ADSL Noise Margin High!

[HoriZon]

Hi all i'm new,

I had a lot of trouble with an old modem (DG834 v3) last week and got lots of disconnections as i was rebooting it a lot etc, bought a new modem a few days ago (newer DG834 v4) but now my noise level is so high its currently:

Connection Speed          5568 kbps          832 kbps
Line Attenuation          27.0 db         12.5 db
Noise Margin               17.3 db          10.0 db

I used to sync at 8128 kbps all the time with a Noise Margin around 6.0 db.

Never had any problems (other than it lowering my sync rate) on the old modem either it didnt disconnect it self at all, phoned idnet the other day and they said there was errors on the up stream which is the reason i got a new modem. They say this one isn't reporting any errors.

Being with idnet for over a year now but this is my first big problem, i know why its high because of all the rebooting but how long does it take to come back down or can i have it reset to a lower number manually??

Thanks

Mark

[Ted]

Hi all i'm new,

I had a lot of trouble with an old modem (DG834 v3) last week and got lots of disconnections as i was rebooting it a lot etc, bought a new modem a few days ago (newer DG834 v4) but now my noise level is so high its currently:

Connection Speed          5568 kbps          832 kbps
Line Attenuation          27.0 db         12.5 db
Noise Margin               17.3 db          10.0 db

I used to sync at 8128 kbps all the time with a Noise Margin around 6.0 db.

Never had any problems (other than it lowering my sync rate) on the old modem either it didnt disconnect it self at all, phoned idnet the other day and they said there was errors on the up stream which is the reason i got a new modem. They say this one isn't reporting any errors.

Being with idnet for over a year now but this is my first big problem, i know why its high because of all the rebooting but how long does it take to come back down or can i have it reset to a lower number manually??

Thanks

Mark

Hi Mark and welcome

I'm assuming that you were on "fastpath" with a sync of 8128, you may have been kicked back to interleaved because of all the disconnections. That will ultimately keep your sync rate lower.
I think its about 5 days for a profile rise and 14 days for the NM to be lowered, if it works

I believe IDNet can request that your NM can be lowered manually if you can convince them the problem is sorted. I'd give them a call.

[HoriZon]

I plan to give them a call as soon as they open on Monday to ask them just that.

I can find out what i am on now with some software but it eludes me which software that is now?

Spoke to a Simon yesterday about the noise level and he did say wait it out basically but i am so impatient tbh, it always used to be 8128 and you kinda get used to it

[Glenn]

  Mark   I believe what Ted has said is correct

[Simon]

Hi Mark, and

I believe IDNet can request that your NM can be lowered manually if you can convince them the problem is sorted. I'd give them a call.

I believe it's more a question of IDNet being able to convince BT to reset the NM, which has been more difficult of late, but it might still be worth a call.

[Rik]

Hi Mark and welcome.

I echo what the others have said, it's often a problem to get BT to reset NM unless they have a record of a cleared fault against the line.

[g7pkf]

Oh be patient most of us would die for stats like that 

10days is the norm.

Or on your knees and grovel to idneton monday.

[HoriZon]

Its not really a fault on the line per say just a fault with my old modem now thats sorted with the new one i want back what i had!!

Will find out if i'm on fastpath or interleaved later as i have remembered how to do it!

[Rik]

At this point, that has little impact, it's only when you get your sync speed back that it may matter. FYI, it's generally thought that 10 or more disconnections in an hour trigger the noise margin increase, so try to avoid too many reboots in a short space of time. If BT stick to the rules, you will need 14 days of stable connection before the margin drops by 3db, repeating again at 14 day intervals until you either reach 6db, or the line becomes unstable.

[Ted]

Hi Mark, and

I believe it's more a question of IDNet being able to convince BT to reset the NM, which has been more difficult of late, but it might still be worth a call.

"convince them" should have read "convince BT". I should have made that more clear.

[Rik]

I knew what you meant, Ted.

[Sebby]

I can't really add anything else that hasn't already been said.

[HoriZon]

Thanks for all the help guys.

One thing if i do request the interleaving to be changed to 'fast' (if its set wrong, not at home atm so cant test) do idnet charge for this as Nildram charged me to put it fast a few years ago???

[Ann]

No, there'll be no charge.    IDNet did this for me last year.  It lasted a couple of days before it suddenly went zap and was back to interleaved.  My line is obviously error prone and it needs to be interleaved for stability.  I was glad I'd tried it though but won't try again.

[HoriZon]

OK at home now and just used telent to find out about Interleaving and its back on!

Code Select Expand



BusyBox v1.00 (2008.03.20-02:06+0000) Built-in shell (ash)
Enter 'help' for a list of built-in commands.

# adslctl info --stats
adslctl: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 0
Channel: INTR, Upstream rate = 832 Kbps, Downstream rate = 5568 Kbps
Link Power State: L0
Mode:                   G.DMT
Channel:                Interleave
Trellis:                ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):       15.3            10.0
Attn(dB):       27.0            12.5
Pwr(dBm):       19.8            12.4
Max(Kbps):      6112            1144
Rate (Kbps):    5568            832
                        G.dmt framing
K:              175(0)          27
R:              16              16
S:              1               8
D:              32              4
                        ADSL2 framing
MSGc:           1               1
B:              175             27
M:              1               8
T:              1               1
R:              16              16
S:              1.0909          8.5714
L:              1408            224
D:              32              4
                        Counters
SF:             3255855         3255914
SFErr:          15              29
RS:             221398170               27674189
RSCorr:         3335            549
RSUnCorr:       113             0

HEC:            9               24
OCD:            0               0
LCD:            0               0
Total Cells:    726854659               0
Data Cells:     33681277                0
Drop Cells:     0
Bit Errors:     0               0

ES:             12              0
SES:            0               0
UAS:            21              0
AS:             55350

INP:            1.45            1.14
PER:            1.90            1.87
delay:          8.72            8.57
OR:             29.33           29.86

Bitswap:        0               0

Total time = 15 hours 23 min 4 sec
SF  = 3255855
CRC = 15
LOS = 0
LOF = 0
ES  = 12
Latest 1 day time = 15 hours 23 min 4 sec
SF  = 3255855
CRC = 15
LOS = 0
LOF = 0
ES  = 12
Latest 15 minutes time = 8 min 4 sec
SF  = 28497
CRC = 1
LOS = 0
LOF = 0
ES  = 1
Previous 15 minutes time = 15 min 0 sec
SF  = 52923
CRC = 0
LOS = 0
LOF = 0
ES  = 0
Previous 1 day time = 0 sec
SF  = 0
CRC = 0
LOS = 0
LOF = 0
ES  = 0
15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
SF  = 52923
CRC = 0
LOS = 0
LOF = 0
ES  = 0
15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
SF  = 52982
CRC = 0
LOS = 0
LOF = 0
ES  = 0
15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
SF  = 52923
CRC = 1
LOS = 0
LOF = 0
ES  = 2
Showtime Drop Reason:   0
Last Retrain Reason:    0
#
#

Always had this off before so its this i will ask to be turned off on Monday.

As for the NM it sorta come down a little now.

[karvala]

I think there is a bit of a misconception here about sync speeds and IP profiles.  Your sync speed is governed by your line length and quality, and is determined automatically each time you connect by the DSLAM at your exchange and your modem, in accordance with the target noise margin as set in your modem (which will be 6dB by default).  There is no artificial limit imposed on your maximum sync speed (except in the case of more than 10 disconnections within an hour, which can lead to increased target noise margin, but this rarely happens in practice); it's entirely a hardware and line quality issue.  It is not limited either by the IP Profile (see below), or the Maximum Stable Rate attained during the initial 10-day training period after a new connection is setup.

By contrast, your IP Profile is the actual data throughput rate, not directly visible in your router info anywhere, which IS governed by your recent connection history.  If your sync speed drops below the minimum amount for your current IP Profile, the profile will be changed to reflect the new sync speed.  If you then resync at a higher speed again, it can take anywhere from just over an hour, up to 5 days, for your IP Profile to catch up (with larger differences taking shorter periods of time).

You can see from that, that there is nothing profile-wise or ISP-wise or BT-wise that is currently preventing you from syncing at a higher rate, for which reason my first piece of advice would be for you to actually reboot your router.  The second observation would be that in terms of your IP Profile, it doesn't matter how many times you reboot in a given period (this is a common misconception), it only matters whether or not your ever sync below the speed required for the IP Profile you want to achieve.

My final and most significant observation would is that I'm afriad you probably still have an upstream noise problem on your line.  I say that simply because your upstream noise margin does not bear the correct relationship with your upstream line attentuation or your downstream noise margin; there is something on your line that is causing a substantial amount of additional upstream noise, and this is likely the reason that you are not syncing higher than you currently are (a reboot may allow you to sync a bit higher, which is why I think you should try it, but it may not be stable and it won't be much of an improvement).  IDNet haven't found any more upstream packet loss for you simply because at present you're syncing so low; you won't get back to your 8128 sync speeds, and correspoding 7150 IP Profile, however until that line noise is sorted out, and your packet loss will start again once your sync speeds start to increase again.

I'd suggest you run a line test, or get the line investigated by BT, or check your filters or with the faceplate off etc.; all the usual troubleshooting steps. 

[LesD]

in terms of your IP Profile, it doesn't matter how many times you reboot in a given period (this is a common misconception), it only matters whether or not your ever sync below the speed required for the IP Profile you want to achieve.

I would agree about reboots in a given time period or even power supply on/offs but it is the multiple disconnects that Rik referred to that should be avoided. I can speak from bitter experience after experimenting with my line about a year ago when simply removing the ADSL plug from the Modem/Router instead of powering off first too many times and ending up with an IP Profile of 135 kbps!  Yes and then waithing three days for it to recover.

It was explained to me at that time that if the line "fades away" like with a power off or a reboot it is not seen as a line fault by the BT kit but pulling the plug causes a sudden loss of connection to the exchange and is seen as a fault. Too many of these sort of disconnects in a certain time frame does have a detrimental effect on your Profile I can assure you.

[Rik]

On the subject of re-training and the 10 per hour trigger, take a look at section 8.5 of a BT PDF here.

[Ann]

That's a useful read, Rik, thanks. 

[Rik]

Handy, isn't it.

[Steve]

What upstream noise margin are we expecting? Mine with a similar attenuation is 29dB but I am only connecting at 448 and obviously looking at the figures a full downstream sync should be obtainable.

[Rik]

I'm not with you, Steve. Unless you're on Home SuperMax your u/s sync will be 448, and the NM will just depend on your line quality, but will usually be in the 20s.

[Steve]

O.K is there  a difference in the upstream noise margin depending on whether your on supermax or normal with the same attenuation.

[Rik]

Yes. On Max, my u/s margin was 21, on SuperMax, it's 9.

[Steve]

So does your lower upstream margin therefore become more susceptible to noise? and is it effected by similar dslam controls if a noise spike occurs? In the OP the lowest margin is the upstream which is the opposite to mine @ 29 up and 15 down.