Data transfer over high latency and high packet loss networks

Sammanfattning: This thesis aims to pin down which aspects aect the data transfer speed through the Internet, especially with regard to latency and packet loss. What is required from a technical point of view in order to effciently mitigate the effects of latency and packet loss to network transfer? What are the diffculties when testing network protocols? The approach is to test four different protocols; TCP CUBIC, Westwood+, Tsunami, and UDT, while gathering metrics such as throughput, the size of the congestion window and slow start threshold, and then analysing the results. The analysis of the results show that latency have the most impact on throughput, effecting the network transfer by decreasing the number of times the congestion window is able to grow in RTT dependant algorithms, effectively decreasing the throughput. Packet loss eects network transfer because protocols interpreting the loss as a congestion problem on which the protocol decreases the sending rate. The size of this decrease is shown to impact the throughput, where an aggressive decrease shows a poorer performance with packet loss. The study can aid anyone who seeks to develop a network transport protocol.