24.5013GPPNon-Access-Stratum (NAS) protocol for 5G System (5GS)Release 17Stage 3TS
In order to interwork with ePDG connected to EPC, the UE shall operate as specified in either subclause 18.104.22.168 or subclause 4.8.3. Which subclause the UE follows is chosen by the UE irrespective of the interworking without N26 interface indicator.
The UE shall not attempt to transfer PDU sessions with PDU session type "Ethernet" or "Unstructured" to an ePDG connected to EPC.
NOTE: PDU sessions with PDU session type "Ethernet" or "Unstructured" cannot be transferred to an ePDG connected to EPC because PDN connections with PDN type "non-IP" or PDN type "Ethernet" are not supported over ePDG connected to EPC.