Question: In the context of Lawful Interception (LI) for 3G security, what is the primary reason for using TPKT (IOT or ISO Transport Service on top of the TCP) to encapsulate CC and connectionStatus messages before transmitting them over TCP?
Option 1: To enable encryption for secure data transfer.
Option 2: Because TCP inherently supports message delineation, ensuring packet integrity.
Option 3: For negotiating the maximum TPDU size during connection establishment.
Option 4: Since upper-layer protocols are not self-describing and TCP lacks inherent message delineation capability.
Explanation: The correct answer is Option 4 because, as stated in the context, TCP is a stream-based protocol without inherent message delineation capabilities, and the upper-layer protocols (like CC and connectionStatus messages) are not self-describing. TPKT is used to provide this necessary delineation, ensuring that messages are properly identified and handled at the receiving end. This highlights the importance of TPKT in maintaining the integrity and manageability of data transmission in telecom networks, particularly in sensitive applications like Lawful Interception.