Cisco Collaboration endpoints are exchanging encrypted signaling messages. What is one major complication in implementing NAT ALG for voice and video devices?

Question

Options

• AInternal endpoints cannot use addresses from the private address space.
• BThe NAT ALG cannot inspect the contents of encrypted signaling messages.
• CNAT ALG introduces jitter in the voice path.
• DSource addresses cannot provide the destination addresses that remote endpoints should use

• A
  5% (2)
• B
  93% (41)
• D
  2% (1)

Explanation

NAT Application Layer Gateway (ALG) works by intercepting and modifying the payload of signaling messages (e.g., SIP or H.323) to replace private IP addresses with public ones, enabling proper media path establishment through NAT. When signaling is encrypted (e.g., using TLS), the NAT ALG cannot read or modify the message contents, rendering it ineffective. This is a fundamental limitation: encryption protects the payload from inspection by intermediary devices, including NAT ALGs. The solution in these scenarios is typically to use a session border controller (SBC) or a Traversal solution like Cisco Expressway that terminates and re-originates the signaling.

No community discussion yet for this question.