An XML Description Language for Web-based Network Simulation R. Canonico, D. Emma, G. Ventre Università di Napoli "Federico II", Dipartimento di Informatica e Sistemistica Via Claudio, 21 – I-80125 – Napoli (Italy) roberto.canonico@unina.it, demma@napoli.consorzio-cini.it, giorgio.ventre@unina.it Abstract 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. 1. Introduction In recent years, simulation has become an indispensable technique to evaluate the performance of communication protocols for computer networks [1]. Quite a large number of network simulators have been developed over the past decade [2, 3, 4, 5, 6, 7]. More recently, simulation has been proposed as an useful tool for network planning and what-if analysis [8, 9, 10, 11]. Packet-level simulation of large scale computer networks is a challenging task, due to the great amount of computation it requires. To overcome such a difficulty, researchers have investigated in two directions: parallelism and abstraction. Parallel simulators [12, 13] rely on multiprocessors and clusters of workstations to achieve the computation power and memory necessary to run large scale simulations. Abstraction, on the other hand, is aimed at reducing the unnecessary details of packet level simulation, in order to obtain a significant picture of the network behavior with a significant reduction of computation time [14, 15]. These two approaches are complementary, and can be exploited at the same time to scale up the potential of network simulation. The combination of analytical models with classical discrete event simulation has lead to so-called hybrid simulation techniques. In the framework of the European INTERMON Research Project [16], the authors are investigating the problem of realizing a powerful network simulation server, based on a cluster of PCs. Our simulation server can be accessed from remote users through a web based interface. This component is integrated in a more general architecture [17], aimed at providing network administrators with a powerful set of tools that can be used for capacity planning and Service Level Agreement tuning and validation. The whole INTERMON architecture relies upon a distributed database, which is updated by proper measurement tools deployed within the real network. To integrate our simulation server with the rest of the INTERMON architecture, it was necessary to define a precise service interface, so that simulation scenarios could be automatically generated from other components and submitted to the server. These reasons have motivated our work, i.e. the use of XML to describe network simulation scenarios that can be automatically translated into simulation scripts, for a variety of network simulators. The rest of this paper is organized as follows. In section 2 we describe the architecture of a network simulation server based on a cluster of PCs that provides a network simulation service that can be accessed through a web-based interface. In section 3, we describe an XML description language that we have defined to describe network simulation scenarios in a simulator-neutral way. In section 4, we present how we managed to automatically translate an XML simulation scenario into an ns-2 simulation script [6]. Finally, in section 5, we present some concluding remarks and future work. 2. A Web Based Network Simulation Server In the context of the INTERMON research project [16], we are developing a web-accessible network simulation server. Our server has been designed according to a 3-tier architecture, as illustrated in Figure 1. Proceedings of the Seventh IEEE International Symposium on Distributed Simulation and Real-Time Applications (DS-RT’03) 1530-1990/03 $17.00 © 2003 IEEE Authorized licensed use limited to: Luiz Perrone. Downloaded on February 19, 2009 at 18:51 from IEEE Xplore. Restrictions apply.