Question: In GTPv1-U, what is the primary consideration for determining the IP Source Address and IP Destination Address in an Echo Request Message?
Option 1: The IP addresses of the underlying network infrastructure (e.g., routers).
Option 2: Randomly assigned IP addresses from a predefined pool to enhance security.
Option 3: The IP addresses of the serving and neighboring cell sites for location services.
Option 4: Respectively, the originating GTP-U entity's IP address and the destination GTP-U entity's IP address.
Explanation: In the context of GTPv1-U, specifically for Echo Request Messages, accurate routing and response receipt are crucial. Setting the IP Source Address to that of the originating GTP-U entity ensures traceability and proper return path for the echo response. Similarly, directing the message to the correct destination GTP-U entity's IP address guarantees the intended recipient processes the Echo Request, vital for maintaining network integrity and facilitating diagnostics across different network elements in telecom environments.