VDSL Performance & Tuning

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202 posts

Master Geek
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#666489 2-Aug-2012 19:42

NZFINEST: do you know if DLM put you on 17a? Or was it requested?

i had it put on. DLM will not set it to 17a the way things are atm
you can't get it put on if you request it as well due to reasons i'm not going to go into but yea. you never know your luck in the future

Anything I suggest or say is my own thoughts and not provided by anyone else unless stated

SamF

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#666601 2-Aug-2012 23:06

stevehodge: SamF: "What I'd like to know is what error threshold DLM considers 'unstable'!"

I'm not sure, but here are my stats since going onto DLM-1:

As you can see my error rate is pretty high, but the connection seems solid and it's been up over a week since DLM moved it to the current configuration.

Holy CRAP man!! That is a LOT of errors!

Geez, if you're consistently on DLM-1 with those error rates then the rest of us will be fine! :D

Napster: @SKYMAX
The SNRM reported in the Fritzbox is RealTime for the current bit rate.

So what's the deal with the SNR as shown in the 'Spectrum' tab? The SNR rates in there are up to 65db!?

Napster

202 posts

Master Geek

#666623 2-Aug-2012 23:23

If i understand it correctly, the Spectrum shows SNR per tone and DSL page shows the SNR Margin. That is what signal is still available before you have too much noise.

The margin is in place because if you had to utilize all of the signal then you would have no room for bursts of noise.

Say you have 50dB SNR average on the spectrum and you have a training margin set at 12dB, you will use 38dB signal and the rest of that 12dB is your margin for noise.

Hope that makes sense :)

SamF

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#666627 2-Aug-2012 23:28

Right, yeah, that makes sense. So basically the SNR margin / target is the minimum SNR tolerable. Anything under this and you would get a re-sync to get the minimum SNR up above the target?

On another topic entirely: INP.

fellaintga pointed me to this interesting doco regarding VDSL. It has this to say about INP:

Impulse Noise Protection (INP)
The copper loop plant is suseptable to short impulses caused by external sources. These impulses cause large bursts of errors, which could have a significant impact on the video picture quality. In order to remove errors, VDSL2 has an impulse noise immunity (INP) capability. INP provides the ability to correct any impulse noise less than 250 microseconds (INP=2, 8 milliseconds latency). VDSL2 can even provide impulse noise protection values up to INP=16, which corresponds to the ability to correct any impulse noise that is less than 3.75 milliseconds.

So that explains a bit about what INP does and is capable of. Napster, you suggested that I could up the INP value on the router end to decrease errors. What I'd like to know is what is the down-side of using INP and what are the consequences of increasing this value?

stevehodge

393 posts

Ultimate Geek
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#666642 3-Aug-2012 00:03

SamF: "Napster, you suggested that I could up the INP value on the router end to decrease errors. What I'd like to know is what is the down-side of using INP and what are the consequences of increasing this value?"

Latency, I assume. I believe you can't have INP-1 or INP-2 without at least latency of 8ms and INP-4 requires 16ms latency.

SKYMAX

43 posts

Geek
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#667157 3-Aug-2012 18:03

Had a resync yesterday morning that I didn't notice.
Biggest change was from 8ms latency to 1ms - yeee-haaa

-JASON-

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SamF

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#667280 3-Aug-2012 22:59

Nice!! That was quick! Not too many errors either!

richms

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#667288 3-Aug-2012 23:09

Hmm, Im on 14dB attenuation since my line was fixed by chorus so hopefully my 23 megs goes up once DLM does its thing, and that pesky 8ms goes away.

Richard rich.ms

Instinct

41 posts

Geek
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#667304 3-Aug-2012 23:46

Hi All,

Been busy so only just getting round to posting my results. Not too flash, but considering my line attenuation I guess I can't complain. I do appear to have a lot of errors. Snap said that my attenuation was around 6db, my old dynalink router reported back 13db and the Fritz reports back 20db... I have cat 5e cabling through the house and had the splitter installed (Bloody expensive when you consider it took the chorus tech 15 minutes to complete the work). See below for results to date.

SamF

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#667307 3-Aug-2012 23:50

Hmm, not too hot there mate!

How far away are you physically from the cabinet?

richms

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#667313 4-Aug-2012 00:09

The bottom end of it is looking better than mine tho...

Was hoping that fixing the cable would clear that up since it seems I dont get to use any more than 40% of what the frequancies go up to on the chart.

Richard rich.ms

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Instinct

41 posts

Geek
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#667316 4-Aug-2012 00:16

SamF: Hmm, not too hot there mate!

How far away are you physically from the cabinet?

Well I thought it was a green box at the bottom of my road :-) Around 500m away. But I'm guessing the VDSL card is installed at the exchange in Three Kings, Auckland. I was getting approx 12.5mb down and 0.8 up on ADSL so this is still an improvement for me.

I've checked the Chorus tool and it looks like I should be connected to Cabinet Name: TIS/BG
Can anyone confirm the physical location of this cabinet?

SamF

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#667319 4-Aug-2012 00:36

Hmm, is it a large green box (2-3m wide, ~1m high?). If so, that's very likely your cabinet.

You can see your cabinet / exchange area using the Chorus Service Availability Tool which will hopefully clear things up a bit.

Instinct

41 posts

Geek
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#667329 4-Aug-2012 01:02

SamF: Hmm, is it a large green box (2-3m wide, ~1m high?). If so, that's very likely your cabinet.

You can see your cabinet / exchange area using the Chorus Service Availability Tool which will hopefully clear things up a bit.

Just grabbed this of streetview. If this is the cabinet, then it's approx 550 meters away.

SamF

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#667330 4-Aug-2012 01:05

Naa, that's not it, it's about 3 times that wide and slightly higher.

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