A network function for supporting end-to-end communication services with and/or without network slices in a communication network , the communication network comprising a first management system for managing a 3GPP 5G subnetwork of the communication network and a second management system (405; 601) for managing a 3GPP legacy subnetwork and/or a non-3GPP subnetwork of the communication network , wherein the network function is configured to provide an interface between the first management system and the second management system (405; 601), wherein the first management system and/or the second management system (405; 601) comprises a plurality of network management functions (501a-c; 505a-c; 603a-b) and/or network management function instances (503a-c) and wherein the network function is configured to select one or more of the plurality of network management functions (501a-c; 505a-c; 603a-b) and/or network management function instances (503a-c) in response to a service request on the basis of a load balancing requirement, a minimum latency requirement defined by the service request and/or a quality of service requirement defined by the service request, wherein the network function is implemented as part of one network management function of the plurality of network management functions (501a-c) of the first management system , or part of one network management function instance of the plurality of network management function instances (503a-c) of the first management system , wherein the network function is configured to generate local identifiers for the network management function (501a-c) or network management function instance (503a-c) of which the network function is implemented as part, and for the selected network management functions (501a-c; 505a-c; 603a-b) and/or network management function instances (503a-c), and the local identifiers are used to store a mapping of management function instances into a local mapping database , and wherein the network function is further configured to store a mapping of a communication service associated with the service request to the mapped management function instances into the local mapping database . wherein the network function is implemented as part of one network management function of the plurality of network management functions (501a-c) of the first management system , or part of one network management function instance of the plurality of network management function instances (503a-c) of the first management system , wherein the network function is configured to generate local identifiers for the network management function (501a-c) or network management function instance (503a-c) of which the network function is implemented as part, and for the selected network management functions (501a-c; 505a-c; 603a-b) and/or network management function instances (503a-c), and the local identifiers are used to store a mapping of management function instances into a local mapping database , and wherein the network function is further configured to store a mapping of a communication service associated with the service request to the mapped management function instances into the local mapping database . <EOS>