This paper addresses the simulation of communication networks with high bandwidth-delay products. We use hybrid models to overcome the computational/memory barriers that packet-level simulators encounter due to the large number of packets present in the network at every instant of time. We describe a set of software tools that constructs these hybrid models for general networks. The networks to be simulated and their parameters are specified in a
network description script language (NDSL)
automatically generates the corresponding a model in the hybrid systems specification language
. We also extend our previous hybrid modeling work to several variants of TCP that appeared recently to improve TCP’s poor performance in high bandwidth-delay product networks. To demonstrate the usefulness of software tools developed and the new TCP hybrid models, we discuss simulation results from Internet-2 Abilene backbone.