Continual dopouts. Opinions please

[humpda]

Hi
Strap yourself in cos this is a bit of a long story...sorry.

I currently have a job open with the Helpdesk but I things do not seem to be progressing too well and I am a bit stuck. I have had a combination of continual adsl drop out coupled with low speeds, though I don't think the two are connected (but could be wrong). Basically since I went naked adsl in December things have gone downhill with the stability of my connection. My sync speeds vary between 3.5Mb and 5.5Mb/s depending on what modem I am using and time of day the modem resyncs. I have a few different modems I have been using; Billion, TPLink and Netcomm in order to eliminate the modems from the problem. According to ADSL2 Exchanges I am approx 3km from exchange (but realise that this is at best a guide). The following is my current modem stats after my latest loss of sync (20 mins ago it reported d/s sync of 4.6Mb):

Annex Type AnnexA
Upstream 384000
Downstream 3744000
Elapsed Time 0 day 0 hr 15 min 47 sec
SNR Margin(Upstream) 23 dB
SNR Margin(Downstream) 17.0 dB
Line Attenuation(Upstream) 31.5 dB
Line Attenuation(Downstream) 52.0 dB
CRC Errors(Upstream) 2
CRC Errors(Downstream) 0
Latency(Upstream) Interleave
Latency(Downstream) Interleave

The problem is the downstream snr margin. This varies considerably from 5 through to 17db (as you can see above). When it hits around 6/7 I start to get heaps of crc errors and the connections dies and resyncs, with snr rate then usually shooting up to 15/17db and then starting to drop again. This process has happened 3 times today, and is a pattern that has been ongoing since December, with not one day having past where the modem has lost sync at least once, but usually multiple times.

Exetel have attempted to run a line test, but the test comes back that there is a circuit still connected on the line so line test can not proceed....I have had a cabler in to check my house wiring and he gave it a clean bill of health but the drop outs continue. So where do I go from here? I have asked if Exetel could escalate the issue to the wholesaler, however they have indicated that this is not possible at this time. This, in combination with speed issues (but this may be due to congestion factors - I am unsure - but this is what was indicated to me by the helpdesk) have made things a bit difficult, especially since I am on naked and carry voice through the DSL conenction as well.

Anyway, if you have any suggestions I could try further in order to attempt to resolve this issue I would be most grateful.

Cheers

Darryl

[Dazzled]

Something rather off-the-wall comes to mind, a sort of last place to look thing. Was the cabler looking for a bridge tap, ie a forked parallel branch that goes nowhere or has nothing fitted to it? You often find these where there has been some DIY extension wiring. It's harmless for phones, but spoils the high frequency part of the ADSL2 signal. Some modems display the result of the high freq tests made on the line in the telnet interface.

[Mixer]

Exetel have attempted to run a line test, but the test comes back that there is a circuit still connected on the line so line test can not proceed....I have had a cabler in to check my house wiring and he gave it a clean bill of health but the drop outs continue.

humpda, just to clarify:
a. When the line test was done nothing at all was connected to your line? No modem, old phones etc.
b. Are you in a block of flats/duplex or is it a free standing house?
c. Any chance of a there being a security system installed?
d. Some older houses I have seen have had remote bell systems wired into back rooms any signs of this?
e. How many phone outlets are there in your place, are you on the one closest to the incoming line?
e. Did you have ADSL2 working prior to going naked?

Mixer

[humpda]

Hi guys
Thanks heaps for responding. Unfortunately I did not get the cabler to check for a bridge tap. I went up into the roof cavity with him and traced the cable from its entry to the house through to the noggin it drops down through. He got rid of about 5m of excess cable and ensured phone cable was sitting elevated away from any electrical cabling. He also replaced the wall outlet with with an updated fitting.

humpda, just to clarify:
a. When the line test was done nothing at all was connected to your line? No modem, old phones etc.
b. Are you in a block of flats/duplex or is it a free standing house?
c. Any chance of a there being a security system installed?
d. Some older houses I have seen have had remote bell systems wired into back rooms any signs of this?
e. How many phone outlets are there in your place, are you on the one closest to the incoming line?
e. Did you have ADSL2 working prior to going naked?

Mixer

a - nope nothing connected. No phones, foxtel (don't have), b2b alarms(don't have) or filters/ Exetel have tried to test the line 3 times with the same result.
b - free standing residence
c - no security installed. Previous owner had cable tv but we have never had it connected.
d - House is 15 years old...no bell systems or other remote paging systems
e - two phone outlets. The second outlet we disconnected to ensure that this was not causing problems and is currently still disconnected. We don't need it as we have voip. The line I am currently connected to is the main outlet and what the cabler identified as the network boundary.
f - Adsl worked fine prior to naked which is why I decided to go naked. We used voip predominately anyway and thought that it would be a good to save a few $ as we rarely used pstn line.

Cabler took my modem outside and connected it directly to cables running into house, thus btpassing internal wiring. We got same downstream attenuation (52db) and snr rate was around 12db. I tried contacting Exetel to see if they could run a line test at that time as this would eliminate house from equation but unfortunately it was not to be.

Thanks for your help guys. It has really got me stumped and is quite frustrating.

Cheers

[humpda]

Some modems display the result of the high freq tests made on the line in the telnet interface.

Hi Dazzled
I am currently using a Billion 7401VGPR3, but also have a tplink 8810 and netcomm nb9w. Do you know if any of these support the above?

Cheers

Darryl

[Need2No]

When I have problems with my naked DSL I -
1. Remove everything from the phone line.
2. Plug in a corded handset.
3. Lift hand piece and listen. Is there is a fast busy tone? No tone - advise Exetel
4. Listen for static sounds. Static on the line? Yes - Advise Exetel.

Regards

[Dazzled]

humpda, I don't have any of those modem models here to play with, but in principle, execute in a terminal/DOS window:
telnet 192.168.1.1 (or whatever IP applies)
Then log in, say
admin admin
Then type ?<enter>
You will normally be in a very stripped down Linux shell, with all the CLI commands the shell understands listed. Type most command names for a list of arguments. Unfortunately every modem make is different.

You can cruise around safely as long as you don't set values. For some Netcomm models you might want adsl info --SNR
You can learn a lot about your modem this way. If you look up how /proc works, you can read information straight from the kernel, eg: cat /proc/net/dev

[humpda]

Hi
Situation has continued. Last night i lost sync around 7pm....snr rate dropped down to under 5 and crc errors went up and connections died. I resysnced modem this morning and it connected at a healthy 5.4Mb...this worked ok to approx 20 mins ago when I noticed while using MSN that it had gone offline. Sure enough snr db had dropped to 4db, crc errors went ballistic and modem lost sync. This time it did not resync immediately. I have done a bit of research and found a tool called DMT that works with broadcom chipsets. I currently have my nb9w plugged in and a currently syncs between 3.5 and 3.9Mb/s. The DMT tool provides some raw data about the connection (and also allows users to tweak values similar to coding gain etc in Billion modems). I have attached an image so people can see the state of my connection and how the dmt tool lays out the data.

The optimum snr rate for my connection seems to be 12db....probably because I am on the stability profile. How the heck do I find what is causing the noise on the line? I have tried turning off hot water (thought that may have been it), selectively turning off heavy power using devices (fridges.freezers etc). Besides a fault in the line somewhere, the only other thing I can think is that near where I live is an industrial estate with a few medium/heavy industries....I guess there could be some big piece of electrical equipement being turned on causing this noise but how to prove this? I checked the line with a chorded handset and got the fast busy tone...could not detect any static, but may try it now that the connection has been playing up.

How can I get Exetel understand that there is an issue somewhere and see if the wholesaler can sought it out...it would be good to go a day or two without going through the sync merry-go-round.

Cheers

[humpda]

Hi
Noise has now disappeared from the line and stats are as follows:
SNR Margin (dB): 18.3 24.0
Attenuation (dB): 49.0 31.0
Output Power (dBm): 18.9 12.6
Attainable Rate (Kbps): 4064 920
Rate (Kbps): 3936 384

Notice that the snr margin has now increased to 18.3db...if I force resync now I will get speed around 5-6Mb/s....but as mentioned something is causing this snr rate to drop down to under 5 at various times during the day.

Cheers

[CoreyPlover]

How can I get Exetel understand that there is an issue somewhere and see if the wholesaler can sought it out...it would be good to go a day or two without going through the sync merry-go-round.

If you have gone through the usual fault logging, you can email resolution@exetel.com.au with your ticket number and your issue will get escalated to senior management