QoS 数据包标记

Packet classification features provide the capability to partition network traffic into multiple priority levels or classes of service. For example, by using the three precedence bits in the Type of service (ToS) field of the IP packet header—two of the values are reserved for other purposes—packets can be categorized into a limited set of up to six traffic classes. After packet classification, other QoS features can be utilized to assign the appropriate traffic handling policies including congestion management, bandwidth allocation, and delay bounds for each traffic class.