The peak information rate (PIR) defines the maximum rate at which packets are allowed to exit the queue. It does not specify the maximum rate at which packets may enter the queue; this is governed by the queue's ability to absorb bursts. The actual transmission rate of an egress queue depends on more than just its PIR. Each queue is competing for transmission bandwidth with other queues. Each queue's PIR, CIR and the relative priority and/or weight of the scheduler serving the queue, all combine to affect a queue's ability to transmit packets.
When defining the PIR for a queue, the value specified is the administrative PIR for the queue. The user has some control over how the administrative PIR is converted to an operational PIR should the hardware not support the exact CIR and PIR values specified. The interpretation of the administrative PIR is discussed in Adaptation rule for queues
The PIR of the queue is configurable under the different qos policies that provide the option to configure the queue parameters – example under service ingress and service egress queue policies, access port policies, network queue policies, and so on