[Devmon] Conditional change of measured / computed value

[W.J.M. N. <ne...@nl...>]

Hello,

monitoring a Cisco switch with devmon 0.3.1-beta1, the test if_dsc 
sometimes gives an alert on a (temporarily) unused interface. The switch 
seems to drop packets (broadcasts?) if the attached host is shut down, 
which is no problem. I would like to prevent a 
packet-drop-threshold-exceeded alert from being generated in such a case.

I've tried to suppress alerts by setting the measured discard rate to 
zero if the packet rate on that interface is small. With ifInPps being 
the input packet rate, if OutPps the output packet rate, the following 
transformation is used:

 ifInDpsR    : DELTA         : {ifInDiscards}
 ifInDps     : SWITCH        : {ifInPps}  <1 = 0, >0 = {ifInDpsR}
 ifOutDpsR   : DELTA         : {ifOutDiscards}
 ifOutDps    : SWITCH        : {ifOutPps} <1 = 0, >0 = {ifOutDpsR}
 ifInDscPct  : MATH          : ({ifInDps}  / {ifInPps} ) x 100
 ifOutDscPct : MATH          : ({ifOutDps} / {ifOutPps}) x 100

It results in a fatal error in devmon:

Got unexpected error while performing math transform on oid ifOutDscPct 
for nlrdlx05: Can't use string ("1") as a HASH ref while "strict refs" 
in use at /opt/devmon-0.3.1-beta1/modules/dm_tests.pm line 2521, 
<$__ANONIO__> line 28512.

How should one change the value of an OID alias?

Kind regards,
  Wim Nelis.



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