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Standard User dustofnations
(learned) Sat 21-May-11 13:47:35
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Stuck on low sync versus SNR/Atten


[link to this post]
 
I seem to be stuck at a disproportionately low speed on my Sky LLU line. Extrapolating from the usual ADS2+ graph/stats checker tools, you would expect in the region of 14Mbps:

Text
1
23
4
ADSL Link               Downstream      Upstream
Connection Speed        9212 kbps       921 kbpsLine Attenuation        35 db           20 db
Noise Margin            14 db           9 db


I wonder if the line profile is stuck.I get _exactly_ the same sync rate on every occasion.

Unfortunately I have a locked down v2 router (DG834G), so I can't telnet in to get more useful connection information (without hacking it, which I would rather not do for now). I have a DG834PN which I might use, from which I have extracted the obfuscated UN/PW.

Anyone experienced an issue like this? Suggestions?

Edited by dustofnations (Sat 21-May-11 15:21:49)

Standard User Oliver341
(knowledge is power) Sat 21-May-11 14:08:04
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Re: Stuck on low sync versus SNR/Atten


[re: dustofnations] [link to this post]
 
Are those stats from the master socket test port?

http://www.plus.net/support/broadband/bbfaults/maste...

Oliver.

Edited by Oliver341 (Sat 21-May-11 14:09:23)

Standard User dustofnations
(learned) Sat 21-May-11 14:19:36
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Re: Stuck on low sync versus SNR/Atten


[re: Oliver341] [link to this post]
 
In reply to a post by Oliver341:
Are those stats from the master socket test port?

http://www.plus.net/support/broadband/bbfaults/maste...


Yes, I'm well aware of the procedure for using the master socket with NTE5 smile. However, the socket is an old-style LJ2/1A, (i.e. there is no master socket) with a BPO junction box.


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Standard User Oliver341
(knowledge is power) Sat 21-May-11 14:22:42
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Re: Stuck on low sync versus SNR/Atten


[re: dustofnations] [link to this post]
 
What's odd is that your upstream noise margin is lower than your downstream, usually the other way around, especially with Sky's somewhat anti-upload line profiles.

Oliver.
Standard User dustofnations
(learned) Sat 21-May-11 14:31:02
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Re: Stuck on low sync versus SNR/Atten


[re: Oliver341] [link to this post]
 
In reply to a post by Oliver341:
What's odd is that your upstream noise margin is lower than your downstream, usually the other way around, especially with Sky's somewhat anti-upload line profiles.


Yes, I have a feeling this may be because I made some improvements a while ago to the line set-up which has improved the downstream SNR, but the profile seems to be stuck and refusing to re-synch.

As you are probably aware the old BPO system is particularly good at collecting EM noise from the bell-wire, and this is before I have resolved the issue with 2 extensions (which are in the old-style star configuration from the junction box).

I'd guess that I'll gain another 3dB at least, but the profile has been stuck for a week, so I haven't bothered doing the rest yet.
Standard User Oliver341
(knowledge is power) Sat 21-May-11 14:41:47
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Re: Stuck on low sync versus SNR/Atten


[re: dustofnations] [link to this post]
 
Certainly worth giving Sky a nudge about raising the profile then, they seem quite obliging when I have done this in the past, and you've got more than 7dB margin in both directions.

Oliver.
Standard User tommy45
(fountain of knowledge) Sat 21-May-11 15:01:28
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Re: Stuck on low sync versus SNR/Atten


[re: dustofnations] [link to this post]
 
Firstly i agree you should get a better sync than what you are currently getting, i can also see the noise margin is higher than it should be which in turn will serve to artificially cap the connection,
The other thing from your post is the router that you are using ,an old v2 netgear which uses the AR7 chipset, not a good choice by sky,
Have you rang sky about this? i estimate with the right router and the DLM set noise margin reset you should see a sync of around 15mbits downstream and there is according to the attenuation no reason why you shouldn't see the full 1.3mbits upload sync
well you certainly would see these figures if sky where like some other isp's did not use dlm at all,and would set target margins as per request and provide fast path , but they don't

Edited by tommy45 (Sat 21-May-11 15:05:13)

Standard User dustofnations
(regular) Sat 21-May-11 15:11:01
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Re: Stuck on low sync versus SNR/Atten


[re: tommy45] [link to this post]
 
In reply to a post by Oliver341:
Certainly worth giving Sky a nudge about raising the profile then, they seem quite obliging when I have done this in the past, and you've got more than 7dB margin in both directions.


On the previous occasions I've had the misfortune of phoning them it was like extricating my fingernails with rusty pliers. If I can avoid having to engage with them before I move to a different ISP, then I shall do so.

In reply to a post by tommy45:
Firstly i agree you should get a better sync than what you are currently getting, i can also see the noise margin is higher than it should be which in turn will serve to artificially cap the connection,
The other thing from your post is the router that you are using ,an old v2 netgear which uses the AR7 chipset, not a good choice by sky,
Have you rang sky about this? i estimate with the right router and the DLM set noise margin reset you should see a sync of around 15mbits downstream and there is according to the attenuation no reason why you shouldn't see the full 1.3mbits upload sync
well you certainly would see these figures if sky where like some other isp's did not use dlm at all,and would set target margins as per request and provide fast path , but they don't


Indeed, I know it should achieve roughly 14Mbps as I stated originally (I've probably run it through the same graphs and estimation equations as you laugh). I also agree the router is pants, my DG834PN has a decent BCM6348 chipset so I might risk the wrath of Sky and use the calculated user-name/password. Using the dgteam firmware I can set the SNR manually on there, so I might as well go and climb into the loft and get it down.

In fact, I'm just waiting for the likes of BE and their ilk to announce their intentions w.r.t LLU/VULA, then I'm off. VDSL2 cab is only 30M away!

Thanks for your input!

Edited by dustofnations (Sat 21-May-11 15:11:22)

Standard User Oliver341
(knowledge is power) Sat 21-May-11 15:51:34
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Re: Stuck on low sync versus SNR/Atten


[re: dustofnations] [link to this post]
 
In reply to a post by dustofnations:
On the previous occasions I've had the misfortune of phoning them it was like extricating my fingernails with rusty pliers. If I can avoid having to engage with them before I move to a different ISP, then I shall do so.

I've never rung them, because it's not free. However the email support, whilst slow (2 to 3 days for a reply is usual), seem to be ok.

Oliver.
Standard User dustofnations
(regular) Sat 21-May-11 18:51:30
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Re: Stuck on low sync versus SNR/Atten


[re: Oliver341] [link to this post]
 
Well, I pulled the whole set-up apart and put the other router in. It connected, but the SNR was very low and kept crashing. However, as is typical with this house, there are a multitude of reasons it might have been doing it to thwart and generally irritate me.

The master phone socket is right near the power entry point, where all of the breakers and meter are, plus loads of really old noisy circuitry from eons ago.

The router is 30cm away from all of this (nowhere else to put it), plus the power brick it is attached to is connected to a power point that is down about 5cm away from all of that stuff. So it wouldn't surprise me if the combination of multiple power bricks, noise from the power system, and having the cupboard all open is what broke everything.

Also when I went down to take it apart, I noticed that someone had the microwave on, which is not far away and very effective at causing interference.

At any rate even when I manually tweaked the SNR it kept connecting at the same speed! It wouldn't surprise me if the router was broken and corroded somewhere, as I was forced to store it in the damp garage for at least 3 months over the winter.

So I'm back to the standard router for now, at least stable. Generally annoyed, my other router is obviously duff - or my procedure to try and test it exposed the system to loads of noise and broke everything tongue. *sigh*
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