Core network node and method therein for obtaining a decision of a CN/RAN endpoint pair for user plane session in a radio communications network

A method performed by a method performed by a core network node for obtaining a decision of a Core Network, CN/Radio Access Network, RAN, endpoint pair for a user plane session between a RAN and a CN in a radio communications network is provided. The RAN comprises multiple RAN transport endpoints, RAN endpoints, and the CN comprises multiple CN transport endpoints, CN endpoints. The core network node obtains (1101) identifiers of available CN endpoints in the CN, and obtains (1102) identifiers of available RAN endpoints in the RAN. The available CN endpoints and available RAN endpoints comprises a number of possible transport endpoint pairs between the RAN and the CN, CN/RAN endpoint pairs. The core network node further obtains (1103) characteristics of a respective transport path of the number of possible CN/RAN endpoint pairs. The core network node then obtains (1108) a decision of a CN/RAN endpoint pair out of the number of possible CN/RAN endpoint pairs, based on the obtained characteristics of the respective transport path of the number of possible CN/RAN endpoint pairs. The CN/RAN endpoint pair is selected for the user plane session between the RAN and the CN in the radio communications network.