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FEC % Calculation

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Bobby
FEC % Calculation

hi,
I'm trying to validate manually the cisco formula used to calculate the percentage of correctable and uncorrectable FECs and put it on a graph, however I find that my result is not exactly in the ranges mentioned by cisco, maybe I'm doing something wrong, someone has any suggestions? this is the procedure I follow:

Get values for uptream0 by snmp:

TIME 8:50 (XY0)
Interface Unerrorreads Corrected Uncorrectables
Cable1/0/U0 360300337 7358499 20809
TIME 8:55 (XY1)
Interface Unerrorreads Corrected Uncorrectables
Cable1/0/U0 360581464 7358511 20828

Formula:
%Correctable = [(Ec1 – Ec0)/ [(Eu1 – Eu0) + (Ec1 – Ec0) + (C1 – C0)]] * 100
Where:
C = Unerroreds
Ec = Correcteds
Eu = Uncorrectables

%Correctable = [(7358511 – 7358499)/ [(20828 – 20809) + (7358511 – 7358499) + (360581464 – 360300337)]] * 100

Is that correct?

frnkblk
Yup, that's what I do with

Yup, that's what I do with the numbers from our BSR64k, and it works like a charm.

Bobby
Should look like this?
Should look like this? haven't found a relation between codeworks and SNR on my upstreams right axis SNR in dB green=snr left axis CW % dark blue=corrected clear blue=uncorrectables [IMG]http://i263.photobucket.com/albums/ii141/xoir/exampleFEC-SNR.png[/IMG]
wittmann
Hi Bobby, which software did

Hi Bobby,

which software did you use for graph?

regards,

wittmann

Bobby
I was pointing where the CW

I was pointing where the CW uncorrected and SNR falls for a month, but not in all cases I find a pattern

[IMG]http://i263.photobucket.com/albums/ii141/xoir/graph-SNR-vs-FEC.png[/IMG]

Wittmann, it's home made development

Bobby
CW vs SNR

I have seen in other upstream where the SNR is more "unstable" and the amount in percentage of uncorrected Codeworks is a bit higher and more consistent, even crosses the limit of 0.5 which is already considered risky, does this graphic looks trustworthy?

[IMG]http://i263.photobucket.com/albums/ii141/xoir/CW-SNR.png[/IMG]

Regards,
Bobby

leozeppelin
There is anybody who uses

There is anybody who uses ZABBIX to monitoring the FEC?

docsis