4 Overview

29.5263GPP5G SystemNetwork Slice-Specific and SNPN Authentication and Authorization servicesRelease 17Stage 3TS

4.1 Introduction

Within the 5GC, the NSSAAF offers services to the AMF and the AUSF via the Nnssaaf service-based interface.

The AMF shall make use of the NSSAAF service when it needs to invoke network slice-specific authentication and authorization for a specific UE and a specific S-NSSAI (see 3GPP TS 23.502 [3] clause 4.2.9.2, and 3GPP TS 33.501 [14] clause 16.2 and 16.3).

The NSSAAF service shall also be used by the AMF to receive slice re-authentication notification or slice authorization revocation notification sent from the AAA-S (see 3GPP TS 23.502 [3] clause 4.2.9.3, 4.2.9.4 and 3GPP TS 33.501 [14] clause 16.3 and 16.4).

The AUSF shall make use of the NSSAAF service when it needs to invoke a primary authentication in SNPN with Credentials holder using AAA server; the AUSF shall also make use of this service during the UE onboarding procedure in SNPN scenarios, when the Default Credentials Server (DCS) uses an AAA server for primary authentication.

Figure 4.1-1 provides the reference model with focus on the NSSAAF.

Figure 4.1-1: Reference model – NSSAAF