NFS/UDP and vfs.nfs.nfs_ip_paranoia=0 does not help

[Daniel Braniss]

Hi,
	While trying to find out why our NSF/ZFS servers now hangs about once a
week, I got hold of a similiar box, and got a bit more ambitious, I connected
it via 2 NICs, to complicate things a bit, the server boots via pxeboot (ie, is
datatless). After fiddling with the default gateway, adding -h to rpcbind and
mountd, things seem ok, but UDP is 'problematic', I could do with TCP
except that am-utils does a fsinfo via UDP when doing a /net/<host> and will 
hang
the client.
even with vfs.nfs.nfs_ip_paranoia=0, when the response from the server
arrives with the 'wrong' ip, an ICMP destination unreachable (port unreachable)
is replied.
in short, on the client:
	this works: mount_nfs -o mntudp server-ip-vlanA:/mnt /mnt
	this fails: mount_nfs -o mntudp server-ip-vlanB:/mnt /mnt
since the response is coming from server-ip-vlanA.

Q: why does this work for TCP and fails for UDP
Q: is there a workaround?

danny