1.4 Relationship to Other Protocols

The User Name Mapping Protocol relies on [RFC1057] and [RFC4506] for communicating with clients by means of the SUNRPC message version 2 and XDR protocols as specified in those documents. The User Name Mapping Protocol uses SUNRPC authentication level AUTH_NULL (as specified in [RFC1057]). The User Name Mapping Protocol uses SUNRPC message version 2 implemented on top of TCP and UDP. The User Name Mapping Protocol message formats are not sensitive to which underlying transports (TCP or UDP) are being used.