sudden CRC on DSL line service causing DSL link to go down along with strange PL

Islam Ghunym · January 12, 2020

so I am fed up from my internet lags and all kinds of issues that appears. I contacted my ISP and it confirmed that DSL link down issue is not their problem and I should contact local service to check my line. well, I did so someone came and checked the line and it seems to be connected properly to local box and he tried to use the phone, but I am not sure if what he did is enough. however I am still having very bad experience in online games with Packet Loss all over the place. I also demanded to check the gateway and they confirmed that there was no issue in my gateway. in case you don't know to subscribe to ISP in my country you have to wait until gateways dedicated to that ISP become available, however I don't have knowledge about networks.

all I can provide here is a details from my modem/router ASUS DSL-N14U and info about trace route. maybe some of you can guess where the hell is my problem.

it is not a speed service 512/2048 KB Up/Down, but speed does not matter here and don't suggest changing ISP because I can't.......

Notes:

1- (image 1) recent general log at the time connection lost in case it is needed

2- general log continue

3- a routing table.

4- here is DSL log:

for SNR margin it gets to 35 ( the pic shows 18 db) and goes down to 0 then DSL link down

Line attenuation still always healthy and great

I am using G.dmt modulation as it is better than ADSL2+ when it comes to lines that affects delays and as long as my max speed is far less than attainable rate I should be fine

I have no idea what power stands for in this log

now for the CRC the image shows 0 CRC but sometimes I get CRC detected and connection goes worse and usually when CRC prompted by DSL log I lose DSL connection multiple times in a row before it stabilize at low CRC count then goes 0 again but even if it is 0 now I have much of PL in any online game

5- traceroute to google DNS showing high and varies delays

6-pinging 30 times to google DNS

7- ping plotter reports

now here as you can see in the first there is a PL! between me and my router however that is not possible as I used differnt devices with both wired RJ45 and wireless connection and it still showing that, howver I tried different modedm from D-link and this report still the same

for first hop x.x.x.33 this is my gateway IP and it shows much delays to 800 ms sometimes (570 in image)

after that a bunch of PL reports distributed all the way. however I don't believe that ping plotter is reporting what is actually going on

now I need your genius minds

mynameisjuan · January 12, 2020

CRCs increment are indication of physical line issues and the only way to resolve them is to repair the line or find out what is causing the sudden spike under load.

SNR 35-18 is a clean connection and with a spike of CRC and SNR plummeting below 6db (stable connection threshold) leads me to believe there is one of the following:

1. High power device near the DSL line indoors - check for power cables parallel to the line

2. AM freq interference - This can include AM radio towers, ham radios to handheld walkie talkie type devices that are near by, is there any devices recently installed?

3. Bad termination either where the drop meets your house or inside - especially this time if you are in the northern hemisphere is cold weather will cause the metal to shrink pulling the line away from a direct connection weakening the connection increasing CRCs

4. You just have a bad pair and during load the CRCs are able appear - DSL uses channels for reserve which can not show CRCs until an event

Im going with a bad termination and start there if you can and look for a pattern (time/device). DSL is not a cut and dry problem->answer. It has a lot of educated guess work.

Im not seeing the latency you are mentioning, you to your router is avg 1.0 and now where does it show 570 to your gateway. Also take latency with a grain of salt on low bandwidth DSL connections because it can be saturated just browsing and will cause spikes, its a side affect of having a slow connection.

Alex Atkin UK · January 13, 2020

Quote

I am using G.dmt modulation as it is better than ADSL2+ when it comes to lines that affects delays

That doesn't sound right at all. My line was 2KM with a lot of aluminium and ADSL2+ still was notably better than ADSL1. Most importantly I'd have less latency issues because I had more upstream bandwidth.

Once this problem is fixed, I'd expect to see your line performing far better on 2+ vs 1.

Islam Ghunym · January 13, 2020

5 hours ago, Alex Atkin UK said:

That doesn't sound right at all. My line was 2KM with a lot of aluminium and ADSL2+ still was notably better than ADSL1. Most importantly I'd have less latency issues because I had more upstream bandwidth.

Once this problem is fixed, I'd expect to see your line performing far better on 2+ vs 1.

In case you don't know G.dmt modulation is always better than ADSL2+ if you have low bandwidth.

Mark this down in your memory you may need this info in the future.

Islam Ghunym · January 13, 2020

On 1/12/2020 at 11:13 PM, mynameisjuan said:

CRCs increment are indication of physical line issues and the only way to resolve them is to repair the line or find out what is causing the sudden spike under load.

SNR 35-18 is a clean connection and with a spike of CRC and SNR plummeting below 6db (stable connection threshold) leads me to believe there is one of the following:

1. High power device near the DSL line indoors - check for power cables parallel to the line

2. AM freq interference - This can include AM radio towers, ham radios to handheld walkie talkie type devices that are near by, is there any devices recently installed?

3. Bad termination either where the drop meets your house or inside - especially this time if you are in the northern hemisphere is cold weather will cause the metal to shrink pulling the line away from a direct connection weakening the connection increasing CRCs

4. You just have a bad pair and during load the CRCs are able appear - DSL uses channels for reserve which can not show CRCs until an event

Im going with a bad termination and start there if you can and look for a pattern (time/device). DSL is not a cut and dry problem->answer. It has a lot of educated guess work.

Im not seeing the latency you are mentioning, you to your router is avg 1.0 and now where does it show 570 to your gateway. Also take latency with a grain of salt on low bandwidth DSL connections because it can be saturated just browsing and will cause spikes, its a side affect of having a slow connection.

I will include details about the line:

the line is connected to local box which is near my house and my shop (shop is down and house up) it also rotated around many other line cables.... the lines like a ball of ropes.... but the terminals seems fine.

after that ball of ropes of lines it comes out near a condition fan or under it I should say (old model ones that has fan outside) then it goes beside some metals that forms the shop outside upper shape then it goes inside the shop to the main opening of the building (a whole from the roof to the ground floor and it opens on the basement) usually this whole is wet during winter but that should not do anything to the line then it goes near 2 other RJ45 and 1 12V DC cable near the wall all the way to my modem. I don't know what do you mean by a high powered device. I have been told that DC lines does not effect DSL cable but AC ones do and there is a column of electricity outside near the house but it is 2 or 3 meters away of local box. add to that this problem is still there while electricity cut so no 220 AC anywhere around me. do you think I should change the cable? or remove it then add it again? because I can't do that myself and I have to request service to do so and that will take days if not a month...

the line should not effect the latency, right? Why do you think I have way much of latency to my gateway? latency goes down after that it does not seem logical to me tho.... XD (I mentioned that ping plotter is showing PL to around 50% from my device to modem. if that was real it should not be a good thing at all it is not about the 1 ms.

About latency spikes I am of course performing this while I am sure not even 1 kb is getting used other than just pinging so it is for sure not because of low bandwidth and I can confirm that even 8 mb connection won't make less latency to me. however the latency should be always 67 ms (to google DNS of course not everywhere) if connection is healthy.