Peak Information Rate - Alcatel-Lucent 7450 Quality Of Service Manual

Although the router is flexible in how the CIR can be configured, there are conventional
ranges for the CIR based on the forwarding class of a queue. A service ingress queue
associated with the high-priority class normally has the CIR threshold equal to the PIR rate
although the router allows the CIR to be provisioned to any rate below the PIR should this
behavior be required. If the service egress queue is associated with a best-effort class, the CIR
threshold is normally set to zero; again the setting of this parameter is flexible.
The CIR for a service queue is provisioned on ingress and egress service queues within
service ingress QoS policies and service egress QoS policies, respectively.
The CIR for network queues are defined within network queue policies based on the
forwarding class. The CIR for the queues for the forwarding class are defined as a percentage
of the network interface bandwidth.

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.
Quality of Service Guide
1. When defining the CIR for a queue, the value specified is the administrative CIR for
the queue.The router has a number of native rates in hardware that it uses to
determine the operational CIR for the queue. The user has some control over how the
administrative CIR is converted to an operational CIR should the hardware not
support the exact CIR and PIR combination specified. The interpretation of the
administrative CIR is discussed below in Adaptation Rule
Single Tier Scheduling.
QoS Policies
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