QoS Policies
7950 XRS Quality of Service Guide
Page 35
Committed Burst Size
The committed burst size (CBS) parameters specify the amount of buffers that can be drawn from
the reserved buffer portion of the queue’s buffer pool. Once the reserved buffers for a given queue
have been used, the queue contends with other queues for additional buffer resources up to the
maximum burst size.
The CBS is provisioned on ingress and egress service queues within service ingress QoS policies
and service egress QoS policies, respectively. The CBS for a queue is specified in Kbytes.
The CBS for network queues are defined within network queue policies based on the forwarding
class. The CBS for the queues for the forwarding class are defined as a percentage of buffer space
for the pool.
Maximum Burst Size
The maximum burst size (MBS) parameter specifies the maximum queue depth to which a queue
can grow. This parameter ensures that a customer that is massively or continuously over-
subscribing the PIR of a queue will not consume all the available buffer resources. For high-
priority forwarding class service queues, the MBS can be relatively smaller than the other
forwarding class queues because the high-priority service packets are scheduled with priority over
other service forwarding classes.
The MBS is provisioned on ingress and egress service queues within service ingress QoS policies
and service egress QoS policies, respectively. The MBS for a queue is specified in Kbytes.
The MBS for network queues are defined within network queue policies based on the forwarding
class. The MBS for the queues for the forwarding class are defined as a percentage of buffer space
for the pool.
High-Priority Only Buffers
High priority (HP)-only buffers are defined on a queue and allow buffers to be reserved for traffic
classified as high priority. When the queue depth reaches a specified level, only high-priority
traffic can be enqueued. The HP-only reservation for a queue is defined as a percentage of the
MBS value.
On service ingress, the HP-only reservation for a queue is defined in the service ingress QoS
policy. High priority traffic is specified in the match criteria for the policy.
On service egress, the HP-only reservation for a queue is defined in the service egress QoS policy.
Service egress queues are specified by forwarding class. High-priority traffic for a given traffic
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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