G-RAN or E-UTRAN, as well as with non-3GPP Access Node (AN). This is described in more detail in Section 3.2, but from the high-level point of view, the NG interface can terminate in either a gNB (or ng-eNB) providing NR (or LTE) radio access; or in the N3IWF network node, providing, e.g. WLAN access. The following provisions have been made in the definition of the NG network interface: 3GPP TS 29.413 defines which NG-AP messages (e.g. paging) and which IEs (e.g. Trace Activation) are not applicable to non-3GPP access. Certain IEs in 3GPP TS 38.413 of the NG-AP are defined to facilitate non-3GPP access, e.g. the paging origin IE, which allows 5GC to page a UE via 3GPP access (e.g. NR) to establish a connection on a non-3GPP access. Overall, the NG interface does not make 5GC truly access-agnostic, but rather allows an operator to use a common core with multiple access technologies. However, the 5GC should be aware which network node (gNB or N3IWF) an NG interface is terminated at. References 3GPP Technical Specification 29.281 (2019). General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U). 3GPP. Available at: www.3gpp.org (accessed May 22, 2020). 3GPP Technical Specification 29.413 (2019). Application of the NG Application Protocol (NGAP) to non-3GPP access. 3GPP. Available at: www.3gpp.org (accessed May 22, 2020). 3GPP Technical Specification 23.501(2019). System architecture for the 5G System (5GS). 3GPP. Available at: www.3gpp.org (accessed May 22, 2020). 3GPP Technical Specification 36.413 (2019). Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP). 3GPP. Available at: www.3gpp.org (accessed May 22, 2020). 3GPP Technical Specification 38.412 (2019). NG-RAN; NG signalling transport. 3GPP. Available at: www.3gpp.org (accessed May 22, 2020). 3GPP Technical Specification 38.413 (2019). NG-RAN; NG Application Protocol (NGAP). 3GPP. Available at: www.3gpp.org (accessed May 22, 2020). 3GPP Technical Specification 38.414 (2019). NG-RAN; NG data transport. 