Why TURN Server Activity is Observed during External Endpoint Call Establishment
Question
A company has enabled ICE to optimize call flows and improve video quality between their Cisco Collaboration endpoints internally and externally.
For which reason would you see activity on the TURN server when a call is established between two external endpoints?
Answers
Explanations
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A. B. C. D.A.
In a Cisco Collaboration environment, ICE (Interactive Connectivity Establishment) is used to optimize call flows and improve video quality between endpoints both internally and externally. ICE uses STUN (Session Traversal Utilities for NAT) and TURN (Traversal Using Relay NAT) protocols to optimize network connectivity and ensure that media flows directly between endpoints, if possible.
When a call is established between two external endpoints, if the network path between the two endpoints is not optimal, ICE may use TURN to optimize the media flow. TURN is a relay server that is used when direct communication between two endpoints is not possible due to firewall restrictions, NAT (Network Address Translation) traversal, or other network issues.
Answer B, "ICE cannot reduce the packet loss on the link," is incorrect because ICE can optimize network connectivity to reduce packet loss using STUN and TURN protocols.
Answer C, "A STUN cannot punch holes in the firewall," is incorrect because STUN is used to determine the public IP address and port of a NAT device, allowing ICE to create a direct media flow between endpoints. If STUN is unable to create a direct media flow, ICE may use TURN to relay media traffic.
Answer D, "The video call is using 4K resolution, which is not supported by ICE with CUCM 12.5," is also incorrect because ICE does not have any limitations on the resolution of video calls.
Therefore, the correct answer is A, "The video call is using encryption, which is not supported by ICE with CUCM 12.5." If a video call is using encryption, ICE may not be able to optimize the media flow, and TURN may be used to relay media traffic between endpoints.
