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[Greybeard33]

Bumping this thread because the band plan has changed again, concurrent with a modem firmware update - see this post: http://forum.kitz.co.uk/index.php/topic,13041.msg246175.html#msg246175 .

[burakkucat]

Thank you. Every little bit of information helps. 

[Chrysalis]

on my line if the issue is crosstalk the tones affected the most are D1 and D2, D1 the worst.  D3 barely affected at all. 

When I had a 90mbit attainable my D1 had higher snr then D2 as one would expect and also higher bitloading, now crosstalk has made D1 and D2 almost equal.  Its D1 and to a lesser extenct D2 where my sync speed has been lost.

I think when people say crosstalk affects short lines more they rather mean crosstalk is the biggest issue for short lines as when attenuation is low external interferience has less affect.  I would expect vectoring to help all lines not just short lines but shorter lines will see bigger speed increases due to the fact they use more tones.

eg. even tho Greybeard33 has a longer line than me and cannot even use D3, his snr on D1 is comparable to mine as crosstalk has trashed my D1 signal. But my D2 is higher than his D2 and I have a D3.

I have not seen your stats, but are you sure the issue you have in D1 is caused by crosstalk from other VDSL2 lines, not just the power mask applied to your line at the DSLAM, up to Tone 512, to protect adjacent long ADSL2+ lines from crosstalk? Theory says that crosstalk increases with frequency, so the D3 band should be the worst affected if the source is another VDSL2 line.

My cabinet is actually closer to the exchange than to my house, so adjacent ADSL2+ lines presumably have a fairly strong signal and so the power cutback needed on my line may be less than on yours. I used to get 18Mb/s sync when I was ADSL2+ myself.

I am talking about the part of D1 that is outside the adsl1 frequency range, in my area the cutback isnt applied above 256.  I do have graphs from before my crosstalk and after. So I can see the affect it has had, both graphs have the cutback for adsl, but the cutback isnt the entire D1 range, its just a part of it.  The cutback tones on my line are actually almost 0 bitloading, it drops the signal a hell of a lot more than making it equal with D2 :p

[boe323]

how do you know what dslam your using, I always thought mine wasn't eci because of not having the eci modem. This is what I have foe dslam on my stats,
DSLAM/MSAN type:   BDCM:0xa415 / v0xa415
DSL mode:          VDSL2
Status:            Showtime
Uptime:            20 hours 22 min 31 sec
is that eci or the other one?
I think bandplan as been changed

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3971)

Oh yes of course, my dslam is Broadcom, not eci, DOH

Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3971)

[Greybeard33]

how do you know what dslam your using, I always thought mine wasn't eci because of not having the eci modem. This is what I have foe dslam on my stats,
DSLAM/MSAN type:   BDCM:0xa415 / v0xa415
DSL mode:          VDSL2
Status:            Showtime
Uptime:            20 hours 22 min 31 sec
is that eci or the other one?
I think bandplan as been changed

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3971)

Oh yes of course, my dslam is Broadcom, not eci, DOH

Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3971)

Yes, that is a Huawei DSLAM.

Your band plan is the same as mine was after the first change last month, which prompted me to start this thread. Since the second change last Friday morning, it is now:

Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3970)

The big change is to the U0 band, which has shrunk and no longer overlaps the D1 band. The other changes only affect a handful of tones at the boundaries of the other bands.

I experienced a drop in DS Max Attainable Rate and SNRM after the first change; since the second one (and concurrent modem update) they are back up to where they were originally. However, this could just be coincidence. My long line is somewhat noisy (capped at 40M, Trellis on, Interleaving ~700, INP 3, Delay 8ms) and there have been previous occasions when there has been a gradual loss of Max Attainable and SNRM, only for them to recover after a resync.

I think it will take weeks rather than days to judge the effect, if any, of these changes. Pure guesswork, but one possibility might be that they are in preparation for the introduction of vectoring?

[boe323]

Ah, sounds like my line, im pretty far from my can also, nearly the limit i think, im only expected to recieve 30meg, but my attainable rate is 61, sync rate 52, so im lucky. Does that mean then i should expect another change to the dslam?.

[Chrysalis]

greybeard which changes are big depends on the line.

On my line those handful of tones you speak of account for about 4.8mbit of my sync speed on D3.

Whilst the D1 changes due to adsl power cutback I expect will gain me 2-3 mbit at the most.  Its also possible the D1 changes have no gain, as with it been shared it may already be used by downstream.  I expect on lines unable to get 20mbit upstream sync the shared is used by upstream, on lines that can get 20mbit upstream without its used by downstream.

[Greybeard33]

greybeard which changes are big depends on the line.

On my line those handful of tones you speak of account for about 4.8mbit of my sync speed on D3.

Whilst the D1 changes due to adsl power cutback I expect will gain me 2-3 mbit at the most.  Its also possible the D1 changes have no gain, as with it been shared it may already be used by downstream.  I expect on lines unable to get 20mbit upstream sync the shared is used by upstream, on lines that can get 20mbit upstream without its used by downstream.

You should count yourself lucky! In the first change D3 gained 12 tones, in the second it lost two and D2 lost two, so that is still a net gain of 8. In my case I have just lost the top two tones of D2 (admittedly only carrying one bit each), without any gain. My US sync has only dropped by about 0.2M, despite U0 losing 7 tones and U1 5, so I suspect the shared tones were being used for DS anyway.

[burakkucat]

DSLAM/MSAN type:   BDCM:0xa415 / v0xa415

BDCM == Broadcom, which implies a Huawei SmartAX MA5616 MSAN. 

[Chrysalis]

greybeard which changes are big depends on the line.

On my line those handful of tones you speak of account for about 4.8mbit of my sync speed on D3.

Whilst the D1 changes due to adsl power cutback I expect will gain me 2-3 mbit at the most.  Its also possible the D1 changes have no gain, as with it been shared it may already be used by downstream.  I expect on lines unable to get 20mbit upstream sync the shared is used by upstream, on lines that can get 20mbit upstream without its used by downstream.

You should count yourself lucky! In the first change D3 gained 12 tones, in the second it lost two and D2 lost two, so that is still a net gain of 8. In my case I have just lost the top two tones of D2 (admittedly only carrying one bit each), without any gain. My US sync has only dropped by about 0.2M, despite U0 losing 7 tones and U1 5, so I suspect the shared tones were being used for DS anyway.

remember the before and after stats you posted?

the before stats had the same sync speed but a very low snr margin.
the after stats you had the same sync speed but a snr margin above 6db (meaning you gained 3db worth of snr from the change) and your attainable jumped by 7mbit.

I think you just looked at your sync speed and ignored the rest.

[boe323]

Since my bandplan change my DS snr is terrible, I could drop right down to 3db from 6.5 in evenings now, as before the change my snr would hardly bugde, maybe drop 1.5db.

[Greybeard33]

remember the before and after stats you posted?

the before stats had the same sync speed but a very low snr margin.
the after stats you had the same sync speed but a snr margin above 6db (meaning you gained 3db worth of snr from the change) and your attainable jumped by 7mbit.

I think you just looked at your sync speed and ignored the rest.

Humph! Well, since then there has been another resync (at 8am on Sunday morning!). Retrain Reason 1, RDI Detector (Remote Defect Indication), which I have never seen before. INP has gone up from 3 to 8, Delay from 8 to 16 and Interleaving Depth from 701 to 1557, while DS sync has dropped from 39998 to 37126. These are about the worst stats I have ever seen, except when I had trouble with REIN last Christmas. Although US sync has actually increased from 7752 to 7832, so perhaps I should be grateful for small mercies!

The DS daily error rates do seem to have got much worse, so DLM seems just to be doing its job. I suppose it is possible the line has suddenly got noisier, but it seems rather a coincidence that this should happen just after the DSLAM and modem changes....

Edit: Having just looked again at the "Broadcom retrain codes" thread, Retrain Reason 1 becomes LOS Detector (Loss Of Signal), if you buy Asbokid's "bitwise left shift" interpretation of the codes, i.e. 2^0=1.

[NewtronStar]

Since my bandplan change my DS snr is terrible, I could drop right down to 3db from 6.5 in evenings now, as before the change my snr would hardly bugde, maybe drop 1.5db.

same here it was steady at 6db in the evening but now going below 4.4db and thats since the firmware update on modem and my interleaving Depth has gone from 455 before update last friday to 1215 so what is this new BandPlan and what is it for and it's not working and it's making things worse for me anyway.....

[Chrysalis]

greybeard I will post my bitloading so you can see how bad my adsl power cutback is, yours seems mild in comparison. Also note how weak my D1 is.  Which considering your line is longer is odd.  I also found a line on the btcare forums, that guy has almost no power cutback at all, barely a dent in his D1.

here is the link.

Also I now posted how my bits and snr looked in dec 2012. Even back then the power cutback was removing approx 15mbit of attainable sync.  Some people seem to be barely losing 5mbit from the cutback.  Also if you remember my earlier comment ref crosstalk, you can see my D3 is least affected by it.

http://community.bt.com/t5/BT-Infinity/Compare-Graph-stats-please/m-p/1044242/highlight/true#M113165

[Ronski]

Since my bandplan change my DS snr is terrible, I could drop right down to 3db from 6.5 in evenings now, as before the change my snr would hardly bugde, maybe drop 1.5db.

same here it was steady at 6db in the evening but now going below 4.4db and thats since the firmware update on modem and my interleaving Depth has gone from 455 before update last friday to 1215 so what is this new BandPlan and what is it for and it's not working and it's making things worse for me anyway.....

Am I starting to see a pattern here, our connection at work has also deteriorated since the modem update, interleaving now being at  1429. See my thread here. Things turned bad yesterday, but the modem updated towards the end of last week.