Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: Jaseb4920 on September 08, 2020, 04:44:23 PM
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Hi guys not sure what’s going on🤔 I’m on eci cabinet roughly 150m away lived at my property 18 months always had 63/20 end of June that went up to 70/20 guessing g.inp was applied to the line as ping went down to 5 from 12 which was the case until early hours this morning around 2am had a resync and download is now at 80 and my downstream snr which usually sits at 6.2 is now rock solid at 3.0😮 I’m definitely not complaining as very happy that the g.inp trial has worked perfectly on my line but wasn’t aware they were trialing the lower dB option like on Huawei cabinets ?
Stats from sky broadband router sr203 basic stats unfortunately
WAN MER 324925 406366 0 0 0 13:57:45
LAN Up 134657335. 89691914 0 2 2 226:03:25
WLAN (2.4 GHz) Up 24685613 95238 0 2 0 226:02:03
WLAN (5 GHz) Up 122449115 28837955 0 2 2 226:02:02
Broadband Link Downstream Upstream
Connection Speed 79999 kbps 20000 kbps
Line Attenuation D1(7.8 dB) , D2(18.6 dB) , D3(29.4 dB) U0(5.9 dB) , U1(17.2 dB) , U2(25.5 dB)
Noise Margin 3.0 dB 11.0 dB
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See https://forum.kitz.co.uk/index.php/topic,25120.0.html
:)
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See https://forum.kitz.co.uk/index.php/topic,25120.0.html
:)
Not the same thing he’s talking about upstream snr I’ve talking about downstream snr lowered to 3db ?
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Not the same thing he’s talking about upstream snr I’ve talking about downstream snr lowered to 3db ?
The same answer applies.
The target is still 6dB.
The Fibre cabinet reboots.
Your line connected at 6dB, before other lines.
You sync higher as there is no other lines creating noise.
Then other lines connected, creating noise, bring your SNRM down to 3dB.
A very common occurrence.
Edit: to add... The DLM only every changes the SNRM target in 1dB steps.
From 6, to 5, to 4, to 3dB.
It never goes from 6dB to 3dB in 1 go.
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@Jaseb4920 It actually is the same thing, there was some cabinet maintenance at 2am so it was restarted and when the various modems/routers resynced you happened to sync a bit earlier at the 6dB target margin at full 80/20 speeds but as all the other lines came up the crosstalk has reduced your actual current snrm to 3dB.
My line which has G.Inp and 3db target margin syncs at 80/20 after an area power cut and continues with a snr of 1.6 dB with no increase in errors. If I resync it drops to around 76 to 77 Mbps at 3 dB margin.
There has been no hard evidence that ECI cabs are getting srnm values below 6dB.
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Test it by rebooting now...
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Test it by rebooting now...
Rebooted this morning at 5am still the same 😁
Broadband Link Downstream Upstream
Connection Speed 79999 kbps 20000 kbps
Line Attenuation D1(7.8 dB) , D2(18.6 dB) , D3(29.4 dB) U0(5.9 dB) , U1(17.2 dB) , U2(25.5 dB)
Noise Margin 3.0 dB 10.9 dB
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@Jaseb4920 Did you power down and restart your modem/router at 5am? If not and it was a DSLAM restart then the same scenario has happened. On the other hand if it was a manual reboot at your end are you absolutely sure you are on an ECI cab? Some PCP cabinets i.e. the existing phone cabinets rather than the newer FTTC cabs have had additional capacity added by the addition of a VDSL2 side pod containing a Huawei DSLAM. It's unlikely that your connection would have been moved but stranger things have happened. :)
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@Jaseb4920 Did you power down and restart your modem/router at 5am? If not and it was a DSLAM restart then the same scenario has happened. On the other hand if it was a manual reboot at your end are you absolutely sure you are on an ECI cab? Some PCP cabinets i.e. the existing phone cabinets rather than the newer FTTC cabs have had additional capacity added by the addition of a VDSL2 side pod containing a Huawei DSLAM. It's unlikely that your connection would have been moved but stranger things have happened. :)
Hi I’m up at 4am most days for work so I powered down the router at 4.30 and powered it back up at 5am and as posted previously 80/20 sync and noise margin still sitting at 3db which I’ve never had before, yes definitely on an eci cabinet as Wrexham north wales was one of the first in wales to get FTTC back in 2013 so no huawei was installed back then but a few now due to capacity issues but my cabinet not one of them only one pcp and one fttc eci cab ?
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Impossible to tell what going on without a modem with advanced stats or an ISP provided profile.
DLM never moves from 6dB to 3dB though, ever, not even during the previous trials.
Even lines that develop serious errors go backwards in 1dB stages, not from 3dB to 6dB.
There are numerous things that can cause you to sync 3dB off the target though.
Edit: here's (https://forum.kitz.co.uk/index.php/topic,22411.msg383313.html#msg383313) a thread showing a line seemingly jumping between 6dB and 3dB.
Advanced stats (including max attainable and minute by minute detailed SNRM) was able to show the line only moved in 1dB increments.
ISP devices don't always poll the SNRM frequently.
The target would also be 3.3dB and not 3.0dB.
it could be a 3.3dB intermittent noise source that isn't enough to effect the sync but is shown in the current SNRM.
A previous crosstalkers with a faulty line can cause this kind of thing.
It could actually be a 3dB SNRM target but history has shown in these forums dozens of examples that looked to be 3dB that weren't, including lines that resync at 3dB.
On the successful Huawei G.INP trial they didn't try xdB profiles.
On the xbB trial the DLM moved in 1dB increments.
I can't see why they would try straight to 3dB on a failing G.INP trial without even trying 5dB.
I'm of the opinion it isn't a 3dB target. Seen this SO many times before.
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My downstream SNR has been at 3.5 dB for 2 weeks now (ECI cabinet). Always on 6.2 before.
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I've found I can force it on open WRT modem setting an Negative SNR offset works. I'm also on a ECI cab so it's handy to have a Lantiq modem.
For a while I couldn't figure out why I kept getting interleaved, I did What Les Suggested and to use a higher SNR offset (9-10db ish) to trigger the cab to release interleaving from my line, I got Interleaving removed and it's ok most of the time but here I Get noise bursts every few days, for about a few minutes or so, go front very low 10's of Error seconds then it jumps by 100 - 200 while the sync holds the Connection is virtually non existent.
While I used to get stable line without out interleaving ( was 80/20 6 years ago ) now even at 50 mbps without interleaving and a 10db or higher margin I can effectively still lose the connection. My line is interleaved again I ended up being able to hold 60mbps with a 3db margin and get no drop outs. but it tends to sync about 52-55 without the SNR margin tweek. Would be real nice to have RETX/G.INP and my modem is ready. I must be have been speed banded too to the 60Mbps profile as I always sync at 60Mbps but that's handy as with this modem I haven't figured out how to set the target speed only adjust the downstream SNR.
Line State:UP [0x0]
Line Mode:G.993.2 (VDSL2)
Line Uptime:1d 15h 59m 57s
Annex:B
Profile:17a
Data Rate:60.000 Mb/s / 20.000 Mb/s
Max. Attainable Data Rate (ATTNDR):54.034 Mb/s / 21.950 Mb/s
Latency:9.0 ms / 0.0 ms
Line Attenuation (LATN):17.0 dB / 19.7 dB
Signal Attenuation (SATN):17.0 dB / 19.6 dB
Noise Margin (SNR):3.6 dB / 6.6 dB
Aggregate Transmit Power(ACTATP):6.5 dB / 6.7 dB
Forward Error Correction Seconds (FECS):767848 / 763
Errored seconds (ES):48 / 3503
Severely Errored Seconds (SES):0 / 2
Loss of Signal Seconds (LOSS):0 / 116
Unavailable Seconds (UAS):87 / 87
Header Error Code Errors (HEC):0 / 0
Non Pre-emtive CRC errors (CRC_P):180 / 0
Pre-emtive CRC errors (CRCP_P):0 / 0
ATU-C System Vendor ID:Infineon 178.6
Power Management Mode:L0 - Synchronized
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Would be real nice to have RETX/G.INP and my modem is ready.
Don't count on that, I had to remove my HH5A with OpenWRT from my Plusnet line as it wasn't stable with G.INP enabled.
It would be fine for days then suddenly resync. I can't remember if that was with 6dB or 3dB SNRm, I didn't want to leave it in case the line got banded or showed up as a problem with the G.INP trial.
The VMG-3925-B10B on the other hand is really stable but syncs lower than the HH5A even at 6dB.
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29 days now and I'm still on 3.4db ???
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29 days now and I'm still on 3.4db ???
I’m on 19 days now Rock solid 3.0db ? Not complaining though as still on the full 80/20 😁
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Don't count on that, I had to remove my HH5A with OpenWRT from my Plusnet line as it wasn't stable with G.INP enabled.
It would be fine for days then suddenly resync. I can't remember if that was with 6dB or 3dB SNRm, I didn't want to leave it in case the line got banded or showed up as a problem with the G.INP trial.
The VMG-3925-B10B on the other hand is really stable but syncs lower than the HH5A even at 6dB.
I'm using an upto date modem driver. with Open WRT if someone has extracted that driver you can usually use it.
It's been solid for 2 and a half months now power cuts aside.
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Something new to report. Some major outages over the weekend and road works near the CAB. The ECI cab must have had an update near the same time too, I think it stole some of the upstream tone/bands to give me a higher noise margin on down stream and now have upstream Interleaving too.
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I think it stole some of the upstream tone/bands to give me a higher noise margin on down stream and now have upstream Interleaving too.
Is that a random guess or are you actually looking at bitloading or something concrete to reach that conclusion?
Band plans are pretty strict. OpenReach uses an of the shelf bandplan with a couple small tweaks.
The same tones/bandplans are used nationwide.
ECI can't just randomly take a bunch of downstream tones and change them to upstream.
There's thousands of sites with ECI and Huawei cabinets on the same PCP. Their bands match (give or take a tone or 2) but don't overlap each other on the downstream/upstream on any tones.
If 1 vendor swapped some of downstream tones for upstream it would cause crosstalk havoc on those tones.
I don't think we've seen a band plan change in VDSL2 for about 7-8 years and it was a small tweaks to stop the 2 vendors overlapping by a couple tones.
See: VDSL tones in use (https://kitz.co.uk/adsl/adsl_technology.htm#vdsl_tones)
The pbparams command on Broadcom chipsets gives the tones in use by the DSLAM.
There's probably an equivalent for Lantiq.
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I'm using an upto date modem driver. with Open WRT if someone has extracted that driver you can usually use it.
It's been solid for 2 and a half months now power cuts aside.
Newer driver than what is in OpenWRT by default? I'd certainly be curious to give it another try if so.
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Is that a random guess or are you actually looking at bitloading or something concrete to reach that conclusion?
Band plans are pretty strict. OpenReach uses an of the shelf bandplan with a couple small tweaks.
The same tones/bandplans are used nationwide.
ECI can't just randomly take a bunch of downstream tones and change them to upstream.
There's thousands of sites with ECI and Huawei cabinets on the same PCP. Their bands match (give or take a tone or 2) but don't overlap each other on the downstream/upstream on any tones.
If 1 vendor swapped some of downstream tones for upstream it would cause crosstalk havoc on those tones.
I don't think we've seen a band plan change in VDSL2 for about 7-8 years and it was a small tweaks to stop the 2 vendors overlapping by a couple tones.
See: VDSL tones in use (https://kitz.co.uk/adsl/adsl_technology.htm#vdsl_tones)
The pbparams command on Broadcom chipsets gives the tones in use by the DSLAM.
There's probably an equivalent for Lantiq.
Guessing i was.
I suspect now it's just ever increasing upstream interleaving. now followed by upstream banding. DLM never touched the upstream previously, upstream in the last 2 weeks it's got cut in half.