AMF determines that a new I-UPF needs to be added for a PDU session.

SMF provides N3 tunnel info of I-UPF to target gNB via AMF.

SMF provides N9 tunnel info of UPF PSA to I-UPF.

SMF provides N9 tunnel info of I-UPF to UPF PSA.

NF A acts as a service consumer and NF B acts as a service producer.

NF A includes a subscription identifier in the request message sent to NF B.

NF A includes a callback URI in the request message sent to NF B.

NF A includes event filtering criteria in the request message sent to NF B.

The gNB is split into three functional modules: a radio unit (RU), a distributed unit (DU), and a centralized unit (CU).

DU performs the non-real time processing of layer 2.

The fronthaul segment connects RU to DU and the midhaul segment connects DU to CU.

CU can be deployed in the cloud as a VNF.