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.

本研究面向网络物理系统（Cyber-Physical Systems，CPS）领域中的传输控制协议（Transmission Control Protocol，TCP）发送侧数据包缓存延迟问题，向科研共同体公开相关数据集。本数据集聚焦于发送侧因纳格尔算法（Nagle algorithm）与延迟确认算法（Delayed Acknowledgement Algorithm）之间的不利交互所产生的缓存延迟——二者最初均被引入TCP，旨在避免网络中出现大量小型数据包的发送行为。
本数据集基于四款实际部署的操作系统采集所得：Windows、Linux、FreeBSD，以及实时操作系统QNX。每种实验场景均采用三台独立的（虚拟）主机运行不同操作系统：其中一台作为数据源端主机，一台作为数据接收端主机，第三台作为网络仿真器，用于在数据源与接收端之间引入人工配置的传播延迟。
为精准测量发送侧缓存延迟，我们为每个已发送数据包记录两个关键时间节点：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完成发送的时刻。每种场景均执行10次独立的实验重复运行。
本次公开的数据集包含所有延迟样本的完整分布，以累积分布函数（Cumulative Distribution Function，CDF）形式呈现。本数据集所展示的实测数据，可直观反映TCP发送侧缓存延迟的量级与规模；更重要的是，该数据集可用于探究此类延迟对网络物理系统或其他采用TCP的实时应用程序性能的影响程度。