A method for managing network function selection, the method being performed by a network functions virtualization orchestrator according to the ETSI ISG NFV, the method comprising: - setting up and maintaining virtualized network functions, - storing identities of first type virtualized network functions and identities of second type virtualized network functions, wherein the first type virtualized network functions corresponding to the identities of the first type virtualized network functions are configured to select one or more of the second type virtualized network functions corresponding to the identities of the second type virtualized network functions, - maintaining, for each identity of the first type virtualized network functions, information regarding identities of the second type virtualized network functions, wherein the second type virtualized network functions corresponding to the identities of the second type virtualized network functions are selectable by the first type virtualized network functions corresponding to the identities of the first type virtualized network functions, based on information regarding physical conditions of the first type virtualized network functions and the second type virtualized network functions, characterized in further comprising: - configuring a first type virtualized network function with the identities of the second type virtualized network functions, wherein the second type virtualized network functions corresponding to the identities of the second type virtualized network functions are selectable by the first type virtualized network function, and with different priorities of the second type virtualized network functions corresponding to the identities of the second type virtualized network functions for different physical conditions, the configuring being performed via a network management interface defined between the network functions virtualization orchestrator and the first type virtualized network function. - setting up and maintaining virtualized network functions, - storing identities of first type virtualized network functions and identities of second type virtualized network functions, wherein the first type virtualized network functions corresponding to the identities of the first type virtualized network functions are configured to select one or more of the second type virtualized network functions corresponding to the identities of the second type virtualized network functions, - maintaining, for each identity of the first type virtualized network functions, information regarding identities of the second type virtualized network functions, wherein the second type virtualized network functions corresponding to the identities of the second type virtualized network functions are selectable by the first type virtualized network functions corresponding to the identities of the first type virtualized network functions, based on information regarding physical conditions of the first type virtualized network functions and the second type virtualized network functions, - configuring a first type virtualized network function with the identities of the second type virtualized network functions, wherein the second type virtualized network functions corresponding to the identities of the second type virtualized network functions are selectable by the first type virtualized network function, and with different priorities of the second type virtualized network functions corresponding to the identities of the second type virtualized network functions for different physical conditions, the configuring being performed via a network management interface defined between the network functions virtualization orchestrator and the first type virtualized network function.