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, the RAN comprises multiple RAN transport endpoints, RAN endpoints, (1111, 1112), and the CN comprises multiple CN transport endpoints, CN endpoints, (1411, 1412, 1421), the method comprising: obtaining identifiers of available CN endpoints (1411, 1412, 1421) in the CN, and obtaining identifiers of available RAN endpoints (1111, 1112) in the RAN, which available CN endpoints (1411, 1412, 1421) and available RAN endpoints (1111, 1112) comprises a number of possible transport endpoint pairs between the RAN and the CN, CN/RAN endpoint pairs, obtaining characteristics of a respective transport path of the number of possible CN/RAN endpoint pairs, obtaining 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, which CN/RAN endpoint pair is selected for the user plane session between the RAN and the CN in the radio communications network, Z wherein the method is characterised by the core network node further obtaining the decision of the CN/RAN endpoint pair by basing it on a negotiation with the RAN comprising to: send a request associated with the user plane session to a RAN node comprising the RAN endpoints (1111, 1112), which request is adapted to comprise either the identifiers to all available CN endpoints (1411, 1412, 1421) or one or more identifiers to a recommended CN endpoint, for the user plane session between the RAN and the CN, and receive from the RAN node, a response to the sent request, which response is adapted to comprise identifiers of one or more recommended CN/RAN endpoint pairs based on the identifiers to all available CN endpoints (1411, 1412, 1421) or the recommended CN endpoint/endpoints (1411, 1412, 1421) in the sent request. obtaining identifiers of available CN endpoints (1411, 1412, 1421) in the CN, and obtaining identifiers of available RAN endpoints (1111, 1112) in the RAN, which available CN endpoints (1411, 1412, 1421) and available RAN endpoints (1111, 1112) comprises a number of possible transport endpoint pairs between the RAN and the CN, CN/RAN endpoint pairs, obtaining characteristics of a respective transport path of the number of possible CN/RAN endpoint pairs, obtaining 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, which CN/RAN endpoint pair is selected for the user plane session between the RAN and the CN in the radio communications network, Z wherein the method is characterised by the core network node further obtaining the decision of the CN/RAN endpoint pair by basing it on a negotiation with the RAN comprising to: send a request associated with the user plane session to a RAN node comprising the RAN endpoints (1111, 1112), which request is adapted to comprise either the identifiers to all available CN endpoints (1411, 1412, 1421) or one or more identifiers to a recommended CN endpoint, for the user plane session between the RAN and the CN, and receive from the RAN node, a response to the sent request, which response is adapted to comprise identifiers of one or more recommended CN/RAN endpoint pairs based on the identifiers to all available CN endpoints (1411, 1412, 1421) or the recommended CN endpoint/endpoints (1411, 1412, 1421) in the sent request. send a request associated with the user plane session to a RAN node comprising the RAN endpoints (1111, 1112), which request is adapted to comprise either the identifiers to all available CN endpoints (1411, 1412, 1421) or one or more identifiers to a recommended CN endpoint, for the user plane session between the RAN and the CN, and receive from the RAN node, a response to the sent request, which response is adapted to comprise identifiers of one or more recommended CN/RAN endpoint pairs based on the identifiers to all available CN endpoints (1411, 1412, 1421) or the recommended CN endpoint/endpoints (1411, 1412, 1421) in the sent request.