Some advice please

Evening guys 'n' gals,

I have read on these forums in the past that you can adjust the noise margin with a piece of software to gain extra speed/sync. Could somebody please advise on how I can do this or point me in the direction I can read up on?

I have the Sky D-Link Router and my Line Stats are below;


ADSL Link Downstream Upstream

Connection Speed 16378 kbps 958 kbps
Line Attenuation 21.5db 10.2db
Noise Margin 7.2db 7.5db

Many thanks in advance, if it's not worth doing based on the above information then please let me know. My Upload seems to be low to me or is the upload speed as good as I am likely to get based on my line stats?

Thanks again and I appreciate any help you can offer

Have you requested the Gaming profile?

Jump into the test socket or get a filtered faceplate.

Yup. Gaming profile all activated...

What difference would a filtered faceplate do?

Can and is it worth changing the Noise Margin ?

Many thanks in advance....

My line with 22dB (19dB ADSL1) attenuation synced at just under 17000 without tweaks, and will hit 19999 if I lower the margin using Mel's password finder app...search for it on Skyuser, you'll need it to get your DSL password to use a router to make this change more permanent.

My DG834v4 and DGN2000 sync at this speed but with a lower margin than the supplied D-Link, presumably due to the fact that the Sky router has a BCM6358 chipset whereas the Netgear's have the older BCM6348.

Expect to see more errored seconds and crc errors as you push the margin below 3dB, which Sky may or may not count and use against you later, and may or may not decrease throughput or cause packet loss. Very much line dependant.

Edited by LadFromWales85 (Fri 04-Feb-11 01:30:35)

Many thanks, I think I will leave as it is. It seems as if my upload is quite low, is it?

Not really much difference between yours and mine and you won't get much higher than that on Sky.

ADSL Link Downstream Upstream
Connection Speed 17695 kbps 1142 kbps
Line Attenuation 20.0db 11.6db
Noise Margin 6.9db 8.1db

Edited by Finguz (Fri 04-Feb-11 12:11:30)

I have a 25dB line and get almost 19meg sync with the default 7dB margain.

Ok ... ?

It is a tad on the low side for that length of line, but not much can really be done about that and difference would be minimal. If you telnet through your router you can see the max speed attainable for your line.

In reply to a post by shaneosborne:

Many thanks, I think I will leave as it is. It seems as if my upload is quite low, is it?

You may find your upstream sync faster if you lower your SNRm with Mel's Password Extractor, even though it's only meant to effect downstream.

I synced with a 1150 upstream at default SNRm and when pushing it down, but I had an 18dB SNRm upstream at 832 on ADSL1. At least on the kit at my exchange, 1150 is the max upstream sync possible as the margin is 10dB and DMT.Tool reports 100% attainable.

BuckleZ appears to have a high quality line, although longer than yours, has less noise, and as such, hits 19000 without pushing the margin down. I can sync at default margin at 18000 if I do it early morning when the noise is lower. While I see a margin as low as 1.8dB when syncing at 19999, BuckleZ probably doesn't drop below 3dB, despite his line being longer.

How can you Telnet into your router?

I think I will stay put on my connection, I don't think it's worth playing around for such little gain tbh.

Thanks for all your input people.....

This is Mel's stuff: http://pathogenrush.blogspot.com/2010/10/dsl-2640s-p...

Many thanks, i've had a look and downloaded the software program.

Can the SNR be changed on the Sky Router and if so, how do I change it?

If I select say -1 will that lower the margin and by how much? Also, what is the default margin on the Sky D-Link?

A little confused

Thanks all for your assistance so far

In reply to a post by shaneosborne:

Many thanks, i've had a look and downloaded the software program.

Can the SNR be changed on the Sky Router and if so, how do I change it?

It says here on that website

V1.5 Added an option for those that want to tweak the snr margin (or execute any shell command) - enable "advanced" in the options menu to use it, but if you've just joined, then do not fiddle with the snr margin before the 10 day DLM process is over as it will affect the DLM process, and likely result in your connection speed being limited below what you're line is capable of. It will now also check the current directory for utelnetd and enable the Telnet button if it is found. If you need telnet access a suitable daemon can be found here http://rapidshare.com/files/428158541/utelnetd

V1.6 Improved the noise margin tweaking options. Note that the noise margin dB adjustments shown on the slider are only approximate, and adjustments of more than -6db might not work with this router's xdslctl command.

Okie dokie, still don't kow what I should move the SNR Slider too.

I/ve set it to -1 to see what happens but once I quit the program and reload it seems to go back to 0

What should I try to set the SNR Slider to? Line stats below;

ADSL Link Downstream Upstream
Connection Speed 16378 kbps 948 kbps
Line Attenuation 21.5db 10.2db
Noise Margin 7.4db 8.0db

The program says Max line rate as: 19492 1112

Sorry, I don't know as I'm on BE

I know the program has lots of support in the skyuser forums. Good luck.
http://www.skyuser.co.uk/forum/extracting-sky-router...

When you bring up the advanced option and a command is added in the box, change the 100 to 20, which will aim to sync with 20% of the default margin, being 7, resulting in 1.4dB, though it always ends up being higher than this, and there is a sync cap as Sky won't let you sync above 19999.

It requires some trial and error, but I started at 20...eventually just chucked in 1 as the line is stable at 19999/1150.

The slider just sets the correct value for the xdslctl --snr command, which overrides the target noise margin set by sky, you need to click the execute button for it to resync with the modified margin.

If you want to tweak the noise margin, I would suggest starting with -2 or -3 dB. -2dB should make the router sync with a noise margin of about 5dB, as Sky set a target noise margin of 7db on their LLU connections. (on Sky connect the target margin can be as high as 15 dB).

If you reduce the noise margin by too much you'll start clocking up CRC errors, which you can check for in the detailed stats. You should also bare in mind that the noise margin will drop down at least a little in the evening (unless you've got an exceptional line), so you need to allow for that. You want the noise margin to remain positive throughout the day.

Edited by AbandonShip (Sun 06-Feb-11 11:31:07)

Many thanks guys ....

I've changed the SNR as advised yet the router still shows the same SNR as before, does it take a while for this to show or should the SNR change as soon as the new value is applied?

ADSL Link Downstream Upstream
Line Attenuation 21.5db 10.2db
Noise Margin 7.5db 8.0db

The SNR values have remained the same and this values stay the same throughout the day and night with very little change (-0.1 / +0.1).

Many thanks in advance

Apparently the hack won't work much longer anyway, as there's a firmware update out for the dsl-2640s, which has fixed the hole.

Grrrrrrrrrreat!

Thanks for your assistance......

In reply to a post by AbandonShip:

Apparently the hack won't work much longer anyway, as there's a firmware update out for the dsl-2640s, which has fixed the hole.

Is there a way to dump the current firmware before we lose root access?

Also, is there anyway of forcing a firmware downgrade? I know there are ways around this with other hardware and firmware but has anyone any knowledge on this particular issue?

Many thanks in advance.....

You could try the following, taken from here

It's for a 2740B but will probably work.

Instructions:

1) Turn off the router, then holding in the reset button on the rear, turn the D-Link back on while keeping the reset button held in, after around 30 seconds the power light goes red.

2) On your computer change the network properties to an IP address of 192.168.1.99 and subnet 255.255.255.0.

3) Open a browser and go to 192.168.1.1, you now see the firmware recovery page.

Edited by Finguz (Mon 14-Feb-11 19:17:50)

It should be possible using the cd supplied with the router, which should contain a dlink recovery utility and original firmware, unless they've done something to prevent downgrading.

However, the router would automatically update again, unless you execute "killall upgrader" before plugging it into the phone line, and you'd need to do that every time you reboot, so it wouldn't be very practical.

Edited by AbandonShip (Tue 15-Feb-11 13:52:55)