Question: What protocol is used to tunnel signaling messages between the Serving GPRS Support Node (SGSN) and the Serving and Packet Data Network Gateway (S-GW) on the S4 interface?
Option 1: General Packet Radio Service Tunnelling Protocol for the control plane (GTP-C)
Option 2: User Datagram Protocol (UDP)
Option 3: Transmission Control Protocol (TCP)
Option 4: Stream Control Transmission Protocol (SCTP)
Explanation: The correct answer is GPRS Tunnelling Protocol for the control plane (GTP-C), as it is specifically designed to tunnel signaling messages between SGSN and S-GW on the S4 interface, ensuring efficient communication and management of signaling traffic in the Evolved Universal Terrestrial Radio Access Network (E-UTRAN).