Two WRED slopes are supported per queue, one each for in-profile or high-priority traffic and out-of-profile or low-priority traffic.
The hardware supports a limited amount of profiles, out of which some are reserved for system internal use and the rest is available for user configuration. It is not possible to allocate a unique profile for each and every queue available on platform. Multiple queues will need to share the same WRED profile. Software manages the allocation of hardware WRED profiles based on user configuration. It automatically allocates a single WRED hardware profile if multiple queues use the same slope parameters (that is, max-average, start-average, drop probability and time average factor). Only if these parameters differ, it allocates a different hardware WRED profile for use by the queue. A WRED profile (that is, each high-slope and low-slope) allows the user to specify the slope parameters, such as maximum average, start average, drop probability, and time average factor (TAF).
Though the WRED profile is shared among queues, the WRED state (for example, average queue size) is maintained independently for each queue in the hardware.