Alcatel-Lucent 7950 Quality Of Service Manual page 32

QoS Policies
Peak Information Rate
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 and is defined by its maximum burst size (MBS).
The actual transmission rate of a service 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
importance of the scheduler serving the queue all combine to affect a queue's ability to transmit
packets as discussed in
The PIR is provisioned on ingress and egress service queues within service ingress QoS policies
and service egress QoS policies, respectively.
The PIR for network queues are defined within network queue policies based on the forwarding
class. The PIR for the queues for the forwarding class are defined as a percentage of the network
interface bandwidth.
When defining the PIR for a queue, the value specified is the administrative PIR for the queue.The
router has a number of native rates in hardware that it uses to determine the operational 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 below in
Page 32
Single Tier Scheduling on page
Adaptation Rule on page 33
57.
7950 XRS Quality of Service Guide