[mrtg] Is it possible to perform mathmatical calculations using ifOperHack?

[Barry Young]

Following on from a previous posting (no replies to date), can someone
answer if it is possible to add the results of ifOperHack (or indeed
ifOperAdmin)
together.

I am using the following target to obtain the number of interfaces up

Target[xx]: ifOperHack.2:public at ipaddr
          + ifOperHack.3:public at ipaddr

Because SNMP variable ifOper can return greater than 1
the ifOperHack translates this value to either 0 (down)
or 1 (up).

So adding these values together should provide the total
number of interfaces up.  But I am presently seeing
zero values in the log file.

I have reviewed the mrtg perl script to ascertain the
behaviour but as I am not a perl developer my understanding
is limited.

Is this a limitation of the ifOperHack and MRTG or is my
target configuration wrong?

Suitable replies much appreciated as I have an urgent
requirement to resolve this.

TIA

Barry Young
European Networks Manager
CHEP International

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