Nagios Support Forum

I'd agree with @Box293 on the FQDN thing, let us know if that's an option for you.

Most of the network devices are not in DNS so FQDN won't work. I could manually maintain the entries in /etc/hosts - but that won't work when there is a clash of IPs.
An NFS share is not an option from behind a firewal - rsync works until you get a clash of IPs.
The only way I can see this working effectively is if Nagios maintains its own rrd files for mrtg in the standard perfdata directory an these are derived from the perfdata itself.

regards Fred

I wish I had a better answer for you, but if rsync, Fusion, and FQDN are not an option then I am not sure what else can be done, aside from pretty heavy modification of the XI system. Fusion + Core machines is sounding like it's the only option that would not be affected by the IP clash, but that's a lot more work.