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[waltergmw]

Hello everybody,

I'm posting the following to give hope to some of those in severe difficulties and also to see if anyone can comment upon the use of filters in these circumstances.
However you do need to dedicate quite some effort and patience to achieve a result and it relies on an ISP who is prepared to be as insistent as you are.
In my opinion Zen have been outstanding with this one just as they usually are.

This fault was raised by Zen on 17th July 2009 on a line with an estimated length of 6913 metres possibly with some aluminium sections. The line is still registering a possible metallic bearer fault and is achieveing quite remarkable results. Like all such lines it registers the downstream attenuation as 63 dB but the 2Wire modem records the actual attenuation as 83.4 dB @ 300 kHz.

http://www.thinkbroadband.com/speedtest/results/id/125101716529598961.html gives 327 kbps down and 345 kbps up.

BT speed test says DSL connection down & up as both 416 kbps, IP profile FOR THE VERY FIRST TIME EVER THIS A.M. as 350 kbps but the IP throughput achieved as only 167 kbps.
(There is obviously a significant difference between how BT and TBB calculate their figures.)

The following screen shots illustrate the performance in more detail.
Note that the DSL unavailable time in the detailed stats picture includes 33 seconds of re-boot time and the final entry on the training history a is "Time now" rather than the time of a re-train.
The questions I have are:-

1.   Is there any modem parameter (or better firmware) I could try changing to improve the performance?

2.  Looking at the bit loading diagram would a RF3 filter or similar provide better performance or would the increased attenuation it causes defeat the purpose ?

http://www.scribd.com/doc/19011287/System-Firmware-Config-45
http://www.scribd.com/doc/19011308/Stats-46
http://www.scribd.com/doc/19011321/Detailed-Stats-47
http://www.scribd.com/doc/19011324/Training-Hist-a-48
http://www.scribd.com/doc/19011330/Training-Hist-b-49
http://www.scribd.com/doc/19011336/Bit-Loading-50

Kind regards,
Walter

[Ezzer]

83db  your lucky to have sync at alland would be better of ona fixed 0.5mb service.definately sound like ali along your route unlikely an rf3 would make any difference

[waltergmw]

Thanks Ezzer,

Can you tell me what happens if a fixed speed configuration discovers a lowering sync. rate and is there a point where it just goes into sulk mode and shuts down?

Kind regards,
Walter

[orainsear]

1.   Is there any modem parameter (or better firmware) I could try changing to improve the performance?

The serial number indicates that the modem that you have is one of the earlier models (single SSID) and is compatible with all the available firmwares.  That being said I think that the main benefits of alternative firmwares (SBC, Singtel) are with the ability to increase the wireless output power.  I'm not really sure if upgrading to BT v5 firmware would make any difference to the ADSL side of things.

The modem is definitely a good device, seems well built with a Faraday cage in it's structure and has plenty of DSL parameters to monitor, however it really doesn't seem to be at all tweakable which is a real shame.

There's a lot more about the modem and a comparison table of the various firmwares at the bottom of this page.

[waltergmw]

Thanks Orainsear,

I've used these modems in a number of difficult places as they do seem remarkably good.
It's a shame 2Wire don't offer standard end-user firmware ones on the open market.
There's certainly plenty of data to grapple with.
Given the state of a lot of the lines, I'm usually content with letting sleeping dogs lie.
My main concern is to eradicate the BT configured interconnections and to stop BT auto-upgrading the firmware, especially with the 3 dual SSID version 5 firmware ones I've just bought.

Kind regards,
Walter

[Drefsab]

Hi Walter, as Ezzer suggested the line may be happier on a fixed rate 512k profile, the risk in this is that with fixed rate if the signal strengh is not enough to attain the 512k sync the line will sit there trying to train until it can get sync. Its certainly worth a try but I would warn the customer that doing so could mean some downtime if it does not go as well as we would hope.

[waltergmw]

Thanks Aaron,

Does anybody know what the minimum parameters are required to achieve a fixed 512 profile?

I've just done a BT speed test with up and down sync speeds of 416 kbps, an IP profile of 250 kbps which I'm expecting to increase to 350 kbps in a day or so and an actual throughput of only 176 kbps.
That's why I'm a little apprehensive.

The current modem params are shown below.
Kind regards,
Walter




[attachment deleted by admin]

[Drefsab]

Its not really a problem to get BT to put it on a fixed rate 512k profile, and with the current stats it should sync, its more a question of how long it will hold it. If you want to try it by all means let me know and I will get it applied.

[waltergmw]

Hi again Aaron,

When it drops and is on a fixed rate, would it keep trying to re-connect or does it need a manual re-boot or power fail ?

You'll see it dropped the connection at 10:04:20 today are recovered at 10:04:38 at 384 kbps.

I'm sending you an e-mail with the detailed log.

Kind regards,
Walter

[Ezzer]

It should always try and retrain for sync regardless of the type of dsl service

[waltergmw]

@ Ezzer - Thanks for the advice. Your next job is to wave a magic wand and eliminate all aluminium cabling from the whole of the UK !!!

@ Drefsab - Assuming that we should get a more stable connection, which would recover immediately after a drop as the one this morning, without the limiting effect of the IP profile drop from 350 to 250 kbps. Thus the fixed rate seems the better option. If the end users notice a poor sync rate they can always do a power-reset around lunchtime to try to increase the sync rate again. So, yes please let's try a fixed 512 rate.

Kind regards,
Walter

[waltergmw]

Hi everybody,

It appears that selecting a capped rate on this poorly performing and very long line has had a significant benefit, though at the expense of some upstream speed.
All speeds are in kbps.
However the major advantage is that the line is now remaining stable and has not retrained for 4 days so far.

TBB Speeds before after down then up
233 346  467 215

BT (old) speed test 163 down, IP profile 250 sync rates 448 down 416 up
BT (new) speedtest 457 down

2wire data before  after

Current rate down up 384 416 576 288
Max rate down up 384 428 900 440
Current noise margin down up 12.0 dB 7.0 dB 7.0 dB 11.0 dB

Kind regards
Walter