The demand for ultra-low latency in modern applications, such as cloud gaming and augmented reality, has exposed the limitations of traditional congestion control algorithms regarding bufferbloat. The Low Latency, Low Loss, and Scalable Throughput (L4S) architecture addresses this challenge by combining scalable congestion controls, such as TCP Prague, low-latency queue management with prioritization, and Accurate ECN (AccECN) feedback. Although Linux kernel implementations exist, the research community lacks a complete, high-fidelity model within the Network Simulator 3 (ns-3) for reproducible experiments. This paper presents an implementation of end-host protocols for the L4S architecture in ns-3, focusing on the porting of TCP Prague from the Linux kernel (v6.12) and the integration of AccECN signaling. Significant engineering challenges regarding the adaptation of kernel logic are detailed, particularly the reconciliation of Linux's packet-based arithmetic with ns-3's byte-based architecture for window management and pacing. Simulation results demonstrate that the proposed model faithfully reproduces the congestion response behaviors observed in real-world testbed scenarios, validating the platform's accuracy. Consequently, this work provides the community with a validated toolset for complex L4S performance evaluations in controlled environments.

翻译：现代应用（如云游戏和增强现实）对超低延迟的需求，暴露了传统拥塞控制算法在缓冲区膨胀问题上的局限性。低延迟、低丢失与可扩展吞吐量（L4S）架构通过结合可扩展拥塞控制（如TCP Prague）、带优先级排序的低延迟队列管理以及精确ECN（AccECN）反馈，解决了这一挑战。尽管已有Linux内核实现，但研究界仍缺乏能够在网络仿真器3（ns-3）中完成可复现实验的完整高保真模型。本文提出在ns-3中实现L4S架构的端主机协议，重点包括将TCP Prague从Linux内核（v6.12）移植至仿真环境，以及集成AccECN信令机制。详细阐述了关于适配内核逻辑的重大工程挑战，特别是如何调和Linux基于数据包的算术运算与ns-3基于字节架构的窗口管理和速率节拍控制方法。仿真结果表明，所提模型能够忠实复现实际测试平台场景中观察到的拥塞响应行为，从而验证了平台的精确性。因此，本研究为在可控环境中开展复杂L4S性能评估提供了经过验证的工具集。