Not sure where to look on your SAN but I have used UnDP to find the IP address listings of say a Cisco switch or router. I would assume this is probably available somewhere in the SNMP queries of the device.
This is by no means a replacement for Solarwinds to poll multiple IP addresses a feature that has been requested numerous times by several customers.
I'm with you on this one.
OpenNMS does this. When it does a discovery by SNMP it groups all the IPs it finds on a node under the same device because it's smart enough to know that it's one device with many IPs.
When free tools do what commercial products can't I get frustrated and have a hard time justifying yearly maintenance and expenses.