Resetting of Noise margin

[Wingnutz]

Thanks to James @ IDnet and with some advice from Rik I managed to get my noise margin reduced to 9db on Monday this week - sync's increased nicely to over 5500kbps.

On returning home today my margin has jumped back to 15db and once again i am sync'ing under 4000kbps.

Now according to my router diagnostic's (it's a 2700hg) i have the following two events

INF  2008-01-14T10:33:24Z  sys:  dsl0: connection lost, reconnecting...
INF  2008-01-16T10:32:20Z  sys:  dsl0: connection lost, reconnecting...
The first one is Monday when the margin was reduced by BT the second almost exactly 48 hours later seems to be the one pushing me back to 15db.

Is this just a coincidence or do you think BT only gave me the 9db on a 48 hour trial. I've logged it with James via e-mail and hope he can sort it for me.

[Sebby]

This is very strange in that it's almost identical to what was happening to me when my margin was reset to 6dB last week.

Every time I checked the router, my SNRM was at a solid 6dB, if not higher, so I knew there was no stability issue. But at around the 48 hour mark, my 2Wire resync'd and my target SNRM had gone up to 15dB.

I contacted IDNet again and surprisingly BT agreed to reset it for a second time. However, exactly the same thing happened 2 days later.

When I contacted IDNet for a third time, they contacted BT, and told me that the DLM was increasing my target SNRM to 15dB due to a high number of errors. It made me wonder if the DLM will increase a margin if a certain number of errors occur in a 48 hour period. It's certainly not something I've heard about in the past, but it appears to be the case.

BT agreed to reset my margin, but to 9dB this time. At the time of writing, I've been sync'd for 47.5 hours, so I'm watching things very closely.

I'm wondering if 9dB is still too low for your line and you should see if you can try 12dB.

I have to admit it does seem strange that we're both using 2700s and have had exactly the same issue, though I don't see how a router could cause the DLM to increase the target SNRM.

Anyhow, I'll let you know if I pass the 48 hour mark; if I do, I think it's fair to say that errors probably were the cause of the DLM kicking in.

[Wingnutz]

ATM      Since Reset      Current 24-Hour Interval      Current 15-Minute Interval      Time Since
Last Event
Cell Header Errors:      3057      206      0      0:05:41
Loss of Cell Delineation:      831      100      0      0:26:15

DSL                        
Link Retrains:      8      3      0      1:35:07
DSL Training Errors:      1      0      0      5 days 1:51:21
Training Timeouts:      0      0      0      0:00:00
Loss of Framing Failures:      6      2      0      8:36:22
Loss of Signal Failures:      6      2      0      8:36:22
Loss of Power Failures:      0      0      0      0:00:00
Loss of Margin Failures:      6      2      0      8:36:22
Cumulative Seconds w/Errors:      1388      105      0      0:05:41
Cumulative Sec. w/Severe Errors:      16      2      0      8:36:22
Corrected Blocks:      184477      2870      4      0:00:03
Uncorrectable Blocks:      3301      220      0      0:05:41
DSL Unavailable Seconds:      323      62      0      1:34:50
ISP Connection Establishment:      5      N/A      N/A      6 days 10:41:49

Sebby,


these are stats collected by the router over the last 6 days - do the errors look high to you ?

Mike

[Sebby]

No, they don't look high at all, but then neither did mine. Interestingly, the errors reported by my 2Wire is significantly less than what was reported on my old SpeedTouch 585v6, so it may well be that the 2Wire is inaccurate.

I've now been sync'd for over 48 hours, so it looks like the increase to 9dB has sorted it for me. Like I said, I'd see if you can get IDNet to convince BT to increase yours to 12dB.

[Wingnutz]

Update -

James has spoken to BT who are under the impression that my exchange should still be negotiating my connection at a 9db margin. He's asked me to double check what my router is reporting and get back to him.

Mike

[Sebby]

Ah, well that's slightly positive; at least it's been acknowledged that something's not quite right. I must say I'm amazed at the decent responses IDNet are able to get out of BT, and how quickly they get them too.

[Wingnutz]

Sebby,

does seem strange that BT still think I'm on a 9db margin. Last night both the router and RouterStats were showing it at 15db with flucuations of 1db either side from around 6pm until 10pm. Shame I didn't save them and include them in my e-mail to James - that's now one for tonight.

Mike

[Rik]

BT have two hands, a left and a right. They are often not connected to the same body! 

[Sebby]

I think it's almost fair to say that if the router is reporting 15dB, then that is the case, and something is wrong at BT's end.

It makes me wonder how many users have similar problems and don't know. Whilst the DLM does a good job of keeping connections stable, it's far from perfect.

[Rik]

It makes me wonder how many users have similar problems and don't know. Whilst the DLM does a good job of keeping connections stable, it's far from perfect.

And many ISPs will be of no use whatsoever in diagnosing and fixing such problems.

[Sebby]

And many ISPs will be of no use whatsoever in diagnosing and fixing such problems.

Absolutely. Can you imagine trying to get an ISP like Pipex to look into this? They'd neither understand what you're talking about nor care. It doesn't bear thinking about. 

[Wingnutz]

And many ISPs will be of no use whatsoever in diagnosing and fixing such problems.

Agreed, the helpful and speedy way IDNet deals with these matters is a real eye opener. If only other companies could follow suit.

[Rik]

They could, if they were prepared to invest in customer service. That they don't, and still survive, is an indictment of the great British public, who are clearly prepared to buy cheaply in preference to well.

[Sebby]

We should consider, though, that IDNet can do it because they are small. If they were big, Simon and Tim couldn't look into everything personally, and this is the downfall of the larger ISPs. I guess that to an extent, IDNet have made the decision to stay a certain size, whilst the bigger ISPs have got to a particular size because that's where they wanted to be. I've kind of argued against myself here, come to think of it...  

[Rik]

I don't fully agree with you, Sebby. I think that Simon and Tim have defined the ethos for IDNet, but they have also been prepared to invest in having enough support staff to carry that throughout the company. As the company gets bigger, so does the support staff, so that the same standards can be maintained even if Simon and Tim are not directly involved themselves.

The key issue is that they want to provide a quality service, regardless of the customer base.

[Sebby]

Point taken. It just seems that at the moment, their size allows them to offer such a great service. If they were to get dramatically bigger, even taking on more staff doesn't guarantee the same good service. Sure, they'll be trained up better than at some of the big ISPs, but can it be the same? Will employees (i.e. not directors) care quite as much as Tim and Simon do? It's the issue that most businesses face these days (in my eyes, certainly).

[Ted]

Hi Wingnutz
Here are my stats for the last 8 days. Yours do look considerably higher than mine, at the moment my NM is 11db

[attachment deleted by admin]

[Sebby]

You will get fewer errors with a higher SNRM. Yours are low considering you've been sync'd for 8 days, xild; Wingnutz's aren't high, though.

[Rik]

Will employees (i.e. not directors) care quite as much as Tim and Simon do? It's the issue that most businesses face these days (in my eyes, certainly).

There must come a point at which the influence of the owners/directors is not enough to ensure that staff do the job to the desired standard. Hopefully, though, not for some time.

[sabre2]

Now I'm confused. I thought that for the SNRM figure, a *higher* number was better? And that it wasn't something that was 'set' anywhere, it was just reporting what it found on the line?

Can someone point me to an explanation?

John

[Rik]

Hi John

Before Max, higher was better. However, Max starts out with a target noise margin of 6db, and then tries to drive your line as fast as it can. If the line is unstable, the target margin will be increased in increments of 3db until stability is achieved (interleaving will also probably be applied).

Prior to Max, your router negotiated a connection at a fixed speed and the noise margin varied according to line quality. Now, your router negotiates a connection at a fixed noise margin and the speed varies. There is often, though, a variation in noise margin over a period which, if severe enough, may force the router to lose the connection and re-sync.

[Sebby]

Just to add to what's already been said...

Higher is better. As Rik says, Max tries to achieve the higher sync by trying to sync at an SNRM of 6dB, whereas with the old fixed rate products, BT did a line test first see if your line would be capable of sync'ing at the fixed rate.

Of course, with Max, if you have a particularly good line, the SNRM won't have to go as low as 6dB in order to achieve full sync anyway.

[sabre2]

Ah, so the fact that my SNRM hover around 6dB is by design? That's reassuring!

John

[Rik]

Indeed, John. Six is where it should be, but you might see that figure drop by 1-2db after dark, as RFI noise increases. OTOH, if you re-sync at night, you might see the figure increase during the day.

[Wingnutz]

OK back home and it appears that i've had another re-sync event during the day

INF  2008-01-17T09:46:42Z  sys:  dsl0: connection lost, reconnecting...

Speed is now back up to 5600kbps and the margin is showing steady at 7db.

Strangly enough this event is timed around the time that James e-mailed me back to say that BT had no idea what was wrong as my line was still showing a target of 9db.

Hmmmmm - BT and it's left hand / right hand .....

Mike