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Author Topic: Vectoring enabled (or not)  (Read 24201 times)

kitz

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Re: Vectoring enabled (or not)
« Reply #15 on: March 16, 2016, 12:25:59 AM »

Quote
Connection speed 107999  VDSL2 Profile 17a

As an aside I thought the theoretical max speed for VDSL2 was 100Mbps.

I was beginning to think I was being stupid, so I went and double checked.  According to ITU G.993.2 specs it is indeed 100Mbps -  max power 14.5dBm

Quote
but I haven't see any improvement in terms of SNRm or max attainable rate:

I wondered if you are lucky enough not to have any crosstalkers...  then I saw this "I had an higher "max attainable rate" (125mbit, now 110mbit)".   
Can you recall your sync speed when you had the 125Mbps max rate?


Out of interest what are your Band Plans (Medley)   eg from the pbParams tab

Code: [Select]
Discovery Phase (Initial) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (33,857) (1218,1959) (2795,4083)
Medley Phase (Final) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (41,857) (1218,1959) (2795,4083)
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loonylion

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Re: Vectoring enabled (or not)
« Reply #16 on: March 16, 2016, 12:27:40 PM »

Quote
Connection speed 107999  VDSL2 Profile 17a

As an aside I thought the theoretical max speed for VDSL2 was 100Mbps.

I was beginning to think I was being stupid, so I went and double checked.  According to ITU G.993.2 specs it is indeed 100Mbps -  max power 14.5dBm

I thought 250Mbps. Wonder where I got that from.
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Ronski

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Re: Vectoring enabled (or not)
« Reply #17 on: March 16, 2016, 01:28:34 PM »

I thought it was 150 Mbps,  didn't someone run some tests with their own equipment.
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gt94sss2

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Re: Vectoring enabled (or not)
« Reply #18 on: March 16, 2016, 02:14:03 PM »

I thought 250Mbps. Wonder where I got that from.

Hmm,  you're never not alone - I thought VDSL2 had a theoretical maximum of 250 Mbit/s as well..
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Dray

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Re: Vectoring enabled (or not)
« Reply #19 on: March 16, 2016, 02:21:50 PM »

Only theoretical though
Quote
The 17MHz VDSL2 profile (17a) uses 4095 tones, with an effective symbol rate of 4kHz. This gives the following total system capacity: 4000 DMT symbols/s * 4095 tones/symbol * 15 bits/tone = 246Mbps to be shared between the two directions.
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ejs

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Re: Vectoring enabled (or not)
« Reply #20 on: March 16, 2016, 02:59:35 PM »

Quote
Connection speed 107999  VDSL2 Profile 17a

As an aside I thought the theoretical max speed for VDSL2 was 100Mbps.

I was beginning to think I was being stupid, so I went and double checked.  According to ITU G.993.2 specs it is indeed 100Mbps -  max power 14.5dBm

In "Table 6-1 – VDSL2 profiles" of G.993.2, the 100Mbps for profile 17a is the minimum maximum speed that the equipment needs to be capable of (upstream+downstream).
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kitz

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Re: Vectoring enabled (or not)
« Reply #21 on: March 16, 2016, 05:34:52 PM »

Indeed whilst 17a may have a total of 4095 tones.. Its split between upstream & downstream and its the 'Annex' which defines which tones are used for what direction.  (We dont use U3 and U4)

As with adsl, some tones arent in use at all. Prime example being the guard bands  (eg 858-881 & 1194-1217 etc which are between D1-U1 & U1-D2 etc respectively). 

Then theres also such things as PCB and PSD masks which ensure that it is impossible to load 15 bits at certain tones.

This is why I was specifically interested in seeing the Band Plan/Medley figures.  I'd already checked the Annex (B) and profile (17a)

It would also be interesting to see a bit loading graph to see if there is any obvious power cut back at certain tones.  Vectoring is supposed to help crosstalk..  and the main reason for PCB is to prevent crosstalk, so I wondered if made any difference.. although I doubt it as there will still be the likely-hood of other technologies such as adsl/adsl2+ being available in the same bundle.
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kitz

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Re: Vectoring enabled (or not)
« Reply #22 on: March 16, 2016, 05:37:01 PM »

Quote
the 100Mbps for profile 17a is the minimum maximum speed that the equipment needs to be capable of (upstream+downstream).

Thanks ejs.   I had seen 100Mbps mentioned elsewhere too, which is why I had that figure in my head -    such as wikipedia
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Ramino

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Re: Vectoring enabled (or not)
« Reply #23 on: March 17, 2016, 03:25:47 AM »

Is G.INP on the upstream set to enabled as standard in Italy ?

Yes

I thought so the UK must be the only country in the world that has it disabled as standard  ::)

Why does the G.INp on upstream is disable by default in UK?
I remember there were some issues with Lantiq for the G.INP on upstream till the end of 2014, but now the problem has been fixed with the new xdsl driver. I got a Draytek 2860NPlus also, and the first firmware with G.INP fully operable came out on March 2015.  ::)
Maybe some UK ISP are providing modem-router equipped with lantiq chipset?


So do you think that G.Vector is really working or not? How much improvement did you see on your line since Vectoring has been enabled?


It seems like it is enabled but I'm not aware why you don't see an improvement. If you post your qln-graph maybe someone can say something to the crosstalk on your line. Probably you don't have any disturbers or their hardware isn't vectoring capable and still generating noise.

On my line 2 weeks ago g.inp and vectoring was enabled and the speed increased a bit.


The improvement depends on how much crosstalk can get cancelled.
My ISP made tests to show how much speed can be recovered with vectoring.


Hi, thank you very much for the respose.

These are my QLN and Hlog.

QLN: http://i.imgur.com/Uoakcq8.png
Hlog: http://i.imgur.com/rNwdh05.png

As for the hardware I think the majority of pepole here are using the modem provided by the ISP. Its a Technicolor equipped with the same broadcom chipset [BCM63168] as the Zyxel (with vectoring support).
Furthermore, I think that almost all devices would support G.Vector properly by now in 2016 , theoretically at least. :)

I would add another detail: with the Draytek 2860N+ I've tried to disable the G.Vector and I did notice that using some old modem codes I cannot even sync with the cab anymore, maybe because the modem its not recognized as "vectoring friendly". Instead, with some newer modem codes I can sync even without Vectoring.
So i think all the connected lines must be vectoring friendly at least, and consequently their crosstalk should be addressed.

Anyway I wonder what the "error samples" are reffering to. Samples of what? The condition of the line that serves the DSLAM to remove the crosstalk?
 

Quote
Connection speed 107999  VDSL2 Profile 17a

As an aside I thought the theoretical max speed for VDSL2 was 100Mbps.

I was beginning to think I was being stupid, so I went and double checked.  According to ITU G.993.2 specs it is indeed 100Mbps -  max power 14.5dBm

Quote
but I haven't see any improvement in terms of SNRm or max attainable rate:

I wondered if you are lucky enough not to have any crosstalkers...  then I saw this "I had an higher "max attainable rate" (125mbit, now 110mbit)".   
Can you recall your sync speed when you had the 125Mbps max rate?


Out of interest what are your Band Plans (Medley)   eg from the pbParams tab

Code: [Select]
Discovery Phase (Initial) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (33,857) (1218,1959) (2795,4083)
Medley Phase (Final) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (41,857) (1218,1959) (2795,4083)

Hi, my Band Plans are the following:



What do you think about it? Are there some remarkable differences from yours or is it almost identical?

When I had 125mbit of attainable the sync speed was the same.
We have currently 2 profile: 50\10 and 100\20 and the bitrate respectively are: 54000*10800 and 108000*21600, so 108000 is the maximum for downstream. :)
Regarding the max speed, as someone already suggested in real pratice its a bit higher than 100mbit.

Anyway, someone knows the commad to disable the G.Vector with a broadcom modem? I would try to see which number I get without Vectoring.
I've tried xdslctl configure --vectoring off but it does not work.

[Moderator edited to adjust the links to the QLN & Hlog plots.]
« Last Edit: March 17, 2016, 04:41:46 PM by burakkucat »
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NewtronStar

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Re: Vectoring enabled (or not)
« Reply #24 on: March 17, 2016, 11:39:14 PM »

Your Band Plans are definitely a Huawei MSAN and you are able to use all tone available to you as seen in the Medley Phase (Final) Band Plan you must be like 100 meters from the FTTC cabinet  :-\
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Bald_Eagle1

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Re: Vectoring enabled (or not)
« Reply #25 on: March 18, 2016, 06:53:14 AM »

There seem to be a couple of significant differences regarding band plans, not least the use of the U3 band (although the QLN & Hlog graphs don't actually show any data for it).


UK ECI DSLAM:-

Discovery Phase (Initial) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (33,857) (1218,1959) (2795,4083)


UK Huawei DSLAM:-

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

or:-

Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3950)


Ramino (probably Huawei):-

Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2783) (2784,3107)
DS: (33,859) (1216,1961) (3256,4071)


I wonder if any of Ramino's U0 band is actually used for bitloading. I thought that was mainly a UK thing to help with the typically longer distances from the cabinets.
« Last Edit: March 18, 2016, 07:01:15 AM by Bald_Eagle1 »
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Al1264

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Re: Vectoring enabled (or not)
« Reply #26 on: March 18, 2016, 12:32:31 PM »


Maybe some UK ISP are providing modem-router equipped with lantiq chipset?


Basically: YES!
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kitz

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Re: Vectoring enabled (or not)
« Reply #27 on: March 18, 2016, 02:36:03 PM »

Quote from: Ramino
Hi, my Band Plans are the following:

Thanks - a couple of different band plans than here in the UK.

The most notable differences are:-
 - You have a U3 band (at tones 2784 - 3107) which isnt in use in the UK
 - Because of this, your downstream D3 starts much later at tone 3256, whereas in UK its 2793/2795 depending on cab type

U0, U1, U2, D1 & D2 are the same.

Quote
We have currently 2 profile: 50\10 and 100\20 and the bitrate respectively are: 54000*10800 and 108000*21600, so 108000 is the maximum for downstream.

Thank you for that confirmation.

Our main two bit rates are 40000*10000 & 80000*20000.  This means max throughput of around 76 Mbps
There was talk about raising it to 100Mb with vectoring but all seems to have gone quiet on that front atm :(

I still wouldn't mind seeing your bit loading.
Here in the uk due to PCB and PSD masks there are several tones that can never fully load.  - see below for a couple of examples. 


Note I had typed this last night as can be seen by the screen cap time...  and must not have hit the post button before hitting my bed as it was still on my PC screen today.  Apologies that BaldEagle has also said some of this since.
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kitz

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Re: Vectoring enabled (or not)
« Reply #28 on: March 18, 2016, 02:38:35 PM »

Quote
I've tried xdslctl configure --vectoring off but it does not work.

It is possible that this is over-ridden by the DSLAM.  The Service Provider has the ability to set certain parameters so they cant be over-ridden by configuration by the end user.

ejs found some info which may give further insight into what the codes mean.

Code: [Select]
#define VECT_WAIT_FOR_CONFIG  0
#define VECT_FULL             1
#define VECT_WAIT_FOR_TRIGGER 2
#define VECT_RUNNING          3
#define VECT_DISABLED         4
#define VECT_UNCONFIGURED     5

Black Sheep also gave a little bit of info on the BT Openreach configurations

Quote
Vector (Full) = the modem is fully compatible with vectoring and on a DSLAM where vectoring is running it will synch in vectored mode and get a speed result based on that.
Vector (Friendly) = the modem is not fully compatible with vectoring, but can provide some information about cross talk to the DSLAM, this means the vector engine gets results from this which it can use to improve performance for those that are compatible, but this modem it’s self will get a standard VDSL speed.
Vector (off) = this is also known as not vector friendly, the modem is not able to support vectoring at all and provides no useful information to the DSLAM about cross talk, and it only gets standard VDSL speed.

At this point I had a horrible thought. What if your disturber was using a modem that wasnt compatible?
The vectoring engine needs information from both modems to be able to effectively cancel FEXT.  If a modem in the same bundle isnt at least vector friendly then the vector engine isnt able to do anything about the crosstalk from that particular line.  Interpretation from Blacksheeps post the disturber is penalised in that they wont get the higher 100Mb speeds.. but poor neighbour is also at a disadvantage and unable to recover any of the speed lost to crosstalk. :/
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ejs

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Re: Vectoring enabled (or not)
« Reply #29 on: March 18, 2016, 03:20:36 PM »

I think the xdslctl command does not recognise --vectoring for the configure sub-command. I don't think there's anything the DSLAM could do, besides not allow you to connect, if you set your modem to claim that it does not support vectoring. I don't know if or how to disable it, you're probably not supposed to want or need to.
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