Yep looks like linux nfs clients do an initail rpc dump port request to get all the rpc ports on the nfs server. I can see that approach has an advantage.
Other unixes nfs clients only do a getport mountd for the one port for mountd, but will need other get port request for other services.
I didnt even know this was happening till a linux nfs client banged it head against a firewall.
Two approaches to the same question (what port to use)
Now I have to convince the firewall folk to make adjustments.