Are a lot of FEC errors anything to worry about?

metalmackey

metalmackey

metalmackey

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Hi Guys,

Are the amount of FEC errors I'm getting cause for concern? I'm with BE, pings and download speeds are fine.

My line stats are:-


Link Information


Uptime: 7 days, 8:48:41

DSL Type: G.992.5 annex A

Bandwidth (Up/Down) [kbps/kbps]: 1,369 / 15,678

Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00

Output Power (Up/Down) [dBm]: 12.0 / 18.0

Line Attenuation (Up/Down) [dB]: 15.0 / 30.0

SN Margin (Up/Down) [dB]: 3.0 / 3.0

Vendor ID (Local/Remote): TMMB / BDCM

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): 9 / 0

FEC Errors (Up/Down): 1,808 / 17,879,906

CRC Errors (Up/Down): 1,808 / 2,054

HEC Errors (Up/Down): 20,527 / 1,528
 
Assuming you have interleaving on, then it's showing the interleaving is working.
If you are on fast path, then it's probably a bug in the modem.
 
Interleaving is on. I was a bit worried because on BE chat someone said it was too high as he only had about 5 million FEC errors in 30 days
 
The reason for the FEC errors is your SNR ratio of 3db is too low, and the interleaving is having to correct a lot of the signal. Depending on your modem, suggest going back to a 6db profile and using DMT tool to set your SNR to 4.5-5db for less correctional errors.

Edit, see your uptime is 7 days, so in reality that's not a lot of errors at all, would suggest turning interleaving off and gaining 1-2mb DL speed.
 
Hmmmmmmmmmmm, so one says just turn interleaving off and someone else says go to 6db and turn it off. What are the disadvantages off turning it off?
 
Interleaving off = better pings usually, with the risk of instability. Everyone is different, it's a case of suck it and see. You can always have it turned on again.
It's also known that Thomson/Speedtouch routers exaggerate the error counts somewhat.
 
metalmackey said:
Interleaving is on. I was a bit worried because on BE chat someone said it was too high as he only had about 5 million FEC errors in 30 days
Click to expand...

HA!! My Cisco 1841 could only register 16384 FECs a second and it would constantly sit at that figure....nearly 60M an HOUR!
 
fluff said:
Nah.
Click to expand...
Agreed.

dave_beast said:
The reason for the FEC errors is your SNR ratio of 3db is too low, and the interleaving is having to correct a lot of the signal...
Click to expand...
Too low for what? Without intending to be pedantic a 'corrected signal' is by a very simple definition corrected in the modem. Please explain the problem here.

I've heard on more than one occasion that the Speedtouch boxes can over report FEC but, regardless, they are corrected errors. I consider the router stats as simply being there for information; what matters is the perceived quality of the connection. Is it stable enough for the user and does it perform to their satisfaction. For me that means it doesn't exhibit packet loss and gives decent throughput. These two aspects are readily evaluated by online gaming or a VoIP application and downloading something like a Linux distro from a reliable high bandwidth server, respectively.

And to echo Carter's post, a high FEC rate may suggest that the connection would be flaky if you were to disable interleaving. Who knows. As the profile change is reversible just simply go try it for yourself if you're curious.
 
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