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Author Topic: FEC Errors with G.INP and interleave depth 4  (Read 11480 times)

Oldjim

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FEC Errors with G.INP and interleave depth 4
« on: September 14, 2017, 12:40:43 PM »

This question is more specific
Using a Billion 8800NL Router
Occasionally the downstream FEC error rate hits about 100,000 FEC per minute with as reported by Routerstats and sticks there until either I initiate a resync or it happens automatically at which point with virtually no change in speed or noise margin it drops to between 100 -300 FEC per minute
Is there a reason why this happens and is there any way to stop it
Software Version     2.32d.dm12 and the latest version doesn't mention a fix for this
Current Stats
Code: [Select]
DSLAM/MSAN type:        BDCM:0xa48c / v0xa48c
Modem/router firmware:  AnnexA version - A2pv6F039g1.d24m
DSL mode:                VDSL2 Profile 17a
Status:                  Showtime
Uptime:                  13 hours 56 min 55 sec
Resyncs:                0 (since 14 Sep 2017 11:38:44)

Downstream Upstream
Line attenuation (dB):  21.3 0.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 48720 8917
SNR margin (dB):        3.5 5.2
Power (dBm):            12.8 6.2
Interleave depth:        4 4
INP:                    54.00 45.00
G.INP:                  Enabled Enabled
Vectoring status:        5 (VECT_UNCONFIGURED)

RSCorr/RS (%):          0.1602 0.1419
RSUnCorr/RS (%):        0.0000 0.0000
ES/hour:                0 0
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Jim
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kitz

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #1 on: September 14, 2017, 01:01:02 PM »

It sounds kind of similar to what happens occasionally on my line.  I can't see you on MDWS to check for further similarities, but this is what happens on mine.

Every day I get a small spike in errors.  Every so often after this error spike, the error rate will go crazy causing a large amount of CRCs and err/Secs.   It will practically flatline at this high level until I reboot the modem.
By which point DLM will have noticed and will take action the next day.   Its a PITA but I havent found out what is causing it.   I usually spot it happening because everything slows down to a crawl during this period and even surfing is problematic.


Screen caps below showing about 7 of these events over the past year.  A couple of times I've spotted it myself and taken action by rebooting the modem to try and minimise DLM action.
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Oldjim

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #2 on: September 16, 2017, 11:24:55 AM »

After a router reboot the error rate bounced up over night to a constant 1 million per minute so will leave it to see what happens
Code: [Select]
DSL mode:                VDSL2 Profile 17a
Status:                  Showtime
Uptime:                  19 hours 8 min 39 sec
Resyncs:                0 (since 16 Sep 2017 10:22:16)

Downstream Upstream
Line attenuation (dB):  21.3 0.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 49116        8812
SNR margin (dB):        3.3 5.6
Power (dBm):            12.9 6.3
Interleave depth:        4 4
INP:                    56.00 46.00
G.INP:                  Enabled Enabled
Vectoring status:        5 (VECT_UNCONFIGURED)

RSCorr/RS (%):          11.0648 0.0768
RSUnCorr/RS (%):        0.0000 0.0000
ES/hour:                0 0

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Jim
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tubaman

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #3 on: September 16, 2017, 11:51:51 AM »

If it is only FECs then these are effectively errors that didn't happen, as they were corrected.
If there's no linked large rise in ES then I'd be tempted to leave it alone and just monitor the situation.
I think I'm right in saying the DLM isn't interested in FECs.
 :)
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kitz

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #4 on: September 16, 2017, 08:48:52 PM »

I don't think it is, although other errors should be taken into account such as Err/Secs.   

Whilst I am not certain, I suspect that for those on G.INP/Huawei cab, DLM  may also monitor some other parameter such as LEFTRS.
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Oldjim

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #5 on: September 17, 2017, 08:56:29 PM »

Router just resynched after major burst
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Jim
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Black Sheep

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #6 on: September 17, 2017, 09:03:29 PM »

Could snadge's link here ( http://forum.kitz.co.uk/index.php?topic=20327.0;topicseen) be anything to do with this ???
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kitz

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #7 on: September 18, 2017, 10:57:57 AM »

@BS - doubtful.    The link is about Internet traffic,  this is more local ie between the modem and DSLAM.

I also had a burst this morning that stayed that way for about half an hour. 
It's a daily event for me which causes a brief noise spike.... and sometimes the noise sticks generating hundreds of thousands of errors until the modem is rebooted.

Graph below shows my spike this morning - see how at about 9:10 my line started generating 18k CRC errors every minute.     It's never at exactly the same time, but will usually be between 9-11am.  The amount of errors also can vary, some days it may just be a few, yesterday it was 12k for only a couple of mins, but it is always there.   

Its been doing it for well over a year..  and its damn annoying when it sticks because DLM will take action the next day even if I manually reboot the modem myself to stop it. OJ & I use different modems, so its not that.

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ejs

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #8 on: September 18, 2017, 06:30:35 PM »

Are you both using the same modem chipset though?
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Oldjim

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #9 on: September 18, 2017, 06:36:54 PM »

I am using the Broadcom chipset which I think is the BCM 63168 and the cab is Huawei
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Jim
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j0hn

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #10 on: September 18, 2017, 07:17:04 PM »

Router just resynched after major burst
I get that when DLM initiates a resync. It gives me a burst of ES/SES/FEC/Retx. It's almost always 10-11 SES. If it was retrain reason 1 then it was possibly DLM resyncing the line.
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Oldjim

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #11 on: September 18, 2017, 07:41:27 PM »

Happened again
Here are the FEC and SES  and then it resyched by itself
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Jim
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j0hn

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #12 on: September 18, 2017, 10:51:56 PM »

Aye you on MDWS?
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Oldjim

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #13 on: September 18, 2017, 11:21:48 PM »

no
and since I switch between various computers and the most obvious one isn't on most of the time it wouldn't help
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Jim
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Oldjim

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Re: FEC Errors with G.INP and interleave depth 4
« Reply #14 on: September 19, 2017, 03:56:16 PM »

FEC rate now back to circa 100,000 but G.INP seems happy with rtx_tx and rtx_c at about 60 per minute and RSCorr (Bearer 1) mostly about 2  per minute all the others are reported as zero
Error seconds are virtually nil
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