Are Containers Coupled with NetEm a Reliable Tool for Performance Study of Network Protocols?

NetEm is a good representative of software-based network emulator often used for testing network protocols and applications under specified network conditions. Many scholars have studied it on physical hosts connected over real networks and observed that NetEm could emulate most network parameters accurately. The popularity of containerization motivates us to investigate the accuracy of NetEm on virtual networks composed of containers. In this paper, we investigate the accuracy of NetEm main functionality on the containers run on Docker, a well-recognized solution for containerization, and compare the results with NetEm performance on a real network connecting physical hosts. We found that NetEm provides the same level of accuracy and stability for packet loss on these two platforms. The TCP throughput under emulated loss and latency was found to be very close when measured on containers and hosts under all circumstances except the scenarios where there is no additional delay combined with packet loss greater than 2%. NetEm offers more accurate delay emulation on physical hosts. On containers, we have observed small additional delay and occasional spikes that can be attributed to time-sharing of CPU in the containerized system. While these must be taken into account when performing a protocol performance study, they are not significant and, therefore, we can conclude that containers coupled with NetEm can be considered a reliable tool for the study of network protocol performance.