Network registration method for traffic transmission and device supporting same

A method performed by an Access and mobility Management Function (AMF) adapted to operate in a wireless communication system, the method comprising:

• performing a first registration procedure for a User Equipment (UE) over a first non-3rd Generation Partnership Project (3GPP) access;
• receiving a registration request message of a second registration procedure from the UE over a second non-3GPP access, wherein the registration request message comprises i) information about an access switching from the first non-3GPP access to the second non-3GPP access, and ii) information about a Multi-Access (MA) Protocol Data Unit (PDU) session related to the access switching;
• transmitting the information about the access switching from the first non-3GPP access to the second non-3GPP access to a Session Management Function (SMF);
• performing an Access Network (AN) release procedure over the first non-3GPP access;
• and
• transmitting a registration accept message to the UE in response to the registration request message.