A Chronicle of My Migration and Problems

[#1]

The odd thing today is that the noise margin has gone up, not down.
Last night, it was varying between 11 and 13, today it's at 14.
DSL Status:   Up     
      DSL Modulation Mode:   ADSL2+     
      DSL Path Mode:   INTERLEAVED     
      Downstream Rate:   8476 Kbps     
      Upstream Rate:   1052 Kbps     
      Downstream Margin:   14 db     
      Upstream Margin:   6 db     
      Downstream Line Attenuation:   30     
      Upstream Line Attenuation:   15     
      Downstream Transmit Power:   0     
      Upstream Transmit Power:   0
Transmission rates are still poor though:

Graham

[#2]

Noise margin going up is good, since it means the noise level has gone down. Could you check the noise margin around the same time as when you posted the stats last night (11PM)? I think it best not to re-sync at the moment (so as not to confuse the DLM), but if you did while the margin is at 14dB, sync speed should increase by a few hundred kbps.
Throughput could be poor at the moment since Mondays are one of the busiest nights and there are major problems due to a cable fault in the Ilford area that is affecting Plusnet broadband capacity.
David

[#3]

As the evening has passed the noise margin has fallen.
The BT Speedtest gave me a result of only about 650 kb. It wanted to perform a second test, (speedtest_domain etc) but this router won't permit that as it expects a password with the logon. The IP rate had been reduced to 3500.
Here's the history for the last few days:
Date Download Speed Upload Speed 
Today 21:43 3196 kbps (400kB/s) 685 kbps (85.6kB/s) Share
Today 21:13 3192 kbps (399kB/s) 686 kbps (85.8kB/s) Share
Today 21:09 3198 kbps (400kB/s) 686 kbps (85.8kB/s) Share
Today 19:32 3198 kbps (400kB/s) 681 kbps (85.1kB/s) Share
Today 19:31 3197 kbps (400kB/s) 675 kbps (84.4kB/s) Share
Yesterday 23:44 3201 kbps (400kB/s) 892 kbps (112kB/s) Share
Yesterday 22:50 3199 kbps (400kB/s) 889 kbps (111kB/s) Share
Yesterday 22:49 3198 kbps (400kB/s) 875 kbps (109kB/s) Share
Yesterday 20:18 3383 kbps (423kB/s) 892 kbps (112kB/s) Share
Yesterday 20:17 3384 kbps (423kB/s) 893 kbps (112kB/s) Share
Yesterday 17:13 3384 kbps (423kB/s) 889 kbps (111kB/s) Share
Yesterday 16:55 3382 kbps (423kB/s) 891 kbps (111kB/s) Share
Yesterday 14:34 3652 kbps (457kB/s) 901 kbps (113kB/s) Share
Yesterday 11:39 3655 kbps (457kB/s) 904 kbps (113kB/s) Share
Yesterday 11:38 3650 kbps (456kB/s) 903 kbps (113kB/s) Share
Yesterday 00:47 3646 kbps (456kB/s) 921 kbps (115kB/s) Share
Saturday 22:56 3639 kbps (455kB/s) 911 kbps (114kB/s) Share
Saturday 22:47 3650 kbps (456kB/s) 908 kbps (114kB/s) Share
Friday 22:55 3649 kbps (456kB/s) 915 kbps (114kB/s) Share
Friday 22:55 3645 kbps (456kB/s) 903 kbps (113kB/s) Share
Friday 01:18 1827 kbps (228kB/s) 937 kbps (117kB/s) Share
Friday 01:17 1826 kbps (228kB/s) 931 kbps (116kB/s) Share
Wednesday 22:15 3205 kbps (401kB/s) 926 kbps (116kB/s) Share
Wednesday 22:15 3197 kbps (400kB/s) 925 kbps (116kB/s) Share
Wednesday 22:12 3198 kbps (400kB/s) 915 kbps (114kB/s) Share
Wednesday 21:36 3195 kbps (399kB/s) 657 kbps (82.1kB/s) Share
Wednesday 00:38 3125 kbps (391kB/s) 897 kbps (112kB/s) Share
Wednesday 00:31 3144 kbps (393kB/s) 904 kbps (113kB/s) Share
Wednesday 00:30 3160 kbps (395kB/s) 907 kbps (113kB/s) Share
Wednesday 00:20 2986 kbps (373kB/s) 900 kbps (113kB/s) Share
Here are a couple of captures from RouterStats Lite:

[#4]

If your IP Profile has reduced to 3500kbps you must have had a re-sync in the speed range 4000-4543kbps. Whether that is due to problems specific to your line or associated with the BT network outage referred to in the Service Status here, or both, is uncertain. I suggest seeing what the situation is like when BT repairs have been completed and Plusnet's network status returns to normal.
Your current speedtests show throughput just under 3200kbps which is consistent with a profile of 3500kbps. Repeated speedtests don't really tell us much until whatever the problem is gets fixed and the sync rate remains steady.
The plots show noise margin during the later part of the evening is approaching what appears to be the 12dB target value.
I'm not sure if Part 2 of the BT Performance Test will contribute anything, but you can enter any password you like (e.g. test), it ignores what you enter.
David

[#5]

No, I am not aware of any resync.
Last night it was as solid as a rock at 8476 Kbps.
Tonight, it;s sync'd at 8228 Kbps.
When you say "target" of 12db for the noise margin - is this a "minimum" target or a "maximum" target?
In other words, do I want to see this figure less then 12 or more than 12 for a "good line"? 
According to the Kitz website I should (as a guide) be looking at the following speeds:
Downstream Attenuation  30dB
Approx Line Length   2.17 km
       

       
dslMAX  7904 kbps    IP Profile   6500 kbps
       
adsl2+ (21CN)  15264 kbps     IP Profile  13000 kbps
       
adsl2+ (LLU)  15264 kbps       Throughput  13509 kbps

I also got my router to tell me a bit more - there don't seem to be any HEC errors:
Item Value
ADSL Line Type ADSL2+
ADSL Line CodingADSL Line Coding INTERLEAVED
Line Attenuation (Down):30  (Up):15
Noise Margin (Down):14  (Up):6
Total Output Power (Down):0  (Up):0
Current State DownStr: 8228(K)  UpStr: 1075(K)
undefined UP
FEC(FAST) (Near):0  (Far):0
FEC(INTERL) (Near):0  (Far):21896
CRC(FAST) (Near):0  (Far):0
undefined (Near):0  (Far):137
HEC(FAST) (Near):0  (Far):0
HEC(FAST) (Near):0  (Far):0
Showtime last(sec) 19717
ADSL FW Version 0.54
ADSL Board Type Annex A

[#6]

The target noise margin is the minimum to be achieved when the router is syncing. The normal default target noise margin is 6dB but the DLM can increase it as one of the tools in its armoury to try to stabilise a connection that drops frequently, or where there are an excessive number of transmission errors. Increasing the target noise margin causes the sync speed to reduce.
The DLM on the 21CN appears to be more responsive than the old network one and if you maintain a solid connection with few errors for several days the target noise margin should reduce. That would increase your sync speed.
Can you get bit loading from your router using the telnet interface? One can plot that using e.g. MS Excel. More conveniently DMT would give a plot it but I'm not sure if it works with your router. More information on Kitz's website. The bit loading plot gives a view of how well your connection is performing.
David

[#7]

Things seem to be moving in the right direction,,,,,,,,,,,

The router is sync'd at 8228 again tonight. Just wish I could get a better Noise Margin perhaps 
The above download result is about 1.3 Mbps higher than I was getting on ADSL with the D-Link-G604T.
The router doesn't seem to want to telnet - the first "black screen" appears and then disappears. I don't think DMT will work either, but I guess I could download it and give it a try.
Graham

[#8]

When you say "The router is sync'd at 8228 again tonight", what causes it to re-sync? Do you turn it off overnight, or is it just a manual restart?
If you can leave the router connected for 3-4 days, and the connection doesn't drop it is possible the DLM will reduce your target noise margin. I believe it forces a re-sync if it does, so no need to keep trying manual re-syncs.
The noise margin behaviour shown on the plot looks OK to me.
David

[#9]

The point I was trying to make was that tonight it is 8228
Last night it was 8228
The night before it was more  - 8467 I think.
The router is left powered on, but the PC isn't., so I can't monitor when the speed changed.
If I can persuade "her indoors"      to let me burn a bit more electricity, I may leave the PC on for a night or two over Easter and see what happens during the "quiet periods".
Graham

[#10]

Thanks, my interpretation was rather adrift.
Does your router give you the WAN uptime, that should be the time since last sync?
David

[#11]

Unfortunately, the router is a little secretive about what is happening.
Howver, I have found a tip on the web to access some info via the "back door" which gives:
ADSL Line Type ADSL2+
ADSL Line CodingADSL Line Coding INTERLEAVED
Line Attenuation (Down):30  (Up):15
Noise Margin (Down):14  (Up):6
Total Output Power (Down):0  (Up):0
Current State DownStr: 8228(K)  UpStr: 1075(K)
undefined UP
FEC(FAST) (Near):0  (Far):0
FEC(INTERL) (Near):0  (Far):225345
CRC(FAST) (Near):0  (Far):0
undefined (Near):0  (Far):1514
HEC(FAST) (Near):0  (Far):0
HEC(FAST) (Near):0  (Far):0
Showtime last(sec) 202411
ADSL FW Version 0.54
ADSL Board Type Annex A
This suggests 202411 seconds which is about 56 hours.
BTW, neither DMT nor OrbMT will run on this router.
If anyone knows of a similar tool that will talk to the Linksys AG241v2, let me know.
Just in passing, the Routerstats log for tonight gave an unusual result (for me anyway)....
When first switched on the PC, the Noise Margin was rock steady at 15db.
Later (about 2.5 hours later) a few spikes appeared.
Later still, things went back to "normal" with lots of changes in the margin.
See images below.

[#12]

Good spot that the Showtime last line gives the WAN uptime.   The change in value between your two posts of those stats is consistent with the time difference and suggests the restart occurred on Tues 07/04/2009 around 4PM.
A faulty line card in a 21CN core router in Sheffield was replaced by BT that day, so it's possible the re-sync occurred as a result of that.
The apparent steady noise margin in your noise margin plot during the day is normal. Your router only displays the value as a whole number so typical variations of +/- 0.25dB will not show. After dark a larger variation is normal, though yours seems on the large size (mine is +/- 0.5dB, though with smaller changes in successive samples). It does seem to get lively though later on. Is there any noticeable interference on your AM radio at these times?
Despite the spikes the noise margin seems more than adequate and I'm hopeful the DLM might reduce your target noise margin to 9dB in another 24 hours.
David

[#13]

Well, I guess I should have seen it coming..........
My line is so noisy today that at first I could only sync at 675 and then 1210 downstream.
After a reboot of the router, it managed to crawl back up to about 4600 and then dropped to 3678.
Noise margin is having some huge spikes down to a figure of -6db (yes. minus 6) and up to 17db.
The line is so noisy that I can hear the crackling over the phone.
Just what you need to happen over a Bank Holiday weekend 
However, looking on the bright side, if my line was "just waiting to fail" (and hence all the "noise" on the ADSL2+ line), then maybe when the line is fixed next week sometime, I might get the speeds I should be getting 
Graham

[#14]

Crackling over the phone is "good" news, it means a voice fault which your phone service provider (is that BT?) should attempt to fix. It is important that there is no broadband fault outstanding when a voice fault is reported and mentioning any broadband fault is to be avoided. However do check that the crackling doesn't go away if you turn off your router then unplug it from the phone line - and check with a corded phone if possible.
Have you by any chance had a lot of rain overnight and today?
Assuming your provider is BT I think 151 is the number to call 24x7. The recommendation is to avoid the automated tests, speak to an adviser and if you can call when noise is present that's ideal - ask them to record they can hear it. However do mention it is intermittent. You could be asked if you've tried using the test socket, which of course you don't have. You might be able to get an NTE5 master fitted free as part of fault diagnosis if you ask the technician (a liberal supply of tea and biscuits might help).
I think you are right to be hopeful that fixing the voice fault should resolve broadband speed problems. Fingers crossed…
David

[#15]

Well, I did phone BT today, and the noise on the line was present at the time.
They did a line test and said that the line was OK 
Of course, then they go down the path of "disconnect all your extensions" and "try a different phone".
So, I've disconnected the extension wiring and the noise is not there.
But of course, this is an intermittent fault and it might have gone away all by itself, whether I disconnected the extensions or not.
I guess I will have to see what happens with the extensions left isolated.
BT is supposed to call me back between 16.00 and 18.00 today to see how things are.
The line has re-synced itself at 8894 Kbps and noise margin is now staedy at 15db.
Unfortunately, because of all the noise problems, BT has dropped the profile to 500K.
Here's the latest speedtest - and upload speed is faster than download