Real-time systems distributed around a network can be found inmany current applications such as embedded electronic systems (invehicles around a controller area network (CAN) network and inairplanes around an avionics full duplex switched Ethernet (AFDX)network), automated production systems in which the sensors,actuators and controllers are interconnected through fieldbuses orindustrial Ethernet, interactive and multimedia applications on theInternet, ... The validation of the temporal correctness of thesedistributed real-time systems requires not only to study the problem ofthe scheduling of tasks on CPUs, but also the scheduling of messagesin the network. For instance, the end-to-end transmission of a message,generated by a task and consumed by another distant one, is oftensubject to a deadline constraint. The underlying network then has toprovide a Quality-of- Service guarantee (for example, that the responsetime of the network has to be bounded) in order to adequately schedulethe transmission of the messages.