In the network field, QoS usually refers to the quality of service. This is a kind of network service, which can provide better service capacity for specific network communication, is a security mechanism of the network, and is a technology used to solve network delay, congestion and other problems. The main goal of QoS is to optimize network performance, especially in the case of network congestion, by giving priority to certain types of data streams to ensure that they can reach their destinations in time and reliably. In QoS, data streams are divided into different categories or priorities, and each category or priority has its own quality of service. For example, some data streams with higher priority can be given priority to ensure their transmission quality and delay. On the contrary, some low-priority data streams may be delayed to reduce the impact of network congestion. The main components of QoS include flow classification, traffic supervision, traffic shaping, interface speed limitation, congestion management and congestion avoidance. These technologies can help network devices manage data streams better and ensure end-to-end quality of service for various services under limited bandwidth resources.