edirections not only imply additional signaling load but also break isolation between different DCNs since all UEs initially attach to the same MMEs before they eventually get redirected to their correct DCN. To significantly reduce the need for redirections and to enhance the level of isolation, Release-14 enhancements to DECOR (referred to as eDECOR and defined in 3GPP TS 23.401, 2019) enable the RAN to directly select the right MME (and thereby the right DCN). To achieve this, the UE provides a DCN-ID to the RAN via Radio Resource Control (RRC) protocol, which the RAN subsequently uses to select an MME that supports this DCN-ID (see Figure 3.2.11). The DCN-IDs to signal to the RAN in a given PLMN are provided to the UE by the Home Public Land Mobile Network (HPLMN). As summarized above, various enablers to support multiple sets of core network function- alities and configurations in the same PLMN have already been specified across various 3GPP releases. Two aspects however have remained unchanged: 3 5G System Overview S1-MME DCN 2 1) DCN ID (2) RAN selects MME that supports DCN ID provided by UE DCN 1 Figure 3.2.11 Release-14 eDECOR reduces the need for redirections by enabling the RAN to directly select the right DCN based on information provided by the UE. Single DCN per UE: a UE can only connect to a single DCN at a time. In other words, even though it is possible to concurrently use different PGWs for different PDN connec- tions of the same UE, all PDN connections should be part of the same DCN. In the EPS architecture this means practically that MME and SGW are shared across DCNs. DCNs do not apply to RAN: the RAN is not always aware of the DCN-ID SO that RAN cannot differentiate UEs that belong to different DCNs. 5GS network slicing as defined in Release-15 (3GPP TS 23.501) addresses these shortcom- ings as follows: A 5GS network slice consists of both RAN and core network, i.e. in contrast to DCNs in EPS 5GS network slices also cover the RAN. Concurrent access to multiple network slices per UE: a UE can