Massive speed fault

[#1]

Helo guys,

I am extremely curios how this is happening.

Most likely to some transient noise (error rate) which has long time disappeared I got the DLM setting the SNRM target to 13db as you can see bellow:

                Down            Up

SNR (dB):        13.9            6.2

Attn(dB):        19.4            0.0

Pwr(dBm):        12.7            7.4

But my biggest surprise came when I've actually ran a diagnostic to get the ACTUAL SNR on all the channels and looked over the noise distribution. While some of the channels are close to 6db but still under 6, there is not a single channel going over with the vast rest of the channels being close or even lower than 3db, nothing related to that 13db snrm target. (file attached)

As this has been going for some time please:

- set my SNRM target to 6 (fixed) forever and ignoring FEC/SES and whatever other error statistics (obviously misconfigured)

- set my inteleave to on ( to mitigate some of the eventual error frames)

While my gaming days are long gone I believe that interleave on, tcp error correction, VPN error correction are more than enough to deal with packet errors.

Max:    Upstream rate = 15030 Kbps, Downstream rate = 76256 Kbps

Bearer: 0, Upstream rate = 15060 Kbps, Downstream rate = 48998 Kbps

Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps

48Mbs link level speed instead of 76Mbs

while the true speed is:

speedtest-cli/speedtest.py 

Retrieving speedtest.net configuration...

Testing from PlusNet (xxxxxxx)...

Retrieving speedtest.net server list...

Selecting best server based on ping...

Hosted by Warwicknet Ltd. (Coventry) [45.57 km]: 19.495 ms

Testing download speed................................................................................

Download: 42.10 Mbit/s

Testing upload speed................................................................................................

Upload: 14.21 Mbit/s

Please correct these as soon as possible. I am happy to have an engineer come over if it is needed, however because the noise is transient I am pretty sure that the cause would be difficult to find.

Edit: mangle IP address

[#2]

Hi there

We're not able to make any remote adjustments to the DLM on a fibre circuit I'm afraid.

Testing your line, your sync speed is slightly below your estimates...

Test Outcome	Pass
Test Outcome Code	GTC_FTTC_SERVICE_0003
Description	No problem found, OAM test is not currently supported on this line.
Main Fault Location	OK
Sync Status	In Sync
Downstream Speed	46.9 Mbps
Upstream Speed	15.1 Mbps
Appointment Required	N
Fault Report Advised	N
NTE Power Status	PowerOn
Voice Line Test Result	Pass
Bridge Tap	Not Detected
Radio Frequency Ingress	Not Detected
Repetitive Electrical Impulse Noise	Not Detected
Cross Talk	Not Detected
Estimated Line Length In Metres	573.1
Upstream Rate Assessment	Reasonable
Downstream Rate Assessment	Reasonable
Interference Pattern	Regular Interference Observed Daily
Service Impact	No Impact Observed
Interference Duration Longest Occurrence	; 00:00 to 23:45
Interference Location	Customer Premise
Interference Observed In Days	14
Home Wiring Problem	Not Detected
Downstream Policing Discard Rate	0.0
Customer Traffic Level	Upstream and Downstream Traffic Detected
Technology	VDSL
Profile Name	0.128M-49M Downstream, Retransmission High - 0.128M-20M Upstream, Error Protection Off

Apart from that your connection is stable with a bit of instability around noon...

As the sync rate is resting below the estimates, I'd advise going through the checks here and if the problem remains then raise a fault to us here and we'll arrange an engineer visit.

[#3]

Thanks Gandalf, I've created the fault: 

#150363729

[#4]

Thanks for raising the fault @Justinian

I've updated your fault ticket for you now.

[#5]

Watch for a 'no fault found' charge.

Your line is currently banded at 49Mb hence the slow sync speed and DLM may remove that given time.

[#6]

Whilst the DLM may adjust the banding/profile, I don't believe this is affecting the sync rate as it is resting a few Mb below the banding.

[#7]

2 Kbps below according to the OP's stats...

eta: hasn't this happened before where the GEA speed is reported as different from the router sync rate?

[#8]

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@Browni wrote:

eta: hasn't this happened before where the GEA speed is reported as different from the router sync rate?

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I think I recall which thread you may be referring to, and I believe it was proven that the line speed from the GEA test is the actual sync rate. I'm can't remember what checks were done to prove it though.

[#9]

Yes I remember seeing that before. The GEA test result knocks a bit of the actual sync speed. The Op should get a considerable increase in speed with the banding removed with the current SNRM at 13.9dB.

@Gandalf I am not convinced that the GEA is reporting the actual sync rate, I seem to recall the reported sync speed is lower if G.Inp (retransmissions) are active. You can't really say that the sync speed in the router stats is wrong, can you?

Anyway I need to start a new thread about a fault on my line.

[#10]

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@Gandalf wrote:

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@Browni wrote:

eta: hasn't this happened before where the GEA speed is reported as different from the router sync rate?

---

I think I recall which thread you may be referring to, and I believe it was proven that the line speed from the GEA test is the actual sync rate. I'm can't remember what checks were done to prove it though.

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It'll be due to the "Retransmission High" profile. The "Downstream Speed 46.9 Mbps" from the test is obviously not the same as the 48,998 kbps from the modem, but the test must be reporting something different by design (probably some G.998.4 related number, possibly the ETR, taking into account the SHINERATIO_RTX).