What a difference a week makes

I joined IDNet in December 2006. I�ve enjoyed top-notch service and support. I�ve bee planning to upgrade to ADSL2+ and swap from BT for the phone. Since BT completed the 21CN upgrade of my line a year ago, my downstream line attenuation was 20, occasionally measured at 21. My SNR margin reduced slightly to a steady 16-15 dB. Downloads speeds were amazing- almost always above 7 mbps.

Last week, 3 March to be precise, my immediate neighbours changed their Internet service from Virgin Media to another ISP, necessitating the reconnection of a BT line. The Openreach van was outside our properties most of the afternoon, during which time my download speed dropped from 7 mbps to 4.3 mbps. It swiftly returned to normal. Between 4 and 7 , the SNR margin fell to a range of 14-11.5 dB. Moreover, a very stable router began to lose sync for brief periods a couple of times per day.

On 8 March, I found that my line had been interleaved. Downstream SNR rose to 15-14, though the line continued to lose sync briefly. FEC errors ran into thousands. I plugged into the test socket, hoping to locate the source, but the problem continued. I installed a new set of micro-filters. I then emailed IDNet support, which has always been second to none.

My first email did not get a reply. My second message got a response just as I was sending through email No 3. The very local BT work was simply written off as coincidence. It�s a whopper coincidence if true. Either way, I did not think the agent took the issue as seriously as did IDNet staff to whom I have spoken about relatively minor issues.

The line was stable yesterday. However, this morning I found that my IP Profile had dropped from 7500 kbps to 7000 kbps and I lost sync for about 12 seconds. I phoned IDNet and spoke to the agent who had answered my email. He insisted the BT work at my neighbours� property is coincidental and suggested I try a new router. I�m doing this right now. Here are the stats from a BT Voyager 2500 I bought as a test router about 3 years ago:

Line Mode G.DMT Line State Show Time
Latency Type Interleave Line Up Time 00:01:49:49
Line Coding Trellis On Line Up Count 1

Statistics Downstream Upstream
Line Rate 8096 Kbps 992 Kbps
Noise Margin 14.9 dB 10.0 dB
Line Attenuation 22.0 dB 12.5 dB
Output Power 19.8 dBm 12.5 dBm
K (number of bytes in DMT frame) 254 32
R (number of check bytes in RS code word) 20 16
S (RS code word size in DMT frame) 1 4
D (interleaver depth) 32 4
Super Frames 387570 387568
Super Frame Errors 4 0
RS Words 52709616 6588656
RS Correctable Errors 554 0
RS Uncorrectable Errors 36 0
HEC Errors 1 0
OCD Errors 0 0
LCD Errors 0 0
ES Errors 0 0

This might prove things one way or the other. If the issue is router�related perhaps I�ll get my excellent stats back eventually. If not, I�ll probably have to live with a line/BT environment that was not what it was on the morning of 3 March.

Whatever the outcome, I�ve had better support as a BT Yahoo customer back in 2002-05. IDNet charge premium prices and, until now I�ve never begrudged a penny. Now I�m thinking I could do as well, if not better, with one of sever ISPs with UK-based support.

I ramble. The principle purpose of this post was to query what you make of the fact that my issue began with my neighbours' reconnection to BT.

Your SNR Margin is too high which indicates noise on the line.

those stats look OK, in 1h50m only 1 HEC error and 36 uncorrectable errors.

It's quite common not to get full sync when interleaved, many routers can only do 7616 interleaved so not a surprise you have 8096 which is one step off 8128 hence the 7000 profile rather than 7150.

You can opt out of interleaving.

Nonsense. The line been stable until now with downtream SNR at 15.5-15 (sometimes 16 dB) for the year since the 21CN upgrade.

Edited by ARD (Thu 10-Mar-11 14:47:22)

I'll sit with interleaving while workiong through router tests, et al. If a router issue is proven I'll ask IDNet to get be back onto fast mode.

No sync loss so far on this router and that's what got me interleaved but the big question is why the sync loss and why did it begin on the very afternoon BT were at work next door.

Latest stats:

Line Mode G.DMT Line State Show Time
Latency Type Interleave Line Up Time 00:05:50:35
Line Coding Trellis On Line Up Count 1

Statistics Downstream Upstream
Line Rate 8096 Kbps 992 Kbps
Noise Margin 14.9 dB 10.0 dB
Line Attenuation 22.0 dB 12.5 dB
Output Power 19.8 dBm 12.5 dBm
K (number of bytes in DMT frame) 254 32
R (number of check bytes in RS code word) 20 16
S (RS code word size in DMT frame) 1 4
D (interleaver depth) 32 4
Super Frames 830956 830954
Super Frame Errors 6 0
RS Words 113010016 14126218
RS Correctable Errors 740 0
RS Uncorrectable Errors 259 0
HEC Errors 5 0
OCD Errors 0 0
LCD Errors 0 0
ES Errors 0 0

Edited by ARD (Thu 10-Mar-11 14:49:23)

True, given your attenuation indicates a short line I guess a high SNR Margin is because of the limit to your sync speed.

The question is, why should your line be unstable? As you have so much margin available, you should be able to accommodate plenty of noise easily. Maybe a line fault then?

What can but shouldn't happen is ,whilst the openreach engineer is working at a street cabinet sometimes fixing one line can sometimes cause another to fault, due to the age and condition of the bt cables and connections,due to them being disturbed or maybe it's cross talk from your neighbors adsl,

Edited by tommy45 (Thu 10-Mar-11 15:32:22)

Well, that is just the sort of thing I wondered about but IDNet (or rather the support agent who has handled my case) insist that the time the problem began is coincidenal. I've just lost sync twice in 35 minutes, despite new filters and a test router. The only time I've had a problem like this in my broadband history was in 2005 when the issue was tracked to an aging line card at the exchange.

If the support I've had from IDEt to date is anything to go by the situation certainly isn't going to improve and I might as well look for an alternative ISP and save myself up to £20 per month.

Edited by ARD (Thu 10-Mar-11 15:48:46)

Something like that happened on the 6th of this month to me. I have always had 3500 download, about 4 years. Suddenly it went down to 400mbs and although it is slowly climobung back up the downlaod is still very slow. Of course nothing to do with BT/Openreach. I saw it happen in front of my eyes on Saturday morning, the router went down and reconnected at the slower speed. Nothing indoors has changed at all si it must be at the exchange or the line to it.

It's a pity there is no where else to go to get information because even Idnet have information kept from them by BT.

It's distressing on two counts:

1) The incident itself
2) Poor support from IDNet

Right now, I feel the only way ahead is to take my neighbours' place on Virgin Media.