Losing sync in JHB (Sandton)

A few nights every now and then my ADSL line is losing sync.

I've had this connection for over a year without any problms at all, but since a few weeks ago I'm getting this intermittent loss of sync.

It seems to be happening more and more, and it is beggining to p!ss me off, it screws up everything that I'm trying to get done.

Usually it occurs between about 20:00 - 23:00.

Is anyone else around Sandton having problems?

What is the likely cause of losing sync? (As far as I'm concerend my hardware is fine, my PCs are fine, and the problem is Telkom screwing around or having problems, nothing on my side has changed at all anyway.)

Are they "fixing" something, installing new lines or what?

I'm going to report a fault as well.

BTW I'm using Telkom's ISP, as well as Axxess prepaid. Using a ZyXel P-2602HWL router, but like I said I'm 100% that my hardware is all good.

What are your line statistics?

What exactly do you mean by line statistics?

noise margin upstream: 24 db
output power downstream: -3 db
attenuation upstream: 25 db

noise margin downstream: 19 db
output power upstream: 0 db
attenuation downstream: 40 db

(Have never really looked at this before, don't know if it's all the required info?)

Pinging 196.25.1.200 with 32 bytes of data:

Reply from 196.25.1.200: bytes=32 time=43ms TTL=251
Reply from 196.25.1.200: bytes=32 time=41ms TTL=251
Reply from 196.25.1.200: bytes=32 time=43ms TTL=251
Reply from 196.25.1.200: bytes=32 time=43ms TTL=251

Ping statistics for 196.25.1.200:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 41ms, Maximum = 43ms, Average = 42ms

Pinging 41.203.17.1 with 32 bytes of data:

Reply from 41.203.17.1: bytes=32 time=24ms TTL=57
Reply from 41.203.17.1: bytes=32 time=23ms TTL=57
Reply from 41.203.17.1: bytes=32 time=21ms TTL=57
Reply from 41.203.17.1: bytes=32 time=24ms TTL=57

Ping statistics for 41.203.17.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 21ms, Maximum = 24ms, Average = 23ms

Pinging 212.58.224.131 with 32 bytes of data:

Reply from 212.58.224.131: bytes=32 time=371ms TTL=117
Reply from 212.58.224.131: bytes=32 time=349ms TTL=117
Reply from 212.58.224.131: bytes=32 time=350ms TTL=117
Reply from 212.58.224.131: bytes=32 time=349ms TTL=117

Ping statistics for 212.58.224.131:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 349ms, Maximum = 371ms, Average = 354ms

Stats from a few minutes later after another desync;

noise margin upstream: 22 db
output power downstream: 2 db
attenuation upstream: 25 db

noise margin downstream: 25 db
output power upstream: 0 db
attenuation downstream: 39 db

You got it - line statistics are the noise margin and attenuation figures. Your figures seem okay, except for the fact that they change after losing synch. I'm not sure what the 'output power' figure means, but that may be your issue because my output power is 8.3dBm and 6.3dBm for downstream and upstream respectively (although dBm vs. dB may be different...)

Has your line's speed been affected (e.g. everything is slower than it used to be)?

Sorry, can't offer any help - log it with Telkom and let us know what they say. Maybe also try and monitor your line statistics on days where you DON'T lose synch, and compare them to days where you do.

Good luck.

Cool wasn't sure if I had all relevant info 'cos I've seen others post more info for line stats, AFAIK so far my line speed hasn't been affected.

Looking at those figures that you posted it seems that your downstream noise margin is between 19dB and 25dB - this is fine if it stays in this range but the fluctuations may be a lot larger. You need to monitor this figure over a period of several hours right up until you lose synchronisation using routerstats and then post the graph.
http://www.vwlowen.co.uk/internet/files.htm
What is your current linespeed? The low output power figures would suggest that it is quite low i.e. 384 or 512K?

The Zyxel P2602 (TI AR7 chipset) can also provide bits per tone data from one of the menus. Can you post this data (tone 0- 31: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00, tone 32- 63: 00 24 57 77 89 99 9a bb bb bb cc dd dd dd dd dd etc.) as well as any information about the number of far/near FEC/CRC/HEC errors etc. (you can get this info from the Zyxmon line quality tab if necessary). You could also do some high quality bits per tone plots using either Zyxmon or OrbMT (choose a TI AR7 based router if necessary) to see whether or not noise is affecting any of the frequency bands that the router would normally use.
http://zyxmon.streamclub.ru/settingse.php
http://zyxmon.streamclub.ru/newse.php

http://blog.orbmu2k.de/tools/orbmt-modem-tool-sidebar-gadget/

I an in the Nothwold area and have the same problem, had it for three weeks and have taken about 10 years off my life dealing with Telkom on the issue, this is how it has progressed;

Had my line for about two years, have always been able to sync at 4096 and have always had a pretty much perfect connection.

About three weeks ago I stsrted to experience resyncs, frequently, some connects would last 1 hour some 10 minutes. I started off replacing all microfilters, handsets and router. Problem persists.

Started with Telkom, two weeks later and they had dropped my maximum sync speed to 1024 "to test", installed new cables throughout my house. very slight improvement.

Another week later and they have traced my line all the way back to the exchange, box by box and made some changes on the dslam ???? whatever that is and I have now been connected for 22 hrs, still at 1 mb.

Some stats:

When I first found the problem -

SNR down = 6 SNR up = 9
Attenuatuion down = 54 up = 30

After replacing all the devices and copper in my house;

SNR down = 12 SNR up = 7
Attenuatuion down = 54.5 up = 30.5

After tracing cable back to the exchange and making changes on the dslam and still at 1024 sync speed.

SNR down = 24.5 up = 6
Attenuation down = 54.5 up = 30.5

Speed tests have been consistant with sync speed when I was at 4096 and now that I am at 1024. if the connection stays stable at 1024 for another day I will have the max sync speed pushed up again.

Any comments would be appreciated, this 1024 connection is not working for me and will have to be increadsd again just not sure whatthe impact will be.

Drastik said:

I an in the Nothwold area and have the same problem, had it for three weeks and have taken about 10 years off my life dealing with Telkom on the issue, this is how it has progressed;

Had my line for about two years, have always been able to sync at 4096 and have always had a pretty much perfect connection.

About three weeks ago I stsrted to experience resyncs, frequently, some connects would last 1 hour some 10 minutes. I started off replacing all microfilters, handsets and router. Problem persists.

Started with Telkom, two weeks later and they had dropped my maximum sync speed to 1024 "to test", installed new cables throughout my house. very slight improvement.

Another week later and they have traced my line all the way back to the exchange, box by box and made some changes on the dslam ???? whatever that is and I have now been connected for 22 hrs, still at 1 mb.

Some stats:

When I first found the problem -

SNR down = 6 SNR up = 9
Attenuatuion down = 54 up = 30

After replacing all the devices and copper in my house;

SNR down = 12 SNR up = 7
Attenuatuion down = 54.5 up = 30.5

After tracing cable back to the exchange and making changes on the dslam and still at 1024 sync speed.

SNR down = 24.5 up = 6
Attenuation down = 54.5 up = 30.5

Speed tests have been consistant with sync speed when I was at 4096 and now that I am at 1024. if the connection stays stable at 1024 for another day I will have the max sync speed pushed up again.

Any comments would be appreciated, this 1024 connection is not working for me and will have to be increadsd again just not sure whatthe impact will be.

Click to expand...

Same problem here with me. Moved into a new place and had my 4Mb line activated. Was fine for the first week and then all my syncing issues started. Mostly happens at night where I can't maintain a connection for more than a minute and then eventually my router will sync at much lower speeds and the connection will hold. But on other days, the router will sync at 4Mb and stay rock solid throughout the day.

I had 2 techies come out to replace the jack + untangle the messy cabling but the problem is still there.

I'm gonna PM rpm about this and see if he'll publish an article about this because it is definitely NOT an isolated incident and it seems that there's a thread a day about sync issues.

Okay here's some graphs that I collected, http://mybroadband.co.za/vb/album.php?albumid=160.

I started the program during a time of major instability, you can see it's going crazy, lots and lots of connection drops there.

They're all uploaded in order BTW, but they aren't one long session, after I had been running it for some time, it bombed out saying "out of memory" and I had to exit and restart the program, also left it over night and it had crashed by the morning when I checked.

I wondered if that's because of a problem with the "lite" version of the program, I'll try the normal one and see if it's different.

What would be considered a good sampling interval? At first I left the default of 15secs, but I changed it to every 5 so I could get more accuracy.

There's a period in the graphs where RS was only registering totally flat 15db, without change, but it was not working properly for some reason, I checked the router's built-in stats and it was different at those times, like 25 or so.

Today it seems to have been a lot more stable, at least I have not experienced any disconnects tonight, you can see some fluctuation in the graphs from today, but no drops right down.

My line speed is 384kbps.

Downloaded that Zyxmon thing, but I don't really know what I should be doing with it? Will try to figure it out soon.

The bits per tone data from my router's stats page;

noise margin upstream: 25 db
output power downstream: -4 db
attenuation upstream: 24 db
tone 0- 31: 00 00 00 00 00 22 23 44 44 44 43 32 22 22 00 00
tone 32- 63: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 64- 95: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 96-127: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 128-159: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 160-191: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 192-223: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 224-255: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 256-287: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 288-319: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 320-351: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 352-383: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 384-415: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 416-447: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 448-479: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 480-511: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
noise margin downstream: 18 db
output power upstream: 0 db
attenuation downstream: 39 db
tone 0- 31: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 32- 63: 00 00 00 22 33 33 33 43 23 44 04 43 34 32 22 00
tone 64- 95: 02 20 22 22 23 23 32 22 20 02 22 22 22 22 20 20
tone 96-127: 00 02 02 22 02 20 00 00 00 00 00 00 00 00 00 00
tone 128-159: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 160-191: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 192-223: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 224-255: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 256-287: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 288-319: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 320-351: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 352-383: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 384-415: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 416-447: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 448-479: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 480-511: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

All for that article, I have noticed other threads that mention these problems, seems like an utter nightmare to fix and if it is commonplace, there must be something very wrong here.

Apparently we recieved an email from Telkom ~month ago that said they were doing work on the lines or something, could they have changed something that could be a cause of this? Would more people being connected in the same area affect it or something?

You definitely do have a problem! If your line was working reliably in the past then I don't think that the problem will be so difficult to repair. If it has never worked reliably before then it might be much more involved. You should now be able to monitor any repairs that Telkom does using Routerstats and Zyxmon (for FEC/CRC/HEC errors).

Your best option is probably to call Telkom at a convenient time and ask them to do a proper line test (LTS) to see if any immediate problems can be detected.

There is some information below that Leftfoot and Dosti posted a while back on how to do this and how to analyse the results from the test. You also mentioned that Telkom has been working on the cables in your area? Would this be the E-side underground cables from the exchange to the street distribution cabinet? If this is the case then it might be an idea to ask them to switch the pair of wires from the exchange to the SDC to see whether or not this fixes the problem.

[Oupa]MrNutz had many months of repeated problems with his line before Telkom finally dispatched the correct technicians to repair and replace sections of his line. He advises that you make sure that the technicians arrive with the correct ADSL test gear - Sunrise Sunset (black unit) and the Dynatel 965p (yellow unit).

I would print out those graphs from routerstats to show to the technician if he needs to visit your residence to fix the fault.

Let us know how things progress!

OK.....as an ex Telkom technician I can tell you the following:

If your DSL modem disconnects (or loses sync) on a regular basis....insist on a line test......in fact insist on the results of that line test (even though it might not make any sense)

Most modern cables in Telkom are PVC but can be influenced by moisture or other systems that carry higher voltages.

The test should reflect:
-absolutely no Earth potential
-no more than 12v contact (foreign -ve)
-also watch out for how many phones are connect to your line at any stage - The more phones, the higher the line capacitance.....the easier it it for your modem to lose sync by not understanding the incomming carrier signal.

I too have a 4meg line and had frequent disconnects at a stage.....insisted on a line test (through the supervisor as the "Kelly personel" operator insisted that because I could browse the net all was Cool)......The test result showed a -38v contact that went to -49v when it rained. note: Audibly I could not hear any problem during normal conversation......somtimes you can here a slight "cross-line" with this type of condition.

A line fault was reported and a spare pair of wires was used to bypass the fault......then the "Kelly personel" chic phoned me back to write the fault off.....once again....insist on the results of a second test....if all is clear then allow them to write the fault off

These people are stats driven.....so its important not to allow them to write the fault off if it is not clear.....you will get higher priority on the system a more people will try to resolve your problem

Incidently.....The testing system (LTS) CANNOT perform a test while you are talking on the line, they have to tell you to put the phone down then ring you back with the results.

Hope this is of help to you guys!


Good chance that if you had a lightning strike on the line that there will be problems elsewhere ie. other lightning protection on phones/faxes etc, poles or the exchange itself degraded. Insulation in cables blown through and perhap touching a tree. "Kelly temps" at Telkom do the line testing most of the time and they ignore some fault conditions. Its a time consuming exercise that they dont like to do on the LTS system. A telkom line test should be no worse that these limits:

Foreign earth - 10M? (line touching the greater mass of the earth through trees, wet soil, nests etc)
Foreign contact or negative (-ve) - <12v (line touching another line through low insulation, dampness, etc.
Line capacitance - more that 8µF on the line indicates too many phones and as such has been known to weaken analogue data signals.

Anything other than this....the line is faulty. I always insist on these results from the "Kelly temp" and if they cant supply it, they have not tested the line. They cannot test the line while you are talking on it, they have to ring you back. If they cant help you with the results immediately, demand to speak to an operator. Do not accept a reference number until the results are given to you.

A standard cable cable pair has:
- an E-SIDE (from Exchange to SDC-Street distribution cabinet
- a V-SIDE (from SDC-Street distribution cabinet) to the terminal equipment

The E-side is usually pressurised to resist water penetration
The V-side is not pressurised an has many connect points and potential problem sources. (trees rubbing through insulation, animals eating insulation, bats urinating and corroding connections...the list goes on)

9 times out of 10 the problem will be on the V-SIDE

In order to change your pair the whole way the tech needs to divert in at least 3 places (the Exchange -MDF, the street box -SDC, and the Local Distribution Point - DP).....can also be as much as ten points if your line in aerial cable fed.

Click to expand...

http://mybroadband.co.za/vb/showpost.php?p=1777488&postcount=6

OLA peeps...

and a line sync problem is such a !@$@! hassle...

if its intermittend - its even worse!

i've got currently a customer on 512/256 adsl - which had a healthy down snr of 35-38 and line attenuation of 32-35...

about 2 weeks ago - they started to experience 30-50 sync drops per day..

so i contacted telkom - and they recon its the router...

fine...so i used my exact duplicate 5102g to test their setup..

now the line is 80% stable - but with snr 12-14 down and attenuation of 48-50!!!

biggest bummer of it all - they are 1.2 km closer to the DSLAM than i am..

wait until i go into overdrive - pi$$ing in their pool mode again

Well a tech came out today. Wasn't really expecting it so quickly (reported fault on Friday or Saturday) so I didn't have the graphs ready to show him or anything.

I don't know what he was doing really (don't know if he did an LTS, don't think so), but he plugged in his own modem and monitored some noise levels, he reckons that the noise levels are much lower when the modem is not plugged in to my lightning/surge protector. So he reccomended to try it without the surge protector and see what happens.

I don't really think it's going to help though, I have been using that protector the whole time previously and my line has been fine up to recently.

How long does an LTS take? Do they generally just carry it out at your request pretty easily? Hopefully you're right about it not being too difficult to fix, it was working perfectly for ~1 year until a month or so ago.

As for the work they did on the cables etc recently, I don't really know what was done, I can hopefully find the email and see if it sheds any light on that.

My advice when testing:

-break setup down to most simple setup : only the router connected - skip ANY surge protectors
-having said that : replace the rj11 going from wallsocket to router
-try another router
-try another rj11 port
-use UPS (line interactive) power rather than eskom power
-make sure the rj11 socket box (if outside the wall) doesn't have any wires coming loose.

run routerstats from there and have a look.

then we go to round #2

@Threepwood: Is everything now back to normal or just wishful thinking ...? I think that the LTS test is all automated - the operator just types a few buttons to activate the system and then calls you back with the results a bit later.

@Nutz: Are those Billions both running the same firmware? Very strange indeed! Did you perhaps try your DG834GT on the line?

hey Yotch...not initially - but now they are - and totally different results.

customer doesn't wanna fork out the cash for a netgear - so i'm getting a dlink cheapy to see what it can do!

i recon its a line problem

Not back to normal no tonight thought seems better, no disconnects but murphy's law the news server runs slowly tonight!

I have been graphing with RS basically every minute that my PC has been on since I first got it installed, so I have a ton of graphs at my disposal

I have tried on several nights plugging the router directly into the wall socket, no surge protector or anything at all between, and nothing else plugged into the line at all, but it didn't seem to help (I was still getting sync drops like that).

By replace the rj11 going from wallsocket to router you mean the whole cable?

I guess by try another rj11 port you mean a different wall socket in my house?Unfortuneately there is only one so I can't do that.

Can't really afford a UPS or anything now, also I don't think anyone I know has one to lend me.

I can try to see if the wall socket's wiring is secure though, is it easy enough to fix or replace if it is?

All that in, tonight the router is hooked up to a line splitter with a fax/phone plugged into the other splitter port, which is how I've been doing it mostly since the Telkom guy came. Like I said tonight it's been stable so far, and it seems like nothing that I have control over is effecting the problem from my monitoring of it the past days.

I'll just keep trying anyway, and get back to Telkom if it continues. The guy who came round gave me a number to contact him on, he said rather that than having another tech come out on the same problem basically.

Drastik said:

I an in the Nothwold area and have the same problem, had it for three weeks and have taken about 10 years off my life dealing with Telkom on the issue, this is how it has progressed;

Had my line for about two years, have always been able to sync at 4096 and have always had a pretty much perfect connection.

About three weeks ago I stsrted to experience resyncs, frequently, some connects would last 1 hour some 10 minutes. I started off replacing all microfilters, handsets and router. Problem persists.

Started with Telkom, two weeks later and they had dropped my maximum sync speed to 1024 "to test", installed new cables throughout my house. very slight improvement.

Another week later and they have traced my line all the way back to the exchange, box by box and made some changes on the dslam ???? whatever that is and I have now been connected for 22 hrs, still at 1 mb.

Some stats:

When I first found the problem -

SNR down = 6 SNR up = 9
Attenuatuion down = 54 up = 30

After replacing all the devices and copper in my house;

SNR down = 12 SNR up = 7
Attenuatuion down = 54.5 up = 30.5

After tracing cable back to the exchange and making changes on the dslam and still at 1024 sync speed.

SNR down = 24.5 up = 6
Attenuation down = 54.5 up = 30.5

Speed tests have been consistant with sync speed when I was at 4096 and now that I am at 1024. if the connection stays stable at 1024 for another day I will have the max sync speed pushed up again.

Any comments would be appreciated, this 1024 connection is not working for me and will have to be increadsd again just not sure whatthe impact will be.

Click to expand...

I dont even know what sync is but i just got new internet connection installed for mb line unshaped and i diconnect ALOT some times 5min sometimes 2 hours then i dc at least 10 times a day.The internet ligth on the modem goes off?Could this be same problem as yours?
Adsl Noob here.I got telkom as provider and on there lines.

I had a similar problem a few months back - turned out to be a cable problem from the outside pole - apparently it was struck by lightning a while back (the inside of the pole-box was black) and this had fried some wires causing shorts when there was the slightest breaze. Telkom replaced the pole junction box and the line from the box to my phone jack - did the trick and my line noise and sync problems were cured...

Another mate of mine had similar sync problems and it turned out to be the inverter he'd hooked up as a backup for the power cuts he was having - there was too much interferance from the inverter, as it was placed under the desk near the phone line - all he did was move it further away to the other side of the room, and the interferance went away...

howardb said:

I had a similar problem a few months back - turned out to be a cable problem from the outside pole - apparently it was struck by lightning a while back (the inside of the pole-box was black) and this had fried some wires causing shorts when there was the slightest breaze. Telkom replaced the pole junction box and the line from the box to my phone jack - did the trick and my line noise and sync problems were cured...

Another mate of mine had similar sync problems and it turned out to be the inverter he'd hooked up as a backup for the power cuts he was having - there was too much interferance from the inverter, as it was placed under the desk near the phone line - all he did was move it further away to the other side of the room, and the interferance went away...

Click to expand...

Do you think my UPS could cause this?
Its close to phone line box thingy on my wall.

Ill even put money on this think its the outside lines

howardb said:

I had a similar problem a few months back - turned out to be a cable problem from the outside pole - apparently it was struck by lightning a while back (the inside of the pole-box was black) and this had fried some wires causing shorts when there was the slightest breaze. Telkom replaced the pole junction box and the line from the box to my phone jack - did the trick and my line noise and sync problems were cured...

Another mate of mine had similar sync problems and it turned out to be the inverter he'd hooked up as a backup for the power cuts he was having - there was too much interferance from the inverter, as it was placed under the desk near the phone line - all he did was move it further away to the other side of the room, and the interferance went away...

Click to expand...

AFAIK this same line of mine was struck by lightning, but years ago. Perhaps residual damage has gotten worse over time? I don't now.

Boomrooker, a UPS is similar to an Inverter AFAIK so it could be your problem I reckon, just try move it away and see.