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Are these uncorrected errors excessive?

grahamn
Rising Star
Posts: 160
Fixes: 1
Registered: 12-09-2010

Are these uncorrected errors excessive?

The title says it really! No corrected errors, loads of uncorrects and low SNR margin....Is this ok or is there something wrong with the line/router etc?
ADSL Information       (ADSL Firmware Version:  E.67.36.1 )  
 ATM Statistics TX Blocks RX Blocks Corrected Blocks Uncorrected Blocks
                              2109943 9391108                 0                            461800
--------------------------------------------------------------------------------

 ADSL Status Mode State Up Speed Down Speed SNR Margin Loop Att.
  ADSL2+ SHOWTIME        1083900 13882300                    3.0        24.5

83 REPLIES
Plusnet Help Team
Plusnet Help Team
Posts: 13,322
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Registered: 27-04-2007

Re: Are these uncorrected errors excessive?

I'd never look at errors alone as an indication of there possibly being a fault. It's best to consider other more immediately noticeable factors such as if you're noticing a lot of disconnections or if speeds are reduced.
As far as I can see with what can be checked from this side I I'd not be too concerned as the connection seems to be quite stable but let me know if you've seen any noticeable effects.
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
grahamn
Rising Star
Posts: 160
Fixes: 1
Registered: 12-09-2010

Re: Are these uncorrected errors excessive?

The problem is, that come the evening, the SNR drops below 2 and eveything just stops...I guess noise almost equals traffic at that point and nothing goes anywhere...except the errors of course, that rocket away...  Cry
Community Veteran
Posts: 19,101
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Registered: 31-08-2007

Re: Are these uncorrected errors excessive?

What modem/router do you use? Can you post the full ADSL stats?
grahamn
Rising Star
Posts: 160
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Registered: 12-09-2010

Re: Are these uncorrected errors excessive?

Many thanks, Draytek 2800VG. Screen shot attached (hopefully!)
grahamn
Rising Star
Posts: 160
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Registered: 12-09-2010

Re: Are these uncorrected errors excessive?

and these stats too.....
Community Veteran
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Registered: 29-01-2009

Re: Are these uncorrected errors excessive?

Adam might not like looking at the error rate alone, but DLM certainly does. Of course it also looks at disconnection rates, but it is perfectly happy to slow down your line if it sees a high error rate without any disconnections.
In your situation, the errors are identified by the "Uncorrected blocks" number, but the important thing is to see - when your line is performing at its worst - how that count is changing relative to the total number of RX blocks.
In the information displayed above, you are seeing about 5% of blocks with errors in. If it stayed at this rate throughout the day, you'd expect to see some impact, but not too heavy - maybe a loss of 10% of your throughput on speedtesters. However, my experience so far suggests that the overall experience degrades much less gracefully when the error rate gets to around 10%.
Next time you get an evening where the experience has halted (and the errors are rocketing), can you take some snapshots of the RX count and the Uncorrected count?
Another possible tool is the TBB Broadband Quality Meter, which sends regular "pings" to your router, and allows you to monitor the latency & level of packet loss. Take a look on TBB's website - that would give you a graphical representation of when everything grinds to a halt.
I have to say that, to me, this error count looks bad enough that it *ought* to have tripped DLM by now. I'm not sure why it hasn't. My copy of the DLM thresholds suggests that an MTBE of 60 seconds should trigger a DLM slowdown (or addition of interleaving); one error per minute over 8.5 hours would be 510 error. This is *way* over that.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
grahamn
Rising Star
Posts: 160
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Registered: 12-09-2010

Re: Are these uncorrected errors excessive?

Thanks WWWombat. just had a "mini outage" (line and sync held but no web access through the broswer or, anything else possible) with SNR down to 1.0 , stats are now 12687297 Rx'd and 514350 uncorrected.
I will download the monitoring tool you suggested as well.
Community Veteran
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Re: Are these uncorrected errors excessive?

Just keep track of those numbers every 30 minutes, over the evening (or more often, if an outage tends to last for less time)
The BQM isn't downloaded as such. It's a server-based setup that sends packets to you, and measures the response. You'll probably need to configure the router so it responds to the pings.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
grahamn
Rising Star
Posts: 160
Fixes: 1
Registered: 12-09-2010

Re: Are these uncorrected errors excessive?

Ahhhhh, glad you mentioned the ping bit, I think that'd disbaled and would expain a very blank graph! Will enable ping.
Update: Even with Ping enabled, nothing...a very blank graph  Undecided....spoke too soon, something is now appearing  Roll eyes
RPMozley
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Re: Are these uncorrected errors excessive?

You'll have to wait a bit for it to fill out.
That's RPM to you!!
Community Veteran
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Re: Are these uncorrected errors excessive?

Just to whet your appetite, here's one I prepared earlier  Cool
The first is when I first got FTTC, and the second is 2 days later, when DLM intervened.
Unfortunately, the fibre modem was locked, so I couldn't get to the actual error stats at the time - and can only see the impact the errors had on the ping packets.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
grahamn
Rising Star
Posts: 160
Fixes: 1
Registered: 12-09-2010

Re: Are these uncorrected errors excessive?

Hi, Very interesting to see this stuff portrayed visually.  Smiley
My monitor has started now, so I will let that run through the night and tomorrow and will post what it shows.
My router did restart just now...not sure if that was because I allowed the ping response which made the router reboot?!?...in any event my Rx and Error blocks went back to zero again.
Graham.
PS: Router now up 35 mins and showing RX Blocks: 1090852,  Uncorrected Blocks: 3923
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Re: Are these uncorrected errors excessive?

What was the noise margin when it restarted? My guess is that it will be 3 and that you have a lower sync speed and that tomorrow during the day you'll see the noise margin much higher. That might mean that you see less errors and a more stable line (until the next daytime sync when you'll be back to square one).
jelv (a.k.a Spoon Whittler)
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Community Veteran
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Registered: 31-08-2007

Re: Are these uncorrected errors excessive?

You will find your error rate is much better now, having had a resync whilst your SNRM was so low, as it will have gone back to the Target value (3dB presumably) albeit with a slightly lower sync speed. (Invariably altering most modem/router settings needs a reboot/resync).