Question: Which interface is used by the MME/SGSN to send the Create Indirect Data Forwarding Tunnel Request message to the SGW as part of Handover procedures or TAU/RAU procedure with Serving GW change and data forwarding?
Option 1: S11/S4
Option 2: S5/S8
Option 3: S6a
Option 4: Gx
Explanation: The Create Indirect Data Forwarding Tunnel Request message is sent on the S11/S4 interface by the MME/SGSN to the SGW as part of Handover procedures or TAU/RAU procedure with Serving GW change and data forwarding. This is a specific requirement for the Evolved Packet System (EPS) architecture, ensuring efficient data forwarding during handovers and other mobility-related procedures.