The 7705 SAR allows two kinds of queue types: Expedited queues and Best-Effort queues. Users can configure the queue type manually using the expedite and best-effort keywords, or automatically using the auto-expedite keyword. The queue type is specified as part of the queue command (for example, config>qos> sap-ingress>queue queue-id queue-type create).
With expedite, the queue is treated in an expedited manner, independent of the forwarding classes mapped to the queue.
With best-effort, the queue is treated in a non-expedited (best-effort) manner, independent of the forwarding classes mapped to the queue.
With auto-expedite, the queue type is automatically determined by the forwarding classes that are assigned to the queue. The queues that are set as auto-expedite are still either Expedited or Best-Effort queues, but whether a queue is Expedited or Best-Effort is determined by its assigned forwarding classes. In the default configuration, four of the eight forwarding classes (NC, H1, EF, and H2) result in an Expedited queue type, while the other four forwarding classes (L1, AF, L2, and BE) result in a Best-Effort queue type.
Assigning one or more L1, AF, L2, and BE forwarding class to an Expedited queue results in a Best-Effort queue type. See Forwarding Classes for more information on default configuration values.
The expedite, best-effort, and auto-expedite queue types are mutually exclusive. Each defines the method that the system uses to service the queue from a hardware perspective.