P protocol provides the following operations: - the mapping between the data flows exchanged with the core network contained in a tunnel, and the Quality of Service to be applied on the radio interface on the uplink and downlink; - marking the identity of the QoS flow in the upstream and downstream packets; - the implementation of reflective QoS on the correspondence of flows in the uplink direction. 8.1.1.1. UE side operations For each PDU session, a default radio bearer is configured. The SDAP entity is configured by the RRC control layer. The configuration allows us to create mapping rules between the identifier QFI of the flow and the corresponding radio medium (bearer). The mapping rules are saved by the mobile until the SDAP entity is released. The mapping rules between the QoS flow and the DRB is controlled by the radio node: - from the RRC signaling which configures the mapping rules between the flow QoS and the radio bearer; - from the mobile which applies the same rules for uplink traffic as for downlink traffic (reflective QoS). Any stream transmitted to the SDAP layer is: - in the absence of a matching rule, sent without adding an SDAP header to the default bearer; - in the presence of matching rules, the flow is routed to the PDCP sublayer of the bearer with or without addition of an SDAP header. The RRC configuration is used to define: - the addition or not of an SDAP header by bearer; - the implementation of QoS or reflective QoS. 208 NG-RAN and 5G-NR To achieve this mapping, it is necessary: - that the base station transmits the QFI indicator to the mobile during a previous exchange; - that the base station informs the mobile to apply reflective QoS. For dual connectivity, the QoS flow of the same PDU session can be transmitted in different DRBs. One SDAP entity is configured for the master node and another for the secondary node. 8.1.1.2. gNB side operations Packets coming from the UPF are encapsulated in a tunnel and transmitted to the gNB via the N3 interface. The QFI identifier is carried by a