nfs udp ports?

[rusty%garnet.Berkeley.EDU at violet.berkeley.edu]

We have a fileserver whose filesystems are mounted by a large number of
clients on campus.  I would like to gather statistics about how much nfs
traffic is is being generated by each client.  NNStat seems like a good
way to do this.  I need to tell NNStat the udp source and destination
ports for nfs in order to collect these statistics but I can't find this
information written down anywhere.  Does anybody know what port numbers
nfs uses?

[[ According to the NFS(4P) manual page, NFS uses remote procedure calls
(RPC) built on top of the external data representation (XDR) protocol.
That's TCP and UDP port 111, according to /etc/services.  But monitoring
that port will get all RCP traffic, not just NFS traffic.  --wnl ]]