CHAPTER 5
Priority Shaper
Earlier, when the priority of a queue at Per-Hop Behavior (PHB) was propagated all the way up the hierarchy
towards the channel level, the PHB classes that had priority at PHB level would only be prioritized over
other classes of subchannels. To avoid this, Priority Shaper feature is implemented.
Priory Shaper feature helps to balance the packet drops between the streams when multiple steams egress
out of a priority queue. Egress QoS policy is supported on Priority Shaper.
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Restrictions for Priority Shaper, page 45
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Configuring Priority Shaper, page 45
Restrictions for Priority Shaper
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Priority Shaper is supported only for PHB level classes.
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Egress QoS Policy map with Priority Shaper can be applied only on the member interface of port channel
and not at the logical level.
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Policer configuration is not supported with the Priority Shaper configuration under same class map.
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Priority Traffic Latency is increased during congestion with Priority Shaper configuration at Q level.
Configure the queue limit with a lesser value for the priority queue to reduce the latency of priority
traffic.
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If the packet is from a 10G interface to a 1G interface, the bustiness is introduced. Due to this, dequeuing
rate of this strict priority queue may be sometimes more than enqueuing. As a result, very few packet
counters are seen in other queues.
Configuring Priority Shaper
Perform the following steps to configure Priority Shaper.
QoS: Policing and Shaping Configuration Guide (Cisco ASR 920 Series)
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