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IQE PIC Excess Bandwidth Sharing Configuration

On other PICs, you can limit the transmission rate of a queue with the transmit-rate exact statement and option. However, on the IQE PIC, you can configure a shaping rate independently of the transmit rate using the shaping-rate statement at the [edit class-of-service schedulers] hierarchy level. Also, other PICs share excess bandwidth (bandwidth left over once the guaranteed transmit rate is met) in an automatic, nonconfigurable fashion. You cannot configure the priority of the queues for the excess traffic on other PICs either.

To share the excess bandwidth on the IQE PICs at the logical interface or queue level, configure an excess-rate statement in addition to a CIR (guaranteed-rate) and PIR (shaping-rate). To apply these limits to a logical interface, configure the statements at the [edit class-of-service traffic-control-profile] hierarchy level. To apply these limits to a specific queue, configure the statements at the [edit class-of-service schedulers] hierarchy level. You must also complete the configuration by applying the scheduler map or traffic control profile correctly.

You configure the excess rate as a percentage from 1 through 100. By default, excess bandwidth is automatically distributed as on other PIC types.

You can also configure the excess-priority statement the provide a high (excess-priority high) or low (excess-priority low) priority for excess bandwidth. If configured, these priorities must be configured at the queue level at the [edit class-of-service schedulers] hierarchy level. The values then apply also to the logical and physical interface levels.

Note: You cannot configure an excess rate for a logical interface if there is no guaranteed rate configured on any logical interface belonging to the physical interface.

The following example configures the excess rate in a traffic control profile:



[edit class-of-service traffic-control-profiles]
for-unit-0-percent {
shaping-rate 10k;
guaranteed-rate 1k;
excess-rate percent 30;
}
for-unit-1-proportion {
shaping-rate 20k;
guaranteed-rate 10k;
excess-rate percent 35;
}

The following example configures the excess rate in a scheduler.



[edit class-of-service schedulers]
scheduler-for-excess-low {
transmit-rate 1m;
shaping-rate 5m;
excess-rate percent 30;
excess-priority low;
}
scheduler-for-excess-high {
transmit-rate percent 20;
shaping-rate percent 30;
excess-rate percent 25;
excess-priority high;
}

Note: All of these parameters apply to egress traffic only and only for per-unit schedulers. That is, there is no hierarchical or shared scheduler support.

You can issue the following operational mode commands to verify your configuration:

show class-of-service scheduler-map
show class-of-service traffic-control-profile

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