System for selecting, for a given user network session in a mobile network, an application server (151, 152) among a plurality of application servers (151, 152) in the mobile network, the mobile network including a user plane, a network control plane, and a network management plane, characterized in that the system is installed and implemented between the network control plane and the plurality of application servers and comprises an apparatus comprising a computer platform and at least one data storage unit including a program code, wherein the apparatus comprises at least: a) a communication interfaces unit which is configured to receive communication messages from and transmit communication messages to at least one application server of the plurality of applications servers and the control plane of the mobile network, b) an obtaining unit which is configured to retrieve a closest application server of the plurality of application servers from a network topology repository stored in the at least one data storage unit wherein the network topology repository stores respective network topology specific relationships between respective application servers (151, 152) and respective mobility anchors (102-1, 103-1) of the user plane wherein the closest application server (151, 152) is determined from the plurality of application servers on the basis of the respective network topology specific relationships between the respective application servers and a respectively current mobility anchor of the given user network session, c) a determining unit which is configured to recognize a change of a relationship between the closest application server (151, 152) and the respectively current mobility anchor (102-1, 103-1) of the user network session in the user plane via the means of a network session repository stored in the at least one data storage unit wherein the network session repository stores a relationship between an unambiguous user network session identifier and the closest application server (151, 152), and, in the case of a change, to trigger an application server handover, wherein the computer platform and the at least one data storage unit including the program code are arranged and interrelated with the apparatus to cause the apparatus to perform the functions of the obtaining unit and the determining unit, when the program code is executed by the computer platform. a) a communication interfaces unit which is configured to receive communication messages from and transmit communication messages to at least one application server of the plurality of applications servers and the control plane of the mobile network, b) an obtaining unit which is configured to retrieve a closest application server of the plurality of application servers from a network topology repository stored in the at least one data storage unit wherein the network topology repository stores respective network topology specific relationships between respective application servers (151, 152) and respective mobility anchors (102-1, 103-1) of the user plane wherein the closest application server (151, 152) is determined from the plurality of application servers on the basis of the respective network topology specific relationships between the respective application servers and a respectively current mobility anchor of the given user network session, c) a determining unit which is configured to recognize a change of a relationship between the closest application server (151, 152) and the respectively current mobility anchor (102-1, 103-1) of the user network session in the user plane via the means of a network session repository stored in the at least one data storage unit wherein the network session repository stores a relationship between an unambiguous user network session identifier and the closest application server (151, 152), and, in the case of a change, to trigger an application server handover,