VDSL Performance & Tuning

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371 posts

Ultimate Geek
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#846508 28-Jun-2013 01:41

Time to jump in on this thread, Just asking to see how my stats looked too some other geeks, I'm on day 4 out of my 10 day testing period so i'm not planning to tweak with things just yet tho.

So far pretty happy but i'm hoping to get on 17a, I wouldn't even mind if i could tweak it to half my upload for more download since I mainly download.

SamF

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#846532 28-Jun-2013 08:37

Wow! That is a VERY clean line mate!!

I have NEVER seen a spectrum graph that tidy and you've obviously run a Cat5e cable out your window and hooked it directly to the cabinet which is sitting outside your house! :D

I would bet the house that you will be on 17a very shortly!

Jexlar

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#846536 28-Jun-2013 08:43

Wow, that's a crazy clean line.....

JonoNZ

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Ultimate Geek
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#846537 28-Jun-2013 08:46

Does anyone have any idea why the initial sync speed varies so much? On such a clean line with low attenuation I'd have thought an initial a sync rate of ~39000 is rather low. I have 11dB attenuation and my initial sync was ~44000, and gone up to ~48000 since then. Does the modem come into play here (Fritz box vs Technicolor)?

SamF

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#846538 28-Jun-2013 08:47

@mikenzb: Actually, do you mind if I steal your spectrum graph to use as an example in the thread summary post? I'd also like to use your 17a spectrum graph as an example when you get onto that profile!

seatil

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#846572 28-Jun-2013 09:31

@mikenzd's spectrum graph: I would have expected more than 39Mbps with an attenuation of 2 and DLM-1.

Looking at the spectrum graph. It looks nice at first glance, but a closer look yields some possible clues to the lower than expected sync rate:

* The ADSL1/2 frequency range peaks at around 45dB. My own line averages 50dB and manages 10 bits per bin, whereas mikenzd's line is managing 9 bits per bin.
* The VDSL frequencies immediately after the ADSL2+ zone peak at 55dB. I'm managing 14 or 15 bits per bin there, he's getting 11 and 12.
* Across the second downstream band he's again reduced bits per bin vs me. 11 vs 12.

That probably more or less accounts for the difference in sync rate (39Mbps vs 45Mbps).

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JonoNZ

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Ultimate Geek
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#846627 28-Jun-2013 10:41

seatil: @mikenzd's spectrum graph: I would have expected more than 39Mbps with an attenuation of 2 and DLM-1.

Looking at the spectrum graph. It looks nice at first glance, but a closer look yields some possible clues to the lower than expected sync rate:

* The ADSL1/2 frequency range peaks at around 45dB. My own line averages 50dB and manages 10 bits per bin, whereas mikenzd's line is managing 9 bits per bin.
* The VDSL frequencies immediately after the ADSL2+ zone peak at 55dB. I'm managing 14 or 15 bits per bin there, he's getting 11 and 12.
* Across the second downstream band he's again reduced bits per bin vs me. 11 vs 12.

That probably more or less accounts for the difference in sync rate (39Mbps vs 45Mbps).

Very interesting, thanks for the explanation.

SamF

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#846628 28-Jun-2013 10:41

I think the sync speeds on new lines are started conservatively and then cranked up later

JonoNZ

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#846630 28-Jun-2013 10:43

SamF: I think the sync speeds on new lines are started conservatively and then cranked up later

My first sync was 44485, so fairly reasonable right off the bat for a line with 11dB attenuation.

stevehodge

393 posts

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#846660 28-Jun-2013 11:30

SamF: I think the sync speeds on new lines are started conservatively and then cranked up later

That's primary via DLM though and he's already on DLM-1. It is weird.

stevehodge

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#846664 28-Jun-2013 11:33

JonoNZ: Does anyone have any idea why the initial sync speed varies so much? On such a clean line with low attenuation I'd have thought an initial a sync rate of ~39000 is rather low. I have 11dB attenuation and my initial sync was ~44000, and gone up to ~48000 since then. Does the modem come into play here (Fritz box vs Technicolor)?

DLM level will make a big difference. There's also quite a lot of variation from sync to sync depending on the line conditions at the time of sync. I imagine the modem could make some difference too.

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6297a1679f9

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#846686 28-Jun-2013 11:58

@SamF, Indeed the cabinet is outside my house (No really its like 5-10 meters away) but I haven't hooked any cat5e onto my line. Only Jackpoint in the house altho, I also don't mind if you take my graph.

I'll see if I do get on 17a might take some time for the DLM to kick in but we'll see.

stevehodge

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#846694 28-Jun-2013 12:02

mikenzb: @SamF, Indeed the cabinet is outside my house (No really its like 5-10 meters away) but I haven't hooked any cat5e onto my line. Only Jackpoint in the house altho, I also don't mind if you take my graph.

I'll see if I do get on 17a might take some time for the DLM to kick in but we'll see.

I remember someone earlier in the thread saying that it is possible to be too close to the cabinet (I think 100m is supposed to be the minimum). The Chorus tech actually ran a cable around his house just to lengthen the drop.

hio77

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#846701 28-Jun-2013 12:14

stevehodge:
mikenzb: @SamF, Indeed the cabinet is outside my house (No really its like 5-10 meters away) but I haven't hooked any cat5e onto my line. Only Jackpoint in the house altho, I also don't mind if you take my graph.

I'll see if I do get on 17a might take some time for the DLM to kick in but we'll see.

I remember someone earlier in the thread saying that it is possible to be too close to the cabinet (I think 100m is supposed to be the minimum). The Chorus tech actually ran a cable around his house just to lengthen the drop.

wouldn't too close simply be a case of needing to lower the power output though? rather than something rather abrupt as adding length to the cable..

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6297a1679f9

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Ultimate Geek
+1 received by user: 29
Inactive user

#846710 28-Jun-2013 12:27

stevehodge:
mikenzb: @SamF, Indeed the cabinet is outside my house (No really its like 5-10 meters away) but I haven't hooked any cat5e onto my line. Only Jackpoint in the house altho, I also don't mind if you take my graph.

I'll see if I do get on 17a might take some time for the DLM to kick in but we'll see.

I remember someone earlier in the thread saying that it is possible to be too close to the cabinet (I think 100m is supposed to be the minimum). The Chorus tech actually ran a cable around his house just to lengthen the drop.

Wouldn't it be the closer the better? Well I don't get that theory.

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