Modeling and analysis of PC-based software routers

PC-based software routers are major and common network elements of today’s Internet infrastructure. In this paper, we model and analyze the performance of PC-based software routers. Our model adopts realistic assumptions of using finite queues and multi-phase services. Specifically, we model a router with two interfaces as two finite queueing systems in tandem with the first queueing system being a two-stage service and the second queueing system being a single-stage service. The two-stage service consists of a first stage in which data-link layer functionalities are performed, and a second stage in which forwarding/routing functionalities are performed. In this paper, we verify and validate our analytical model by using simulation and real experimental measurements obtained from a PC router with two interfaces. In addition, we discuss how our analytical models can be used to analyze a router with multiple interfaces. From our models, we derive equations for key features and performance measures of engineering and design significance. These features and measures include throughput, packet loss, packet delay, average number of packets in the queues and in the overall system, and CPU utilization and availability.