Portmapper is the only network service that must have a dedicated port (111). Other RPC network services can be assigned port numbers statically or dynamically, if the services register their ports with the host's local Portmapper. The RPC server can register or unregister their services by using the following calls:

svc_register()

Associates a program with the service dispatch routine

Removes all local mappings to dispatch routines and port numbers

Registers a procedure with the local Portmapper and creates a control structure to remember the server procedure and its XDR routine