Prior to the MESCAL project there was no publicly available tools capable of simulating large inter-domain networks of 100s of ASs while modelling the behaviour, treatment and performance of end-to-end flows. Since such a simulator was developed as part of MESCAL it is envisaged that it will be released for public consumption under an open-source license. The release of the simulator is seen as a valuable contribution since it has a number of strengths over existing offerings including:

• The ability to simulate large inter-domain networks: The focus is on the macroscopic behaviour of the inter-domain network avoiding the need to spend processing time on the details of per packet traffic treatment and TCP-level BGP communications protocols. In this way networks of 100s of ASes can be simulated within a reasonable run time (for a full mesh of demands – 1000s ASes if the demands are sparser).
• Simulation of end-to-end flow treatment: it is possible to calculate the network utilisation caused end-to-end traffic demands across the network of ASes and simulate queuing delays and delivered QoS with aggregate flow interaction models. Although the simulator has implemented inelastic traffic models to date it is possible to extend this to elastic demand models.

Taken together these features have allowed MESCAL to simulate the macroscopic behaviour of large inter-domain networks (in the order of 1000 ASes) and this has been used to prototype and fine-tune q-BGP policies which are based on static administratively-set or monitored/dynamically injected QoS attributes within q-BGP messages. The simulator’s design makes it easily extensible to support additional features such as g-QCs (global QoS classes) or CAC (connection admission control).

Further reading:

P. Levis, M. Boucadair, P. Morand, J. Spencer, D. Griffin, G. Pavlou, P. Trimintzios, A New Perspective for a Global QoS-based Internet, to appear in the Journal of Communications Software and Systems, 4th quarter 2005. [pdf document]

MESCAL deliverable D3.2, "Final experimental results: validation and performance assessment of algorithms and protocols for inter-domain QoS through service-driven traffic engineering", Chapter 4, section 4.1. [link]