ty for a given QoS flow is hosted by the SN, the MN first provides sufficient QoS-related information to enable the SN to configure appropriate SCG resources and to request the configuration of appropriate MCG resources. For instance, the MN may offer MCG resources to the SN (for Guaranteed Bit Rate QoS flows, may indicate the amount offered to the SN on a per-QoS flow level), then the SN decides whether to map the QoS flow to an SCG bearer, an MCG bearer, or a split bearer. If the SN decides that an MCG or a split bearer should be configured (i.e. MCG resource is required), the SN needs to provide the relevant information back to the MN: the DRB-level QoS parameters and the QoS flow to DRB mapping information. Since both the MN and the SN are allowed to establish/modify/release DRBs on their own for QoS flows terminated at their SDAP entities, coordination of DRB IDs between the MN and the SN is needed in MR-DC with 5GC to ensure unique allocation of DRB IDs for a UE. This is unlike EN-DC where the SN is not allowed to establish/modify/release a DRB on its own (it has to request the MN to or be requested by the MN) - and thus only the MN assigns a DRB ID (5 bit space) for a UE regardless of whether it is served by the MN or the SN.7 For unique allocation of DRB IDs in MR-DC with 5GC, the SN assigns DRB IDs for the bearers it terminates, based on the IDs available for use offered from the MN. If a termination point is changed for a DRB (e.g. from the MN to the SN or vice versa), the node initiating the procedure indicates the corresponding DRB ID and is informed (by the node who accepted DRB offloading) whether the indicated DRB ID is available. For QoS flows assigned to the SN SDAP entity, the SN may remove or add SCG resources for the corresponding bearers, as long as the QoS for the respective QoS flow is guaran- teed. For each PDU session, including split PDU sessions, at most one default DRB may be configured at the MN or the SN. As in EN-DC, also in all the other MR-DC options all the possible bearer type c