ocedures are supported for non-3GPP access and which information elements (IEs) of the procedures that are used are not applicable for non-3GPP access. The initial aspiration of the 3GPP work was to make 5GC "access-agnostic," which has been largely fulfilled; however, in some specific cases the 5GC has to be aware whether it is a 3GPP gNB or a non-3GPP N3IWF that terminates the NG interface and therefore it would probably be more correct to call this functionality a "common core," rather than "access-agnostic core." NG-AP procedures can be categorized as follows: Interface management procedures UE context management procedures UE session management procedures UE mobility management procedures Paging procedures PDU session management procedures Transport of NAS messages procedures Others (trace, location reporting, UE radio capability management, etc.). In the present chapter we describe only the subset of the most commonly used procedures. For a detailed description of all the procedures, please refer to 3GPP TS 38.413. NG-AP protocol differentiates between UE-associated and non-UE-associated signaling. For the former, a logical association for that UE must be established between the NG-RAN node and the AMF, which generally involves the allocation of temporary UE identifiers at both sides, which are used to identify that UE association. 3.3 NG Radio Access Network 3.3.3.1.1 NG Interface Management Interface management procedures are used to establish the NG interface, to tear it down, to reset it (when and if needed), and to allow gNB and AMF to exchange and update con- figuration information. The relevant NG-AP procedures are: NG Setup RAN/AMF Configuration Update AMF Status Indication Overload Start/Stop Reset and Error Indication. NG Setup is the first procedure initiated by a gNB after the Transport Network Layer (TNL) association with an AMF has become operational. It carries the list of Tracking Areas (TAs) supported by a gNB, a list of PLMNs within each tracking area, and some other informa- tion. If the 