of onion rings that you did not order?

Yup.  RS Error Correction is almost always turned on at the same time as interleaving. 

It's not so much interleaving that reduces the sync speed, but rather the fact RS encoding that comes with interleaving incurs overheads which reduces the available sync speed.

One of the things I kept pointing out during the introduction of G.INP is that people tend to use the word Interleaving when really we should be saying Error Protection.   In short, you have INP which uses Interleaving and FEC (RS encoding).  Then you have G.INP which uses retransmission.

[Ixel]

Unless you're using a modem which has a Lantiq/Infineon chipset, in which case RS is applied on the downstream whether fastpath or not.

I happen to notice when 'traditional interleaving' is applied. My thoughts are something along the lines of "a bit of sync rate lost and increased latency". As a person who plays quite a bit of first person shooter games online I notice the difference (as strange as it might sound to some), so I much prefer the lowest latency possible. I'd rather have a slightly reduced sync rate instead of 'traditional interleaving'.