NFS Client changing it's source address? (FreeBSD 10.2)

[Rick Macklem]

I wrote:
> - Reconfigure your NFS server so that it never drops idle TCP connections.
>   (FreeBSD never drops an NFS TCP connection until umount, but some others
>    like Solaris NFS servers drop idle connections.)
Oops, I forgot that the kernel RPC (I wasn't the author) does drop idle TCP
connection(s) from client(s) after 6 minutes without RPC activity).
I can't remember if the client side times out for NFS?

The only time the idle timeout is disabled in the server is for NFSv4.1 with
a backchannel on the TCP connection.
Disabling it on the server is a 1line source change, but there isn't a sysctl
for it (maybe there should be?).

rick