The 5G System architecture consists of the following network functions (NF).

Service-based interfaces: This Service based interface is connected to each interface.

The 5G System Architecture contains the following service-based interfaces:

Reference points

The 5G System Architecture contains the following reference points:

The 5G system reference Point interface us a set if Point to point interfaces which inter connect those Network Elements.

• 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.
• NOTE 1:        The traffic forwarding details of N6 between a UPF acting as an uplink classifier and a local data network are not specified in this Release of the specification.
• 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.
• 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.
• N29i:        Reference point between I-NEF and SMF in the VPLMN.
• N30:        Reference point between PCF and NEF.
• NOTE 2:        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 3: in some cases, a couple of NFs may need to be associated with each other to serve a UE.
• In addition to the reference points above, there are interfaces/reference point(s) between SMF and the CHF. The reference point(s) are not depicted in the architecture illustrations in this specification.
• NOTE 4:        The functionality of these interface/reference points are defined in TS 32.240 [41].
• N32:        Reference point between SEPP in the visited network and the SEPP in the home network.
• NOTE 5:        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.
• N40:        Reference point between SMF and the CHF.
• NOTE 6:        The reference points from N40 up to and including N49 are reserved for allocation and definition in TS 23.503 [45].
• N50:        Reference point between AMF and the CBCF.
• N51:        Reference point between AMF and NEF.
• N51i:        Reference point between I-NEF and the AMF in the VPLMN.
• N52:        Reference point between NEF and UDM.
• N53:        Reference point between the I-NEF and the NEF.
• N55:        Reference point between AMF and the UCMF.
• N56:        Reference point between NEF and the UCMF.
• N57:        Reference point between AF and the UCMF.
• N58:        Reference point between AF and the NEF