And you hit it -- I created an instance of Nagios to monitor our network. I was originally using ICMP, but I'm having second thoughts.
One of the advantages of SNMP is you can report back the status of the port -- is it up, is it down, is it admin down. The disadvantage is if the port gets changed for whatever reason, now you have to go and change the monitoring. But if you test by IP address, it's good either way.
But if you test by IP address and someone else has duplicated it elsewhere in the network (never happens, right??), then if the uplink port goes down, you don't know it.
So I'm just looking for how others feel about this value judgment. As I mentioned, I'm leaning toward converting everything to SNMP ifOperStatus/ifAdminStatus queries.