PDU Session Establishment

The PDU Session Establishment in a Network Slice to a DN allows data transmission in a Network Slice. A PDU Session is associated to an S-NSSAI and a DNN. Following diagram illustrates the procedure of PDU Session Establishment:

Figure 2-3 PDU Session Establishment

The following is performed for PDU Session Establishment:

• If the AMF is not able to determine the appropriate NRF to query for the S-NSSAI provided by the UE, the AMF sends a GET request to the NSSF. The AMF queries the NSSF with this specific S-NSSAI , the NF type of the NF service consumer, Requester ID, PLMN ID of the SUPI and location information.
• The NSSF determines and returns the appropriate NRF to be used to select NFs/services within the selected Network Slice instance. The NSSF may also return an NSI ID identifying the Network Slice instance to use for this S-NSSAI.

  When a PDU Session for a given S-NSSAI is established using a specific Network Slice instance, the CN provides to the (R)AN the S-NSSAI corresponding to this Network Slice instance to enable the R(AN) to perform access specific functions.