Speeds dropping on router reset and Speed seems to be stuck?

[User05]

As I mentioned, there is noise that is stopping you from getting up to 4.8mbps again. You're not capped. If those stats are from the test socket, then there's not much that can be done.

[ufo]

As I mentioned, there is noise that is stopping you from getting up to 4.8mbps again. You're not capped. If those stats are from the test socket, then there's not much that can be done.

I am reading, I am hearing, but I can't say I'm understanding.


If you look closely, you will see that the noise levels are no different in either case, both are remaining at 6.9 dB.


In some cases now, it is also increasing at times to 7.3 dB, yet no matter about this increase, even if I wait it out or alternatively if I reboot - I can still never achieve any higher than 4352kbps - so still 500 less than I could previously achieve with identical attenuation and identical noise margin.

It is not a good idea to reboot your router too often, this can lead to DLM kicking in and making things worse.

Also, want to try and work this out....

If I am on a 1mb line, would my sync be 1024 ?
So therefore, if it was a 4mb line, it would be 4096?

Here's the confusing part. On a 1mb line max download speed is around 128 kb/s.
So multiply this out for a 4mb line - 4 x 128 kb/s = 512 kb/s download speed although I'm sure there must be some overhead

I was previously achieving around 485 kb/s download speed when connected at 4832 downsteam.


Yet now, I am connected at 4532 downstream and can't achieve any higher than around 435 kb/s download speed.



Doing the same kind of sums, 3.5 x 128 kb/s = 448 kb/s, so take away a little overhead and it would appear to suggest I am stuck at around a 3.5mb/s connection.

All very confusing.

[timc]

You will never be able to download at 100% of the sync speed. Typically it'll be range of 80-85% of the sync speed. Redo your calculations bearing that in mind.

[User05]

Just because the noise margin isn't dipping from 6.9/7, doesn't mean that there isn't noise stopping you from going higher. I'll try and explain it a different way:

- Your line is already uncapped. To what? Sky could only tell you this, but it's not important. What is important is that it is not capped, so if the line could train in higher, it would (dependant on noise levels).
- If you want to sync in at 4.8mbps again, then you're going to need a SNR higher than Sky's target SNR of 7dB. Typically, every dB = a certain amount of kbps. You don't have any spare from the target, so the speed will not go up with a reboot.
- As to why it has dropped? That's where troubleshooting comes in i.e. trying the test socket etc. If those stats, as I've said, are from the test socket with no extensions, then there really isn't much that can be done bar trying to reboot the router at less 'noisy' periods.

[ufo]

You will never be able to download at 100% of the sync speed. Typically it'll be range of 80-85% of the sync speed. Redo your calculations bearing that in mind.

In that case then, after redoing my calculations it's worse than I'd thought.

At my old speed =
was previously achieving around 485 kb/s download speed when connected at 4832 downsteam.


so if this is downloading at 80-85% of my achievable rate my actual connection speed was:
485 kbs / 82.5% (to give 1%) x 100% / 128 kbps =
* So my actual connection was of 4.71mb/s - seems about right


At my new/existing speed now, achieving around 435 kb/s download so if this is 80-85% then:
435 kbs / 82.5% (to give 1%) x 100% / 128 kbps =
my connection speed is actually now 4.11 mb/s, jeez it's worse even than I thought



BUT, the Sky guys agreed and told me they had previously recorded it themselves (must have been from a DLM or something) at 4.75mb



Man it's getting complicated

Just because the noise margin isn't dipping from 6.9/7, doesn't mean that there isn't noise stopping you from going higher. I'll try and explain it a different way:

- Your line is already uncapped. To what? Sky could only tell you this, but it's not important. What is important is that it is not capped, so if the line could train in higher, it would (dependant on noise levels).
- If you want to sync in at 4.8mbps again, then you're going to need a SNR higher than Sky's target SNR of 7dB. Typically, every dB = a certain amount of kbps. You don't have any spare from the target, so the speed will not go up with a reboot.
- As to why it has dropped? That's where troubleshooting comes in i.e. trying the test socket etc. If those stats, as I've said, are from the test socket with no extensions, then there really isn't much that can be done bar trying to reboot the router at less 'noisy' periods.

Thanks for all this info, all this I get and was aware every dB = some certain amount of kbps.

The only problem here is that I believe I read on another post that on longer lines (anything with attenuation higher than 31), Sky automatically sets the noise margin at 6.9 dB and then allows it to adjust only after the initial connection/sync/login has been made.

This is fine, I will often see it connecting in at 6.9 dB, and within seconds it will go up to 7.3 dB.

The problem is that the downstream doesn't go up at all (or down for that matter, except if I would reboot the router), which would suggest that maybe their so-called "light DLM" which they told me is *always* running, isn't actually running at all otherwise it would be adjusting it for me automatically?

[User05]

I think you're maybe referring to seamless rate adaption, something that Sky do not support/implement. You need to reboot the router to get a different sync rate.

A .4dB change in noise margin will not induce DLM to kick in as that's just normal noise fluctuation that occurs throughout the day. DLM has two roles - one monitors the line 24/7 collating data. The second will then run an optimisation period (to up to 10 day period that you see referred to) if it sees the line is not profiled optimally. In your case, DLM will see the line is profiled fine and not kick in.

[ufo]

I think you're maybe referring to seamless rate adaption, something that Sky do not support/implement. You need to reboot the router to get a different sync rate.

A .4dB change in noise margin will not induce DLM to kick in as that's just normal noise fluctuation that occurs throughout the day. DLM has two roles - one monitors the line 24/7 collating data. The second will then run an optimisation period (to up to 10 day period that you see referred to) if it sees the line is not profiled optimally. In your case, DLM will see the line is profiled fine and not kick in.

I feel like I'm on the telephone with Sky again. Although I do appreciate the info you're giving.

SRA sounds like what I'm talking about alright, the Tier 2 I spoke to some time ago was convinced it was running though as I'd explained the only way to get a different sync rate was a reboot so I was convinced it wasn't.

Now I'm told sky definitely don't use it.

Arrrgh. Any wonder the whole thing gets so frustrating.

The DLM that monitors the line 24/7 collating data, what is it doing with that data when it's not running the optimisation period?

And is that entire data range that DLM has been monitoring (from the beginning of my subscription) viewable (in graph or table or csv form or whatever) to both a Tier 1 or Tier 2? Or does it just plot points at regular intervals (e.g. Once a week)?



The issue in the end still being, I have lost around 50 kb/s of download speed through no change of my own, the only thing I can see any different is that a DLM recently completed (10 days ago).

As I had not disconnected any time before 2-3 days ago for months, the only remaining factor can be is that the DLM so-called "optimisation" process, has reduced my line to this. If DLM is the culprit, it has effectively reduced my line by at least around 0.5 mb/s every six months since I first subscribed to Sky. DLM really is the devil.

Do Sky use BrAS profiles or do they have their own? If so, what are they and is there a listing of them anywhere?

[User05]

The DLM that monitors the line 24/7 collating data, what is it doing with that data when it's not running the optimisation period?

Nothing; it stores it.

And is that entire data range that DLM has been monitoring (from the beginning of my subscription) viewable to both a Tier 1 or Tier 2?

One system that CST have access to will show this.

DLM really is the devil.

If Sky have already undone the changes that DLM have done, then DLM is nothing to do with this. By all means, if you really care about the kbps that you have lost, then call Sky and see if they can do anything more for you.

Do Sky use BrAS profiles or do they have their own? If so, what are they and is there a listing of them anywhere?

No, they don't.

[ufo]

If Sky have already undone the changes that DLM have done, then DLM is nothing to do with this. By all means, if you really care about the kbps that you have lost, then call Sky and see if they can do anything more for you..

Whether they have actually "undone" those changes or not I just don't know, so far it doesn't look like anything has been done.

I already have called them, but I'm waiting a callback from CST.

It would be helpful to know what to ask them though or what to aim for.

Asking for my lost kbps back will probably just get the usual back I am guessing - your line is achieving it's max. On the other hand there might just be a gem in there who wants to help and knows exactly what settings to tweak to get those lost kbps back. Just seems to be a bit of a lottery.

[IWasNotTheEnemy]

Unless the SNR can be increase with setup changes your end there's little to no chance of Sky doing anything to get the half a meg back as it's the physical line limiting things