Digital Twin technology facilitates the monitoring and online analysis of large-scale communication networks. Faster predictions of network performance thus become imperative, especially for analysing Quality of Service (QoS) parameters in large-scale city networks. Discrete Event Simulation (DES) is a standard network analysis technology, and can be further optimised with parallel and distributed execution for speedup, referred to as Parallel Discrete Event Simulation (PDES). However, modelling detailed QoS mechanisms such as DiffServ requires complex event handling for each network router, which can involve excessive simulation events. In addition, current PDES for network analysis mostly adopts conservative scheduling, which suffers from excessive global synchronisation to avoid causality problems. The performance analysis of optimistic PDES for real-world large-scale network topology and complex QoS mechanisms is still inadequate. To address these gaps, this paper proposes a simulation toolkit, Quaint, which leverages an optimistic PDES engine ROSS, for detailed modelling of DiffServ-based networks. A novel event-handling model for each network router is also proposed to significantly reduce the number of events in complex QoS modelling. Quaint has been evaluated using a real-world metropolitan-scale network topology with 5,000 routers/switches. Results show that compared to the conventional simulator OMNeT++/INET, even the sequential mode of Quaint can achieve a speedup of 53 times, and the distributed mode has a speedup of 232 times. Scalability characterisation is conducted to portray the efficiency of distributed execution, and the results indicate the future direction for workload-aware model partitioning.

翻译：数字孪生技术为大规模通信网络的监控与在线分析提供了便利。因此，快速预测网络性能变得至关重要，尤其对于分析大规模城域网中的服务质量参数而言。离散事件仿真是一种标准的网络分析技术，可通过并行与分布式执行进一步优化以加速，即并行离散事件仿真。然而，对诸如DiffServ等详细QoS机制进行建模，需要对每个网络路由器进行复杂的事件处理，这可能涉及过多的仿真事件。此外，当前用于网络分析的PDES大多采用保守调度策略，为避免因果性问题而需进行过多的全局同步，这影响了性能。针对真实世界大规模网络拓扑和复杂QoS机制的乐观PDES性能分析仍不充分。为填补这些空白，本文提出一个仿真工具包Quaint，它利用乐观PDES引擎ROSS，对基于DiffServ的网络进行详细建模。同时提出了一种新颖的每路由器事件处理模型，以显著减少复杂QoS建模中的事件数量。Quaint已在一个包含5000台路由器/交换机的真实城域规模网络拓扑上进行了评估。结果表明，与传统的仿真器OMNeT++/INET相比，即使Quaint的顺序执行模式也能实现53倍的加速，而其分布式模式更达到了232倍的加速。通过可扩展性表征来描绘分布式执行的效率，结果指明了未来面向工作负载感知的模型划分方向。