Section: 4.22.6.2.5 5GS to EPS mobility without N26 interface
Content: Based on the signalling flow in Figure 4.11.2.2-1, the procedure is performed with the following differences and modifications: - In step 10 (and step 13 in clause 4.11.2.4.1), if the MA PDU Session is established in both 3GPP and non-3GPP accesses and the MA PDU Session is moved to EPS and if the UE and the network does not support MA PDU Session with 3GPP access connected to EPC, the PGW-C + SMF triggers the MA PDU Session Release procedure over non-3GPP access. PGW-C + SMF and UE locally release the context related to ATSSS operation, e.g. ATSSS rules and Measurement Assistance Information for the relevant session. If the UE and the network support MA PDU Session with 3GPP access connected to EPC, the UE includes a "MA PDU Request" indication and the PDU Session ID in the PCO, the SMF should keep the user-plane resources over non-3GPP access in 5GC and use the PDN Connection as the 3GPP access leg of the MA PDU Session. - In step 13, during the additional PDN Connectivity Procedure, if the MA PDU Session is established in both 3GPP and non-3GPP accesses and if the UE and the network support MA PDU Session with 3GPP access connected to EPC, the UE includes a "MA PDU Request" indication and the PDU Session ID in the PCO, the SMF should keep the user-plane resources over non-3GPP access in 5GC and use the PDN Connection as the 3GPP access leg of the MA PDU Session. If the UE and the network does not support MA PDU Session with 3GPP access connected to EPC and the MA PDU Session is moved to EPS, the PGW-C + SMF triggers the MA PDU Session Release procedure over non-3GPP access. PGW-C + SMF and UE locally release the context related to ATSSS operation, e.g. ATSSS rules and Measurement Assistance Information for the relevant session(s). - Step 14 is also performed for the MA PDU session(s) transferred to EPS.