Three-Color Policer Configuration Guidelines

Color-Blind Mode

In color-blind mode, the three-color policer assumes that all packets examined have not been previously marked or metered. If you configure a three-color policer to be color-blind instead of color-aware, the policer ignores preexisting color markings that might have been set for a packet by another traffic policer configured at a previous network node.

Color-Aware Mode

In color-aware mode, the three-color policer assumes that all packets examined have been previously marked or metered. In other words, the three-color policer takes into account any coloring markings that might have been set for a packet by another traffic policer configured at a previous network node. At the node where color-aware policing is configured, any preexisting color markings are used in determining the appropriate policing action for the packet.

In color-aware mode, the three-color policer can increase the packet loss priority (PLP) level of a packet, but never decrease it. For example, if a color-aware three-color policer meters a packet with a medium PLP marking, it can raise the PLP level to high, but cannot reduce the PLP level to low.

For two-rate, three-color policing, the Junos OS uses two token buckets to manage bandwidth based on the two rates of traffic. For example, two-rate policing might be configured on a node upstream in the network. The two-rate policer has marked a packet as yellow (loss priority medium-low). The color-aware policer takes this yellow marking into account when determining the appropriate policing action. In color-aware policing, the yellow packet would never receive the action associated with either the green packets or red packets. This way, tokens for violating packets are never taken from the metering token buckets at the color-aware policing node.