关键词: 服务质量, 最早时限优先, 尽力服务, 带宽保证, 时间粒度

Abstract: With the development of the computer network and communication technology, there are not only some users who need the service of the Internet, but also people who need providing real-time requirements and bandwidth assurance in many network applications. In this way, there are three kinds of primary network businesses：best-effort, real-time and bandwidth assurance businesses. How to realize packet scheduling for multi-service at the same time to achieve the control of Quality of Service become a problem worthying of study. According to the Earliest-Deadline-First algorithm, the improved EDF algorithm which is based on three kinds of primary services regarding the need of network users in the current stage is put forward. In this algorithm, a new bandwidth assurance strategy on time granularity and the schedule process based on three different models are provided. And then, the presented algorithm is simulated in the SIM network simulation environment. The results show that the improved algorithm can reduce the delay of business flows and increase the bandwidth assurance rate. As a whole, the performances of network QoS are improved.

Key words: quality of service, the earliest deadline first, best-effort service, bandwidth assurance, time granularity