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Standard User Andrue
(eat-sleep-adslguide) Sat 20-Jan-18 16:05:10
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DSL dropped. Much better sync on manual connect


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That was weird. I left the house for an hour and about fifteen minutes before I got back my HG612 lost sync. And it stayed lost. First I knew was when I switched my Sky box on and it whined about having no internet. So I power cycled the HG612 and it reconnected just fine. But here's the (good) thing: My speed tests have jumped from around 55Mb/s where they've been for six months back to around 67Mb/s where they used to be before openreach relocated my PCP.

It's great to be back on my original speed but a bit weird that my HG612 couldn't re-establish sync automatically.

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Andrue Cope
Brackley, UK
Standard User Andrue
(eat-sleep-adslguide) Sat 20-Jan-18 19:26:12
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Re: DSL dropped. Much better sync on manual connect


[re: Andrue] [link to this post]
 
Well that's curious. I was talking about this with a friend and he pointed out that he had a similar experience. Months on a reduced sync then a sudden correction at an unusual time of day (ie;not early hours). In his case his modem resynced by itself but the similarity is that it happened while he was running a lengthy upload. And that's what I'm doing. Just before I went out I kicked off a backup to the cloud (some 400GB of data). It's almost as if continuous upload saturation triggers the better sync.

Two cases is hardly proof but it's a curious co-incidence.

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Andrue Cope
Brackley, UK
Standard User burble
(member) Sat 20-Jan-18 20:06:58
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Re: DSL dropped. Much better sync on manual connect


[re: Andrue] [link to this post]
 
For many many months my HG633 was rock solid at around 4mb, then the speed crept up to 5mb, but after a week or two it dramatically dropped to around 1mb, this is now the norm and it needs to be rebooted every couple of weeks.


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Standard User Andrue
(eat-sleep-adslguide) Thu 08-Feb-18 15:55:00
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Re: DSL dropped. Much better sync on manual connect


[re: Andrue] [link to this post]
 
Just checked my profile and:

The current Downstream BRAS rate is: 67.84 Mbps
The current Upstream BRAS rate is: 20 Mbps

So it looks like it's still holding. Pity I didn't think to check the profile back when it was running slow :-/

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Andrue Cope
Brackley, UK
Standard User andy88
(eat-sleep-adslguide) Sat 10-Feb-18 00:24:28
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Re: DSL dropped. Much better sync on manual connect


[re: Andrue] [link to this post]
 
a drop and re-sync was probably caused by high error rate per min/per hour

so if there is no traffic.... no errors
now you generate a high (and continuous) traffic load,
and the error counter/per time period increases...

Normally you would expect it to re-sync lower, to reduce the likely error rate.
but when it looks at the history / of the moment conditions, it is a good thing that it tried to upgrade adapt the line also.

A manual reboot or disconnect / re-connect (preferably via the GUI option than pulling the phone plug !) could/can achieve the same in a shorter timescale.

as you say, worth knowing.
Standard User j0hn83
(committed) Sat 10-Feb-18 02:02:23
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Re: DSL dropped. Much better sync on manual connect


[re: andy88] [link to this post]
 
so if there is no traffic.... no errors
now you generate a high (and continuous) traffic load,
and the error counter/per time period increases...

That's not how DSL works.
Standard User andy88
(eat-sleep-adslguide) Sat 10-Feb-18 12:03:58
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Re: DSL dropped. Much better sync on manual connect


[re: j0hn83] [link to this post]
 
Enlighten me then...
how 'does' it work and my assessment be incorrect ?
i.e. why would additional traffic not add to the probability of increases errors.
Happy to learn.

Surely there is background sync, a nice simple data pattern - and it is stable.
But when actual varying data is passed there is increased usage of the spectrum and additional opportunity for corrupted reception.
Standard User j0hn83
(committed) Sat 10-Feb-18 12:39:10
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Re: DSL dropped. Much better sync on manual connect


[re: andy88] [link to this post]
 
No need to be sarcastic or a ****. It just doesn't work like that.

If I plug in my modem, get sync and walk away (without even connecting my router and establishing a PPP session (so no data) I get a consistent 1000 FEC every minute. If I connect my router, and hammer 50Mb down, I get a consistent 1000 FEC every minute.

Think of it like a train constantly running on a line. When your transferring data it's within the carriages, but the carriages are always running. The mechanics are checking the carriages for errors, they don't care how many people are on board.
Well you data is the people. The error checking doesn't touch your data. It doesn't even know it's there (It's all in PTM packets).

Edited by j0hn83 (Sat 10-Feb-18 12:43:33)

Standard User andy88
(eat-sleep-adslguide) Sat 10-Feb-18 13:38:11
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Re: DSL dropped. Much better sync on manual connect


[re: j0hn83] [link to this post]
 
There are plenty of protocols with (to use your analogy) constant empty carriages.
Likewise, plenty that establish a maximum performance rate during initial handshake sequences.. .but then do not need to use all of that coded capability until demanded. The null / holding frames are reliable and highly interference tolerant. (yes, we can debate whether they would be better used to stress the system at this time... but that's another discussion)

So when those carriages are filled less benign/null data, it starts to have an effect.
Therefore the error checking of the carriages (packets) would reflect any corruption seen whilst carrying different data.

Now it could be that the coding of the data, is such that it has been designed to be 100% equal, but most systems do not achieve that goal, the change to actual non-null data has an impact in some (sometimes rare) situations.

So why/how does the sending of non-null packets not differ from sending data specific ones. i.e. how would my proposal be incorrect in the context of xDSL/FTTx transmission and better, the poster's issue actually be caused. The poster is seeing an issue, so lets go explain that.
Standard User j0hn83
(committed) Sat 10-Feb-18 14:37:21
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Re: DSL dropped. Much better sync on manual connect


[re: andy88] [link to this post]
 
Perhaps my analogy wasn't detailed enough. Think of your line as train tracks. When the DSL is in sync the line is always full of carriages. Imagine a never ending train, always running on the line. The data inside is irrelevant, it has no impact on the train.
Data being transmitted doesn't change anything physical on the line. Power levels, SNR, noise, etc, all remain the same.

It's the same how crosstalk doesn't change wether your neighbour is using their connection or not. It's a constant noise. As long as the line is synced it creates the noise that disturbs your line. The neighbour randomly downloading a 100Gb file doesn't create any additional noise.

What the OP is describing is called a coincidence. Doing a large upload during the line resyncing cannot increase sync. The data being transmitted on xDSL has no impact on any of the lines characteristics.
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