DeSRTO: An Effective Algorithm for SRTO Detection in TCP Connections

摘要

Spurious Retransmission Timeouts in TCP connections have been extensively studied in the scientific literature, particularly for their relevance in cellular mobile networks. At the present, while several algorithms have been conceived to identify them during the lifetime of a TCP connection (e.g., Forward-RTO or Eifel), there is not any tool able to accomplish the task with high accuracy by processing off-line traces. The only off-line existing tool is designed to analyze a great amount of traces taken from a single point of observation. In order to achieve a higher accuracy, this paper proposes a new algorithm and a tool able to identify Spurious Retransmission Timeouts in a TCP connection, using the dumps of each peer of the connection. The main strengths of the approach are the great accuracy and the absence of assumptions on the characteristics of TCP protocol. In fact, except for rare cases that are not classifiable with absolute certainty at all, the algorithm shows no ambiguous nor erroneous detections. Moreover, the tool is also able to deal with reordering, small windows, and other cases where competitors fail. Our aim is to provide to the community a very reliable tool to: (i) test the working behavior of cellular wireless networks, which are more prone to Spurious Retransmission Timeouts with respect to other technologies; (ii) validate run-time Spurious Retransmission Timeout detection algorithms.