Ethernet access egress queuing and scheduling is very similar to the Ethernet access ingress behavior. Once the Ethernet pseudowire is terminated, traffic is mapped to up to eight different forwarding classes per SAP. Mapping traffic to different forwarding classes is performed based on the EXP bit settings of the received Ethernet pseudowire by network ingress classification.
Queue-type and profile scheduling are both supported for Ethernet access egress ports. If the queues are configured according to the tables and defaults described in this guide (implying a default mode of operation), the configuration is as follows:
CoS-8 to CoS-5 Expedited in-profile
CoS-4 to CoS-1 Best Effort in-profile
CoS-8 to CoS-5 Expedited out-of-profile
CoS-4 to CoS-1 Best Effort out-of-profile
In this default configuration, for queue-type scheduling, CoS-8 to CoS-5 are serviced by the Expedited scheduler, and CoS-4 to CoS-1 are serviced by the Best Effort scheduler. This default mode of operation can be altered to better fit the operating characteristics of certain SAPs.
With profile scheduling, the Ethernet frames can be either in-profile or out-of-profile, and scheduling takes into account the state of the Ethernet frames in conjunction with the configured CIR and PIR rates.
After the queuing, an aggregate queue-type and profile scheduling takes place in the following order:
Expedited in-profile traffic
Best Effort in-profile traffic
Expedited out-of-profile traffic
Best Effort out-of-profile traffic
Once the traffic is scheduled using the aggregate queue-type and profile schedulers, the per-port shapers shape the traffic at a sub-rate (that is, at the configured/shaped port rate). Per-port shapers ensure that a sub-rate is met and attainable at all times.