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High FEC error rates causing disconnections

antiquebrit
Grafter
Posts: 76
Registered: 09-12-2009

High FEC error rates causing disconnections

Is there anything that can be done about my download SNmargin currently at 14.5?  Sad
Also the router no does not show any data transferred!!  Shocked  See below. 
Thanks
David

DSL Connection
Link Information

Uptime: 7 days, 22:49:09
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 2,592
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 17.0
Line Attenuation (Up/Down) [dB]: 31.5 / 55.0
SN Margin (Up/Down) [dB]: 17.0 / 14.5
Vendor ID (Local/Remote): TMMB / TSTC
Loss of Framing (Local/Remote): 3 / 0
Loss of Signal (Local/Remote): 1 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 24 / 0
FEC Errors (Up/Down): 22 / 88,684
CRC Errors (Up/Down): 22 / 455
HEC Errors (Up/Down): 15 / 397
17 REPLIES
Superuser
Superuser
Posts: 9,377
Thanks: 692
Fixes: 51
Registered: 06-04-2007

High FEC error rates causing disconnections

It's a design feature of the Thomson router not to show any data transfer, nothing to worry about.
With regard to the high noise margin, what is your target noise margin (the value immediately after restarting the router)? (If you need to restart to find out I suggest doing this during daylight hours when noise levels are usually lower.)
My guess is your target noise margin is probably 12dB. However what has caused the DLM to increase it to that value? Have you experienced lots of disconnections or high numbers of transmission errors?
David
antiquebrit
Grafter
Posts: 76
Registered: 09-12-2009

High FEC error rates causing disconnections

Thanks for your response spraxyt.
After a restart this is what I get, below.
There have been minimal disconnections recently but a lot of FEC errors.
david

DSL Connection
Link Information

Uptime: 0 days, 0:01:17
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 3,776
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 18.5
Line Attenuation (Up/Down) [dB]: 31.5 / 56.0
SN Margin (Up/Down) [dB]: 16.0 / 9.0
Vendor ID (Local/Remote): TMMB / TSTC
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 0 / 0
FEC Errors (Up/Down): 0 / 15
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0
MrC
Grafter
Posts: 523
Thanks: 2
Registered: 17-07-2008

High FEC error rates causing disconnections

That's a very respectable sync rate given your attenuation (56dB). Your FEC error count in your earlier post is also very good for the amount of time the connection had been up. Basically your line is working quite well and any improvement at all is going to be marginal.
Superuser
Superuser
Posts: 9,377
Thanks: 692
Fixes: 51
Registered: 06-04-2007

High FEC error rates causing disconnections

Quote from: antiquebrit
SN Margin (Up/Down) [dB]: 16.0 / 9.0

That shows your target noise margin is 9dB which is lower than I thought it might be.
As mentioned in the previous response, your line stats are quite decent. Large numbers of FEC error aren't necessarily anything to worry about (my stats show 2 million FEC errors over 5 days, with 1500 CRC errors, and 1450 HEC errors).
Could you post the stats again later on tonight?
David
antiquebrit
Grafter
Posts: 76
Registered: 09-12-2009

High FEC error rates causing disconnections

Thanks spraxyt and MrC for your thoughts.  I will post another set of stats tonight as suggested.
What gets my goat is that I get these decent figures after a restart but without exception the noise margin and the bandwidth are reset overnight to much less decent values. Angry
david
antiquebrit
Grafter
Posts: 76
Registered: 09-12-2009

High FEC error rates causing disconnections

Wow! 3 million FEC errors in 7 hours.  Shocked
david

DSL Connection
Link Information

Uptime: 0 days, 3:04:35
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 3,776
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 18.5
Line Attenuation (Up/Down) [dB]: 31.5 / 56.0
SN Margin (Up/Down) [dB]: 17.0 / 9.0
Vendor ID (Local/Remote): TMMB / TSTC
Loss of Framing (Local/Remote): 43 / 0
Loss of Signal (Local/Remote): 5 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 75 / 0
FEC Errors (Up/Down): 0 / 3,154,111
CRC Errors (Up/Down): 0 / 1,088
HEC Errors (Up/Down): 0 / 33
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

High FEC error rates causing disconnections

1,773,696,831 errors in 10 days. I'm not convinced they are real error.
antiquebrit
Grafter
Posts: 76
Registered: 09-12-2009

High FEC error rates causing disconnections

There you are it has auto reset already!!! Angry
DSL Connection
Link Information

Uptime: 0 days, 0:08:04
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 3,328
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 17.5
Line Attenuation (Up/Down) [dB]: 31.5 / 56.0
SN Margin (Up/Down) [dB]: 16.0 / 9.5
Vendor ID (Local/Remote): TMMB / TSTC
Loss of Framing (Local/Remote): 43 / 0
Loss of Signal (Local/Remote): 5 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 84 / 0
FEC Errors (Up/Down): 0 / 287
CRC Errors (Up/Down): 0 / 2
HEC Errors (Up/Down): 0 / 2
Superuser
Superuser
Posts: 9,377
Thanks: 692
Fixes: 51
Registered: 06-04-2007

High FEC error rates causing disconnections

Quote from: antiquebrit
Wow! 3 million FEC errors in 7 hours.  Shocked
...
Uptime: 0 days, 3:04:35
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 3,776
...
FEC Errors (Up/Down): 0 / 3,154,111
CRC Errors (Up/Down): 0 / 1,088
HEC Errors (Up/Down): 0 / 33

The uptime shown by the router is actually 3 hours - which implies it restarted around 1:30pm, though the sync speed is identical to the value this morning. That FEC error rate is high, and from my experience with the Thomson router it appears to restart once the value approaches 4 million, which ties in with what you are experiencing.
The sync speed is higher than normal for 56dB attenuation (Kitz calculator gives 3424kbps for 6dB target noise margin, so around 2850kbps for 9dB target. However it seems Interleaving is having to work very hard (FEC errors) at the higher sync rate (previous stats showed 89000 FEC errors in almost 8 days synced at 2592kbps).
Whether that count is genuine or not is a debatable point; do you have another router to try?
I think this topic would benefit from being in its own thread, perhaps titled "High FEC error rates causing disconnections". Do you mind if I ask the moderators to split these posts off?
David
David
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

High FEC error rates causing disconnections

Are high FEC errors causing the disconnects?
I'm using a thomson router
Uptime: 10 days, 12:06:30
FEC Errors (Up/Down): 0 / 1.976.951.305
Close to 2 billion errors is somewhat higher than 4 million and no resyncs in the 10 days.
Superuser
Superuser
Posts: 9,377
Thanks: 692
Fixes: 51
Registered: 06-04-2007

High FEC error rates causing disconnections

I was just going on my experience, don't think I've got much beyond 4 million before it restarted. How many CRC and HEC errors have you had?
David
antiquebrit
Grafter
Posts: 76
Registered: 09-12-2009

High FEC error rates causing disconnections

Thanks spraxyt for your thoughts.
By all means do ask the moderators to create another thread.
I have a version 6 speedtouch I could try and a an old safecom GWART2-54125.  I will try one of these, or even both when I have time.
Thanks again.
David
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: High FEC error rates causing disconnections

Quote from: spraxyt
I was just going on my experience, don't think I've got much beyond 4 million before it restarted. How many CRC and HEC errors have you had?

Uptime: 10 days, 23:30:16
Modulation: G.992.5 annex A
Bandwidth (Up/Down) [kbps/kbps]: 959 / 2.268
Data Transferred (Sent/Received) [MB/GB]: 484,33 / 3,16
Output Power (Up/Down) [dBm]: 12,5 / 0,0
Line Attenuation (Up/Down) [dB]: 28,0 / 48,5
SN Margin (Up/Down) [dB]: 7,0 / 8,5
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 1.373 / 0
FEC Errors (Up/Down): 0 / 2.167.085.708
CRC Errors (Up/Down): 0 / 68.284
HEC Errors (Up/Down): 0 / 37.321

Uptime nearly 11 days with no resync
defiant
Grafter
Posts: 92
Registered: 03-07-2009

Re: High FEC error rates causing disconnections

fec count shows how many errors your modems fixed HEC and CRC errors are worse. im going to guess bitswapping is whats hammering your connection the longer its connect this is what ive been finding with a st585v6 or st585v7 with TSTC at the exchange.
i monitored the snr with adsl1 and adsl2 modulation and what i get is alot of bitswaping since changing modulation to adsl2+ im getting alot less bitswaps showing in the snr graph and this is with dmttool configured to read snr every 2 seconds.
just something i thought you may find interesting and perhaps worth a little look.