Partially reliable transport service

An analytic model is presented for a partially reliable transport protocol based on retransmissions. The model illustrates tradeoffs between two QoS parameters (delay and throughput), and various levels of reliability. The model predicts that the use of a reliable transport service when an application only needs a partially reliable one causes considerable throughput decreases and delay increases in lossy networks. On the other hand, over lossy networks, an unreliable transport service is unable to respect an application's loss tolerance. In lossy environments, partially reliable transport service avoids the extra cost of a reliable transport service, and, simultaneously, guarantees the minimal reliability that an application requires. A retransmission-based partially reliable transport service can be provided through either sender-based or receiver-based loss detection and recovery. Results show that both techniques provide almost identical reliability and delay. However, a sender-based approach provides better throughput than a receiver-based approach at high acknowledge loss rates.