New BB FEC errors

thenewoc

thenewoc

thenewoc

Soldato
Joined
9 Mar 2012
Posts
10,083
Location
West Sussex, England
Hi

If I have FEC errors on a new BB connection that's just been installed a few days ago, will DLM improve by itself or should I raise a support ticket into the quality of the connection?

Also is it right that it shows 0 output power (down)?

It's a Technicolor TG582n router so I can't turn interleaving off myself can I?


I've restarted my router as I was getting next to no upload speed at all.

Now:

Uptime: 0 days, 0:39:40

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 988 / 7,375

Data Transferred (Sent/Received) [MB/MB]: 31.04 / 172.21

Output Power (Up/Down) [dBm]: 12.8 / 0.0

Line Attenuation (Up/Down) [dB]: 23.8 / 43.0

SN Margin (Up/Down) [dB]: 12.0 / 12.1

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / 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): -

Error Seconds (Local/Remote): 3 / 0

FEC Errors (Up/Down): 18 / 92

CRC Errors (Up/Down): 12 / 4

HEC Errors (Up/Down): 11 / 32


Before:

Uptime: 0 days, 21:01:12

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 974 / 7,262

Data Transferred (Sent/Received) [MB/GB]: 143.62 / 1.33

Output Power (Up/Down) [dBm]: 12.8 / 0.0

Line Attenuation (Up/Down) [dB]: 23.9 / 43.0

SN Margin (Up/Down) [dB]: 12.7 / 12.1

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / 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): -

Error Seconds (Local/Remote): 73,274 / 0

FEC Errors (Up/Down): 2,347 / 275,140,719

CRC Errors (Up/Down): 1,883,369 / 4,664,935

HEC Errors (Up/Down): 751,630 / 2,557,042
 
Last edited:
I'd be more concerned about the HEC errors than the FEC. To an extent FEC are normal on an interleaved line, although you do seem to have had quite a few, which could be due to DLM. I doubt the provider would look into anything unless it were terminal inside the 10 day period.
 
Tealc said:
I'd be more concerned about the HEC errors than the FEC. To an extent FEC are normal on an interleaved line, although you do seem to have had quite a few, which could be due to DLM. I doubt the provider would look into anything unless it were terminal inside the 10 day period.
Click to expand...

Hi, I'm not sure why my line is interleaved though. I've just moved from Sky back to a BT line. Prior to moving to Sky, I was with Plusnet and my line wasn't interleaved.

This is how it looked when I was with Plusnet.

System uptime: 0 days, 16:59:44
Bandwidth (Up/Down) (kbps): 448 / 9.195
Line attentuation (Up/Down) (dB): 24,1 / 43,0
SN Margin (Up/Down) (dB): 17,4 / 5,0
Loss of Framing (Local/Remote): 9 / 0
Loss of Signal (Local/Remote): 1 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Errors Seconds (Local/Remote): 1.238 / 9
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 244 / 1.725
HEC Errors (Up/Down): 91 / 5.383
 
So you think I should wait until the service has been up for 10 days? Should it just sort itself out through DLM or if it doesn't should it be raised with provider?

Since restarting router the upload speed has improved now to 0.77 Mbps whereas just prior to the restart I was only getting 0.07 Mbps roughly.
 
During dlm you will expect drop outs and errors as the system changes connection speeds and methods to provide the best stable speed. It should eventually settle. If you did contact your ISP they will just fob you off as you are in dlm, at the end they may be able to help, if theres an actual issue.
 
So overnight i'm back to my upload speed having completely tanked to nothing so I get page load errors all the time.

My router stats look horrendous..

Uptime: 0 days, 10:15:43

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 980 / 7,154

Data Transferred (Sent/Received) [MB/GB]: 95.83 / 1.73

Output Power (Up/Down) [dBm]: 12.6 / 0.0

Line Attenuation (Up/Down) [dB]: 23.9 / 43.0

SN Margin (Up/Down) [dB]: 12.3 / 13.0

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 9 / 0

Loss of Signal (Local/Remote): 1 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 25,620 / 0

FEC Errors (Up/Down): 16,025,363 / 95,529,536

CRC Errors (Up/Down): 1,132,363 / 1,619,825

HEC Errors (Up/Down): 2,054,136 / 888,902
 
There's a common misconception that something magical happens in the first 10 days of a broadband installation: it doesn't.

What does happen is the minimum downstream sync speed during the first 10 days is recorded (Fault Threshold Rate - FTR). If you ever have a fault in which the downstream sync speed is lower than the FTR, the fault can be investigated as a slow-speed fault.

DLM is in fact running all the time and will increase interleaving, the target SNRM, etc. It will do whatever it needs to do in order to stabilise the line and reduce the number of errors.

DLM takes error seconds and CRCs into account. It does not take FECs into account as these are corrected errors - they don't affect the connection in any way. It will also look at how often your line resyncs, if it's too often, it will do whatever it can to increase the time between resyncs.

Your line is, to put it kindly, erroring a lot. The high amount of errors will certainly be affecting your throughput.

The first thing to do is to plug the modem into the test socket. Do you have a test socket?
 
Hi, thanks for the info. It certainly seems high to me too compared to other times we've switched provider.

It seems to have a brain fart after a few hours of jogging along to an OK performance and the suddenly the errors shot up massively and I then find I have almost no upload speed at all. If I restart the router then the connection behaves OK again for 5 or 6 hours approx. The connection went down completely this morning and I got a web page from the router saying the connection wasn't there and it was inializing. Since it has come back online its been OK. I'll know if it's gone weird again since it makes the internet almost impossible to use without any upload, I just get page not loading errors or empty response errors. If that happens I will try and use the test socket but I currently have a vdsl filtered faceplace so that is plugged into the test socket. I'm not sure it's our equipment anyway as I say as soon as I restart the router it sorts things out.

Been back up for just over 2.5 hours and fingers crossed it won't suddenly go off the scale on errors again.

Uptime: 0 days, 2:41:40

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 988 / 7,451

Data Transferred (Sent/Received) [MB/MB]: 40.93 / 396.08

Output Power (Up/Down) [dBm]: 12.8 / 0.0

Line Attenuation (Up/Down) [dB]: 23.9 / 43.0

SN Margin (Up/Down) [dB]: 11.8 / 12.0

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 9 / 0

Loss of Signal (Local/Remote): 1 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 42 / 0

FEC Errors (Up/Down): 53 / 6,110

CRC Errors (Up/Down): 23 / 24

HEC Errors (Up/Down): 21 / 91
 
Unfortunately I don't have a spare modem and router apart from the Sky hub which will be locked down as far as entering the required link connection settings. I can try the adsl cable from that modem/router though if the problem reoccurs.
 
Overnight something hiccuped again...

Uptime: 0 days, 23:49:34

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 988 / 7,451

Data Transferred (Sent/Received) [MB/GB]: 160.96 / 2.74

Output Power (Up/Down) [dBm]: 12.8 / 0.0

Line Attenuation (Up/Down) [dB]: 23.9 / 43.0

SN Margin (Up/Down) [dB]: 12.0 / 11.8

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 9 / 0

Loss of Signal (Local/Remote): 1 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 10,904 / 0

FEC Errors (Up/Down): 6,250,088 / 41,785,359

CRC Errors (Up/Down): 488,684 / 685,131

HEC Errors (Up/Down): 947,223 / 390,384
 
ISP has confirmed something isn't right with a line test so waiting on an OR engineer appointment now. Background noise on line also confirmed.

Fingers crossed for a better connection soon.
 
Yeah, those errors are nuts. I personally get 17,615 CRC errors a day.

However, you should get more stats on that line, and ignore the rest. ES is the most important error figure as DLM will look at that one the most. It'll take your past 24 hours and divide it by the error seconds, and if you're below a certain margin, it will hit you. More CRCs generally mean more ES though.
 
The most concerning thing is your SNRM is at a target of (I assume) 12dB and yet you're still getting crazy errors. The idea of a higher target SNRM is to reduce those errors.

Yes there is definitely something wrong with your line. Does your line sound crackly at all?
 
4.6 million CRC's down stream in 21 hours must be some sort of record :p

I assume the DLM set the SNRM and maybe we weren't interleaved initially but would be understandable if the DLM has loosened up parameters to try and compensate for the line quality.

The ISP spoke to me earlier on the line and knew straight away that the line sounded noisy. It didn't sound that bad to me but they deal with this every day so am happy to take his word on it. To me it has a feint hiss in the background but during our conversation it did crackle a few times. Did a test with things as they were and then using the test socket and he confirmed the number of errors were unacceptable and the voice call was noisy with and without the test socket.

With Plusnet the SNRM came down to 5dB so we were getting around 9 Mbps.

Hopefully I will get confirmation tomorrow of an OR Engineer appointment just in case they don't solve it on their side of the NTE5.

Seemed a bit strange how it could be working OK for a few hours but then the error rate would jump up from a fairly normal figure to a crazy high one. Was just having a google on HR fault and found some examples of people who seemed to have a similar situation where theirs was working OK but then some burst of noise was occurring on their line so I think perhaps it's something like that.
 
AlecR said:
Your line is interleaved because on fast path I doubt you'd get any data throughput at all.

It sounds more and more like an HR fault, coupled with REIN perhaps?
Click to expand...

Quick question for you Alec, since you seem to know quite a bit about all of this - how many errors are you getting per day?

My line is pretty quiet during the day but then from 9pm-1am or so every single night it will spike like crazy (relatively), with the CRC jumping to 30-300 (maybe once it will hit 2000!) up and down until 1am where it'll suddenly quieten down again.

Any reason why its always between that timeframe? DLM won't hit me for it because BT's ES limit is 2880 and that error spike leaves be around 1400-1600 by the end of the day according to my telnet stats. I'd just like to know what could be a common cause for this type of thing, since it definitely scares me that a bad day could have DLM hit me.
 
Noticed a bit of a jump in speed last night so checked the router stats today and things seem to have become more stable. No visit from an engineer or appointment as expected so hopefully it's something they've sorted from their end.

Uptime: 0 days, 7:54:18

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 992 / 7,462

Data Transferred (Sent/Received) [MB/GB]: 82.02 / 1.76

Output Power (Up/Down) [dBm]: 12.9 / 0.0

Line Attenuation (Up/Down) [dB]: 23.8 / 43.0

SN Margin (Up/Down) [dB]: 12.1 / 11.7

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / 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): -

Error Seconds (Local/Remote): 65 / 0

FEC Errors (Up/Down): 8 / 3,748

CRC Errors (Up/Down): 0 / 111

HEC Errors (Up/Down): 0 / 576
 
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