The port scheduler policy defines a set of eight priority levels. To allow for the application of a scheduling weight to groups of queues competing at the same priority level of the port scheduler policy applied to the Vport, or to the Ethernet port, a group object is defined under the port scheduler policy, as follows:
config>qos>port-scheduler-policy>group group-name rate pir-rate [cir cir-rate]
Up to eight groups can be defined within each port scheduler policy. One or more levels can map to the same group. A group has a rate and, optionally, a cir-rate, and inherits the highest scheduling priority of its member levels. For example, the scheduler group for the 7450 ESS and 7750 SR shown in the Vport in Figure: Applying a port scheduler policy to a Vport consists of level priority 3 and level priority 4. Therefore, it inherits priority 4 when competing for bandwidth with the standalone priority levels 8, 7, and 5.
A group receives bandwidth from the port or from the Vport and distributes it within the member levels of the group according to the weight of each level within the group. Each priority level competes for bandwidth within the group based on its weight under congestion situation. If there is no congestion, a priority level can achieve up to its rate (cir-rate) worth of bandwidth.
The mapping of a level to a group is performed as follows:
config>qos>port-scheduler-policy>level priority-level rate pir-rate [cir cir-rate] group group-name [weight weight-in-group]
The CLI enforces that mapping of levels to a group are contiguous. In other words, a user would not be able to add a priority level to group unless the resulting set of priority levels is contiguous.
When a level is not explicitly mapped to any group, it maps directly to the root of the port scheduler at its own priority like in existing behavior.