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[Jonken]

Hi I've been lurking on this site for a couple of days now and I must say that it must be the best there is for broadband trouble shooting and information.

My problem is that the rx sync speed keeps droppping to 160kbps. I've literally changed everything here - router (Netgear DG834), router power supply, connecting cable, filter; I'm running it with the filter plugged directly into the test jack on the BT master socket and all extensions and extension wiring are disconnected.

When the line is failing I get this from RouterStats

Sat 01 Nov 2008  18:56:19   86.26.82.4   Rx-Noise= 10   Tx-Noise= 17   Rx-Sync= 2144   Tx-Sync= 448
Sat 01 Nov 2008  18:56:39   86.26.82.4   Rx-Noise= 10   Tx-Noise= 17   Rx-Sync= 2144   Tx-Sync= 448
Sat 01 Nov 2008  18:56:59   86.26.82.4   Rx-Noise= 10   Tx-Noise= 17   Rx-Sync= 2144   Tx-Sync= 448
Sat 01 Nov 2008  18:57:19   86.26.82.4   Rx-Noise= -5   Tx-Noise= 17   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  18:57:39   86.26.82.4   Rx-Noise= -5   Tx-Noise= 17   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  18:57:59   86.26.82.4   Rx-Noise= -5   Tx-Noise= 17   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  18:58:19   86.26.82.4   Rx-Noise= -7   Tx-Noise= 17   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  18:58:39       Rx-Noise= 2   Tx-Noise= 16   Rx-Sync= 160   Tx-Sync= 448
Sat 01 Nov 2008  18:58:59   86.26.83.211   Rx-Noise= 3   Tx-Noise= 16   Rx-Sync= 160   Tx-Sync= 448
Sat 01 Nov 2008  18:59:19   86.26.83.211   Rx-Noise= 3   Tx-Noise= 16   Rx-Sync= 160   Tx-Sync= 448

It'll stay like this for a while (I can't see, at the moment, any pattern in failure times or duration but RouterStat has only been running for one day) then it'll do this

Sat 01 Nov 2008  19:04:59   86.26.83.211   Rx-Noise= 3   Tx-Noise= 16   Rx-Sync= 160   Tx-Sync= 448
Sat 01 Nov 2008  19:05:19   86.26.83.211   Rx-Noise= 3   Tx-Noise= 16   Rx-Sync= 160   Tx-Sync= 448
Sat 01 Nov 2008  19:05:39   86.26.83.211   Rx-Noise= -10   Tx-Noise= 16   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  19:05:59   86.26.83.211   Rx-Noise= -10   Tx-Noise= 16   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  19:06:19   86.26.83.211   Rx-Noise= -10   Tx-Noise= 16   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  19:06:39   86.26.83.211   Rx-Noise= 0   Tx-Noise= 0   Rx-Sync= 0   Tx-Sync= 0
Sat 01 Nov 2008  19:07:00       Rx-Noise= 12   Tx-Noise= 17   Rx-Sync= 1984   Tx-Sync= 448
Sat 01 Nov 2008  19:07:19   86.0.126.242   Rx-Noise= 12   Tx-Noise= 17   Rx-Sync= 1984   Tx-Sync= 448
Sat 01 Nov 2008  19:07:39   86.0.126.242   Rx-Noise= 11   Tx-Noise= 17   Rx-Sync= 1984   Tx-Sync= 448
Sat 01 Nov 2008  19:07:59   86.0.126.242   Rx-Noise= 12   Tx-Noise= 17   Rx-Sync= 1984   Tx-Sync= 448

I'm at the end of quite a long line the downstream loss is 55dB to 59dB depending on the sync rate and the upstream loss is 15.5dB

Now, of course, because this is happening 3 or 4 times a day I'm only a data transfer rate of 135kbps

Virgin have accepted it as a fault but I'm not exactly filled with confidence as to their fault finding abilities or their commitment to non-cable ADSL customers. Is there anything else I can try? {besides changing ISP }

Oh this may raise a chuckle. I stupidly thought that a copy of the log the above extracts were taken from might assist Virgin tech support so I sent an email to support@virgin.net detailing how the log was obtained (new router, master socket, no phones connected etc etc) and attatched the log requesting that it be forwarded to their tech support people dealing with this fault. Back comes a reply suggesting that I might like to try the following which was a list of tests all of which I'd just told them I'd done. But the best bit was:-

<quote> Please be informed that due to limited support we are unable to pass the information to other department.</quote>
from you'll remember support@virgin.net

So in a supposed communications company one department can't talk to another - words failed me.

[roseway]

Hi and welcome

If you're getting that result when plugged into the test socket, the cause must almost certainly be external. It could be some sort of line fault or a very large source of intermittent interference. One simple thing you can check when the connection is in its 'bad' state is to dial 17070 and then press 2 for the quiet line test. If you hear anything apart from a faint hiss you can report it to BT as a voice fault.

Another possibility is REIN, and you can get some information on that here.

Hopefully Virgin will get some BT investigation under way, but they don't fill me with confidence, I have to say.

[b4dger]

Hi,
Do your logs look the same during the day?
Lot's of people have problems as darkness fall with ADSL Max - but your change in SNRM does look rather extreme!

Has your provider got BT to test the line yet?
If you pick a phone up to hear the dial tone do the router stats change? Sometimes when you have a physical line problem (HR fault) the line behaves differently when it's in use - so this is worth testing.
What version is your DG834 ? If it's an early version it'll have an AR7 chipset - my quite long rural line (51db attenuation) dropped every afternoon on ADSL Max with a Netgear DG834v2 until I changed to a Speedtouch 585v6 with a broadcom chipset.

So many questions...

[Jonken]

Thanks to roseway & b4dger.

I should have put in my original post I tried the quiet line test (did I mention I've been lurking, looking and learning for a couple of days ), there's no difference between good and faulty condition, the line's remarkably noise free in both cases. I even tried the ringback test (75vac ringing current should shake a line up nicely) not even that would induce the fault to appear or clear. In short, nothing I do on the telephone side of the filter affects the noise figures in either the good or faulty condition.

b4dger my DG834 is even older than yours was it (or rather they I've got 2, one with the latest firmware the other with one version back, identical results with both)  is a v1 but having said that up to a week ago it synced perfectly OK maybe not at the fastest I could get but stable enough syncing between 1600 and 2400 depending as you say on the time of day.

A further question
If the output level of the exchange broadband equipment dropped what effect would I see in the router stats?
I'm pretty certain that the noise margin figure would plummet (as I'm seeing) but would the line loss figure change. My line loss figure changes from 56/59dB at approx 2000kbps (good) to 54/55dB at 160kbps (bad)

John

[kitz]

>> If the output level of the exchange broadband equipment dropped what effect would I see in the router stats?

I presume by that, you mean output power?  If so less power does mean that your sync speed will be less as the adsl signal will not be as strong.  Output power is controlled by the dslam/router, and I believe it can be reduced to eliminate the possibility of crosstalk.

>> but would the line loss figure change.

afaik it shouldnt have any bearing on looploss.  In fact attenuation should more or less remain static.

>> My line loss figure changes from 56/59dB at approx 2000kbps (good) to 54/55dB at 160kbps (bad)

Thats weird... and the wrong way round.  Lower attenuation is better and in theory should give you the higher sync.  There must be other things going on at the same time such as a large deterioration of the SNR.  As mentioned attenuation shouldnt really change (as long as youre using the same equipment), and changes in attenuation normally indicate a problem with the wiring either internal or on BTs.

[Jonken]

Hi Kitz Great site!

I don't think I made my question clear what I meant was, taking a hypothetical case-

Assume dslam has output power of -10dB and the line loss is 40dB so router sees a rx power of -50dB and reports a line loss of 40dB on its stats page.

Now if the dslam goes faulty and drops its output power to -20dB (it still thinks its outputting -10dB) so the router now sees a rx power of -60dB. Now is the router 'smart enough' to differentiate between a 10dB drop in dslam output and a 10db increase in line loss. If it is it will continue to report a 40dB line loss. If not it will now show a 50dB line loss as it also assumes the dslam is still ouputting -10dB

That still doesn't seem very clear, hope you see what I'm getting at.

>>My line loss figure changes from 56/59dB at approx 2000kbps (good) to 54/55dB at 160kbps (bad)

I must admit that I assumed that as the 'sync speed' dropped so the 'line signal frequency' dropped bringing the line loss down the frequency/loss curve and the loss hadn't 'improved' as much as it should, logical but in retrospect probably incorrect.

John

[mr_chris]

Yes, I see what you're getting at... but I'm afraid my answer is I don't know enough about DSLAM <-> router interaction to be able to say whether what you're saying is feasible or not. It certainly makes good theoretical sense that a faulty line card in the DSLAM could cause attenuation variations in this way, if the dslam is reporting output power of say 20dB... and yet only outputting at 10dB, then I see how the router may get confused by this.

After all, router stats are very reliant on a lot of information provided by the DSLAM.

Interesting theory - but in any case, a problem that definitely needs fixing!

With those results it needs a BT engineer to come out to you, and this is what you should be pushing Virgin for. They will probably warn you that you may get charged if they don't find a fault... I wouldn't worry about that. Keep hold of the sync logs in case it doesn't happen while the engineer is there, but you obviously have a fault which requires manual intervention somewhere along the line to fix it!

Good luck, keep us updated