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P4 serves as a programming language for configuring flexible and programmable network data planes, facilitating the development of custom protocols and programmable switches, and driving innovation in software-defined networking and network function virtualization. While the Linux container based network emulator, Mininet, coupled with the BMv2 software P4 switch, is widely used for rapid prototyping of P4-based applications, BMv2’s diminished performance raises fidelity concerns under high traffic and large network scenarios. In this paper, we introduce a lightweight virtual time system integrated into Mininet with BMv2 to enhance fidelity and scalability. By applying a time dilation factor (TDF) to interactions between containers and the physical machine, we optimize the emulated P4 network’s perceived speed from the application processes’ perspective. System evaluation demonstrates accurate emulation of significantly larger networks under high loads with minimal system overhead. We showcase our system’s utility through two network applications: an emulation of a TCP SYN flood attack and an ECMP load balancer. Evaluating against a production-grade software switch, Open vSwitch, and a physical testbed, we highlight the virtual time system’s improvement in temporal fidelity despite the observed performance degradation in BMv2 software switches. 

Network emulation allows unmodified code execution on lightweight containers to enable accurate and scalable networked application testing. However, such testbeds cannot guarantee fidelity under high workloads, especially when many processes concurrently request resources (e.g., CPU, disk I/O, GPU, and network bandwidth) that are more than the underlying physical machine can offer. A virtual time system enables the emulated hosts to maintain their own notion of virtual time. A container can stop advancing its time when not running (e.g., in an idle or suspended state). The existing virtual time systems focus on precise time management for CPU-intensive applications but are not designed to handle other operations, such as disk I/O, network I/O, and GPU computation. In this paper, we develop a lightweight virtual time system that integrates precise I/O time for container-based network emulation. We model and analyze the temporal error during I/O operations and develop a barrier-based time compensation mechanism in the Linux kernel. We also design and implement Dynamic Load Monitor (DLM) to mitigate the temporal error during I/O resource contention. VT-IO enables accurate virtual time advancement with precise I/O time measurement and compensation. The experimental results demonstrate a significant improvement in temporal error with the introduction of DLM. The temporal error is reduced from 7.889 seconds to 0.074 seconds when utilizing the DLM in the virtual time system. Remarkably, this improvement is achieved with an overall overhead of only 1.36% of the total execution time.