Provisions for matching response messages to request messages.
Provisions for authenticating the caller to service and
vice-versa.
Besides these requirements, features that detect the following are
worth supporting because of protocol roll-over errors, implementation
bugs, user error, and network administration:
RPC protocol mismatches.
Remote program protocol version mismatches.
Protocol errors (such as misspecification of a procedure's
parameters).
Reasons why remote authentication failed.
Any other reasons why the desired procedure was not called.