Our research focuses on the transmission of multi-layer, real-time video traffic over ATM (Asynchronous Transfer Mode) networks. This issue covers several aspects of multimedia networking and ATM such as traffic definitions and descriptions, traffic management, buffer management, ATM adaptation layers and video application layers. We propose a new ATM traffic management and buffer management model together with the appropriate application and adaptation layer requirements. This new model is to solve the quality degradation problem of real-time video and efficiency degradation problem of the ATM network due to congestion on the network switches. The main assumption in this research is that the real-time video traffic is content based coded and consists of several video objects. One video source with various video objects introduces the need for multiple priorities. However, there exists no adequate method for managing a single connection for multi-priority video traffic over ATM networks. The current ATM traffic management model takes care of only two levels of priorities, which are application independent. Multi-priority traffic will complicate the traffic management, the buffer management and the work of the ATM adaptation layers. On the other hand, by allowing the network to have several priority layers during a connection, the quality of the real-time video and the efficiency of the network will be improved.