Ridiculous FEC's

Over the last 68 hours my CRC errors are at the rate of 20 to 45 an hour.

FEC's on the other hand vary dramatically.
Over the same period they average over 900,000 an hour.
Over the last 67 mins they have increased by just over 26 million.

The Speedtouch 546 v5 in the past has reported quite normal readings but perhaps its started to act up.

Is this level of errors realistic and possible ?.

I'm tempted to re-sync and hope things don't deteriorate.

Sync rate 8096, Target SNM 6 dB with actual margin varying between 5.5 and 8.5 dB.

Update: 68 hrs 45 mins and 99.77 million FEC's.

http://i2.tinypic.com/4hb94x3.png

That does seem high. I've been connected a similar time to you (actually about an hour longer) and I've had 1,837,528 FEC errors. Are you using microfilters or a faceplate?

I'm connected direct to an ADSL filtered Faceplate with one phone connected to the faceplate.

In the recent past I've had 'normal' readings although they did vary quite a bit.
I've never had values remotely resembling these.

I'm surprised there seems to be very little obvious negative impact.

Edited by deleted (Fri 09-Feb-07 23:49:02)

It does seem a high amount, but as I've discovered recently, it's generally not an issue and will have no noticable impact, so I wouldn't worry.

Has interleaving just been switched on?

I thought interleaving reduces errors?

I've been looking into this, and it appears to me that there is no "normal" level for FEC and CRC errors - you should only be concerned if there is a sudden rise. Let's hope that Pavlo's problems were short-lived.

First point to note is that when a router reports FEC errors as a single figure then it's usually referring to errors that it has corrected. So you wouldn't expect this to have any impact unless the CRC errors are also increasing.

However, assuming that this is a genuine figure (not just the router reporting nonsense) then it suggests that you are getting bit errors occurring in every frame received, but not enough to lose sync. This suggests a tone being knocked out, but the modem is failing to re-allocate the bits to other tones. Any chance there's a pirate radio station has started up nearby for example? Also does your router have a bitswap configuration option, and if so is it turned on?

If this is right then you would expect a resync to solve the problem.

Thanks for the further replies.

Has interleaving just been switched on?
Interleaving has been on since last June.

Let's hope that Pavlo's problems were short-lived
Over the last 12 hrs FEC's at the rate of 28 million per hour.

So you wouldn't expect this to have any impact unless the CRC errors are also increasing
CRC's are reasonably consistent

Any chance there's a pirate radio station has started up nearby for example
Interesting thought but I think extremely unlikely in my location - similarly I have no knowledge of any other source of interference appearing recently.

I was using DMT to drop the Margin from 15 dB to 10 dB until a few days ago - speeds 7500'ish and few errors.
I used DMT to set the Margin back to 15 dB prior to BT dropping the Target SNM back to 6 dB.
The speed went up to 8096 and initially the errors were reasonable and then they increased as above.

I believe the Speedtouch Router with Firmware 6.1.4.7 uses bit swapping but I know little about the subject.

If this is right then you would expect a resync to solve the problem
I was tempted to re-sync last night and thought better of it.
My margin has been 7.5 dB for a couple of hours so I

AFAIUI FECs are corrected errors from the error correction process included with BT type interleaving. It was kindly explained to me that so-called interleaving not only includes interleaving but also additional error correction that reduced efficiency.

CRCs are errors that got through uncorrected.