RTTn

RTTn refers to a specific type of real-time transport protocol known as Real-time Transport Protocol over TCP. Unlike the standard RTP, which typically operates over UDP, RTTn utilizes TCP as its underlying transport layer. This choice is driven by the need for reliable data delivery, which TCP guarantees through mechanisms like acknowledgments and retransmissions.

The primary advantage of using TCP for real-time transport is its inherent reliability. This can be beneficial in scenarios where packet loss is a significant concern and the application cannot tolerate missing data, even if it introduces some latency. Examples might include certain voice or video conferencing applications in environments with unstable network conditions.

However, the use of TCP for real-time transport also presents challenges. TCP's reliability features, particularly its congestion control mechanisms, can introduce variable delays and jitter, which are detrimental to real-time applications that prioritize low latency. The head-of-line blocking problem in TCP can also exacerbate these delays, as a lost packet will hold up the delivery of subsequent packets. Consequently, RTTn is not as widely adopted as standard RTP over UDP, which is generally preferred for its lower overhead and predictable latency characteristics in typical real-time communication scenarios. The decision to use RTTn often involves a trade-off between guaranteed delivery and acceptable latency.