Introduction
3GPP TS 23.501 Defines the 5G System Architecture as a Service Based Architecture
- NF Service Producer : NF service exposed by
- NF Service Consumer : Authorized NF along the service based interface (SBI)
- NF Service Operation
Network Functions may offer different functionalities and thus different NF services. Each of the NF services offered by a Network Function shall be self-contained, acted upon and managed independently from other NF services offered by the same Network Function (e.g. for scaling, healing).
A service based interface represents how the set of services is provided or exposed by a given NF. This is the interface where the NF service operations are invoked.
The following Control Plane interfaces within the 5G Core Network specified in 3GPP TS 23.501 [3] are defined as service based interfaces: Namf, Nsmf, Nudm, Nnrf, Nnssf, Nausf, Nnef, Nsmsf, Nudr, Npcf, N5g-eir, Nlmf.
NF Service
The NF service should include the following mechanism:
- Registration and De-Registration : to make the NRF aware of the available NF instances and supported services
- Discovery : to enable a NF Service Consumer to discover NF Service Producer instance(s) which provide the expected NF service(s)
- Authorization : to ensure the NF Service Consumer is authorized to access the NF service provided by the NF Service Producer
Service Based Architecture (TS23.501)
The 5GSA Control Plane communicate mainly using HTTP2/SBI protocol where NFs exposes and provide available service. Interfaces generally identified –> n<NF>.
Namf: AMF
Nsmf: SMF
…..
Nnef, Npcf, Nudm, Naf, Nnrf, Nnssaaf, Nnssf, Nausf, Nudr, Nudsf, N5g-eir, Nnwdaf, Nchf, Nucmf
The 5GSA Architecture also employ Non-SBI Interfaces.
- 5Gs User Plane uses direction connection to 5GC. 3GPP defined these connections as follow:
- 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.
- 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.
- N30: Reference point between PCF and NEF.
- N31: Reference point between the NSSF in the visited network and the NSSF in the home network.
Although more than 20years working on Mobile Telecommunications – Core Network. Always wanting to learn and try new things.