The 7210 SAS supports Strict Priority and WFQ mode of scheduling or a mix of both.
On the 7210 SAS-K 2F1C2T, schedulers are used at SAP-ingress, SAP-egress, access-uplink port ingress and access-uplink port egress.
On the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C, schedulers are used at SAP-ingress, SAP-egress, network port ingress, network port egress, hybrid port ingress, hybrid port egress, access-uplink port ingress, and access-uplink port egress.
The scheduler uses 2 loops: the CIR loop and PIR loop, each with 4 priorities. The configured priority of the queue determines the service order of the queue in the CIR loop and the PIR loop. The scheduler first goes through the CIR loop, where it services all the queues which are operating at less than CIR rate according to their priority (that is, higher priority queues get services earlier than lower priority queues). It then goes through the PIR loop, where it services all the queues which are operating above the CIR rate (but less than PIR rate) according to their priority (that is, higher priority queues get services earlier than lower priority queues).
If there are multiple queues configured with the same priority, in the CIR loop the queues are scheduled using WFQ, with the configured weight (that is, pir-weight) of the queue used to determine the proportion of the available bandwidth that is provided to the queue. In the PIR loop, the queues are scheduled using WFQ, with the configured weight (that is, pir-weight) of the queue used to determine the proportion of the available bandwidth that is provided to the queue (using WFQ).