QoS技术的核心问题是如何在只具有尽力服务特性的通信网络中提供超越这一特性的服务质量。规模越来越大，种类越来越多并且应用日益复杂的各种网络相继出现，使得QoS技术成为一个相当复杂并涉及诸多因素的技术，实现QoS控制的难度大大增加。-QoS technology is the core issue is how the only serving the characteristics of communication networks to provide special beyond the the quality of services. Increasing scale, and more and more types of application of the increasingly complex networks have emerged one after another. makes QoS technology to become a very complex and involve many technical factors, QoS control to achieve the difficulty increased dramatically.