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[joss]

Good morning one and all.

Posted below are sats displaying high CRC and ES errors, on the downstream side. Can anyone help with to regards what causes this high level of errors? Also what could I do to try and lessen them? As you can see the router was last rebooted 1 days 1 hours 18 min 7 sec.

Total Up Time (As Reported):
 1 days 1 hours 18 min 7 sec

Noise Margin:     6.4   dB
Connection Rate:  7936  Kbps
Line Attenuation: 28.0  dB
Power:            19.8  dBm
Max Rate:         8672  Kbps
 
SF:               8734123
SF Errors:        1054
Reed Solomon:     1187840792
RS Corrected:     1299645
RS Un-Corrected:  28875
HEC:              778
Errored Seconds:  784
Severe ES:        3
Interleave Depth: 64

[roseway]

Those error rates are fairly high but not disastrously so. In about 1500 minutes of uptime you had about 13 minutes worth of errored seconds, i.e. less than 1%. This wouldn't have had a significant effect on performance, and doesn't appear to be causing instability.

The cause of the errors could be just about any sort of interference or minor line or wiring problem. You might be able to home in on a cause by installing Routerstats and seeing how the noise margin varies over time, and the general advice here is always worth looking through to get the best out of your connection.

[joss]

Those error rates are fairly high but not disastrously so. In about 1500 minutes of uptime you had about 13 minutes worth of errored seconds, i.e. less than 1%. This wouldn't have had a significant effect on performance, and doesn't appear to be causing instability.

The cause of the errors could be just about any sort of interference or minor line or wiring problem. You might be able to home in on a cause by installing Routerstats and seeing how the noise margin varies over time, and the general advice here is always worth looking through to get the best out of your connection.

Hi Eric
I have router stats installed and I can report that the SNRM is generally rock steady at 6db daytime, then dropping off to as low as 4db late evening which touch wood has not caused a re sync for a good while.
The Errors have shot up recently and I can't help but ponder MTU in this. Last week I could not access my on line banking nor a few other web sites. nor would Xbox360 connect. On speaking to ZEN support they said to lower the MTU to 1200 from 1458. This did allow normal usage once again.
However after a week I put the MTU up to 1400 which seems to be ok. No problems with above mentioned web sites and xbox 360.

I'll get a copy of DrTCP and have a play with that to see if it makes any difference.

Thanks again

[roseway]

I don't think that the MTU will affect error rates reported by the router.

[kitz]

MTU wont affect the line stats error rate.

It can however cause the other symptoms such as failure to access some secure sites.
1200 seems a bit low - 1400 is about the lowest I'd recommend but thats for the likes of AOL/TalkTalk.  1458 should be fine.  1430 is a favourite of mine.

[joss]

MTU wont affect the line stats error rate.

It can however cause the other symptoms such as failure to access some secure sites.
1200 seems a bit low - 1400 is about the lowest I'd recommend but thats for the likes of AOL/TalkTalk.  1458 should be fine.  1430 is a favourite of mine.

Understood Kitz

I did try 1430 but the Halifax banking just would not have it at all so back to 1400. Personally I think Halifax on line banking need to make some changes.

[kitz]

Do you have your router set to block pings?

Some websites such as grc.com make a big thing about if you can be pinged... but in actual fact blocking pings at your router can 'break the internet'.
When you make your router unpingable, this also turns off the ICMP protocol.  ICMP is a valid internet protocol and is needed for something called Path MTU Discovery (PMTU) to work properly.

Although grc.com is a very good site... many people disagree with the alarms it gives out about being pingable or not. 
Having your router pingable does no harm, its not like an outsider can ping a PC direct through a NAT router.  But having it turned off can make your router the point of being the blackhole where packets are dropped.. which then stops you from being able to connect to some secure sites.

[joss]

Do you have your router set to block pings?

Some websites such as grc.com make a big thing about if you can be pinged... but in actual fact blocking pings at your router can 'break the internet'.
When you make your router unpingable, this also turns off the ICMP protocol.  ICMP is a valid internet protocol and is needed for something called Path MTU Discovery (PMTU) to work properly.

Although grc.com is a very good site... many people disagree with the alarms it gives out about being pingable or not. 
Having your router pingable does no harm, its not like an outsider can ping a PC direct through a NAT router.  But having it turned off can make your router the point of being the blackhole where packets are dropped.. which then stops you from being able to connect to some secure sites.

Morning Kitz

Actually I did have ICMP ping turned off. It is now allowed so I shall see if that helps with things here.

thanks

[joss]

Good morning one and all.

Posted below are sats displaying high CRC and ES errors, on the downstream side. Can anyone help with to regards what causes this high level of errors? Also what could I do to try and lessen them? As you can see the router was last rebooted 1 days 1 hours 18 min 7 sec.

Total Up Time (As Reported):
 1 days 1 hours 18 min 7 sec

Noise Margin:     6.4   dB
Connection Rate:  7936  Kbps
Line Attenuation: 28.0  dB
Power:            19.8  dBm
Max Rate:         8672  Kbps
 
SF:               8734123
SF Errors:        1054
Reed Solomon:     1187840792
RS Corrected:     1299645
RS Un-Corrected:  28875
HEC:              778
Errored Seconds:  784
Severe ES:        3
Interleave Depth: 64

As a follow up to the original post and stats posted, I have again over the same time period and after a re boot take the same set of stats. for comparison.
After allowing Pings as suggested, below are the results.

Total Up Time (As Reported):
 1 days 1 hours 50 min 42 sec

Noise Margin:     7.3   dB
Connection Rate:  7936  Kbps
Line Attenuation: 28.0  dB
Power:            19.8  dBm
Max Rate:         8608  Kbps
 
SF:               10550320
SF Errors:        4784
Reed Solomon:     1434843584
RS Corrected:     149327421
RS Un-Corrected:  33591
HEC:              3336
Errored Seconds:  1352
Severe ES:        27
Interleave Depth: 64

CRC:  4784
LOS:  0
LOF:  0
ES :  1352


Bytes Transferred (ppp0):
  Tx: 144490601 (137.7 MiB)
  Rx: 2619436220 (2.4 GiB)

It would seem that the crc and error seconds are still very much on the up.

[jeffbb]

Hi

The errors do look a bit high ,but that is comparing to mine . I must admit I am not really sure what sort of error rate is acceptable before you need to be concerned . One thing that seems to be important is whether the errors are evenly spread or are coming in bursts .  Perhaps someone can give some guidance .

Regards Jeff

[kitz]

High error rates normally coincide with noise bursts which cause reduction in the signal strength (SNR), is routerstats showing any noise bursts, or are they possibly happening too quick to perhaps be captured?

[joss]

High error rates normally coincide with noise bursts which cause reduction in the signal strength (SNR), is routerstats showing any noise bursts, or are they possibly happening too quick to perhaps be captured?

SNR is very stable and has been for a good few weeks. usually around 6-7db through the day. Come evening it can drop as low as 4db.
Nothing obvious in the way of spikes in the snr tracing under router stats.

[kitz]

The high error rates indicate some sort of noise on the line - possibly static type interference.

Block coding error correction (Reed Solomon Error Correction) is normally pretty good at correcting very quick noise bursts.  The high level of FECs tends to back up the possibility of noise bursts.

As jeff says - state of line also depends on whether these come in a batch or if they are spread out over time.

[joss]

The high error rates indicate some sort of noise on the line - possibly static type interference.

Block coding error correction (Reed Solomon Error Correction) is normally pretty good at correcting very quick noise bursts.  The high level of FECs tends to back up the possibility of noise bursts.

As jeff says - state of line also depends on whether these come in a batch or if they are spread out over time.

Looking at router stats graph of CRC EF  broadly match tracings of each other. The CRC can, and does go off the chart in batches through out the day and evening. With periods where the CRC "castellate" around 0-5 CRC. and are spread out.

[joss]

As an update, I rang ZEN tech support yesterday and explained what was happening. A very nice guy spent a good hour or so running tests at their end. In total they ran the test 21 times and got strange results. Out of the 21 tests only 3 actually gave the same results. The other 18 tests either failed or gave conflicting information.
Zen are still looking into this.

Total Up Time (As Reported):
 19 hours 48 min 8 sec
 
CRC:  70
LOS:  0
LOF:  0
ES :  15


Bytes Transferred (ppp0):
  Tx: 37424217 (35.6 MiB)
  Rx: 701464289 (668.9 MiB)

  IP address: xxx.xxx.xxx.


Unsurprisingly, my SNR has gone up to 12db and sync down to 6500 due to the tests and re sync of router. Having said that the CRC count has dropped considerably.
The gear I ordered from ADSL Nation should arrive soon. So I will install that and take things from there.