naschenweng.info

In a previous post I explained the significance of SNR and attenuation for ADSL lines.

I have spent now a significant amount of time to write scripts to retrieve the ADSL-statistics for my Netgear DG834v4 ADSL router. The script will equally work on any Broadcom based modem-router which allows access to telnet and supports the command "adslctl".

The solution is really simple and consists of one perl-script collating the information and a CGI-script which then produces the stats in real time from your webserver:

I have deployed the solution on my Synology DiskStation DS107+ (FW722) and had the solution running now for a day. If you want to run this on the Synology, you will need to install rrdtool via ipkg. If you want to run it on another Linux-based environment, ensure that you have access to the command-line version of rrdtool and rrdcgi (which comes bundled with rrdtool).

My current setup produces stats every 15 minutes and reports on the following stats:

• Ping statistics. Currently against my local ISP - saix.net, but scripts are easy to modify to include your own pings
• ADSL signal to noise ratio (up / down)
• ADSL attenuation (up / down)
• Power output (up / down)
• Maximum ADSL data rate (up / down)
• ADSL sync speed (up / down)

All stats are reported per hour, day, week and month. In the future I want to enhance the scripts to provide additional useful reports for the Netgear DG834.

By now you are probably asking "Where is the download-link?" --- well here is the thing, my hosting and the popularity of this site is starting to cost me a bundle. So I am introducing donation-ware. It is up to you to decide if you want to donate USD 1,00 or a million (yeah baby) using PayPal via the donation-button below. The donation is absolutely save and you will receive the download-link automatically via email (link is valid for 24 hours). Further, I will email you any updates to the scripts and will look at implementing any recommendations you have.

I think this sounds like a fair deal, especially since it took me in access of 60 hours just getting those scripts done (don't get a fright though - the scripts are simple - that's the beauty of the solution).

If you want to use the scripts, donate below (you require a running version of Perl with Net::Telnet and Net::Ping, rrdtool -- the scripts will run on the Synology out of the box).

As an ADSL n00b I wanted to understand how the technology works and how to get the most out of it. In essence if you want to improve speed and increase stability you need to familiarise yourself with SNR (signal to noise ratio) and attenuation. Many ADSL-routers will provide you with those stats.

SNR or Signal to Noise Ratio:
Describes the ratio of usable data-signals on your line. You can associate the "signal" with the data traveling across your ADSL-line and the "noise" as the unwanted interference affecting the signal. The higher the number the better for this measurement. In some instances interleaving can help raise the noise margin to an acceptable level.

6dB or below is bad and will experience no synch or intermittent synch problems
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with little or no synch problems
20dB-28dB is excellent
29dB or above is outstanding

If your SNR is below 12dB you are pretty much screwed and will not get a consistent level of ADSL-service. You could try to convince Telkom to rewire the cabling - but this is unlikely to happen.

Attenuation:
Is the reduction in signal strength on your phone line. In ADSL this may be reported as "loop loss" and is the natural deterioration of the ADSL signal over distance from the exchange. Attenuation is normally directly linked to the length of your line. Copper is traditionally used in the local loop and the higher gauge of copper will give the best signal, however some lines may have some aluminium or aluminium joints on the line which will increase resistance... as will oxidisation of joints. The lower the dB the better for this measurement.

20dB and below is outstanding
20dB-30dB is excellent
30dB-40dB is very good
40dB-50dB is good
50dB-60dB is poor and may experience connectivity issues
60dB or above is bad and will experience connectivity issues

The standard signal attenuation spread for a given speed is somewhere in the region of 25-30dB for ADSL1 speeds (if we had ADSL2/2+ this would be).

The following guide (distance vs. attenuation vs speed) gives you an guestimate what you can achieve:
<1km should be 23-24Mbit (nice speed, but doesn't it bug you that Telkom people walk through your bedroom?)
1.0km = 13.81dB = 23Mbit
1.5km = 20.7dB = 21Mbit
2.0km = 27.6dB = 18Mbit
2.5km = 34.5dB = 13Mbit
3.0km = 41.4dB = 8Mbit
3.5km = 48.3dB = 6Mbit
4.0km = 56dB = 4Mbit
4.5km = 62.1dB = 3Mbit
5.0km = 69dB = 2Mbit
>5.0km (you are pretty much poked --- sorry for you)

You will not be able to fix attenuation (unless you relocate straight next to the exchange). You will however be able to influence Telkom or your ISPs - use tooling such as MRTG to measure your variances and log incidents against them. It is unlikely that they will move the exchange closer, but you could combat SNR (check your wiring, climb into the manhole and see if your underground wire is of the cheap kind etc).

I decided to abort my Telkom-science project in the pursuit of getting broadband. Although I had an existing IBurst connection, I thought it would be most patriotic to use our nations broadband service provider. It is just a pity that Telkom does broadband really badly and half of their service-staff and installation teams seem to have no clue what is going on or how to provide customer service.

It is now 64 days after I applied and during that time Telkom did not (as promised) phone me to arrange an installation date. I have now decided to cancel my line installation and stick with IBurst - at least they could provide me with broadband service within 2 hours.

Find the history of this ordeal below:
2008-01-19: Allocated telephone number. Was told that line will be installed within 21 days.
2008-01-29: Phoned for status. Was told installation only available on 28th Feb. Asked to get higher priority.
2008-01-31: Phoned for status. Still end of February.
2008-02-05: Phoned for status. Contact number was missing. Install date 27th Feb. Complex seems to run on optic fibre, might require conversion fee. Spoke to Johann/Springs
2008-02-21: Phoned for status. Installation still on 27th Feb.
2008-02-27: Telkom installation team arrived un-announced. Installation team did not want to wait for 30 minutes and left.
Spoke to Andries (technician 082 373 7586) to arrange for installation on Saturday 1st March.
2008-03-01: Technician did not arrive. Spoke to 10219 and was told that installation will happen on 8th March. Phoned Andries and was told that he is on leave.
2008-03-05: Spoke to 10219 and reconfirmed that installation is on 8th March. Also confirmed that line will support ADSL. (Not given an answer, this can only be established once the line is installed)
2008-03-08: (8:30) Phoned to confirm installation for today. Engineer arrived at 9:00am – no line installed since he did not bring cabling. Got phone-call at 15:30 from head-office that engineer got denied access – confirmed with guardhouse and no-one from Telkom arrived.
2008-03-11: Spoke Johann/Springs and he will follow up.
2008-03-18: Spoke to Leon - still have not received any notification that cabling will be pulled through. Has been escalated as very important – will receive feedback within 4 hours.
2008-03-20: (12:25) Spoke to Mkangeli. Was told that this will be escalated again and I should receive a phone call with order installation by COB.

Trying to get decent (and cheap) broadband in South Africa is like finding a virgin in a brothel. Mobile and wirless technologies are good but the latency associated with such service is unbearable when playing games online. If you have ever attemped playing COD4 against international players you will know what I mean.

So it is the most patriotic thing to do, and choose the national carrier: Telkom - this was my first mistake.

Having moved into a new house, for whatever bizarre reason, I can not not have ADSL installed right away. I need to first have a phone line installed, and once this is done can I apply for ADSL. For another bizarre reason, Telkom is only able to tell me if I will get ADSL for certain once that line is installed.

Telkom staff expect you to remain at home waiting for them, if they choose to pitch up to install a line. So it is more than natural to expect that if you specify that you're not at home and need to be called when their technician comes out, surely they should call when their technician comes out? NO.

IS TELKOM BREAKING THE LAW? - apparently so: ICASA published its ADSL regulations in August 2006, calling for – among other things – the installation of an ADSL service within 30 working days. It has now been more than 30 working days (since initial application on 19th January) to just get a telephone line installed.

The installation date given by Telkom translates into 30 to 40 working days – clearly in contravention of ICASA’s ADSL regulations. This may however not be the only regulation which Telkom is in contravention of. The ADSL regulations prohibit port prioritization – something which is still part and parcel of Telkom’s standard ADSL offering.

If you happen to choose an ISP other than Telkom you get further penalised by not getting the prompt service of having an ADSL port allocated to you (this would be bad, Telkom can certainly not give the same customer service to the competition).

Needless to say - I am still without a telephone line and will probably have another 4-6 weeks waiting time to have ADSL access installed - in short it is quicker to go and visit the Northpole: