FEC errors

I am getting a large number of Local Interleaved FEC errors - about 3500 per minute. This occurs on a regular basis and starts in the early evening. For example, this evening my stats were:

Atten. 37dB
SNR 12.5dB
Sync 5152

I have just re-booted and my stats are now:

Atten. 36.5dB
SNR 11.5dB
Sync 5216

after the re-boot the errors have stopped.

I seem to start getting errors when the SNR drops in the evening, but if I re-boot the sync can actually improve as seen in the above figures. If I re-boot in the morning I will sync at around 6.5M, this will hold for the day but at about 7pm I will see a drop in SNR followed by lots of FEC errors and eventually a re-sync. Sometimes after a re-sync I will get the errors starting again which can be cured by a re-boot.

I assume this amount of errors is a problem. Is there anything I can do about it?

Sounds as though you have interleaving on your line - the FEC errors indicate that it is doing its job properly. Interleaving is applied to noisy lines to improve stability. You will incur a hit on your pings; however if you are not a gamer then this should not be an issue.

Yes, I have interleaving on the line and I expect some FEC errors as a result. Most of the time I get fairly few but when I start to get such a large number I thought it might be unusual.

The other point that is interesting is that when I re-boot, as in the example in my post, the errors disappear but the SNR gets worse.

I am not a gamer so pings are not a big issue for me. However, I have not seen an increase in ping times. For example, an average ping to www.bbc.co.uk is about 25ms now. I don't think I have ever seen it less than 23ms even when I was on a fixed line in fast mode.

In reply to:

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Yes, I have interleaving on the line and I expect some FEC errors as a result

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As far as I know FEC errors are corrected errors and it's only the CRC errors that can't be corrected and this data has to be re-sent wasting bandwidth.

I also have interleaving enabled and I have a lot more FEC 'errors' than CRC errors so it means that interleaving is working on my longish line.

True - FEC errors are corrected errors.

I have now had the router connected for about 24 hours. In this time I have had about 1,280,000 FEC errors and only 8 CRC errors. I can look at my router stats and watch the FEC errors increase at a steady rate of about 3,500 per minute even with no internet activity. My SNR is about 12.5dB - 13dB. If I were to force a re-sync now I would expect the errors to stop completely with very little change to my sync or SNR.

It just seems a little odd the steady high rate of errors I am getting.

In reply to:

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I can look at my router stats and watch the FEC errors increase at a steady rate of about 3,500 per minute even with no internet activity. My SNR is about 12.5dB - 13dB.

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I agree that there is something wrong with your line and on such a high SNR as well.

For comparison purposes, on a 7 day, 14 hour and 53 minute uptime I have aprox 298,000 FEC errors, aprox 3,600 HEC errors and aprox 2,800 CRC errors.