[This is preliminary documentation and subject to change.]
IP Precedence allows packets passing through core network devices that operate on Layer 3 information, such as routers, to have their relative priority differentiated from one another. IP Precedence is established by the setting of specific bits in the IP header. With IP Precedence, Layer 3 devices can establish precedence-based cues and provide better service (when packet service is subject to cueing, as is the case under significant traffic loads) to packets that have higher priority.
In order for IP Precedence to be effective, Layer 3 devices must be IP Precedence-enabled.