NSSF Overview

This section includes information about NSSF Installation in 5G environment.

Network Slice Selection Function (NSSF) selects the network slicing instance (NSI), determines the allowed network slice selection assistance information (NSSAI) and set AMF to serve the UE. AMF can retrieve NRF, NSI ID, and target AMFs as part of UE initial registration and PDU establishment procedure.

Oracle NSSF interaction with NRF allows retrieving specific NF services to be used for registration request. It also allows mechanism for registration and subsequent notification Function Instance Discovery.

The NSSF supports the following services:

Nnssf_NSSelection Service

This service is used by NF Service Consumer (AMF) to retrieve the information related to network slice. It also enables the NSSF to provide the AMF the Allowed NSSAI and the Configured NSSAI for the Serving PLMN.

Nnssf_NSSelection Service

This service supports GET request during the following procedures by UE:

• Initial Register: When the NSSF is able to detect authorized network slice information for the requested network slice selection information, the response body includes a payload body containing at least the allowed NSSAI, target AMF Set or the list of candidate AMF(s).
• PDU session establishment: This service allows to update the S-NSSAI(s), the NF service consumer such as AMF support on NSSF per TA basis, to subscribe and notify any change in status of the SNSSAIs available per TA (unrestricted) and the restricted S-NSSAI(s) per PLMN in that TA in the serving PLMN of the UE.