[Nagiosplug-help] problems with check_icmp

Andreas Ericsson ae at op5.se
Wed Jun 11 07:51:58 CEST 2008

Rodrigo Augusto Fagundes Pacheco wrote:
> Dear Andreas,
> My problem with check_icmp is the big difference between the values running
> with the same syntax. the hosts are in the same bus network that my Nagios
> server, with less than 1ms the RTA.Percebo that the problem is happening
> only in our host of lan and not hosts of wan.
> See examples:
> running manually  CLi:
> genesis1:/usr/local/nagios/libexec# ./check_icmp -n 5 -H
> OK - rta 0,143ms, lost 0%|rta=0,143ms;200,000;500,000;0;
> pl=0%;40;80;;
> displayed by nagios
> <image showing 5,286ms RTA>

And I'm telling you that a round-trip average difference of 5 milliseconds
is definitely not cause to go looking for bugs. It's simply one of those
things that happen, depending on network load, or how much load the host
is under, or the state of the cable, or any of a hundred other different
reasons. The test-run output from the forum you linked in your previous
mail also shows some higher latency figures when run from the command-line,
which is perfectly acceptable.

It was good that you sent me the picture though, cause now I can tell you
to increase your warning thresholds for your PING checks. No human will
ever notice a difference between 0ms and 50ms, so for your LAN checks,
you almost certainly want to set it to 50ms for warnings.

HTH (hope that helps)

Now please don't bother me again about this issue. It's taken up too much
time already, and none of the conversation has (up until now) been on
nagios-users at lists.sourceforge.net where it could actually have helped
someone else. I'm posting it to there though, and also to nagiosplug-help
but solely for archival purposes (hi, future; sorry for cross-posting) so
that future admins finding 5-10ms discrepancies between different runs of
a PING plugin can find an answer there instead of looking me up.

Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

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