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[GigabitEthernet]

I seem to accumulate a massive number of FEC errors on a daily basis. I know these are not issues in themselves, but could it indicate some interference perhaps?

Here are my stats:

Code: [Select]

Max: Upstream rate = 1040 Kbps, Downstream rate = 8808 Kbps
Path: 0, Upstream rate = 1040 Kbps, Downstream rate = 8174 Kbps


Link Power State: L0
Mode: ADSL2+
TPS-TC: ATM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 4.4 5.8
Attn(dB): 44.0 22.2
Pwr(dBm): 0.0 12.7

Code: [Select]

Since Link time = 11 hours 16 min 15 sec
FEC:      878980      0
CRC:      112      403
ES:      86      266
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0

[burakkucat]

Well, yes. Definitely something is causing a problem to the data transfer on your line but, fortunately, the error correcting code is able to salvage the data without needing to request a retransmission of the affected block.

Here are my corresponding statistics --

Code: [Select]

Max:    Upstream rate = 952 Kbps, Downstream rate = 5848 Kbps
Path:   0, Upstream rate = 940 Kbps, Downstream rate = 5820 Kbps

Link Power State:       L0
Mode:                   ADSL2+
TPS-TC:                 ATM Mode
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        1.5             6.0
Attn(dB):        50.5            28.6
Pwr(dBm):        19.9            12.8


Code: [Select]

Since Link time = 26 days 7 hours 34 min 25 sec
FEC:            551889657               0
CRC:            846990          1203
ES:             128384          948
SES:            14623           1
UAS:            0               0
LOS:            1               0
LOF:            0               0

You seem to be clocking up FECs at a rate of nearly 1300 per minute, whereas for my line it is a rate of nearly 14564 per minute!

Care to swap lines? 

[Black Sheep]

Wow, Mr Cat ..... thats a lot of interleaving going on there, never mind ES !! You look to have issues yourself there bud ??!!

[burakkucat]

Wow, Mr Cat ..... thats a lot of interleaving going on there, never mind ES !! You look to have issues yourself there bud ??!!

Thanks for confirming it. Now if you would care to arrange to be seconded to the East Anglia region, with a particular bias towards the EABSE exchange, then I might be inclined to do battle with TalkTalk to arrange for an Openreach technician sheep appointment! 

With regards to the Huawei HG612's ability to "hang-on" during a "noisy onslaught", I have watched the DS SNRM reach zero, go negative (to -1 dB) and then some more (to -1.9 dB) whilst still providing throughput. It was only when the DS SNRM reached -2.0 dB that the device let go and invoked a re-sync event. I am suitably impressed with the BCM6368 within the device. 

[Black Sheep]

LOL .... the way the floods are going up here, there's half a chance I may end up sailing past E. Anglia in the very near future !!

[GigabitEthernet]

So, is there anything I can do?

[burakkucat]

In my opinion, probably not.    Unless, that is, you have thousands of pounds that you are prepared to give to the BT Group plc. 

Are you concerned because of a sudden noticeable effect on your line's performance or is it just because you have the means to observe the statistics? If it is the latter, I would suggest that you do as I do and just ignore the figures. 

[GigabitEthernet]

So, there is nothing I can do about this noise?

[burakkucat]

   Hmm . . . Assuming that is your QLN graph, you could determine the frequency of each distinct, major peak and then: (1) check to see if it is an authorised broadcast transmission (2) monitor the frequency with some suitable directional apparatus, with the aim of locating its source.

[GigabitEthernet]

  Hmm . . . Assuming that is your QLN graph, you could determine the frequency of each distinct, major peak and then: (1) check to see if it is an authorised broadcast transmission (2) monitor the frequency with some suitable directional apparatus, with the aim of locating its source.

I wouldn't even know how to start?

[burakkucat]

I wouldn't even know how to start?

From the beginning, from first principles! 

We know that in the UK an xDSL service has tones spaced at 4.3125 kHz.

Thus Tone 0 begins at 0 Hz and extends up to 4.31249999999 . . . kHz. Tone 1 begins at 4.3125 kHz and extends up to the start of Tone 2. Tone 2 starts at 2 x 4.3125 kHz and extends up to the start of Tone 3.

Hence the range of frequencies for Tone N is from (N x 4.3125) to ((N + 1) x 4.3125) kHz.

We now look at an accurate QLN plot and annotate each peak with its closest tone number (or numbers). By substituting for N, in the above, we can calculate the frequency range of the "noise" signal. We can then compare those frequencies against known LW and MW broadcast stations, using the Medium Wave Radio site, for example. If there is no match, then the peak in question could be due to some extraneous event. If that is the case, you will need some form of portable receiver (with a directional aerial system), maps of your locality, a notebook, lots of time and patience.

[GigabitEthernet]

Thank you, bk.

[Jonnyteg]

Fec errors are not considered a problem, unless service affecting.  I have seen fec errors increment from the dsl out in the exchange.

Crc events or error seconds are a problem, you have some    your snr is dipping over time asuming target of 6db for you i would reccomend a router reset every 2 days let the fault develop and when it gets worse report to your cp.

[Black Sheep]

JT .... it obviously depends on the level of FEC's, and the speed in which they increment. A lazy way of faulting a circuit is to increase the depth of interleaving, thus giving more FEC's. It is IMO, masking a real-life fault condition.

Interleaving is a great way of stabilising a circuit, but both the OP and B*Cat have far too much interleaving taking place on their circuits.    

[GigabitEthernet]

My DS interleaving depth is currently 64. I could ask for this to be lowered, but then surely I would get more CRCs and ES?