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Administrator MrSaffron
(staff) Sat 09-Apr-11 14:34:51
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Re: DSLAM Profile question


[re: deleted] [link to this post]
 
Its not horrendous, but suspect the size of the FEC count is the main reason for profile not lowering.

BT will be working on the assumption, if the interleaving has uncorrected errors at this speed, then lowering margin and running line faster will create more uncorrected errors and at some point the retransmits these produce negate any faster connection speed.

Solve the uncorrected errors and lower the FEC count and a lower margin may be possible.

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User deleted
(deleted) Sat 09-Apr-11 16:15:08
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Re: DSLAM Profile question


[re: MrSaffron] [link to this post]
 
I seem to be getting some issues whereby my SN Margin drops to 0 as does my sync speed. My modem resyncs at this time, so not sure if it's modem causing the problem or reacting to the problem. This seems to have happened at about 11am on the past couple of days (since I have been running routerstats.
Anyway My figures seemed to be worse when I installed the NTE5 ADSL faceplate as opposed to using the NTE5 with a normal faceplate and separate filter. So I have gone back to the original faceplate and separate filter to see if that changes things at all.
My initial sync rate and Noise Margin figures are the same though.
Apart from that I have a spare router I can try, albeit an old SMC barricade. There are no extensions currently wired in and I have no ringwire connected. The BT Line enters my house by the front door on an old style POTS socket where it is jumpered onto another cable that goes through to my computer room where the NTE5 is located. Not sure if it's cat5 but it is UTP of some sort within the house and the run isn't near anything that I can think of that might cause interference. A quiet test on the phone proved ok a week or so ago.
Thinking about it the phone is cordless, may be worth trying a wired phone for a while.
I'll let it soak for a while with the old faceplate and filter in place and see what happens. Unless anyone has any other ideas?
Standard User XRaySpeX
(knowledge is power) Sat 09-Apr-11 18:18:32
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Re: DSLAM Profile question


[re: MrSaffron] [link to this post]
 
In reply to a post by MrSaffron:
Look at the error counts, you are getting errors that interleaving cannot cope with.
His error counts are insignificant. OP forgot to post the BlueEther's Errors page, which I find the most informative:
Check Error Seconds
You have had 11 seconds in which errors happened in the last 20h 58m 49s on the down link.
That is an average of 6,866 seconds between each errored second.

* Error Seconds on the upstream are kept on the DSLAM so are imposable to diagnose problems from our end.

Check FEC Errors
Known as Forward Error Corrections, these are error corrections implemented by the interleaving process between the modem and DSLAM in the exchange.

The firmware on your Thompson Speedtouch has a bug in it that miss-represents the FEC up errors, please ignore these errors
There have been 0.0141% FEC errors on the downstream since your last resync
As these errors are corrected errors thy are not necessarily something to worry about but might slow your throughput down as the router has to correct the errors before passing them on to your PC.


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Standard User deleted
(deleted) Sun 10-Apr-11 13:07:02
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Re: DSLAM Profile question


[re: XRaySpeX] [link to this post]
 
Again at mid morning today I had a sudden drop to zero in my noise figure. Roputer doesn't seem to have restarted this time but it resynced at as slightly slower speed.
Looks like my filter is off the hook.

Have posted below the same stats as before but also a copy and paste of the Errors tab from BlueEther. Is that what you refer to XRaySpecs? Seem to be more errors than last time. Are they significant or not? Obviously the noise spikes are what is causing the problem. I use cordless phone usualy and do notice occasional noise when using it.. When I replace it with wired handset and do quiet line test it seems to be practicaly silent. Should I ditch the wireless phone as a test?

In reply to a post by XRaySpeX:
His error counts are insignificant. OP forgot to post the BlueEther's Errors page, which I find the most informative


This is the data from the summary page that BlueEther gives you to copy and paste....
BlueEther's stats checker at http://adsl.tin2tin.net thinks my line is made of [color=orange]some Welsh hill farmers old fence.[/color]
Can you help me fix my line?

http://adsl.tin2tin.net/yourstats.php?statsID=151332
[color=red]Down sync is low (35% of the theoretical maximum).[/color]
[color=red]Very high SNR at 15.1 down / 24 up.[/color]
[color=red]SN margins vary by too much.[/color]
[color=green]Attenuation looks normal.[/color]
[color=green]Output power looks normal.[/color]
[color=orange]There are some of FEC errors.[/color]
Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
22
Uptime:                 17h 43m 51s 
Modulation:             G.DMT - Interleaved on Annex A                                (Up Stream)     /       (Down Stream)
Sync:                           448     /       6880Data Transferred:               /       
Attenuation:                    14.5    /       24SN Margin:                              24      /       15.1
Power:                                  11.9    /       19.8Vendor:                                 /       
Modem:                  an unknown modem with adslctlLoF:                                    0       /       0
LoS:                                    0       /       0Error Sec.:                             0       /       162
FEC (Uncorrected):                      327FEC (Corrected):                                439784
FEC (RS Counter):                       268595338 
HEC (Errors):                           0       /       14Data Cells:                             0       /       1792604
 CRC (SFerr):                                    0       /       17
Supper Frames:                  3949981 /       3949931


This from the Errors tab.... Is this what you refer toXRaySpecs??

Check Error SecondsYou have had 162 seconds in which errors happened in the last 17h 43m 51s on the down link.
That is an average of 394 seconds between each errored second.


* Error Seconds on the upstream are kept on the DSLAM so are imposable to diagnose problems from our end.

Check FEC ErrorsKnown as Forward Error Corrections, these are error corrections implemented by the interleaving process between the modem and DSLAM in the exchange.


There have been 0.16% FEC errors on the downstream since your last resync
As these errors are corrected errors thy are not necessarily something to worry about but might slow your throughput down as the router has to correct the errors before passing them on to your PC.

Check CRC ErrorsKnown as a cyclic redundancy check this is used to verify the proper frame transmission between the transmitting and receiving end.
These errors often mean that data has to be retransmitted and will slow the throughput transmission down. In extreme cases can lead to disconnections.


There have been 17 CRC errors on the downstream.


* CRC errors on the upstream are kept on the DSLAM so are imposable to diagnose problems from our end.

Check HEC ErrorsUsed to check and rectify the cell headers, if these errors are too high it will slow the throughput transmission down.


There have been 14 HEC errors on the downstream.
That is 0.0008% of the data cells.

* HEC errors on the upstream are kept on the DSLAM so are imposable to diagnose problems from our end.
Standard User deleted
(deleted) Sun 10-Apr-11 13:17:59
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Re: DSLAM Profile question


[re: deleted] [link to this post]
 
You need to track down the cause of the mid-morning noise (which is causing your SNR margin drop).

Does anything in your house switch on at that time? Microwave, central heating, recording etc.

Does anything nearby create radio interference at that time?
Standard User deleted
(deleted) Sun 10-Apr-11 13:44:01
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Re: DSLAM Profile question


[re: deleted] [link to this post]
 
Hi John, yes I've been trying to establish the cause but I can't think of anything that's on at the times that it happens. It's not at a set time every day but in the area of mid day +/- 2 hours roughly.
Washing machine seemed a likely culprit but it was off this morning at the time of the spike.
Freezer and fridge cut in and out throughout the day so would expect it to happen at more varied times if it was one of them.
Heating not on at the time.
All these are at least 10ft away from the phone line.
Could it be my wireless phone? I do notice occasional noise on it when I go off hook which isn't there when I use a wired handset and do a quiet line check.
Externaly I know we had a mains water burst in the area yesterday which was repaired with all the associated power tools in action but they aren't there today. There is some building work going on down the road but, again, they aren't working today. Next door is doing up his house but can't hear him doing anything at the time.
It seems strange because a few weeks ago I took all my extension wiring out because it was a real mess and my speed weren't great and got speed test result of >6Mbps consistently. Nothing has changed in house since then except the addition of an ADSL faceplate on my NTE5, which I have tried swapping back so it isn't that.
I tried a different router and saw no change in Noise or sync figures so swapped back.
Would it be worth changing it over for a long term test?
The only problem is I have my Netgear router configured as I want it and the SMC isn't cabable of exactly replicating my set up. For instance I can't find a way on the SMC to give items a fixed IP address like my music server and printer so that everyone can find it on the same address all the time.
Standard User deleted
(deleted) Sun 10-Apr-11 14:16:18
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Re: DSLAM Profile question


[re: deleted] [link to this post]
 
Just tried putting SMC barriacade on the line. Sync speed and noise much the same as Netgear. Problem is I can't get RouterStats to see it.
It logs oin ok but I can't get it to graph the stats at all. I think it's because everything is in tables in the smc UI and I can't find a simple html page to pint it to so won't get the same stats off it frown
Standard User deleted
(deleted) Sun 10-Apr-11 14:35:33
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Re: DSLAM Profile question


[re: deleted] [link to this post]
 
What you describe doesn't sound like a router problem. It does sound like you are getting noise on the line. I'm not familiar with wireless phones, perhaps that is a candidate.
Standard User deleted
(deleted) Sun 10-Apr-11 17:33:33
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Re: DSLAM Profile question


[re: deleted] [link to this post]
 
In reply to a post by john2007:
What you describe doesn't sound like a router problem. It does sound like you are getting noise on the line. I'm not familiar with wireless phones, perhaps that is a candidate.


Totaly agree John. I'm not at all convinced it's my Router, a. it's been solid up to now and b. When I put the other one on it makes no difference.
It just that, apart from the cable leading accross my house to the NTE5 box all I have is one filter plate, a cable and a router to swap. The BT riser cable comes in by my front door and is jumpered via a connectioon block to a lead running accross the front of my house (in the roof space above front ground floor) to my "office" where the NTE5 is terminated. Only one extension connected to NTE5 as well so pretty confident that's OK.
I would like to say I have eliminated all noise sources in the house but whenever I do a quiet line check it's fine.
I have taken the cordless phone out for a while to see if that has any effect. It is a DECT phone but is quite old.
I'm running a washing machine cycle and watchinmg the graph whilst it's running just to bve certain it isn't that.
Think I'll have to get Eclipse to get BT involved. Not sure thay can expect me to do much more.
Standard User deleted
(deleted) Sun 10-Apr-11 17:45:17
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Re: DSLAM Profile question


[re: deleted] [link to this post]
 
Don't think it's washing machine. Just finished it's cycle. I did see a blip of approx 2dB towards the end but nothing as severe as the drops to zero I've been seeing.
I'm assuming a swing of a couple of dB isn't anything to worry about??
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