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FEC

Community Veteran
Posts: 4,852
Thanks: 121
Fixes: 24
Registered: 14-07-2009

FEC

I'm sitting here looking at a new Technicolor router (replacing an old failed router).  The attenuation is 54dB, SNR margin reads 14.5dB, presumably targetting 15dB and the downstream sync rate is around 1700kbps.
What's disconcerting me is the downstream FEC count which equates to around 400 errors per minute.  In fact the count goes up every time I refresh the page.  I've checked filters, wiring and the like but to no avail.
Is a high FEC count a contra-indication for getting the SNR margin set back to 6dB?  Is there anything else I can do about it?  Or should I not worry?  A quick speed test came within reasonable proximity of the IP Profile so there is no obvious effect from these errors.
7 REPLIES
Community Veteran
Posts: 38,460
Thanks: 1,027
Fixes: 62
Registered: 15-06-2007

Re: FEC

A high FEC count with a15dB noise margin is an indication of line problems but won't seriously affect the speeds
What are the CRC counts doing
With that high an FEC count there is no way the line will support a lower noise margin
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: FEC

Hi ReedRichards,
I've just taken a look at your line and it's not showing anything to worry about. Your SNR is very low but your line seems to be working fine with it. Your line is generating a few errors but Interleaving seems to be clearing these up for you anyway. I wouldn't worry about the FEC errors to be honest.
Your lien will move your SNR up to 6db if your line starts to drop or the line quality comes Red. (Line quality is something we check on our end through the DLM Data)
If you start to notice this becoming service affecting, let us know so we can get it looked into further for you.
Chris Pettitt
Cloud Environments Engineer
Community Veteran
Posts: 38,460
Thanks: 1,027
Fixes: 62
Registered: 15-06-2007

Re: FEC

Chris
We are not discussing his line
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: FEC

Right, sorry, that wasn't made all that clear to me.
Chris Pettitt
Cloud Environments Engineer
Community Veteran
Posts: 4,852
Thanks: 121
Fixes: 24
Registered: 14-07-2009

Re: FEC

Yes, thanks, Chris, but Oldjim is correct; not my line (which is superbly stable).
I thought I remembered that the line in question had a 6dB noise margin last week.  That was with a different (unreliable) router and also before my client unplugged her old phone and filter and plugged a new phone directly into the socket - which took down the broadband for a few days.
Do Plusnet keep records of old SNR targets for the last several weeks?
 
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: FEC

It is possible that we do, that depends on the last time the DLM Data was updated. If it has been updated a few times over the last few weeks, we can pull that information.
Chris Pettitt
Cloud Environments Engineer
Community Veteran
Posts: 4,852
Thanks: 121
Fixes: 24
Registered: 14-07-2009

Re: FEC

Chris, I'll send you a PM with the client information.