Need Advice: ADSL line SNR fluctuations and super frame errors

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RH360

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I have been puzzled the last 2 months about intermittent ADSL speed fluctuations and periods of total data communication loss.

Below is my Dlink 2500U stats right after the last period of reduced speed. Typically I get full line speed on a 2mbps capped account, but for this period of about 45min the speed dropped to 30kB/s down and 15kB/s up.

Untitled.jpg

When the speed drop started the SNR on the downstream was at 11dB. As can be seen above it is now at 18dB and the speed is back to normal. I have also plotted the SNR over a couple of weeks and it varies between as low as 10dB and as high as 21dB. Is this acceptable or even normal behaviour? Could this have the drastic impact on the attainable download speed as observed?

Of more concern is the ratio of Super Frame Errors to Super Frames. Just as the speed drop started the ratio was less than 0.1%, but as can be seen the ratio is now approaching 1%. This was only after about 45 minutes. So clearly the ratio for that 45 minute period was a lot higher than 1%. What impact does these errors have on attainable speed and is this acceptable or even normal?

There are also HEC and OCD errors. I have no idea what these are or if it is important. Any thoughts on this?

During this period of slow speed I did do a continues ping to my ADSL modem and did not see any lost packets or high ping times out of the normal.

I have phoned Telkom before and they did a port reset, but this made no difference.

I just need some confirmation on this forum that there is indeed a problem with my line and that the stats observed on my modem is not normal/acceptable. What do I tell Telkom to come and do. I have the feeling that they will say everything is fine.
 
I have had the same issue, but mostly my line was usable with SNR of 6.0. About two weeks ago my SNR started to fluctuate between anything from 6.0 to only 0.1 and the line would lose sync. Happened every 15 minutes - 30 minutes so I lost it! and logged yet another fault.
(Logged 5 Telkom faults over the last 3 months already most just got closed), Telkom_ZA helped me to get it escallated and the last one made a difference.

Downstream SNR (dB) is now mostly on 6.0 (Full line speed), on occasion drops down to 3.3 (my speed drops to 1/10th of line speed) but al least no more disconnects. Now I only have a bad line 10% of the time. I am also wondering if I should log another fault, or should I be happy paying R480pm + ISP for such a service?

I have been contemplating cancelling and going with a WISP, but I still hope that my area will get VDSL soon
 
The S/N ratio should be as high as possible, with yours being very acceptable.

I have just had a problem similar to yours: however my SNR was hovering around 6.0, which is Telkom's minimum.

The issue was finally resolved by replacing the on-board LAN port with a LAN card. Now I am back to my 10Mb, even with a SNR of 6.0 !
 
Your stats look fine, here's my DSL-2500U on a very stable 8Mbps line:

DSL2500U-stats.png

... SNR down is normally around 11dB, I'm about 2.5km from the exchange.
 
Had a slow period again tonight. The stats below shows 20% Super Frame Errors. What are Super Frame errors and is the percentage an indication of a physical line problem? At one point I spotted the SNR dropping to 9dB, but still above the minimum of 6dB for a stable connection. Could the Super Frame errors be due to a congested exchange. I am on the Welgemoed exchange in Cape Town about 2.5km away.

Capture.PNG
 
Old thread but does not look like anyone gave the answer. Your modem is in ADSL 2 mode, you need to place it in G.dmt mode. Super frame errors will be gone once that is done. Your exchange is not adsl2 or 2+ capable. Only G.Dmt
 
irBosOtter said:
Old thread but does not look like anyone gave the answer. Your modem is in ADSL 2 mode, you need to place it in G.dmt mode. Super frame errors will be gone once that is done. Your exchange is not adsl2 or 2+ capable. Only G.Dmt
Click to expand...

If he can sync with ADSL2+ then his exchange supports it.

PS: SA doesnt use the ADSL2 standard.
 
Rickster said:
If he can sync with ADSL2+ then his exchange supports it.

PS: SA doesnt use the ADSL2 standard.
Click to expand...

Well, exchange I connect to does not support 2 or 2+ but I can still sync on those modes, but when that up speed of 507 comes up and you have super frame errors (if your router shows it like the Dlinks) then you know it's the mode that's not supported on one of the sides. A quick change to G.dmt will make those super frame errors disappear cause the wrong mode on one side is what's causing it...
 
irBosOtter said:
Well, exchange I connect to does not support 2 or 2+ but I can still sync on those modes, but when that up speed of 507 comes up and you have super frame errors (if your router shows it like the Dlinks) then you know it's the mode that's not supported on one of the sides. A quick change to G.dmt will make those super frame errors disappear cause the wrong mode on one side is what's causing it...
Click to expand...

So if you can sync on ADSL2+ and connect to the internet but you have an upload rate of less than 512 what does that mean?
 
irBosOtter said:
Well, exchange I connect to does not support 2 or 2+ but I can still sync on those modes, but when that up speed of 507 comes up and you have super frame errors (if your router shows it like the Dlinks) then you know it's the mode that's not supported on one of the sides. A quick change to G.dmt will make those super frame errors disappear cause the wrong mode on one side is what's causing it...
Click to expand...
Er no. You're completely wrong. It means your SNR is crap and you're trying to run at too high a speed. Switching to G.dmt resolves it because that technology handles longer distances from the exchange better than ADSL2+.
 
Messugga said:
Er no. You're completely wrong. It means your SNR is crap and you're trying to run at too high a speed. Switching to G.dmt resolves it because that technology handles longer distances from the exchange better than ADSL2+.
Click to expand...

Thank you.
 
irBosOtter said:
Old thread but does not look like anyone gave the answer. Your modem is in ADSL 2 mode, you need to place it in G.dmt mode. Super frame errors will be gone once that is done. Your exchange is not adsl2 or 2+ capable. Only G.Dmt
Click to expand...

Thanks for coming to an old thread to post helpful information. I am testing G.dmt mode now. Will report back, but so far no problems. Does this indicate that I have a line problem I should resolve with Telkom? Since the change to G.dmt my SNR down is sitting steady at 23-24dB range.
 
RH360 said:
I have been puzzled the last 2 months about intermittent ADSL speed fluctuations and periods of total data communication loss.

Below is my Dlink 2500U stats right after the last period of reduced speed. Typically I get full line speed on a 2mbps capped account, but for this period of about 45min the speed dropped to 30kB/s down and 15kB/s up.

View attachment 121021

When the speed drop started the SNR on the downstream was at 11dB. As can be seen above it is now at 18dB and the speed is back to normal. I have also plotted the SNR over a couple of weeks and it varies between as low as 10dB and as high as 21dB. Is this acceptable or even normal behaviour? Could this have the drastic impact on the attainable download speed as observed?

Of more concern is the ratio of Super Frame Errors to Super Frames. Just as the speed drop started the ratio was less than 0.1%, but as can be seen the ratio is now approaching 1%. This was only after about 45 minutes. So clearly the ratio for that 45 minute period was a lot higher than 1%. What impact does these errors have on attainable speed and is this acceptable or even normal?

There are also HEC and OCD errors. I have no idea what these are or if it is important. Any thoughts on this?

During this period of slow speed I did do a continues ping to my ADSL modem and did not see any lost packets or high ping times out of the normal.

I have phoned Telkom before and they did a port reset, but this made no difference.

I just need some confirmation on this forum that there is indeed a problem with my line and that the stats observed on my modem is not normal/acceptable. What do I tell Telkom to come and do. I have the feeling that they will say everything is fine.
Click to expand...

Following up on my first post. As suggested I changed the mode to G.Dmt and had no problems for a while, but recently I have started to have the same problems again.

About once a day now the internet speed will get really slow down to about 10-20kB/s. Inspecting the ADSL stats shows that the Super Frame Errors number is increasing rapidly. Ping times to sites indicate packet loss. After rebooting the ADSL modem everything is back to normal.

Tested with an older Netgear modem and seeing the same symptoms. Could this just be a case of two faulty modems, or is it my line?

How can I test my line and what do I ask Telkom to do/test?
 
Rickster said:
I would like to change this statement, some exchanges do support (or have enabled) ADSL2.
Click to expand...

Please don't derail my thread. My post repeated for visibility:

Following up on my first post. As suggested I changed the mode to G.Dmt and had no problems for a while, but recently I have started to have the same problems again.

About once a day now the internet speed will get really slow down to about 10-20kB/s. Inspecting the ADSL stats shows that the Super Frame Errors number is increasing rapidly. Ping times to sites indicate packet loss. After rebooting the ADSL modem everything is back to normal.

Tested with an older Netgear modem and seeing the same symptoms. Could this just be a case of two faulty modems, or is it my line?

How can I test my line and what do I ask Telkom to do/test?
 
I would change all RJ-11 cables (short as possible) and filters, if that doesnt work call Telkom.
 
What am I suppose to tell Telkom? This is happening randomly every day.
 
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