Understanding Packet Loss Priorities
Packet loss priorities (PLPs) allow you to set the priority for dropping packets. You can use the PLP setting to identify packets that have experienced congestion. Typically, you mark packets exceeding some service level with a high loss priority—that is, a greater likelihood of being dropped. You set PLP by configuring a classifier or a policer. The PLP is used later in the work flow to select one of the drop profiles used by random early detection (RED).
You can configure the PLP bit as part of a congestion control strategy. The PLP bit can be configured on an interface or in a filter. A packet for which the PLP bit is set has an increased probability of being dropped during congestion.