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[adslmax]

Last night the G.fast was lost connection for 20 minutes, no G.fast DSL light. When it back on up and running. I went to dslstats to check what going on? I was surprise the Openreach TTB SNR has changed to 2.1dB? Been like this all day today! Has Openreach start trail target SNR 2dB?

Latest:
Downstream   Upstream
Line attenuation (dB):     38.7      0.0
Signal attenuation (dB):   N/A      N/A
Connection speed (kbps):   237971      34828
SNR margin (dB):           2.1      2.1
Power (dBm):               0.0      4.0
Interleave depth:                
INP:                       550.00      540.00
G.INP:                     Not enabled      Not enabled
Vectoring status:          Not monitored      

[Alex Atkin UK]

I'd be more inclined to believe something happened to power cycle the cabinet and you synced quicker than other people so got the pre-crosstalk sync bonus.  Although, no idea if that works the same on g.FAST with it having SRA.

[j0hn]

Reboot the modem (ONCE) to find out?

With SRA it should maintain the target SNRM by lowering the sync speed.
Even on a DSLAM reboot like Alex mentions, SRA should hold the target margin.

OpenReach haven't released a new G.Fast SIN or released any briefings about changes.
The SIN still says

1.2.2 G.fast Noise Margins
Currently the default target signal-to-noise ratio margin is set to 3dB in both the
upstream and the downstream directions. The actual value shall be determined by the
Dynamic Line Management (DLM) algorithm based on line stability and can vary
between 3 and 28dB (in 1 dB steps). The upstream and downstream margin settings
are independent of each other.
Lines may also have higher margins when they are at the rate cap for the product.

[gt94sss2]

Reboot the modem (ONCE) to find out?

I would just leave it alone. If it is due to syncing early, Max can enjoy the temporary speed increase.

If OR are actually playing with DLM, then disconnecting may make DLM think the line is not stable at the lower SNRM..

[adslmax]

Checked dslstats for a quick look:

Downstream   Upstream
Line attenuation (dB):     38.7      0.0
Signal attenuation (dB):   N/A      N/A
Connection speed (kbps):   237980      33819
SNR margin (dB):           2.1      2.9
Power (dBm):               0.0      4.0
Interleave depth:                
INP:                       550.00      540.00
G.INP:                     Not enabled      Not enabled
Vectoring status:          Not monitored      

RSCorr/RS (%):             0.2264      0.2783
RSUnCorr/RS (%):           0.0000      0.0000
ES/hour:                   0      0

[burakkucat]

Does a G.Fast circuit use vectoring?    I can't remember.

[gt94sss2]

Yes, vectoring is built-in to the g.fast standard

[burakkucat]

Thank you for refreshing the memory cells.

So as long as Max resists the urge "to fiddle", his service should continue to operate well.

[adslmax]

Yes the G.fast does have Vectoring say the openreach engineer in May when I did asked him about crosstalk on G.fast he say, no it won't be affected by this as all G.fast does have vectoring on it.

Code: [Select]

xdslctl info --pbParams
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    1
Last initialization procedure status:   0
Max:    Upstream rate = 37519 Kbps, Downstream rate = 237061 Kbps
Bearer: 0, Upstream rate = 37728 Kbps, Downstream rate = 237671 Kbps

Discovery Phase (Initial) Band Plan
US: (348,1249) Gfactor=4
DS: (342,1160) Gfactor=4
Medley Phase (Final) Band Plan
US: (348,1247) Gfactor=4
DS: (342,1098) Gfactor=4

VDSL Port Details               Upstream                Downstream
Attainable Net Data Rate:        37519 kbps             237061 kbps
Actual Aggregate Tx Power:          4.0 dBm                 0.0 dBm
====================================================================================
  VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
  Line Attenuation(dB): N/A 0.0 N/A N/A N/A 38.7 N/A N/A
Signal Attenuation(dB): N/A 0.0 N/A N/A N/A 38.7 N/A N/A
        SNR Margin(dB): N/A 0.0 N/A N/A N/A 0.0 N/A N/A
         TX Power(dBm): N/A 0.0 N/A N/A N/A 0.0 N/A N/A
        kl0(dBx100):      N/A     N/A     N/A     N/A     N/A     N/A     N/A     N/A   
ZySH>


[GigabitEthernet]

May I kindly suggest not worrying about such things and just using your connection? I am so jealous of the speed you get already

[j0hn]

May I kindly suggest not worrying about such things and just using your connection? I am so jealous of the speed you get already

I see no problem with him posting this thread. He doesn't seem worried and was simply asking a question and attempting to add to the general pool of knowledge around G.Fast noise margins and SRA.

There was a thread in the last couple days with a user doing nothing more than bragging about getting over 2.3Gb/s on their FTTP and nobody told them to just use their connection.

It's the 1st and only time I've seen G.Fast run below the target SNRM and it's both the upstream/downstream.
I found this thread interesting.

[meritez]

@adslmax

has the upstream snr moved any higher than 2.9db?

[adslmax]

@adslmax

has the upstream snr moved any higher than 2.9db?

No it always stay below 2.1dB and 3.1dB never go higher for upload. Downstream are between 2.1dB and 2.3dB all day in the last two days now. But, I don't know why downstream snr went lower since loss of DSL connection few days ago on the 24th August but j0hn say there is no change on DLM by Openreach. Maybe the G.fast cabinet connected me to the quicker one (use to wait for 4 minutes for fully sync up and running when line atten was 39.4dB but now it connected quicker at 2 minutes for fully sync up and running as line atten reduced to 38.7dB but downstream snr was still same at 2.1dB instead of 3.1dB) very weird. But, I aren't complaint. I was surprised to have faster G.fast at 237/37 now as last June it was 227/32 with both snr at 3.1dB

[meritez]

I'd hammerit with a few linux distro downloads from www.distrowatch.com to make sure it's stable 

[GigabitEthernet]

I see no problem with him posting this thread. He doesn't seem worried and was simply asking a question and attempting to add to the general pool of knowledge around G.Fast noise margins and SRA.

There was a thread in the last couple days with a user doing nothing more than bragging about getting over 2.3Gb/s on their FTTP and nobody told them to just use their connection.

It's the 1st and only time I've seen G.Fast run below the target SNRM and it's both the upstream/downstream.
I found this thread interesting.

That post was equally pointless