School of Specs 38.300v19.3.0

3GPP 38.300 v19.3.0 — the document's own text

16.3.4.2 AMF and NW Slice Selection

RAN selects the AMF based on a Temp ID or NSSAI provided by the UE.

Figure 16.3.4.2-1: AMF selection
Figure 16.3.4.2-1: AMF selection

In case a Temp ID is not available, the NG-RAN uses the NSSAI provided by the UE at RRC connection establishment to select the appropriate AMF (the information is provided after MSG3 of the random access procedure). If such information is also not available, the NG-RAN routes the UE to one of the configured default AMF(s).

The NG-RAN uses the list of supported S-NSSAI(s) previously received in the NG Setup Response message when selecting the AMF with the NSSAI. This list may be updated via the AMF Configuration Update message.