The 7210 SAS-R6 and 7210 SAS-R12 equipped with an IMM-c card do not use the configured CBS and MBS parameter values in the queue management policy. The CBS and MBS values are system-defined for each queue. That is, CBS and MBS parameters are not user-configurable. In this section, references to modifying the CBS and MBS values in the queue management policies applies only to the 7210 SAS-R6 and 7210 SAS-R12 equipped with an IMM-b card.
A set of profiles or templates are available in hardware for configuring the queue parameters such as CBS, MBS, and WRED slopes. These profiles are available for use with multiple queues in the system. Queue management policies allow the user to define the queue parameters and allow sharing among the queues.
A single system buffer pool is available for use by all the queues in the system. Users can allocate the amount of buffers that each queue can use by specifying the CBS and MBS parameters in the queue management policy.
Weighted Random Early Detection (WRED) is available to manage buffers during periods of congestion. WRED slopes are supported for each queue in the system. Queue management policies allow the user to configure slope parameters that dictate a WRED profile for each queue. Each queue supports the following slopes:
slope for in-profile or high priority traffic
slope for out-of-profile or low priority traffic
Each slope allows specifying the start-average, the max-average, the drop-probability and the Time Average Factor (TAF). Each queue has a default slope policy. Multiple queues in the system can share a single policy. If a policy is shared the system computes the WRED drop probabilities for each of the queues separately based on their average queue length.