Abstract: Network service of high quality is not only guaranteeing real-time traffics but also getting the best-effort services from the Internet while providing definite bandwidth.The maxim delay of real-time traffics is one of the most important indexes evaluating network quality of service.Based on this，the formulas is given out to calculate the maximal delay of real-time queues on the premise that the network can provide some services including bandwidth assurance service and real-time and best-effort services by importing TCP congestion control algorithm.

摘要： 高质量的网络服务是既能保证实时数据的正常传递，又能与Internet连通实现尽力服务，并且还能满足一定的带宽。而实时数据传输的最大时延是考核网络服务质量的重要指标之一。为此，论文给出了引入TCP拥塞控制算法后，同时满足带宽保证、实时与尽力服务三种服务的网络中实时队列最大时延的计算公式。