entifies the assigned AMF and 5G-TMSI identifies the UE uniquely within the AMF. The 5G-S-TMSI is the shortened form of the GUTI to enable more efficient radio signaling procedures. AMF Name is used to identify an AMF. It can be configured with one or more GUAMIs. At any given time, the GUAMI value is exclusively associated to one AMF name. Data Network Name (DNN) is equivalent to an APN which may be used to select an SMF and UPF(s) for a PDU session, to select N6 interface(s) for a PDU session, or to determine policies that are applied to a PDU session. Internal-Group Identifier is used to identify a group as the subscription data for a UE in UDM may associate the subscriber with different groups. A UE can belong to a limited number of groups. The group identifiers corresponding to a UE are provided by the UDM to the SMF and when PCC applies to a PDU session by the SMF to the PCF. The SMF may use this information to apply local policies and to store this information in charging data record. Generic Public Subscription Identifier (GPSI) is used for addressing a 3GPP subscrip- tion in different data networks outside of the 3GPP system. The 3GPP system stores within the subscription data the association between the GPSI and the corresponding SUPI. GPSIs are public identifiers used both inside and outside of the 3GPP system. The GPSI is either a mobile subscriber ISDN number (MSISDN) or an external identi- fier. If MSISDN is included in the subscription data, it will be possible that the same MSISDN value is supported in both 5GS and EPS. There is no one-to-one relationship between GPSI and SUPI. 1.2.2.3 User-Plane and Control-Plane Protocol Stacks 1.2.2.3.1 Control-Plane Protocol Stacks The 5GC supports PDU connectivity service which provides exchange of PDUs between a UE and a data network. The PDU connectivity service is supported through PDU sessions that are established upon request from the UE. In order to establish a PDU session and access to the PDN, the UE must establish user plane and control plane over th