QoS (Quality of Service) is an issue about the long-term reliability and usability of network, with a explicate meaning how users think of network actions in the course of holding net- connection and grouping transfers.

• QoS(Quality of Service)服务质量指的是网络一个长期可靠性和可用性问题，其引申含义是用户在保持网络连接和传输分组过程中，对网络行为的看法。