Vistad

Vistad (Visualisation et Illustration par Simulation de Télétrafic: Application au Dimensionnement) is an applet allowing the simulation of different queuing systems (pure loss system with infinite population, pure loss system with finite population, infinite-queue queuing system). It allows to represent in a graphic form the evolution of the offered load, the throughput, the number of clients in the systems,... The applet also displays various relevant values (blocking probability, mean number of clients in the queue,...) obtained by simulation and by classical analytical laws (Erlang B, Erlang C, Engset). It is then possible to understand when these laws may be used and when they cannot be used (of course because the basic assumptions of the analytical models are not verified).

With Vistad, it is possible to simulate:

• pure loss system with infinite population (Erlang B)
• infinite-queue queuing system (Erlang C)
• pure loss system with finite population (Engset)

A practical work (text [PDF], correction [PDF]), associated to the use of these applets, allows to understand the behavior of pure loss  and infinite-queue systems.

Vistad was developed in the framework of the Invocom project. Some e-learning lessons on queuing systems are available here. They can be advantageously used with the applet.

• Français
• English
• Deutsch
• Español
• Português
• 中文
• Other languages