Coarse-Grained Network Simulation for

Evaluating the performance of large-scale wide-area applications such as content distribution networks and replicated Internet services through simulation presents formidable challenges. Among them is the need to balance competing needs: ensuring accuracy by choosing an appropriate level of detail, and making these large-scale simulations tractable by minimizing required computational resources. As an alternative to packet-level simulation, we evaluate the applicability of coarse-grain transfer-level simulation to wide-area networked applications and services, and discuss the tradeoffs inherent to such an approach. We introduce GUTS,a high-level wide-area network simulator whose goal is to enable simulation of realistic Internet-scale topologies, under a range of realistic workloads