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[ColinS]

if its the old graph script then FEC=CRC due to the web gui bug.

No, it's not, so it isn't.

[kitz]

Jeeze 3.5 m - Thats one hell of a lot of FEC's....  !!!    What the heck was going on there Colin?


I only mentioned it because the engineer said it far exceeded the fault threshold for my line.  After the burst they continued at about 100-200 per second whilst the line was open...  then stopped when the phone was put back on the hook.

I was told what he'd consider the fault threshold for my line, and I was surprised that it was quite low.  I'm deliberately not going to quote it though because it is based on line length and I dont want anyone googling this at a later date and thinking they have a fault without knowing all the other factors.   Some of it may be down to the individual engineers interpretation based on whatever else they observe during their tests.   It stands to reason that a short line with 18dB of SNRm is not expected to generate as many errors as a long line with say only 3dB of SNRm.

These CRC/HEC noise bursts also likely correlate with the problems on my voice line where callers would complain about hearing a very high pitched burst of static that shrieked down the phone line and hurt their ears. 

Oddly I never heard that at my end despite several callers mentioning it. The line would be very noisy hissy crackly and just couldnt hear what the other person was saying and then either the voice and/or dsl would drop out.

Also bear in mind that my voice line had become increasingly unusable over the last 2 weeks..  and last weekend I wasnt even able to use it to speak with anyone. I could dial out... but we wouldnt be able to hear anything at all.  This is also the same period when my upstream wouldnt sync at more than 15Mb.

I also found out yesterday that such a high level of HECs (for my line) is considered symptomatic of a physical line fault (as opposed to say REIN) as long as all other obvious causes have been eliminated...  and of course its not simply that the line is running on too low a target SNRm

[Chrysalis]

yeah, since you are used to almost no errors when you seeing 200 a second thats a big alarm, infact on any line 200 a second is a problem, you will see noticeable packetloss with that error rate.  A better indicator I feel is looking at SES stats.  Generally if you only seeing ES's then the erorr rate is probably not high enough to be a problem, if you seeing SES's then usually performance is also affected.

I expect the error rate threshold is determined by line length and quality, this I already believed to be the case anyway, like I mentioned in another post, the way customers get treated seems dependent on the area, if an area with good short lines then a line with errors and low sync will stand out like a sore theumb and get treated as a fault, but if an area half the lines are syncing low and high error rates are the norm then it will be treated as normal service.  I am of course interested in your threshold :p  curious if my current error rate is above that threshold.  My error rate on vdsl was about 300 crc a day (when I had 90 attainable with spare snrm), about 600 a day after dropped to 73 with 6.5db snrm, and since then its been anything between about 600 a day and 1200 a day.  Since 2 days ago tho when my line resynced itself the error rate has gone down again to about 600 a day and the upstream error rate plummeted that was previously about 200-300 a day and now about 60 a day. Thats 60 a day on a 14db margin as my upstream attainable is now over 30mbit.  This error rate doesnt give me any visible packetloss.

Also regarding voice quality, whenever I have had a BT line, its been bad, now if I use it there is a background hiss and audio is quiet both ends.  This I have always just considered normal as my BT lines have always been like this, when I had a VM line the quality was very different, my mobile phone is much clearer and louder than my BT landline.  But again I think is down to what is acceptable in any given area.

The big question is, is your fault cleared up now?

[kitz]

A better indicator I feel is looking at SES stats.

Agree that ErrSec & SES give a better indication than total count, because when looking at line stats you dont often know if its burst or continous.

When recording with DSLstats/HG612Modem_stats I would see ESecs and SES during the 'burst periods' when the phone was in use.

Now I may be wrong (BS could perhaps confirm) but I dont recall seeing ErrSec & SES displayed on the JDSU.  Its a small screen and from what I can recall by looking over his shoulder it only showed CRC/HEC/FEC on the page that the engineer was watching when doing his tests.  It may have been on another page or further down the screen?

error rate threshold is determined by line length and quality, this I already believed to be the case anyway

It makes total sense for it to be this way.

My error rate on vdsl was about 300 crc a day (when I had 90 attainable with spare snrm)

In this respect the engineer is limited in that they can only monitor for a 5-15 min period.  Tough luck if its intermittent    The past 2 engineers have been good and know their stuff and have also both been interested in stat monitoring progs.   Luck of the draw with engineers and how much they now.

Ezzer gives a general guide here

whenever I have had a BT line, its been bad, now if I use it there is a background hiss and audio is quiet both ends.

Mine used to be good, then it started getting a cyclic hiss..  obviously this then progressed to noise being worse than the voice level.   
Now its a very slight background hiss on QLT, but call quality is clear.  I have only tested with cordless though since the fault.  Id need to plug my old corded phone back in to give a better indication.

The big question is, is your fault cleared up now?

Its been up for nearly 2 days and SNRm hasnt budged.   Can use phone without any problems and nothing happening to the SNRm.  Looks like Ive had a few FECs on the upstream  and a some CRC/HEC on the downstream but Im not too bothered as all seems well as far as Im concerned.   

Im ignoring my upstream RS graph which is periodically blipping with 4.5e+006 spikes.
Also need to do a full modem power recycle as I could do with monitoring from fresh and clear out any totals, because theres a hell of a lot of ES & SES which were likely picked up the day before the fault was cleared.


---
Edited to correct stupid typ0

[Chrysalis]

Well a JDSU wouldnt need ES and SES as when its used its been looked at live.

Whilst a modem tallies the errors over a long period of time, its unlikely someone is sitting watching it 24/7 so the eS and SES give an idea exactly as you said if the errors are spread out or not. so 300 CRC errors with 60 ES and 0 SES would suggest an average of 5 errors per occurance and none of them been serious.

[Black Sheep]

Wrong again. Here's a 'Screen snapshot' of my very own JDSU.

[kitz]

Now I may be wrong (BS could perhaps confirm) but I dont recall seeing ErrSec & SES displayed on the JDSU.  Its a small screen and from what I can recall by looking over his shoulder it only showed CRC/HEC/FEC on the page that the engineer was watching when doing his tests.  It may have been on another page or further down the screen?

Thank you BS for the screenie & putting us right

[Chrysalis]

[burakkucat]

Wrong again. Here's a 'Screen snapshot' of my very own JDSU.

Purrfect. That saves me having to scrabble around in my 'what not' whilst looking for the appropriate image! 

[kitz]

Closing this off now, as my ticket from PN has just auto-closed too.

3 weeks its been like this.   
Stats arent as good on this line as they used to be on the other pair, when it wasnt being stupid.   
But at least Im stable and able to use the phone again.

[burakkucat]

That is essentially a purrfect SNRM graph. 

[Chrysalis]

yeah its very good, it does seem kitz is in a pretty good area for dsl.  But I can understand why she is annoyed losing what was previously better stats as we all want perfection.  But at least its now stable and with still a decent snrm.