A Dataset for Buffering Delays Due to the Interaction Between the Nagle Algorithm and the Delayed Acknowledgement Algorithm in Cyber-Physical Systems Communication

Here, we provide the research community with a data set for the buffering delays that data packets experience at TCP sending side in the realm of Cyber-Physical Systems (CPSs). We focus on the buffering that occurs at the sender side due to the the adverse interaction between the Nagle algorithm and the delayed acknowledgement algorithm, which both were originally introduced into TCP to prevent sending out many small-sized packets over the network. The data set is collected using four real-life operating systems: Windows, Linux, FreeBSD, and QNX (a real-time operating system). In each scenario, there are three separate different (virtual) machines running various operating systems. One machine, or an end-host, acts a data source, another acts as a data sink, and a third acts a network emulator that introduces artificial propagation delays between the source and the destination. To measure buffering delay at the sender side, we record for each sent packet the two time instants: when the packet is first generated at the application layer, and when it is actually sent on the physical network. In each case, 10 different independent experiment replications/runs are executed. Here, we provide the full distribution of all delay samples represented by the cumulative distribution function (CDF). The data exhibited here gives an impression of the amount and scale of the delay occurring at sender-side in TCP. More importantly, the data can be used investigate to what degree these delays affect the performance of cyber-physical systems or other real-time applications employing TCP.我们为科研界提供了一套数据集，用于研究信息物理系统（Cyber-Physical Systems, CPSs）领域中，数据包在传输控制协议（Transmission Control Protocol, TCP）发送端所经历的缓冲延迟。我们聚焦于发送端因Nagle算法与延迟确认算法之间的负面交互所产生的缓冲延迟——这两种算法最初被引入TCP，均是为了避免网络中传输大量小型数据包。 本数据集依托四款实际投入使用的操作系统采集构建：Windows、Linux、FreeBSD以及QNX（一款实时操作系统）。在每种实验场景中，均使用三台独立的（虚拟）机器运行不同的操作系统：其中一台作为终端主机充当数据源，另一台作为数据接收端，第三台则作为网络仿真器，用于在数据源与接收端之间引入人工设置的传播延迟。 为了测量发送端的缓冲延迟，我们为每个已发送数据包记录两个时间点：数据包首次在应用层生成的时刻，以及其实际在物理网络中发送的时刻。每种实验场景均会执行10次独立的重复实验。 本次我们提供了所有延迟样本的完整分布，以累积分布函数（Cumulative Distribution Function, CDF）的形式呈现。 本次展示的数据集能够直观体现TCP发送端延迟的总量与规模；更为关键的是，该数据集可用于探究此类延迟对信息物理系统或其他采用TCP的实时应用程序性能的影响程度。