Question: What security mechanisms are required to protect traffic on the Xn reference point, specifically for the transport of control plane data and user data?
Option 1: Only IPsec ESP with IKEv2 certificate-based authentication
Option 2: Only DTLS with mutual authentication, integrity protection, replay protection, and confidentiality protection
Option 3: Both IPsec ESP with IKEv2 certificate-based authentication and DTLS with mutual authentication, integrity protection, replay protection, and confidentiality protection
Option 4: Neither IPsec nor DTLS is required
Explanation: According to the security requirements for the Xn interface, both IPsec ESP with IKEv2 certificate-based authentication and DTLS with mutual authentication, integrity protection, replay protection, and confidentiality protection are necessary to protect traffic on the Xn reference point. This ensures that control plane data and user data are integrity, confidentiality, and replay-protected.