Simulation of large scale network scenarios is a challenging task and requires a great amount of computational power. Hence, realizing web-accessible simulation servers is a key step for the success of network simulation as a useful instrument in the context of network administration and capacity planning. This paper presents an XML-based description language for describing network simulation scenarios. For the proposed language, we also present an XSL translation process that can be used to automatically translate a simulation scenario into a simulation script for a well known network simulator. This work is part of a larger project, aimed at implementing a cluster-based network simulation server to be integrated in a distributed system for QoS monitoring, SLA validation and measurement-based modeling in an inter-domain environment.