Background

In the traditional IP network, the forwarding device treats all packets equally, adopts “First in, first out” (FIFO) to process all packets and tries best effort to transmit the packet to the destination, so it cannot provide any guarantee for the reliability and delay of the packet transmission.

However, with the development of the IP network, the new applications based on the IP network emerge in endlessly, which put forward new requirements for the service quality of the IP network, especially the demand for the service packets with high real-time requirement is more obvious. For example, the network flow media, VoIP and other real-time services put forward high requirement for the transmission delay of the packets. If the packet transmission delay is long, the user cannot accept (relatively, E-mail and FTP services are not sensitive to the transmission delay). To support the communication services with different service quality requirements, it is required that the network can intelligently distinguish different communication types, so as to provide the corresponding service. The capability of distinguishing the communication types is the basic premise of providing different service qualities for different communications, so the best-effort service mode of the traditional IP network cannot meet the requirements of the present IP network application. The QoS (Quality of Service) technology is to solve the problem, so as to meet the different service quality requirements of the users for the network.