Vehicles use to interconnect their equipments specifics networks such as CAN, VAN or TTP/C. Generally, the realtime applications exchange information on dedicated network and the other traffic is supported by an other communication system. The differentiation of these two networks enables to easily guarantee the level of Quality of Service required the control of the vehicles (brake, ESP . . . ). The new trends which we can observe are to implement only one network to transport all kinds of information and also to cancel determinist networks for using Ethernet networks. The objective of this paper is to model Ethernet networks in order to study theirs capacities to support in a same time both real-time traffic and entertainment traffic.