Determining IP address of NFS server on client

Hi. We use an Isilon cluster system to provide our NAS. The Isilon uses a round-robin DNS setup to spread mount requests across the many nodes of the cluster. When a node needs work, the filesystems that are mounted to it need to be moved to other nodes prior to shutting the node down. I haven't been able to determine a way to identify what IP address a client is mounting to. Output from df or the mount command simply report the DNS name for the cluster, the that address that was selected. Does anyone know of a way on a Solaris client to determine what IP address a mount point is using?

If the NFS servers are all still working and have some form of Unix running on them then I would run a "showmount -a" on the NFS server you wish to move client mounts from, this will list the clients that have mounts from that server and what directories they are mounting.
At the client you could run a "snoop" filtering on NFS type packets only and then run a command to an "ls" inside each NFS mount to generate some traffic and see what IP addresses it is going to that way? A bit drastic I know!

Yes I have tried the showmount command on the Isilon, but it shows all clients that have mounted the volume since uptime. This doesn't always yield accurate results, as client mounts can come and go.
I had considered snoop, but I am trying to create an automated mount monitoring program that I can run from any client to see what NFS mounts it is using, and which servers it is mounting from. In the case of the Isilon, I need to know which node is the serving node.