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9.9. Using NFS over TCP

The default transport protocol for NFS is TCP; however, the Fedora kernel includes support for NFS over UDP. To use NFS over UDP, include the mount option -o udp when mounting the NFS-exported file system on the client system. Note that NFSv4 on UDP is not standards-compliant, since UDP does not feature congestion control; as such, NFSv4 on UDP is not supported.
There are three ways to configure an NFS file system export:
For example, on demand via the command line (client side):
mount -o udp shadowman.example.com:/misc/export /misc/local
When the NFS mount is specified in /etc/fstab (client side):
server:/usr/local/pub    /pub   nfs    rsize=8192,wsize=8192,timeo=14,intr,udp
When the NFS mount is specified in an autofs configuration file for a NIS server, available for NIS enabled workstations:
myproject  -rw,soft,intr,rsize=8192,wsize=8192,udp penguin.example.net:/proj52
Since the default is TCP, if the -o udp option is not specified, the NFS-exported file system is accessed via TCP.
The advantages of using TCP include the following:
The main disadvantage with TCP is that there is a very small performance hit due to the overhead associated with the protocol.