QoS Policies
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7950 XRS Quality of Service Guide
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
Single Tier Scheduling on page 57
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
Summary of Contents for 7950
Page 12: ...Page 12 7950 XRS Quality of Service Guide List of Figures ...
Page 16: ...Preface Page 16 7950 XRS Quality of Service Guide ...
Page 82: ...Editing QoS Policies Page 82 7950 XRS Quality of Service Guide ...
Page 90: ...Applying Network Queue Policies Page 90 7950 XRS Quality of Service Guide ...
Page 96: ...Editing QoS Policies Page 96 7950 XRS Quality of Service Guide ...
Page 98: ...Command Hierarchies Page 98 7950 XRS Quality of Service Guide ...
Page 108: ...Command Hierarchies Page 108 7950 XRS Quality of Service Guide ...
Page 156: ...Basic Configurations Page 156 7950 XRS Quality of Service Guide exit exit ...
Page 164: ...Queue Depth Monitoring Page 164 7950 XRS Quality of Service Guide ...
Page 304: ...Service Queue QoS Policy Commands Page 304 7950 XRS Quality of Service Guide ...
Page 368: ...Command Hierarchies Page 368 7950 XRS Quality of Service Guide ...
Page 430: ...Configuration Commands Page 430 7950 XRS Quality of Service Guide ...
Page 532: ...Editing QoS Policies Page 532 7950 XRS Quality of Service Guide ...
Page 552: ...Editing Advanced Policies Page 552 7950 XRS Quality of Service Guide ...
Page 600: ...Command Hierarchies Page 600 7950 XRS Quality of Service Guide ...
Page 602: ...QoS Commands Page 602 7950 XRS Quality of Service Guide ...
Page 610: ...Standards and Protocols Page 610 7950 XRS Quality of Service Guide ...
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