Line errors

[Rik]

I see what you mean, Griff. 

[Glenn]

I didn't say I knew the answer, but it should be there somewhere.

[.Griff.]

lol..

If it helps I have now received 101118355 bytes and the packet count is 316590. The same page says "Cell errors" of 3828.

[.Griff.]

It would be informative if you could get a comparison from another user as what your seeing may be relatively normal for BT's  implementation of FTTC.

This is another FTTC users error log after about four hours uptime -



Compare that with my 5.30pm screenshot and there's a massive difference.

[Steve]

I agree,it's almost as if your sync is set too high and all you get is a load of errors. Trouble is what the heck you do about it I've no idea.

[.Griff.]

Right it's sleepy time for Griff so here's the latest error count. Nothing will be using the connection until I post again tomorrow.

[.Griff.]

I've just turned the Pc back on and taken another screenshot -



Between 00.10AM and 11.05AM NO DEVICE was connected to the internet. The only activity taking place was the Thinkbroadband Quality Monitor pinging my router.

Other FTTC users typically have CRC errors in the double figures whereas in less than 24 hours I have over 1million. 500,000 of which took place in the middle of the night when I wasn't even using the internet!!

[Steve]

The vdsl modem your using Griff do you know it's history?

[.Griff.]

The vdsl modem your using Griff do you know it's history?

Brand new out of a sealed box. Latest model/revision "2B" and it left the factory on 22nd June 2011.

My friend who obtained it for me is an Openreach manager.

[.Griff.]

Pertinent comments from another FTTC user (and somewhat expert) on TBB -

http://forums.thinkbroadband.com/fibre/t/4042173-re-how-do-my-stats-look.html

It's a bit odd. What's become obvious now that we have a few SNR graphs is that griff_90 has a noisy line - at least compared to mine and Orly's.

If you look at his noise graph he's getting measurements of about -115 to -120 dBm/Hz whereas Orly's (and my - will post graphs later) is -135dBm/Hz.

BUT his SNRs are actually better than either mine or Orly's, presumably because of a short line and low attenuations, so he really should be getting a better sync.

I note that the attainable rate in the pic he posted was 44.5Mbps whereas his sync was only 38Mbps - it looks like he has a bit of a noisy line with some diurnal variation which ultimately is hurting his max sync a bit.

Note that VDSL because of the large bandwidths is sensitive to small drops in the reported SNRM figures. On mine an 0.3dB drop in SNRM wiped over 600Kbps off the attainable speed.

Ever since December last year I've had issues with this connection. In January two OR engineers spent an entire afternoon at my property testing all the internal wiring, sockets, and performing repeated tests on the line. Each time they performed a test (which took about 10 minutes) the error count kept rising. They changed something over in the distribution point in the communal hallway (I live in apartments) and carried on performing tests. After four hours the errors kept rising the longer they left the tests running and they eventually left saying there was nothing more they could do.

A few days later Idnet informed me that "the problem" was fixed and that was the end of the matter as far as they were concerned. However ever since Christmas my IP Profile has bounced up and down, the interleaving level has increased and my TBB QM shows a lot of packet loss. Combine all that with the fact I'm now able to prove over 1million errors occurred on my line in the last 24 hours and it all points to a problem.

[Steve]

What I'm trying to work out is whether the dip to -135 is good or bad , my guess is that it's bad as if you reference that with your putty.log the margin for that group of tones is reduced, oddly it picks out one particular group and then recovers. I guess noise from somewhere is being induced into the broadband signal , goodness knows how you find it as any of your neighbours could be the source.

http://www.idnetters.co.uk/forums/index.php/topic,26821.msg640235.html#msg640235

http://www.idnetters.co.uk/forums/index.php/topic,26821.msg640119.html#msg640119

[.Griff.]

I think I'll just live with it Steve.

It's annoying but practically impossible to resolve and I certainly don't want to get high blood pressure trying to get to the bottom of it.

[.Griff.]

I'm almost reluctant to post this for fear of tempting fate but here goes.

I guessing part of the problem perhaps is where the master socket is installed in my property. It's basically in one corner of the lounge right next to two satellite feeds, the aerial feeds and numerous electrical points. So within a very small footprint there's the modem, an LCD TV, Sky+ HD box, home cinema, WDTV Live and DECT phone. All of which could be potential sources of interference I guess.

As a result I turned of all the electrical items and reset the modem. Five minutes later the error count was 10,000+. Damn... Resets modem again.

Then I disconnected the phone line and turned off the base station. Five minutes later the error count was 10,000+. Damn again... Resets modem again.

Scratching my head I'm walking round the room looking for any other electrical items I might have missed.. Nope can't see any.... wait a sec! I'd left both DECT handsets turned on. Let's try turning them off as well.

It's now been nearly 15 minutes and the error count is 76. Ok it's not zero but it's a lot better than 10,000+.

Has anyone else had issues with DECT handsets themselves in the past?

[Steve]

They are claimed to be a source of noise although I've not personally had an issue with them.My DECT handsets have a 'green setting' which reduces the wifi range etc whether it helps reduce interference I've no idea.

[MisterW]

Like Steve, I've heard that they can cause noise problems but not had any issue myself. You would have thought that the base unit ( which is closer to the modem I assume ) is going to be more of a problem than the handsets...

Edit: that's a point Steve, my handsets ( Siemens ) have a similar mode which is enabled.

[Steve]

I'm not sure whether with the base station off you will also get more interference as the phones will be searching for the base station.

[.Griff.]

Looks like I tempted fate after all.

CRC errors   38531
FEC errors   917    
HEC errors   12595

Oh well. Thanks anyway guys. I'm off to bang my head against the wall.

[jezuk1]

I turned my DECT handset and base station off about a month ago as part of a test to see if I get better performance from my line but I haven't seen any difference in all honesty.
From my experience it's nice to dig up these numbers but it sets the brain in motion and begins a long process of analysis and testing which normally doesn't yield anything productive 

You're getting good sync speeds, as long as the DLM is happy then I personally wouldn't worry too much about it (athough like you, I would be occupied with trying to understand why). An example here with my line - when sync'd at 13991 the CRC error count sits almost perfectly at zero. When the line is sync'd at 15477 the CRC count stacks up at quite a rapid rate (around 100000+ per day). Both speeds are perfectly stable and I haven't seen any drops but the DLM clearly prefers the slower profile. Now I would much rather see the higher sync speed because despite having to resend a greater percentage of packets the net result is a faster line with quicker downloads. I don't understand how the DLM works but perhaps in your case it decided to tolerate the CRC errors on the basis that the line is stable, instead of lowering the sync speed by a few thousand kbps.

[.Griff.]

I still can't get these errors out of my head. Every day that goes by another FTTC user unlocks his/her modem and provides their stats ALL of which have little to no errors at all.

I can't dig up my street so I'm resorting to crawling around my building looks for clues as to what is causing the interference on the lines and I might have a couple of leads.

Firstly the BT distribution point for the five apartments in under the stairs in a small cupboard along with the main electricity feed into the building and five electricity meters and all the associated cabling. Is that a potential issue?

Secondly when they built these apartments seven years ago they were the last to be built out of the whole development and they literally rushed to finish them with the quality of fittings and finish suffering as a result. In the lounge they located the BT master socket in a corner and literally surrounded it with electricity points and satellite feeds. Again could this be a source of interference?

(And before anyone says it I'm going to pick up a cheap portable radio this afternoon)

[Rik]

Firstly the BT distribution point for the five apartments in under the stairs in a small cupboard along with the main electricity feed into the building and five electricity meters and all the associated cabling. Is that a potential issue?

Secondly when they built these apartments seven years ago they were the last to be built out of the whole development and they literally rushed to finish them with the quality of fittings and finish suffering as a result. In the lounge they located the BT master socket in a corner and literally surrounded it with electricity points and satellite feeds. Again could this be a source of interference?

(And before anyone says it I'm going to pick up a cheap portable radio this afternoon)

Yes, yes and good idea, Griff.

[.Griff.]

Engineer booked for Thursday.

[Lance]

Good luck! How has the fault been reported? Has it been based on the error count the average user wouldn't know about?

[.Griff.]

Reported a noise on the line (which there is intermittently).

I spoke to two of my neighbours (all in the same block) and they've also had problems with intermittent noise on the line.

Combine all that and the errors I've decided to request an OR visit. To be honest I wish I'd persued it more in January when OR confirmed errors on the line with their own equipment but fobbed me off about it.

[Rik]

 

Start frying the bacon, Griff.

[.Griff.]

Just spent 30 minutes chatting to an Openreach Coach I know. (Remember that OR modem I got the other week  )

I've explained everything, the intermittent noise during calls, the CRC errors, the fact my neighbours (in the same block) also hear intermittent noise, the previous OR guys seeing errors on their "Hawk"  and he says in his experience it all points to noise on the line caused by a "HR" fault.

Apparently he's going to perform a remote "ACT" test tomorrow morning and call me with the results.

Unfortunately he lives in London so he can't exactly pop round and have a look himself.