The NF Service Consumer (e.g. new AMF) shall inform the SMF that it has taken over the role of serving the UE (e.g. it has taken the responsibility of the signalling towards the UE), when so required by TS 23.501 and TS 23.502, as follows.
The NF Service Consumer shall update the SMF with the new serving AMF, by sending a POST request, as specified in clause 5.2.2.3.1, with the following information:
servingNfId set to the new serving AMF Id;
the supportedFeatures IE indicating the optional features it supports, if at least one optional feature defined in clause 6.1.8 is supported;
other information, if necessary, e.g. to activate the user plane connection of the PDU session (see clause 5.2.2.3.2.2).
Same as step 2a of Figure 5.2.2.3.1-1. In addition, the SMF shall include the supportedFeatures IE in the response, if the supportedFeatures IE was received in the request and at least one optional feature defined in clause 6.1.8 is supported by the updated SM context resource.
The NF Service Consumer (e.g. AMF) shall request the SMF to transfer QoS flows to and from Secondary RAN node, or more generally, handle a NG-RAN PDU Session Resource Modify Indication, as follows.
The NF Service Consumer shall request the SMF to modify the PDU session, as requested by the NG-RAN, by sending a POST request, as specified in clause 5.2.2.3.1, with the following information:
N2 SM information received from the 5G-AN (see PDU Session Resource Modify Indication Transfer IE in clause 9.3.4.6 of TS 38.413), including the transport layer information for the QoS flows of this PDU session (i.e. 5G-AN's GTP-U F-TEIDs for downlink traffic);
Upon receipt of such a request, if the SMF can proceed with switching the QoS flows of the PDU session, the SMF shall return a 200 OK response including the following information:
N2 SM information (see PDU Session Resource Modify Confirm Transfer IE in clause 9.3.4.7 of TS 38.413), including the list of QoS flows which were modified successfully and the list of QoS flows which failed to be modified if available.
If the SMF cannot proceed with switching the QoS flows of the PDU session, the SMF shall return an error response, as specified for step 2b of Figure 5.2.2.3.1-1, including:
N2 SM information (see PDU Session Resource Modify Indication Unsuccessful Transfer IE in clause 9.3.4.22 of TS 38.413).