4.2.7 Reference points

The 5G System Architecture contains the following reference points:

N1: Reference point between the UE and the AMF.

N2: Reference point between the (R)AN and the AMF.

N3: Reference point between the (R)AN and the UPF.

N4: Reference point between the SMF and the UPF.

N6: Reference point between the UPF and a Data Network.

N9: Reference point between two UPFs.

The following reference points show the interactions that exist between the NF services in the NFs. These reference points are realized by corresponding NF service-based interfaces and by specifying the identified consumer and producer NF service as well as their interaction in order to realize a particular system procedure.

N5: Reference point between the PCF and an AF or TSN AF.

N7: Reference point between the SMF and the PCF.

N8: Reference point between the UDM and the AMF.

N10: Reference point between the UDM and the SMF.

N11: Reference point between the AMF and the SMF.

N12: Reference point between AMF and AUSF.

N13: Reference point between the UDM and Authentication Server function the AUSF.

N14: Reference point between two AMFs.

N15: Reference point between the PCF and the AMF in the case of non-roaming scenario, PCF in the visited network and AMF in the case of roaming scenario.

N16: Reference point between two SMFs, (in roaming case between SMF in the visited network and the SMF in the home network).

N16a: Reference point between SMF and I-SMF.

N17: Reference point between AMF and 5G-EIR.

N18: Reference point between any NF and UDSF.

N19: Reference point between two PSA UPFs for 5G LAN-type service.

N22: Reference point between AMF and NSSF.

N23: Reference point between PCF and NWDAF.

N24: Reference point between the PCF in the visited network and the PCF in the home network.

N27: Reference point between NRF in the visited network and the NRF in the home network.

N28: Reference point between PCF and CHF.

N29: Reference point between NEF and SMF.

N30: Reference point between PCF and NEF.

NOTE 1: The functionality of N28 and N29 and N30 reference points are defined in TS 23.503 [45].

N31: Reference point between the NSSF in the visited network and the NSSF in the home network.

NOTE 2: In some cases, a couple of NFs may need to be associated with each other to serve a UE.

N32: Reference point between a SEPP in one PLMN or SNPN and a SEPP in another PLMN or SNPN; or between a SEPP in a SNPN and a SEPP in a CH/DCS, where the CH/DCS contains a UDM/AUSF.

NOTE 3: The functionality of N32 reference point is defined in TS 33.501 [29].

N33: Reference point between NEF and AF.

N34: Reference point between NSSF and NWDAF.

N35: Reference point between UDM and UDR.

N36: Reference point between PCF and UDR.

N37: Reference point between NEF and UDR.

N38: Reference point between I-SMFs and between V-SMFs.

N40: Reference point between SMF and the CHF.

N41: Reference point between AMF and CHF in HPLMN.

N42: Reference point between AMF and CHF in VPLMN.

NOTE 4: The functionality of N40, N41 and N42 reference points are defined in TS 32.240 [41].

N43: Reference point between PCFs.

NOTE 5: The functionality of N43 reference point is defined in TS 23.503 [45].

NOTE 6: The reference points from N44 up to and including N49 are reserved for allocation and definition in TS 32.240 [41].

N50: Reference point between AMF and the CBCF.

N51: Reference point between AMF and NEF.

N52: Reference point between NEF and UDM.

N55: Reference point between AMF and the UCMF.

N56: Reference point between NEF and the UCMF.

N57: Reference point between AF and the UCMF.

NOTE 7: The Public Warning System functionality of N50 reference point is defined in TS 23.041 [46].

N58: Reference point between AMF and the NSSAAF.

N59: Reference point between UDM and the NSSAAF.

N60: Reference point between AUSF and NSWOF.

NOTE 8: The functionality of N60 reference point is defined in TS 33.501 [29].

N80: Reference point between AMF and NSACF.

N81: Reference point between SMF and NSACF.

N82: Reference point between NSACF and NEF.

N83: Reference point between AUSF and NSSAAF.

N84: Reference point between TSCTSF and PCF.

N85: Reference point between TSCTSF and NEF.

N86: Reference point between TSCTSF and AF.

N87: Reference point between TSCTSF and UDM.

N88: Reference point between SMF and EASDF.

N88a: Reference point between I-SMF and EASDF.

N89: Reference point between TSCTSF and AMF.

N96: Reference point between TSCTSF and NRF.

N97: Reference point between two NSACFs in different PLMNs.

N99: Reference point between two NSACFs within the same PLMN.

N110: Reference point between EIF and AF.

N111: Reference point between EIF and NEF.

N112: Reference point between EIF and UDM.

N113: Reference point between EIF and PCF.

N114: Reference point between EIF and SMF.

N115: Reference point between SMF+PGW-C and the NSSAAF.

NOTE 9: The reference points from N90 up to and including N95 are reserved for allocation and definition in TS 23.503 [45].

NOTE 10: The reference points from N100 up to and including N109 are reserved for allocation and definition in TS 32.240 [41].

The reference points to support SMS over NAS are listed in clause 4.4.2.2.

The reference points to support Location Services are listed in TS 23.273 [87].

The reference points to support SBA in IMS (N5, N70 and N71) are described in TS 23.228 [15].

The reference points to support AKMA (N61, N62 and N63) are described in TS 33.535 [124].

The reference points to support 5G ProSe are described in TS 23.304 [128].

The reference points to support 5G multicast-broadcast services are described in TS 23.247 [129].

The reference points to Support Uncrewed Aerial Systems (UAS) connectivity, identification and tracking are described in TS 23.256 [136].

The reference points to support SBA in GBA and GBA push (N65, N66, N67 and N68) are described in TS 33.220 [140] and TS 33.223 [141].

The reference points to support SMS delivery using SBA are described in TS 23.540 [142].

The reference points to support Ranging based services and Sidelink Positioning are described in TS 23.586 [180].

The reference points to support Ambient IoT are described in TS 23.369 [220].

The reference points to support for Integrated Sensing and Communication are described in TS 23.137 [223].