Each queue provides the following options:
an option to use two slopes per queue on non-ring ports - a high-priority RED slope and a low-priority RED slope
an option to use four slopes per queue on ring ports – a non-ring high-priority RED slope, a non-ring low-priority RED slope, a ring high-priority RED slope, and a ring low-priority RED slope
The high-priority RED slope manages access to the shared portion of the buffer pool for high-priority or in-profile packets. The low-priority RED slope manages access to the shared portion of the buffer pool for low-priority or out-of-profile packets. See Buffer pools for more information.
By default, the high-priority and low-priority slopes are disabled.
When a queue depth exceeds the queue CBS, packets received on that queue must contend with other queues exceeding their CBS for shared buffers. To resolve this contention, RED slopes are used to determine buffer availability on a packet-by- packet basis. A packet that is either classified as high-priority or considered in-profile is handled by the high-priority RED slope. This slope should be configured with RED parameters that prioritize buffer availability over packets associated with the low-priority RED slope. Packets that are classified as low priority or out-of-profile are handled by this low-priority RED slope.