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Mystified at Zero FEC errors

Luzern
Seasoned Pro
Posts: 3,220
Thanks: 315
Fixes: 2
Registered: 31-07-2007

Mystified at Zero FEC errors

Here is an abbreviated report from my 585 v7 router taken this morning and a full one this evening.
Morning
Uptime:   2 days, 19:52:05
FEC Errors (Up/Down):   0 / 0
CRC Errors (Up/Down):   0 / 11,914
HEC Errors (Up/Down):   0 / 7,360

Evening

Uptime: 3 days, 6:12:08
DSL Type: G.992.5 annex A
Bandwidth (Up/Down) [kbps/kbps]: 443 / 7,776
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 1.00
Output Power (Up/Down) [dBm]: 12.5 / 0.0
Line Attenuation (Up/Down) [dB]: 25.0 / 46.0
SN Margin (Up/Down) [dB]: 16.5 / 4.0
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 44 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 14,261
HEC Errors (Up/Down): 0 / 8,842
You will see that whilst downstream CRC and HEC errors are amassing, FEC errors are absent.
I am told this is a sign that Interleaving is off, but in Member Centre > Connection Settings> Broadband Interleaving it is shown as on.
I am thinking if a router reboot might be worthwhile, but wondering if either there is a fault with the router or a glitch has happened at PN's end, so that I am working unwanted Fastpath,or the router's info is wrong.
Please advise Smiley
No one has to agree with my opinion, but in the time I have left a miracle would be nice.
14 REPLIES
Community Veteran
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Registered: 15-06-2007

Re: Mystified at Zero FEC errors

Please clarify
Quote
I am told this is a sign that Interleaving is off, but in Member Centre > Connection Settings> Broadband Interleaving it is shown as off.
Community Veteran
Posts: 1,412
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Registered: 29-01-2009

Re: Mystified at Zero FEC errors

I hope I'm reading those stats correctly... It looks like you have a downlink sync speed of 7776kbps, which seems remarkably high given the downlink attenuation figure of 46dB. According to Kitz's predictor, that attenuation should only give around 5792kbps.
All the same, the maximum sync speed with interleaving turned on is 7616kbps, so a figure above this does indeed suggest that interleaving is turned off (BTW you put "off" twice in your post).
FEC errors are the ones corrected by the forward-error-correction scheme that is turned on/off at the same time as interleaving, so a zero count is a direct indication that the FEC process has been turned off and, by implication, that interleaving is turned off too.
Your CRC errors suggest you are getting around 180 errors per hour, or just under 0.1%
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
Community Veteran
Posts: 14,469
Registered: 30-07-2007

Re: Mystified at Zero FEC errors

The connection is ADSL2+ (G.992.5) so the fact that the sync rate is above 7616 no longer applies or can be interpreted as interleaving on.
Community Veteran
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Registered: 29-01-2009

Re: Mystified at Zero FEC errors

Good point. The only clue left is the FEC value then...
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
Luzern
Seasoned Pro
Posts: 3,220
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Registered: 31-07-2007

Re: Mystified at Zero FEC errors

Quote from: Oldjim
Please clarify
Quote
I am told this is a sign that Interleaving is off, but in Member Centre > Connection Settings> Broadband Interleaving it is shown as off.

Embarrassed Text now corrected
No one has to agree with my opinion, but in the time I have left a miracle would be nice.
Community Veteran
Posts: 38,460
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Registered: 15-06-2007

Re: Mystified at Zero FEC errors

From memory I think that the standard setting for interleaving used to be auto and only when it was specifically changed by the Plusnet systems does the connection settings get it right
Luzern
Seasoned Pro
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Registered: 31-07-2007

Re: Mystified at Zero FEC errors

What Member Centre says
Interleaving
Interleaving is a form of error correction that helps to improve the stability of high-speed broadband. You currently have interleaving switched on.
While improving stability, interleaving can increase ping times. This can cause problems for online gamers. For this reason, we offer the ability to turn interleaving off.
BTW it's only in the last few days that FEC errors have been absent.
Warning! Turning interleaving off may reduce the stability of your broadband connection. We recommend leaving it turned on. If you turn interleaving off, there is no option to turn it back on again.
Control interleaving
Your interleaving status: ON

No one has to agree with my opinion, but in the time I have left a miracle would be nice.
Superuser
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Registered: 06-04-2007

Re: Mystified at Zero FEC errors

Possibly the interleaving status in On, but the Depth is 1 - which means it is actually Off. Since you haven't requested it be turned off the setting is probably Auto but the DLM reckons your line is fine without it.
David
puddy
Grafter
Posts: 1,571
Registered: 10-06-2007

Re: Mystified at Zero FEC errors

Since i invested in a BT-i plate i dont  seem to get any hec crc or fec errors
puddy
jojopillo
Grafter
Posts: 9,786
Registered: 16-06-2010

Re: Mystified at Zero FEC errors

Hi lucerne,
I've just been checking the status of your line on the BT systems and interleaving is currently Auto which means it can be changed. The interleaving is currently in the off or fast state as of the 17th December.
Jojo Smiley
Luzern
Seasoned Pro
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Registered: 31-07-2007

Re: Mystified at Zero FEC errors

Hi JoJo Smiley
So that solves the mystery: my line is on auto, and, pace spraxyt, "interleaving status in On, but the Depth is 1 - which means it is actually Off ". Just as long as eventually it won't muck things up, I'll leave as it is.
All that concerned me was that nothing untoward was happening at either end.
@others
I do have a very good connection. For some unknown reason it has climbed in the last couple of months , so at a road distance of 2.7km (via cabinet's known location) it is as now. Cannot fathom why, unless preparation for FTTC due 09/11 has side effects.
Thanks  all for your time Smiley
No one has to agree with my opinion, but in the time I have left a miracle would be nice.
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Mystified at Zero FEC errors

Glad it's all working, thanks Lucerne - let us know if there's anything we can do for you Smiley
Community Veteran
Posts: 1,412
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Registered: 29-01-2009

Re: Mystified at Zero FEC errors

Quote from: lucerne
@others
I do have a very good connection. For some unknown reason it has climbed in the last couple of months , so at a road distance of 2.7km (via cabinet's known location) it is as now. Cannot fathom why, unless preparation for FTTC due 09/11 has side effects.

Each joint in the cable adds some additional attenuation especially if it is (or goes) bad. A rising attenuation might be a sign that BT added some joints in your cable as part of installation of their fibre paths, but I didn't think they disturbed existing circuits when doing that. And I wouldn't have thought it would be that noticeable either.
Another reason might be that you have a line that is starting to get iffy - but then you'd see that in the noise figures too.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
Luzern
Seasoned Pro
Posts: 3,220
Thanks: 315
Fixes: 2
Registered: 31-07-2007

Re: Mystified at Zero FEC errors

@ WWWombat
I think you may have the wrong end of the stick. I no way am I concerned about the line with its rising connection speed. Were you thinking that SNR was a problem or the attenuation? SNR is not high and attenuation only rose when connection went adsl2+, which is normal.
My OP was an enquiry not a complaint, something probably rare on the forum these days: it's east to read in complaint mode. Wink
No one has to agree with my opinion, but in the time I have left a miracle would be nice.