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Normal CRC error rate?

mgillespie
Grafter
Posts: 222
Registered: 08-04-2007

Normal CRC error rate?

Wondering what the regular RX CRC error rate should be.
My connection seems to stall some times.
Looking at my router stats:
ADSL2+(G.992.5)
Up Speed:444937
Down Speed:14336000
SNR Margin:7
Loop Attenuation:32
I am getting 0.4% CRC on the RX.
RX packets (over 3 days) 12761850
RX CRC errors (over same period) 59750
9 REPLIES
wykehamhouse
Grafter
Posts: 260
Registered: 01-02-2013

Re: Normal CRC error rate?

You are getting approximately 19917 CRC errors a day and approximately 830 CRC errors an hour. That is rather high. However, is interleaving disabled? If so, then you can expect high errors like these due to having no error correction and all correctable errors (if interleaving were to be enabled) becoming uncorrectable errors. In addition, to the errors all come in one burst or do they accumulate slowly?
mgillespie
Grafter
Posts: 222
Registered: 08-04-2007

Re: Normal CRC error rate?

How can I tell if interleaving is enabled or disabled?
I did have it changed once, but not sure if it stayed when I changed package.
Community Veteran
Posts: 38,460
Thanks: 1,030
Fixes: 62
Registered: 15-06-2007

Re: Normal CRC error rate?

Look at your pings - if they are about 30 then it is enabled if it is about 20 then it isn't
mgillespie
Grafter
Posts: 222
Registered: 08-04-2007

Re: Normal CRC error rate?

Pinging www.plus.net is bang on 30ms so I guess it's not enabled.
Is there any other way to diagnose why my CRC error rate is high?  The line itself doesn't sound noisy, and it's a brand new ADSLNation X1Fe faceplate filter (and nothing else connected).
It's now getting annoying, as it's impossible to stream LoveFlim without it stalling mid-way in HD (which requires a 3Mbps internet connection, despite having a 14Mbps connection)
mgillespie
Grafter
Posts: 222
Registered: 08-04-2007

Re: Normal CRC error rate?

Out of interest, tried forcing my router (Draytek 2820) to use ADSL2(G.992.3)    and it's been rock solid, with 0 CRC errors all evening and perfect streaming (abiet at 9656888 sync speed).
So it seems I at least have an option to force a slower speed that's more reliable.  Would like to get the ADSL2+ stuff sorted out still thou.
Can someone explain the difference?
Community Veteran
Posts: 5,472
Thanks: 292
Fixes: 4
Registered: 11-08-2007

Re: Normal CRC error rate?

Quote from: ClashcityRocker
How can I tell if interleaving is enabled or disabled?

As you are using a Draytek 2820, try using telnet to login to the device, and type "adsl status" at the prompt.
For example in a command window -
> telnet 192.168.1.1
Account:  <router-admin-username>
Password: <router-admin-password>
Type ? for command help
> adsl status
  --------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
  Running Mode            :    G.DMT      State                : SHOWTIME
  DS Actual Rate          :  8128000 bps  US Actual Rate      :  448000 bps
  DS Attainable Rate      :  8128000 bps  US Attainable Rate  :  1328000 bps
  DS Path Mode            :        Fast    US Path Mode        :        Fast
  DS Interleave Depth    :        1      US Interleave Depth  :        1
  NE Current Attenuation  :        8 dB    Cur SNR Margin      :      14  dB
  DS actual PSD          :    15. 9 dB    US actual PSD        :    12. 3  dB
  ADSL Firmware Version  : 232201_A
  -------------------------------- ATU-C Info ---------------------------------
  Far Current Attenuation :        4 dB    Far SNR Margin      :      30  dB
  CO ITU Version[0]      : 00005453      CO ITU Version[1]    : 00005443
  DSLAM CHIPSET VENDOR    : < TI >
> quit

If your line IS interleaved then the DS and US "Path Mode" will say "Interleave",
of if NOT interleaved they will say "Fast" as shown above.
Hope that helps  Wink
Community Veteran
Posts: 5,472
Thanks: 292
Fixes: 4
Registered: 11-08-2007

Re: Normal CRC error rate?

Have you checked whether you have the best firmware loaded for your ADSL2+ line ?
From this release note - http://www.draytek.co.uk/support/download/readme_v2820.txt
Quote
Release Notes for Vigor2820 series
Firmware Version : 3.3.7.3 (Release)
Release Date : 12th October 2012
Build Date : 3rd October 2012
Applicable Models : Vigor2820, Vigor2820n, Vigor2820Vn, Vigor2820Vsn
ADSL Modem Code : 232201
Locale : UK Only / Annex A Only (inc UK Annex M)
******************************************************************************
IMPORTANT NOTE: Do not upgrade directly from 3.3.5 (and earlier) to 3.3.7.3.
Due to differences in the Web UI and functionality the router MUST first be
upgraded to 3.3.5.2 prior to upgrading to 3.3.7.3.
Upgrade your router to Version 3.3.5.2 first, and afterward upgrade the router
to Version 3.3.7.3.
NOTE: ADSL Modem Codes
For general purpose usage on UK lines, modem code 232201 is recommened
For ADSL2+ Annex M lines, the latest modem code 2471201 is suggested
For line speeds of less than 4Mbps, on lower quality lines a modem code with mor
conservative paramaters, 211801 is suggested.
mgillespie
Grafter
Posts: 222
Registered: 08-04-2007

Re: Normal CRC error rate?

 
> adsl status
  --------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
  Running Mode            : ADSL2(G.992.3)      State                : SHOWTIME
  DS Actual Rate          :  9656888 bps  US Actual Rate      :  444937 bps
  DS Attainable Rate      : 10688000 bps  US Attainable Rate  :  1224000 bps
  DS Path Mode            :  Interleave    US Path Mode        :  Interleave
  DS Interleave Depth    :      64      US Interleave Depth  :        1
  NE Current Attenuation  :      27 dB    Cur SNR Margin      :        6  dB
  DS actual PSD          :    19. 7 dB    US actual PSD        :    11. 9  dB
  ADSL Firmware Version  : 2471201_A
  -------------------------------- ATU-C Info ---------------------------------
  Far Current Attenuation :      14 dB    Far SNR Margin      :      29  dB
  CO ITU Version[0]      : 00004946      CO ITU Version[1]    : 0000544e
  DSLAM CHIPSET VENDOR    : < IFTN >
>
mgillespie
Grafter
Posts: 222
Registered: 08-04-2007

Re: Normal CRC error rate?

Really low error rate when I force to ADSL2 (rather than ADSL2+).  Is this something a line test could identify?